# Escort Fighter Performance Comparison (1 Viewer)



## Zipper730 (Apr 20, 2022)

This was kind of inspired by the thread about the what-if idea of modifying a Supermarine Spitfire for additional range: I remember hearing of the idea of using the Hawker Tempest as an escort, and things of that sort (there was some information based on range on that page).

I was thinking about the various fighters that existed that either were used or were usable as escorts during the Second World War. I was thinking about obviously the available range, the way range could be improved, and the performance data of the aircraft (i.e. how they compared to each other, and adversary planes) in terms of performance and maneuverability.


BTW: I'm tagging members that were in the previous thread for obvious reasons.



 33k in the air
, 

 ColFord
, 

 DarrenW
, 

 davparlr
, 

 drgondog
, 
E
 EwenS
, 
G
 Geoffrey Sinclair
, 

 GregP
, 

I
 IdahoRenegade
, 
M
 MIflyer
, 
P
 PAT303
, 
S
 Shortround6
, 
T
 ThomasP
, 

 tomo pauk
, 

 Wild_Bill_Kelso
, and 
W
 wuzak


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## PAT303 (Apr 21, 2022)

The P51 was the quintessential escort fighter but it really didn't come into it's own until 1944, the Spitfire, if the MkIII with two stage Merlin was developed could have escorted bombers out to the Ruhr from the end of the BoB, from the 60 series onwards models, (MkVIII, IX) could have been handy out to around 400 Miles radius from 1942 but it was really maxed out at around 500-550 miles. The P47 was in my opinion too much of a fuel pig to be seriously considered, it could carry lots of fuel but it wasn't efficient by any means and the N/M series got their range by simply carry vast amounts of it, a fantastic fighter if used to it's advantages, the P38 had serious range but it's performance was not up to par until the L series which made it a later war aircraft but once it's issue's were sorted it was a top class fighter, the A6M compromised everything for range, it's slow speed and nil protection made it useful only in the Pacific against weaker opponents and I personally do not like the Zero at all, it's without doubt the most overrated aircraft of the war for me and I would not want to fight in it. I don't think anything else fits the bill.

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## pbehn (Apr 21, 2022)

The first thing that needs to be done is to identify the urgent need for a daylight escort fighter for deep penetration raids in Europe. It may seem obvious now, but it wasnt at the time. The strategic bombing campaign had high priority, but (for example) the V1 campaign diverted strategic bombing resources to defeat it. The Tempest was the only fighter able to catch a V1 in level flight, and didnt have the altitude performance to escort US heavy formations. At all times UK airspace had to be defended, not only from attack but also recon, this was vital before D-Day.

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## Shortround6 (Apr 21, 2022)

pbehn said:


> The Tempest was the only fighter able to catch a V1 in level flight, and didnt have the altitude performance to escort US heavy formations.


OK, explain how the Tempest is a long range fighter?
I understand you are agreeing.

Look at Data card.


http://www.wwiiaircraftperformance.org/tempest/Tempest_V_Sabre_IIB_ADC.jpg



Normal internal fuel was 154 imp gallons or 4 gallons more than a P-51B without fuselage tank.
You have that whacking big Sabre engine in the nose that can suck down fuel at a stagger rate.

From the notes. 5 minutes at combat rating was worth 68 miles of range at Max weak mixture. and 105 miles at most economical.
After warm up at climb to altitude the Tempests was rated as having a 680 mile range at most econ, (285mph at 20,000ft) except that if you use 20 minutes at combat rating you are down( 4 times 105 miles equals 420 miles) to 260 miles for the return flight. Doesn't matter what kind of drop tanks you can put on it.

The Early P-47s held 254 imp gallons of internal fuel had they had crap range for escort work. 
The later ones had 308 imp gallons.
The Tempest may well have been lower drag than the P-47 but unless you can cram another 100 Imp gallons into it it won't make the distances needed regardless of the altitudes. 

The Tempest was a very good performing fighter down low.
Now add about 1/2 ton for the extra fuel and tank/s. 
Now figure out to get it to perform at 25,000ft.

Please look ant many of the other proposals or the time lines of the aircraft.
The US was, rightly or wrongly, planning on use the B-17s and B-24s for this mission in 1941-42 (look at the efforts made in constructing the aircraft factories and engine plants) 
and in 1940-41-42 the ability to build either a single engine or twin engine fighter that could under take 500-600 mile radius missions was rather lacking. 

Fuel got a lot better from 1940-42 (about a 30% in increase in max power in liquid cooled engines) which improved the power to weight ratio of planes using the existing (or modified) engines. Longer runways allowed higher gross weights for the aircraft (both bombers and fighter) better propellers, and so on.

There was a lot more than just jamming more fuel tanks into existing aircraft.

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## pbehn (Apr 21, 2022)

Shortround6 said:


> OK, explain how the Tempest is a long range fighter?
> I understand you are agreeing.
> 
> Look at Data card.
> ...


The Tempest was mentioned in the OP, my point was that the Tempest wasnt suitable, but even if it could be made suitable, there were other jobs that needed doing, you cannot make every plane an escort.

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## Zipper730 (Apr 21, 2022)

PAT303 said:


> The P51 was the quintessential escort fighter but it really didn't come into it's own until 1944


It kind of had some of the best mix of qualities including (obviously) long-range, a good rate of acceleration in level-flight and dive, zoom-climb characteristics, rate of roll, and a respectable dive-speed. Climb rate was excellent when lightly loaded, and pretty good when heavily loaded for the escort mission (excellent at high altitude).


> the Spitfire, if the MkIII with two stage Merlin was developed


I didn't know that was proposed.


> from the 60 series onwards models, (MkVIII, IX) could have been handy out to around 400 Miles radius from 1942 but it was really maxed out at around 500-550 miles.


I don't remember seeing numbers of 500-550 miles...


> The P47 was in my opinion too much of a fuel pig to be seriously considered


The P-47N, regardless of efficiency, could carry a massive amount of gas. It's range was even better than the P-51.



pbehn said:


> The first thing that needs to be done is to identify the urgent need for a daylight escort fighter for deep penetration raids in Europe. It may seem obvious now, but it wasnt at the time.


... and the RAF usually bombed Germany at night. That said, they did do some daytime operations leading up to D-Day (it proved workable).


> the V1 campaign diverted strategic bombing resources to defeat it.


Yeah, I suspect the Mosquito NF variants. While the Tempest had the best low-altitude performance, I remember hearing that other aircraft were used for intercepting the V1's, however.

From an intellectual exercise, the Tempest does look like a good design. It has a lot of good characteristics off the bat

Climb rate appears to be among the best
Roll-rate is excellent across much of, if not the entire speed-range, and seems among the best (if not the best) above 300-350 mph
Acceleration rate in level flight was said to be phenomenal and, I'd imagine it'd be among the best in dive-acceleration, and it was good to around Mach 0.83 in dives (while the Spitfire was a bit better at 0.85, it accelerated slower and had lower airspeed-limits).
I'd imagine the airplane would have a remarkable zoom-climb rate owing to low drag, excellent acceleration, and a decent overall mass.
While it has some of the following disadvantages

Critical altitude is lower than the P-51B, topping out at around 19000 feet. While the aircraft seems to retain a good degree of speed all the way up to around 25000', it's climb-rate dips more than speed with altitude. Somewhere between 10000-20000', the P-51B starts to generate a climb-rate that exceeds the Tempest Mk.II, and, by 30000', it has over twice the climb-rate.
Compared to the Tempest Mk.II, however: It (provided I did my conversions right) does appear to be superior to the Fw 190A across significant portions of the envelope in terms of rate of climb. With the Fw 190D, there appears to be an advantage from 0' to around 19500' with the Fw-190D doing around 40 fpm better around 30000'.
There are some unknown areas

Handling: I'm not sure how it compares to the P-51 in terms of low-speed handling, particularly in terms of stall-speeds (power on/off -- honestly, even the pilots manual doesn't seem to include that) and resulting rate of turn, as well as how stall characteristics compare.
Fuel: I'm not sure how easy it is to pack fuel into various areas of the aircraft as was done on the Mustang & Spitfire, with the ability to pack fuel behind or below the pilot doable on both aircraft, or in parts of the leading-edge of the wings on the Spitfire.

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## pbehn (Apr 21, 2022)

Zipper730 said:


> It kind of had some of the best mix of qualities including (obviously) long-range, a good rate of acceleration in level-flight and dive, zoom-climb characteristics, rate of roll, and a respectable dive-speed. Climb rate was excellent when lightly loaded, and pretty good when heavily loaded for the escort mission (excellent at high altitude).
> I didn't know that was proposed.
> I don't remember seeing numbers of 500-550 miles...
> The P-47N, regardless of efficiency, could carry a massive amount of gas. It's range was even better than the P-51.
> ...


You could but why would you? It would not have been as good as a P-51B/C D or the contemporary P-47. There were 1,700 Tempests made, it was probably the allies best fighter at low level and was needed against the V1 and post D-Day operations. It became operational in April 1944, by that time there was hardly a shortage of P-51s and P-47s which were both better in performance at altitude and range.

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## tomo pauk (Apr 21, 2022)

pbehn said:


> The first thing that needs to be done is to identify the urgent need for a daylight escort fighter for deep penetration raids in Europe. It may seem obvious now, but it wasnt at the time. The strategic bombing campaign had high priority, but (for example) the V1 campaign diverted strategic bombing resources to defeat it. The Tempest was the only fighter able to catch a V1 in level flight, and didnt have the altitude performance to escort US heavy formations. At all times UK airspace had to be defended, not only from attack but also recon, this was vital before D-Day.



These points don't apply to Luftwaffe that much? Granted, their Bf 110 inventory was not big enough to fight off RAF. Luftwaffe will also probably try to attack defenses of UK airspace, rather than to defend it.
These points also don't apply to the Japanese, they employed escort fighters over the long ranges.



Shortround6 said:


> OK, explain how the Tempest is a long range fighter?
> I understand you are agreeing.
> 
> Look at Data card.
> ...



Jamming more fuel into existing aircraft was the most important thing, and was also easiest thing to do. Hardest thing was admitting to oneself that LR fighters are not just needed, but feasible.
Tempest was a 'victim' of jamming more fuel in an aircraft not once, but twice in ww2. 1st, the 130-something imp gal fuel quantity was increased by installing a 30-something IG fuel tank in one wing leading edge, and them extra fuel was installed in another wing LE. Second fuel increase was done after it was necessary (late summer of 1944, on an unknown number of aircraft) since RAF tactical squadrons were in France by that time. 
With ~190 IG (the data sheet you've linked to notes 188; works to about 220 US gals ) and 2x90 IG drop tanks, the range was 1720 miles (data sheet linked shows 1770) . Sabre will use more fuel than Merlin, but fuel mileage was far better than on the P-47.



Shortround6 said:


> Please look ant many of the other proposals or the time lines of the aircraft.
> The US was, rightly or wrongly, planning on use the B-17s and B-24s for this mission in 1941-42 (look at the efforts made in constructing the aircraft factories and engine plants)
> and in 1940-41-42 the ability to build either a single engine or twin engine fighter that could under take 500-600 mile radius missions was rather lacking.
> 
> Fuel got a lot better from 1940-42 (about a 30% in increase in max power in liquid cooled engines) which improved the power to weight ratio of planes using the existing (or modified) engines. Longer runways allowed higher gross weights for the aircraft (both bombers and fighter) better propellers, and so on.



Bf-110 was certainly able to provide 500-600 mile radius in 1940 provided it has drop tanks. Zero with drop tank will do 500+ miles radius. A Fw 190 with DB 601 and two drop tanks would've been also very rangy.
An American 'P-110C' with V-1710-33 will emulate the Bf 110C. So will, in 1941, a fighter with two turbocharged V-1710s. 1942 give even more options. A "Western Ki-61" was feasible in 1938 for British and Germans.
British are in best place engine-wise, but they don't have a doctrine for escort fighters' role. Americans are also hampered with same problem.

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## pbehn (Apr 21, 2022)

tomo pauk said:


> These points don't apply to Luftwaffe that much? Granted, their Bf 110 inventory was not big enough to fight off RAF. Luftwaffe will also probably try to attack defenses of UK airspace, rather than to defend it.
> These points also don't apply to the Japanese, they employed escort fighters over the long ranges.


As I read the OP it was referring to escorts for strategic bombing missions from UK. There is a post war idea that the need for a log range escort was obvious, in hindsight it was but it wasnt until mid 1943 that the USA themselves kicked into high gear to provide one. The first P-51Bs to arrive in UK did not have the rear fuselage tank because they were made before this decision was made. The Japanese identified that they needed escorts and so they had them. The Germans didnt, in my opinion because they were as surprised by the rapid fall of France as much as everyone else and hadnt considered a strategic campaign against UK in 1940.

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## Shortround6 (Apr 21, 2022)

I keep repeating, what was possible in 1943 (or end of 1942) was not possible in 1938 or 1940 or 1941.

The Typhoon was designed to have a similar radius of action to the Spitfire and Hurricane. It's larger fuel capacity only fed the bigger engine for about the same period of time.

The British had self inflicted gun shot wounds in both feet due to crappy propellers in the late 30s. Doesn't matter how much fuel you can stuff in the plane or under it if you can't the majority of your fighter fields to take off from ( the Fields were being enlarged at a frantic rate in 1939-43). 

You also have to consider what bombers you want to escort. 
A fighter that will work while escorting a Mitsubishi G3M2 is just about useless trying to escort a formation of B-17Ds 



tomo pauk said:


> A "Western Ki-61" was feasible in 1938 for British and Germans.


You might be able to design it. Actually building it is a bit harder. 
British need to adopt constant speed propeller about 2 years earlier, yes other countries were doing it 1938. 
British need the bigger air fields. 
British need to cut the armament on their "escort fighters" as opposed to their interceptors. Perhaps six .303s? 
A Ki-61 has about 20% higher wing loading than a Spitfire II.

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## tomo pauk (Apr 21, 2022)

pbehn said:


> The first P-51s to arrive in UK did not have the rear fuselage tank because they were made before this decision was made.



I reckon you mean the 1st Merlin-powered P-51s? Those were long-ranged even without the fuselage tank.



pbehn said:


> The Japanese identified that they needed escorts and so they had them. The Germans didnt, in my opinion because they were as surprised by the rapid fall of France as much as everyone else and hadnt considered a strategic campaign against UK in 1940.



Germans bought the Bf 110 as an escort fighter (among other tasks it was expected to perform). Expected target of Germany's strategic campaign was France before 1940.



Shortround6 said:


> I keep repeating, what was possible in 1943 (or end of 1942) was not possible in 1938 or 1940 or 1941.
> 
> The Typhoon was designed to have a similar radius of action to the Spitfire and Hurricane. It's larger fuel capacity only fed the bigger engine for about the same period of time.



I'm not advocating a 430+- mph fighter with 500 mile radius for 1939. A 350 mph fighter with 500 mile radius was certainly feasible in 1939, though.
Second sentence reinforces the notion that official doctrine matters. AM/RAF was not asking for a long range fighter when Typhoon was mooted, they asked for performance and firepower.



Shortround6 said:


> The British had self inflicted gun shot wounds in both feet due to crappy propellers in the late 30s. Doesn't matter how much fuel you can stuff in the plane or under it if you can't the majority of your fighter fields to take off from ( the Fields were being enlarged at a frantic rate in 1939-43).
> 
> You also have to consider what bombers you want to escort.
> A fighter that will work while escorting a Mitsubishi G3M2 is just about useless trying to escort a formation of B-17Ds



RAF does not have to have a majority of it's fighter outfitted with hard-to-come-by propeller. Outfit the dedicated long-range fighters with at least 2-pitch prop and work from there.

"The B-17Ds were delivered to the Army from February to April of 1941" per Joe Baugher. Americans can have a fighter with turbo-charger(s) to escort them in 1941. RAF can have a long-range Spitfire III to escort them. Or a 2-engined LR escort fighter, Merlin 45 will do there if there is not enough of Merlin XXs.



Shortround6 said:


> 1 - You might be able to design it. Actually building it is a bit harder.
> 2 - British need to adopt constant speed propeller about 2 years earlier, yes other countries were doing it 1938.
> 3 - British need the bigger air fields.
> 4 - British need to cut the armament on their "escort fighters" as opposed to their interceptors. Perhaps six .303s?
> 5 - A Ki-61 has about 20% higher wing loading than a Spitfire II.



(my bullet points)
1 - Instead of turret fighters, start making LR fighters.
2 - My idea is to start with 2-pitch unit, and adopt the CS unit when available.
3 - They are in better shape to make them than the Japanese. Need-be, LR fighters can also use bomber bases, after all they are here to protect the bombers.
4 - Six .303s will do for the starters.
5 - Okay.


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## Shortround6 (Apr 21, 2022)

pbehn said:


> There is a post war idea that the need for a log range escort was obvious, in hindsight it was but it wasnt until mid 1943 that the USA themselves kicked into high gear to provide one.



A P-40E needed about 400ft (133 yds) *more* room to take-off and reach 50ft than a P-40 no letter.

That is with both planes holding 120 US gallons fuel, not even full internal fuel.
The P-40 had about 1040hp for take-off and grossed 6655lbs.
The P-40E had 1150hp for take-off and grossed 8098lbs for the take-off test, and that result is about 600 shorter than the distance shown in the Take-off, climb and landing chart for 8100lbs. 

Until you get the Merlin 61 engine showing up the US didn't have an engine that would give them the aircraft performance and the range and the desired armament. 
Lets not forget that the P-47 could fly twice as far as Spitfire at low speeds with both running on internal fuel. The P-47 was a fuel hog but it was also a flying tank truck compared to most other fighters in 1942/early 43 and it wasn't near enough. 

The B-17 and B-24 with their higher altitudes also required the escorts to burn a large amount of fuel just to get up to 25,000ft to start escorting.

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## pbehn (Apr 21, 2022)

tomo pauk said:


> I reckon you mean the 1st Merlin-powered P-51s? Those were long-ranged even without the fuselage tank.
> 
> 
> 
> Germans bought the Bf 110 as an escort fighter (among other tasks it was expected to perform). Expected target of Germany's strategic campaign was France before 1940.


My post was already edited to P-51B (my keyboard is now very old "B" and "N" sometimes need a hammer). The Germans may have bought the f 110 for that but not to take on an integrated defence system, fitting of external tanks to Bf 109s was log after the start of the BoB.


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## tomo pauk (Apr 21, 2022)

pbehn said:


> My post was already edited to P-51B (my keyboard is now very old "B" and "N" sometimes need a hammer).


Okay.


pbehn said:


> The Germans may have bought the f 110 for that but not to take on an integrated defence system, fitting of external tanks to Bf 109s was log after the start of the BoB.



French (nor Polish - another country that 'stole' Imperial German territory, thus high on the German to-kill list) was certainly not as integrated as what RAF or Luftwaffe had by 1939.
Yes, fitting the drop tank on the Bf 109 was too late.


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## pbehn (Apr 21, 2022)

Shortround6 said:


> A P-40E needed about 400ft (133 yds) *more* room to take-off and reach 50ft than a P-40 no letter.
> 
> That is with both planes holding 120 US gallons fuel, not even full internal fuel.
> The P-40 had about 1040hp for take-off and grossed 6655lbs.
> ...


I agree, which is why I dont understand the discussion, the P-47 had more range from the start, the P-51B had more range, so why push more Spitfires to be long range escorts, they did their job in the early days and there were other jobs to do, especially in the Med and far east.

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## Shortround6 (Apr 21, 2022)

tomo pauk said:


> 1 - Instead of turret fighters, start making LR fighters.
> 2 - My idea is to start with 2-pitch unit, and adopt the CS unit when available.


Anything was better than turret fighters, Chain 5-6 Defiants together and use them as anchors for the RN.

You don't get a huge improvement tin performance with the 2 speed units. You get of the ground quicker but after there isn't much difference in performance of the aircraft. 
Spitfires changed from low pitch to high pitch at about 170mph and that is where the prop stayed until landing. 
the 2 pitch prop also only changed the prop pitch by 20 degrees. The Rotol was good for 30-35 of pitch change, the Curtiss electric was good for at least 25 degrees of pitch change. 

US airlines were using fulling feathering props on 20 different airlines in 1938. 





And they were being built in a bunch of different countries. 
In England they were so short of constant speed props that some Beaufighters got two speed props which basically meant than an engine failure doomed the aircraft. 
The Lockheed in the picture was_ supposed _to be able to fly at 4000ft at full gross weight on one engine. When given 550hp engines instead of 450hp engines it was supposed to be able to fly at 9,000ft. 

For the Spitfire the constant speed prop was worth almost 3 minutes in climb from sea level to 20,000ft. 
Trying to fight with the prop locked in full pitch while carrying even several hundred pounds of extra fuel was a handicap the escort fighters didn't need.

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## Shortround6 (Apr 21, 2022)

pbehn said:


> I agree, which is why I dont understand the discussion, the P-47 had more range from the start, the P-51B had more range, so why push more Spitfires to be long range escorts, they did their job in the early days and there were other jobs to do, especially in the Med and far east.


Just about any fighter could use a bit more range.
Just what are you going to have to give up to get it?
An extra 20-30 gallons in a Spit might be doable, depends on the engine and tactical situation. but an extra 30 gallons is not going to get to the Ruhr and back let alone any futher.

We keep posting this picture 




They built at least 40 of them, They were used by 3 different squadrons, (at the same time?) 
There are performance figures for them. If you stick the tank in the rear fuselage you get rid of most of the drag but the loss of climb rate is going to be fairly close.
The idea that you can stick _even more fuel_ inside an early Spitfire and wind up with a useful escort fighter needs some careful evaluation. 

A standard ML II was supposed to climb at 2,175fpm at 20,000ft.
With the tank the climb rate dropped to 1420fpm. 
Adjust for drag (about 25mph in speed) but you are not going to get most of the climb back. 
For a Spitfire V fitting four 20mm guns instead of two 20s and four .30s cost just about 1 full minute to climb to 20,000ft. from a difference of about 400lbs in weight. 
For these tests the Merlin 45 was running at 9lbs of boost at 2850 rpm.


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## pbehn (Apr 21, 2022)

Shortround6 said:


> Trying to fight with the prop locked in full pitch while carrying even several hundred pounds of extra fuel was a handicap the escort fighters didn't need.


But there was little possibility that any UK fighter would have to fight with a wooden fixed pitch prop. The question was what variable pitch prop do you fit, which depends on how much power the plane has, which depends on things like is 100 octane fuel available.


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## SaparotRob (Apr 21, 2022)

Aren't we just coming back to two different doctrines of two different air forces?
RAF. Bombers (which will always get through) are offensive and attack by night. Fighters are defensive for daylight defense.
USAAC. Bombers (which will always get through) are offensive and attack by day in an unassailable phalanx too high, too fast and too heavily armed. Fighters, well, I'm kinda' hazy on what the US theory was, even if Claire Chennault wrote a book explaining it. 
The RAF didn't need escort fighters. They needed point defense.
The USAAC didn't need escort fighters. Until they did.

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## pbehn (Apr 21, 2022)

SaparotRob said:


> Aren't we just coming back to two different doctrines of two different air forces?
> RAF. Bombers (which will always get through) are offensive and attack by night. Fighters are defensive for daylight defense.
> USAAC. Bombers (which will always get through) are offensive and attack by day in an unassailablephalanx too high, too fast and too heavily armed. Fighters, well, I'm kinda' hazy on what the US theory was, even if Claire Chennault wrote a book explaining it.
> The RAF didn't need escort fighters. They needed point defense.
> The USAAC didn't need escort fighters. Until they did.


The US didnt need escorts but almost always had them, the question was how far those escorts took them or could take them. Mission 1 by VIII bomber command attacked Rouen marshalling yards escorted by several squadrons of Spitfires. 17 August 1942 - This Day in Aviation

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## Shortround6 (Apr 21, 2022)

pbehn said:


> But there was little possibility that any UK fighter would have to fight with a wooden fixed pitch prop. The question was what variable pitch prop do you fit, which depends on how much power the plane has, which depends on things like is 100 octane fuel available.


I am not talking about the wooden fixed pitch prop.
The 2 pitch prop, some times called two speed, and often called variable pitch (sounds much better than fixed pitch) but all the same propeller only offered (most of the time) two pitches. 
There is a set of directions on how to operate a switch to get pitch settings in-between two limits but I am not sure all planes had that.
In any case one of the test planes describes how the propeller was set up so that at take off 2850rpm and 6 1/4lbs boost the prop was at 32 1/2 degrees pitch (at 42in radius) and at about 2000ft with a speed of 170 IAS the prop was changed from fine to coarse pitch and the speed increased to 185 IAS while the engine rpm dropped to 2070rpm at 6 1/4lbs boost. 185IAS was considered the best climbing speed in coarse pitch. 
It doesn't have much of anything to do with 100 octane fuel. What you want for coarse pitch is the prop pitched to give you the max speed at 3000 rpm (engine speed) at 17,000ft or above. IF you reduce pitch to give you better climb down low (under 17,000ft or so ?) you will either over speed the prop at the higher altitudes or have to throttle back a bit. The 100 octane fuel only gives you more power several thousand feet below FTH.

See this report. 




__





Spitfire Mk I K.9793 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com





even with the two pitch prop when climbing they never got the engine over 2440 rpm which is severely going to limit boost and power output. 
A constant speed allowed 2600rpm and 6 1/4 boost at any altitude below 11,000ft. 
Later they approved a climb rating of 2850rpm and with the impeller spinning faster the 6 1/4 lbs could be held higher.
In combat you could use the full 3000rpm.

Maybe
If you over rev the engine at too a low a speed your prop will be slipping in the air and not giving good thrust. The constant speed prop is supposed the adjust the pitch setting to keep the prop from over speeding for the conditions. Like letting you use 3000rpm and 6 1/4 lbs boost at 170 mph while climbing in fine pitch and then keeping the prop pitch increasing while the speed and/or altitude increases. 



Anything you do with a two pitch prop is going to be a comprise.


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## pbehn (Apr 21, 2022)

Shortround6 said:


> I am not talking about the wooden fixed pitch prop.
> The 2 pitch prop, some times called two speed, and often called variable pitch (sounds much better than fixed pitch) but all the same propeller only offered (most of the time) two pitches.
> There is a set of directions on how to operate a switch to get pitch settings in-between two limits but I am not sure all planes had that.
> In any case one of the test planes describes how the propeller was set up so that at take off 2850rpm and 6 1/4lbs boost the prop was at 32 1/2 degrees pitch (at 42in radius) and at about 2000ft with a speed of 170 IAS the prop was changed from fine to coarse pitch and the speed increased to 185 IAS while the engine rpm dropped to 2070rpm at 6 1/4lbs boost. 185IAS was considered the best climbing speed in coarse pitch.
> ...


Werent Rotol variable pitch props in place before the BoB and an improved DH version optimised for a lower altitude but greater altitude range introduced with the Spitfire Mk II?


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## Milosh (Apr 21, 2022)

http://www.spitfireperformance.com/Flight_DH_CSP_9_Dec_1943.pdf


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## Admiral Beez (Apr 21, 2022)

The Germans had a terrible time using twin-engined, two-seater fighters as daylight bomber escorts. Would the British have failed as badly had they sent the Mosquito fighter variant as a daylight bomber escort?


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## GregP (Apr 21, 2022)

You might try looking at this:

Comparitive Performance of Fighter Aircraft

This is a comparison of the way the aircraft WERE in real life, not how they were with your particular desired modifications.

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## Howard Gibson (Apr 21, 2022)

Zipper730 said:


> This was kind of inspired by the thread about the what-if idea of modifying a Supermarine Spitfire for additional range: I remember hearing of the idea of using the Hawker Tempest as an escort, and things of that sort (there was some information based on range on that page).
> 
> I was thinking about the various fighters that existed that either were used or were usable as escorts during the Second World War. I was thinking about obviously the available range, the way range could be improved, and the performance data of the aircraft (i.e. how they compared to each other, and adversary planes) in terms of performance and maneuverability.


From 1943 on, the Americans were successful under a very specific set of circumstances. The B-17s, B-24s, and the escorting P-38s and P-47s were turbocharged. The bombers flew in at 25,000 to 28,000ft, and combat against P-47s took place at 30,000ft. If you were flying a P-47, you wanted to fight at 30,000ft. The later Mustangs had two-stage superchargers, so they were effective at high altitude too. The Germans did not bring two-stage supercharges into service until the closing weeks of the war. 

Let's re-run the American daylight bomber campaign at 15,000 to 20,000ft, or let's give the Germans two-stage superchargers. Now, the American fighters do not have a gross advantage in performance. Their large fuel loads slow them down and make them more vulnerable to the Germans. Lower altitudes help German flak.

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## 33k in the air (Apr 22, 2022)

Howard Gibson said:


> The bombers flew in at 25,000 to 28,000ft, and combat against P-47s took place at 30,000ft.



There were numerous bombing missions which flew under 26,000 feet. Of 372 bombing missions of the 303rd Bomb Group, the lowest bombing altitude:


```
11,000 to 13,900 feet:  11  ( 3.0%)
14,000 to 16,900 feet:  18  ( 4.8%)
17,000 to 19,900 feet:  31  ( 8.3%)
20,000 to 22,900 feet:  77  (20.7%)
23,000 to 25,900 feet: 178  (47.8%)
26,000 to 28,900 feet:  54  (14.5%)
29,000 and over:         3  ( 0.8%)
```

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## GregP (Apr 22, 2022)

How about we not re-run the war except in the "what if: category, which is rather notorious for having no correct answers to any questions.?

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## Jabberwocky (Apr 22, 2022)

Shortround6 said:


> Just about any fighter could use a bit more range.
> Just what are you going to have to give up to get it?
> An extra 20-30 gallons in a Spit might be doable, depends on the engine and tactical situation. but an extra 30 gallons is not going to get to the Ruhr and back let alone any futher.
> 
> ...



That wing tank is such a horrible kludge. 

I've always been a little mystified by the RAF's failure in 1940 to 1944 to fit fuel tanks behind the pilot on combat versions of the Spitfire. After-all, they were happy enough to fit them in front of the pilot (Spitfire) and both in front and to the side of the pilot (Hurricane). And they were happy to do it from late 1944 onwards. Why not earlier?

The PR Mk IB had a 29 gal fuel tank sitting behind the pilot. It was flying missions over France in early 1940. The reports were that it was somewhat unstable with the rear tank full, but takeoff was fine and handling was close to normal once most of the rear tank had been used up.

The Mk V had 29 or 33 gal fuel tanks fitted for various ferry missions to Malta in 1942. Again though, the tanks were removed once the Spitfires made it to Malta. 

The 29 gal rear tank seems to be a viable option to turn a short range fighter into a medium range fighter. I'd argue that adding a third more fuel capacity at the cost of rate of climb was an acceptable trade-off for mid 1941 onwards. Of course, I'm writing with the benefit of hindsight. From the RAF's perspective in early to mid 1941, a renewed daylight offensive might only have been days or weeks away.

If the RAF did decide to modify some Spitfires, the question then becomes how many? And what's the potential cost in terms of a weaker interceptor force? You have to go all in on the concept - it's no good having penny packet numbers, otherwise they'll end up locally overwhelmed by German interceptors and the long-range squadrons rapidly become combat ineffective from losses and exhaustion.

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## PAT303 (Apr 22, 2022)

Shortround6 said:


> If you stick the tank in the rear fuselage you get rid of most of the drag but the loss of climb rate is going to be fairly close.


This is the bit that annoys me the most, one of the reasons Spitfires only had 85G of fuel was to keep the weight down so they could climb fast, the reason they had to climb fast was because they didn't have enough fuel to loiter. By simply putting 20G under the seat as per Sydney Cottons mod or a rear 30G tank as fitted to the MkV the requirement of fast climbing is gone. In the BoB Spitfires could have been launched 10 minutes earlier and be sitting at altitude using the extra fuel instead of waiting until the last minute and climbing like hell from underneath the approaching Luftwaffe aircraft. Once the Merlin got 100 octane fuel, CS props and 1200hp the tactics should have change to suit.

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## drgondog (Apr 22, 2022)

Shortround6 said:


> Until you get the Merlin 61 engine showing up the US didn't have an engine that would give them the aircraft performance and the range and the desired armament.
> Lets not forget that the P-47 could fly twice as far as Spitfire at low speeds with both running on internal fuel. The P-47 was a fuel hog but it was also a flying tank truck compared to most other fighters in 1942/early 43 and it wasn't near enough.
> 
> The B-17 and B-24 with their higher altitudes also required the escorts to burn a large amount of fuel just to get up to 25,000ft to start escorting.


SR - why are you discounting P-38? It paralleled the P-51B in range, and had the combat radius superior to P-47 during its entire life cycle until N.


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## Shortround6 (Apr 22, 2022)

PAT303 said:


> Once the Merlin got 100 octane fuel, CS props and 1200hp the tactics should have change to suit.


They were getting the 100 octane fuel, slowly, over the winter of 1939/40. The story of it arriving just in time is fiction, at best. 
See: https://live.staticflickr.com/65535/49597915996_bedb2b59d3_b.jpg

Assuming that the 100 octane was available at the fields the approval of using 12lbs of boost was issued March 20th 1940.
The constant speed props were going to take a bit longer. But any Merlin III could be fitted with a Rotol propeller. 
That was the whole reason for the Merlin III. It used a universal prop shaft that would take either the Rotol or the DH prop.
I believe the Merlin II would only take the wood prop or the DH Prop? But the universal shaft was showing up in the summer of 1939. 
The 100 octane was not going to change "tactics" as the 100 octane didn't change normal climbing power. 

There is a test of a Spitfire I armed with two 20mm cannon and four .303s that went about 6380lbs. 
They used 2850rpm and 6lbs of boost and the time to 20,000ft was almost 1.5 minutes slower. 

Rate of climb is not all about climbing to altitude. Rate of climb at altitude affects how hard the plane can turn and maintain altitude or at least, not loose altitude as fast, which is going to affect tactics.

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## Shortround6 (Apr 22, 2022)

drgondog said:


> SR - why are you discounting P-38? It paralleled the P-51B in range, and had the combat radius superior to P-47 during its entire life cycle until N.


Sorry, senior moment?

But some what seriously the P-38 was conceived as a long endurance interceptor. 2 Hours I believe the specification said? 
It started with 400 gallons of internal fuel but the self sealing tanks cut that to 300 and 300 gallons for 2 engines doesn't sound all that great. 
Granted it got drop tanks before _some_ other US fighters but the US was sticking drop tanks under the P-39 and P-40 to restore original range/endurance requirements. 
But not really to turn them into escort fighters. 
Forget the B-17, the B-26 was "supposed" to fly 2000 miles as was the B-25. 
No way you were going to fly P-40s and P-39s with small single belly tanks as escorts for even anything but the shortest Medium bomber missions. 
The P-38 also gained about 175hp over time in the F model. 
going from 1100hp to 1325hp take-off may have made things easier for take-offs? The 1325hp rating only showed at the end of 1942 and the early engines were not rated to use that power at altitude due to lack of cooling/intercooling/needing new turbos?) 
The P-38 was doing good things in other theaters but it didn't show up as a long range escort in Europe until about the same time as the Mustangs. 

It did a lot of long range work in the Pacific but the Enemy interceptors weren't as strong and most people weren't operating at the same altitudes as the B-17s/B-24s.

The High altitude/high speed requirements of Europe make things harder for the escorts. Just getting to 25,000ft instead of 15,000ft sucks up fuel. 
the need to be at near operational height and speed when crossing the coast makes things more difficult than the Pacific where the Japanese (or Americans) could use more time/distance to get up to altitude while burning off fuel before getting into high risk areas. Same on the way back, Pacific long range missions could use more time flying at lower altitudes and slower speeds. Not saying it was easy, Allied pilots forced down over Germany probably had a higher survival rate by coming down on land that ditching in water or trying to land on an atoll.

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## tomo pauk (Apr 22, 2022)

Shortround6 said:


> Until you get the Merlin 61 engine showing up the US didn't have an engine that would give them the aircraft performance and the range and the desired armament.
> Lets not forget that the P-47 could fly twice as far as Spitfire at low speeds with both running on internal fuel. The P-47 was a fuel hog but it was also a flying tank truck compared to most other fighters in 1942/early 43 and it wasn't near enough.



2-stage R-2800 was flying much earlier than the Merlin 61, talk year and a half? American-produced equivalent was late vs. a 2-stage R-2800 by ~2.5 years?
That nobody made an 1-engined fighter around the turbocharged V-1710 was no fault of the V-1710. The 2-engined P-38 worked, if with shortcomings ( a lot of them had nothing to do with engine choice).
R-1830 + turbo were in service by mid-1941 - again a valid powerplant for an escort of B-17s.

Shortcoming of the P-47 was that someone specifying it left out the requirement for drop tanks. The turbocharged R-2800 was in production and service months before the 2-stage Packard Merlin.


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## Shortround6 (Apr 22, 2022)

tomo pauk said:


> 2-stage R-2800 was flying much earlier than the Merlin 61, talk year and a half? American-produced equivalent was late vs. a 2-stage R-2800 by ~2.5 years?
> That nobody made an 1-engined fighter around the turbocharged V-1710 was no fault of the V-1710. The 2-engined P-38 worked, if with shortcomings ( a lot of them had nothing to do with engine choice).
> R-1830 + turbo were in service by mid-1941 - again a valid powerplant for an escort of B-17s.
> 
> Shortcoming of the P-47 was that someone specifying it left out the requirement for drop tanks. The turbocharged R-2800 was in production and service months before the 2-stage Packard Merlin.


The P & W two stage engines were better than single stage engines but you can't substitute mechanical two stage R-1830s for turbo R-1830s. 
The turbo installations needed more bulk/volume even it not a lot more weight of actual engine components. 
However the turbo systems will allow 1200hp at 25,000ft instead of 1000hp at 19,000ft. 
The turbo systems will also allow 700hp at 25,000ft in lean cruise. The two stage engine in the F4F may give 700hp cruise at 19,000ft? 

The P-43 is your best choice for a Turbo R-1830 escort fighter, as least for starters. Perhaps you can do better without a 1935 airframe but you need room for the turbo, the intercooler, the ducts. 
And if you want 150-200 US gallons of fuel you are going to need a wing close the size of the P-43, or a fat fuselage. 
The air at 25,000ft is about 82% as dense as the air at 19,000ft so you need more air for the same power, you need more air for the intercoolers and if you are trying to make 1200hp instead of 1000hp you need 20% more combustion air, 20 % more intercooler air and 20% more cooling air. 

A fighter with a single Turbo Allison has got a similar problem. The engine itself may be OK, but you need to go through the chain of turbos, B-2 to B-13 to B-33 inorder to get to the higher performance levels. You have to go through a few turbo regulator set ups and you have to follow the Allision progression in bottom end improvements. If you also have to figure out the intercooler problem. They were build P-38Hs and 38Js at the same time because they could not get the intercoolers for the 38Js fast enough to keep up production. 
No waving the magic wand and getting B-13 turbos and P-38J intercoolers in the fall of 1942

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## 33k in the air (Apr 22, 2022)

Shortround6 said:


> It [the P-38] did a lot of long range work in the Pacific but the Enemy interceptors weren't as strong and most people weren't operating at the same altitudes as the B-17s/B-24s.



The second engine also provided a measure of safety redundancy for those long flights over open ocean.


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## tomo pauk (Apr 22, 2022)

Shortround6 said:


> The P & W two stage engines were better than single stage engines but you can't substitute mechanical two stage R-1830s for turbo R-1830s.
> The turbo installations needed more bulk/volume even it not a lot more weight of actual engine components.
> However the turbo systems will allow 1200hp at 25,000ft instead of 1000hp at 19,000ft.
> The turbo systems will also allow 700hp at 25,000ft in lean cruise. The two stage engine in the F4F may give 700hp cruise at 19,000ft?



FWIW, please note that I haven't listed the 2-stage R-1830 as a viable option for the USAAC/AAF - they have better options, including the R-2800. Turboed R-1830 is/was much better for the task of escorting the B-17s/-24s (granted, not beyond 1942 vs. Germany).



Shortround6 said:


> The P-43 is your best choice for a Turbo R-1830 escort fighter, as least for starters. Perhaps you can do better without a 1935 airframe but you need room for the turbo, the intercooler, the ducts.
> And if you want 150-200 US gallons of fuel you are going to need a wing close the size of the P-43, or a fat fuselage.



Fuselage bulk is already dictated by the R-1830 diameter. I'd take the wing size of the P-43; granted, the wing structure will need to start with the simple 2-spar layout, so the proper fuel tanks can be installed instead the problematic tanks the P-43 had.



Shortround6 said:


> A fighter with a single Turbo Allison has got a similar problem. The engine itself may be OK, but you need to go through the chain of turbos, B-2 to B-13 to B-33 inorder to get to the higher performance levels. You have to go through a few turbo regulator set ups and you have to follow the Allision progression in bottom end improvements. If you also have to figure out the intercooler problem. They were build P-38Hs and 38Js at the same time because they could not get the intercoolers for the 38Js fast enough to keep up production.
> No waving the magic wand and getting B-13 turbos and P-38J intercoolers in the fall of 1942



The as-is turboed V-1710s will do.
People doing the intercoolers for P-38 need to take a long, hard look on what the proper intecoolers look like on other US aircraft that have intercoolers.


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## Zipper730 (Apr 22, 2022)

pbehn said:


> You could but why would you? It would not have been as good as a P-51B/C D or the contemporary P-47. There were 1,700 Tempests made, it was probably the allies best fighter at low level and was needed against the V1 and post D-Day operations. It became operational in April 1944, by that time there was hardly a shortage of P-51s and P-47s which were both better in performance at altitude and range.


For some reason, I thought the Tempest was operational earlier actually. I am interested about the low-speed handling characteristics of the Tempest against the P-51 regardless (merely out of curiosity).


> As I read the OP it was referring to escorts for strategic bombing missions from UK.


Technically, I was thinking of allied forces. Regardless, it seemed the Axis powers largely had developed escort capabilities as time went on.



tomo pauk said:


> These points don't apply to Luftwaffe that much?


I was mostly thinking of allied fighter designs that could be modified for extreme range. Truthfully, you make some good points, but the Bf 110, had it been used for free-ranging fighter-sweeps, it would have demonstrated considerably better effectiveness. That said, I'm really glad they didn't!


> These points also don't apply to the Japanese, they employed escort fighters over the long ranges.


For the most part, yes. That said, they had considerable advantages over fighters operating over Europe.


> Jamming more fuel into existing aircraft was the most important thing, and was also easiest thing to do. Hardest thing was admitting to oneself that LR fighters are not just needed, but feasible.


True enough -- there was a pervasive attitude that bombers would be able to hack it alone, and if not, they could just get through at night.


> Tempest was a 'victim' of jamming more fuel in an aircraft not once, but twice in ww2. 1st, the 130-something imp gal fuel quantity was increased by installing a 30-something IG fuel tank in one wing leading edge, and them extra fuel was installed in another wing LE. Second fuel increase was done after it was necessary (late summer of 1944, on an unknown number of aircraft) since RAF tactical squadrons were in France by that time.


I didn't know that. I thought it had the fuselage tank and wing-tanks (interspar tank) off the bat, with a 30-imperial gallon tank added after.

It could carry 2x45 or 2x90 imperial gal. tanks off the bat if I recall. I'm not sure what penalty came in terms of g-load limits, but the Tempest was pretty tough structurally (if I recall, it compared decently with the F4U-1).


> British are in best place engine-wise, but they don't have a doctrine for escort fighters' role. Americans are also hampered with same problem.


The British had the best engine options, particularly the fact that they had many inline engines that were either operational, or very close to operational. They also proceeded at a decent clip with jet development as well (they technically noticed the benefit of jets before the Germans did, but proceeded to develop it slower). Unfortunately, they really proceeded as slow as molasses when it came to developing variable-pitch/constant-speed propellers, often opting to use fixed-props for fighters, an occasionally twin-pitch design for a couple bombers early on (something ironic because of the fact that the technology existed).

The United States quickly adopted variable pitch propellers because we probably had better connections between industry and government, and this gave our aircraft better low speed performance in particular (though the Spitfire showed a significant performance increase when they were fitted with a variable pitch propeller at high TAS if I recall). It would also appear that we were better at stuffing more fuel into a given volume of space for fighter aircraft. This seemed to stem from geography.

The USN operated over large areas of ocean, which favored long-range (the RN:FAA probably also built more range into their aircraft as well for the same reason).
The USAAF generally liked having range in fighter planes for the purposes of ferrying them around at bare minimum: It would also appear that there was more interest in using them to either carry out or support interdiction operations.
When it came to engines, there was interest in inline engines mostly for the US Army, but the USN largely was a bigger fan of developing radials with the exception of airships (that said, they did develop the X-1800/H-2600 and H-3130/3730), and there was little demand for inlines in the commercial area since cowling-design made radials effective in all but the fastest cases, there was a depression on, and the Army had lots of inline designs that they were looking into, which ended up resulting in relatively little money going to any of them. There also appeared to be a tendency to lag in terms of switching from one concept to another, such as gas-turbine engines. We either stayed with propellers, and occasionally looked into the motorjet.



Shortround6 said:


> The Typhoon was designed to have a similar radius of action to the Spitfire and Hurricane. It's larger fuel capacity only fed the bigger engine for about the same period of time.


From what I remember, the British had a problem with their wind-tunnels that led to problems with higher speed aircraft, owing to the fact that their full-size wind-tunnel had some turbulence producing characteristic, and it obfuscated the degree of turbulence produced by the aircraft. While they appeared to have figured out some correction factors for certain ranges of speed, as they went into faster territory, they found their guesswork produced wildly varying results.

This seemed to be how they came up with the misguided assumption that the Beaufighter would be capable of 370 mph (if I recall, it was capable of around 315-325) and the Typhoon could do around 450 mph (it had trouble squeaking past 400 initially). Interestingly, the reason Supermarine avoided falling into that trap was because they produced lots of race-planes and had plenty of hands-on experience with high speed aerodynamics. The US & Canadians were also able to back up Supermarine on the issue of wing-thickness.

I'm not sure when the British realized they had this problem, but it seems that it was probably at some point in 1940 (the Mosquito was built in late 1940 and had a normal wing thickness).You also have to consider what bombers you want to escort.


> You also have to consider the fighter opposition you'll face: The P-38 could achieve a radius of action about 1000 miles out with 2 x 165 gallon tanks, but it would have to cruise fairly slow to do it.





tomo pauk said:


> Instead of turret fighters, start making LR fighters.


Turret fighters proved a pretty dumb idea in practice: From what I remember, the idea was based on upward tilting guns that could vary in elevation, and be swung around as well in the event they couldn't reach the bomber in time (or the bomber was higher flying).


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## GregP (Apr 22, 2022)

PAT303 said:


> This is the bit that annoys me the most, one of the reasons Spitfires only had 85G of fuel was to keep the weight down so they could climb fast, the reason they had to climb fast was because they didn't have enough fuel to loiter. By simply putting 20G under the seat as per Sydney Cottons mod or a rear 30G tank as fitted to the MkV the requirement of fast climbing is gone. In the BoB Spitfires could have been launched 10 minutes earlier and be sitting at altitude using the extra fuel instead of waiting until the last minute and climbing like hell from underneath the approaching Luftwaffe aircraft. Once the Merlin got 100 octane fuel, CS props and 1200hp the tactics should have change to suit.



The requirement for fast climbing was never gone. Before radar got decent, the Brits had very little warning of incoming German attacks from the air, and needed to get up there quickly. That requirement never really "went away," the warning time just got a bit better, and the Spitfires could get into a position from which, if not superior, was at LEAST not nearly as much if a disadvantage before the Germans were over their targets.

The Spitfire was the best piston fighter of the war for getting to high altitude quickly in the ETO, and was needed for that task until the Luftwaffe was so busy defending the Reich that attacks on the UK were not in the cards.

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## pbehn (Apr 22, 2022)

Zipper730 said:


> For some reason, I thought the Tempest was operational earlier actually. I am interested about the low-speed handling characteristics of the Tempest against the P-51 regardless (merely out of curiosity).
> 
> Technically, I was thinking of allied forces. Regardless, it seemed the Axis powers largely had developed escort capabilities as time went on.


What is "low speed" the landing speed of a Tempest was 110 MPH, a low speed handling competition between those two is like a parking competition for F1 cars. The German part of the Axis scaled back manufacture of machines that needed daylight escort from 1943, Attacks on UK were done at night.


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## FLYBOYJ (Apr 22, 2022)

> Zipper730 said:
> For some reason, I thought the Tempest was operational earlier actually. I am interested about the low-speed handling characteristics of the Tempest against the P-51 regardless (merely out of curiosity).
> 
> Technically, I was thinking of allied forces. Regardless, it seemed the Axis powers largely had developed escort capabilities as time went on.





pbehn said:


> What is "low speed" the landing speed of a Tempest was 110 MPH, a low speed handling competition between those two is like a parking competition for F1 cars. The German part of the Axis scaled back manufacture of machines that needed daylight escort from 1943, Attacks on UK were done at night.


Actually I think what is meant is "Maneuvering Speed" AKA as "Va." Maneuvering speed for a P-51 is shown to be around 265 MPH.


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## Zipper730 (Apr 22, 2022)

pbehn said:


> What is "low speed" the landing speed of a Tempest was 110 MPH


Maneuvering speed.



FLYBOYJ said:


> Actually I think what is meant is "Maneuvering Speed" AKA as "Va." Maneuvering speed for a P-51 is shown to be around 265 MPH.


Correct: If I recall, a rough approximation is the stall-speed x square-root of rated g-load, with the exact calculation being: V = sqrt (2L/((CL)(ρ)(A)

Do you (or 

 drgondog
) have these figures for the two aircraft?


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## GregP (Apr 22, 2022)

Speeds are mph I.A.S.:

Looking at the Tempest V pilot manual, the approach speed, gear up, flaps up in 120 mph; 100 mph with flaps down. It says, "Do not turn below 135 - 140 mph. Max div speed at altitude (35,000 ft) is 340 mph, up to 540 mph (10,000 ft).

There is no V-g diagram, so there is no maneuvering speed listed. Perhaps at ww2aircraftperformance.


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## Zipper730 (Apr 22, 2022)

GregP said:


> Speeds are mph I.A.S.


From what I recall, the Tempest doesn't seem to have (based on the pilot's manual) any correction at the lower end of the speed range. Not sure about the Spitfire.


> There is no V-g diagram, so there is no maneuvering speed listed.


The British seem to miss stuff in manuals that we usually put in. The F4U had a V-N diagram


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## GregP (Apr 22, 2022)

Zipper730 said:


> From what I recall, the Tempest doesn't seem to have (based on the pilot's manual) any correction at the lower end of the speed range. Not sure about the Spitfire.
> The British seem to miss stuff in manuals that we usually put in. The F4U had a V-N diagram



You mean position correction for airspeed? The stall speed, gear down was 75 mph and 85 mph gear up. That's I.A.S. But, with the caveat to not turn below 135 - 140 mph, I'd say the stall is not gentle. I can't think of another aircraft that has bad handling 50 mph above stall other than an F-4 Phantom. It doesn't handle worth a crap below 350 knots and turns below that speed are pretty much with rudder only.

Seems like the Tempest may be a kindred spirit that likes thing a bit faster than other contemporary fighters. The Spitfire and Hurricane handled great around stall.

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## Jabberwocky (Apr 23, 2022)

GregP said:


> You mean position correction for airspeed? The stall speed, gear down was 75 mph and 85 mph gear up. That's I.A.S. But, with the caveat to not turn below 135 - 140 mph, I'd say the stall is not gentle. *I can't think of another aircraft that has bad handling 50 mph above stall *



Maybe not 50 mph above, but I recall reading somewhere that early Ki-44-Is had a really vicious accelerated stall, hence the need to fit the automated combat maneuvering flaps after the first few production examples were delivered. Japanese pilots also expressed dislike for the Ki-44s oversensitive elevators, which had a tendency to put the aircraft into a snap stall if handled roughly. As a lot of pilots transitioned from the Ki-43, which had very nicely balanced controls, this may have exacerbated the problem.

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## Howard Gibson (Apr 24, 2022)

GregP said:


> How about we not re-run the war except in the "what if: category, which is rather notorious for having no correct answers to any questions.?


What happens if you design a point interceptor and I design a long range escort fighter with both of us using equivalent technology? My aeroplane will have larger fuel tanks, and I will set up the aerodynamics to provide efficient high speed cruise. Your aeroplane will be smaller and lighter, and it will be optimised for manoeuvrability, acceleration, climb and top speed. My aeroplane will be faster in a dive. You do need heavier armament to knock down my bombers, which increases your weight a bit. 

I am facing the classic military problem of fighting at the end of extended communications. I cannot just say I am going to design an escort fighter that will be superior to whatever it is you have, unless I have some technological and/or logistical advantage, like high octane fuel, turbochargers, and an effective training program for my new pilots.


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## pbehn (Apr 24, 2022)

Howard Gibson said:


> What happens if you design a point interceptor and I design a long range escort fighter with both of us using equivalent technology? My aeroplane will have larger fuel tanks, and I will set up the aerodynamics to provide efficient high speed cruise. Your aeroplane will be smaller and lighter, and it will be optimised for manoeuvrability, acceleration, climb and top speed. My aeroplane will be faster in a dive. You do need heavier armament to knock down my bombers, which increases your weight a bit.
> 
> I am facing the classic military problem of fighting at the end of extended communications. I cannot just say I am going to design an escort fighter that will be superior to whatever it is you have, unless I have some technological and/or logistical advantage, like high octane fuel, turbochargers, and an effective training program for my new pilots.


Who designed a long range escort in WW2? Certainly not the USA or British. They adapted designs for the role that were originally designed for something else.

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## Snowygrouch (Apr 24, 2022)

Admiral Beez said:


> The Germans had a terrible time using twin-engined, two-seater fighters as daylight bomber escorts. Would the British have failed as badly had they sent the Mosquito fighter variant as a daylight bomber escort?


"
The exchange ratio of the Bf-110 was positive at the BoB as well. "common knowledge" indeed appears to be a "common myth". Also factoring in that the Bf-110c was the worlds most effective bomber interceptor platform in 1940 may explain why the exchange ratio was that positive. From known losses and kills such as analysed by danish author
Christer Bergström, Luftskrid over kanalen (2006)


* Spitfire: 550 confirmable kills 329 losses -exchange ratio is 1.7: 1
* Hurricane: 750 confirmable kills 603 losses -exchange ratio 1.2: 1
* Bf 109 780 confirmable kills 534 losses – exchange ratio 1.5: 1
* Bf 110 340 confirmable kills 196 losses – exchange ratio 1.7: 1

The Bf-110 suffered from a negative exchange ratio only when forced to close escort orders in late august and early september 1940. Before and after this time (when these orders were lifted again), the exchange rate was very positive in favour of the Bf-110 as was the mean average from august to oct.
"






bf110 exchange ratio


It's common knowledge that the bf110 performed poorly during the Battle of Britain, but it seems to have done much better over Dunkirk against British fighters. Looking in 'Battle of France, Then and Now', the bf110 had a slightly positive exchange ratio against Hurricanes and Spitfires. There...



ww2aircraft.net





After having recently got copies of the British Air Intelligence files on the Me110, I have changed my mind about it, and now view it as thoroughly under-rated.

The British found it had extremely surprising manuverability, very pleasant flight charactistics, combined with heavy firepower, superb pilot vision
and very good climb/zoom.

I had previously assumed it was a deadweight slug, based on "common wisdom", it seems that it was a lot better than it is usually given credit for. Of course
making it viable against single engine opposition requires very specific tactics...

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## Geoffrey Sinclair (Apr 25, 2022)

Snowygrouch said:


> From known losses and kills such as analysed by danish author Christer Bergström, Luftskrid over kanalen (2006)
> 
> * Spitfire: 550 confirmable kills 329 losses -exchange ratio is 1.7: 1
> * Hurricane: 750 confirmable kills 603 losses -exchange ratio 1.2: 1
> ...


Williamson Murray, Luftwaffe strength 28 June 1940 1,107 Bf109 to 357 Bf110, or about 3 to 1 Bf19 to Bf110

Wood and Dempster, 10 August 1940, Bf109 1,101 establishment, 934 strength, 805 serviceable, Bf110 301 / 289 / 224, or over 3 to 1 Bf109 to Bf110.

So Bergstrom reports the Bf110 force scored about 1 confirmed kill for each of its initial strength, the Bf109 about 0.8. Then when you factor in multi engine multi crew aircraft generate fewer sorties per aircraft than single engine single seaters, and the close escort tactics, Bergstrom is reporting the Bf110 was a much better fighter than the Bf109, longer ranged, scoring as high as maybe 50% more confirmed kills per sortie over the course of the Battle of Britain, if allowed to optimise its tactics.

The Battle of Britain Then and Now says Fighter Command had 1,026 total losses for the Battle, with 798 due to enemy action and 40 more unknown, of the enemy action losses 672 are attributed to enemy fighters or enemy aircraft. Bergstrom has 1,120 confirmed kills by Luftwaffe fighters, which means up to another 450 non RAF Fighter Command aircraft are confirmed shot down, which would be mostly from Bomber Command and Coastal Command. Bergstrom says over the Battle of Britain the Luftwaffe fighters shot down 3 Fighter Command to 2 other RAF command aircraft. Bomber Command lost 382 aircraft in the period to all causes, 103 by day, 279 by night, 187 of the losses came down on British territory. Using Boiten's Nachtjagd War Diaries and the Bomber Command Losses series 15 day and 23 night losses are due to Luftwaffe fighters, 14 more losses are to unknown causes.

That still leaves hundreds from Coastal Command to make up the numbers, total all causes losses on operations for all of 1940 were 310, few are logged as lost to fighters, see Coastal Command Losses by Ross McNeill.

The old Luftwaffe kill claims list I have for the Battle of Britain has ZG26 and ZG76 but is missing ZG2, the ZG units logging 231 claims, some of which were disallowed, the JG units 1,894, again including some that were disallowed. Bergstrom more than halves the Bf109 claims, but must have several hundred more claims by Bf110 that the old list I have is missing.

Williamson Murray, losses to end September 1940, Bf109 398 enemy, 79 ops, 41 non ops, Bf110 214 enemy, 9 ops, 12 non ops

The Battle of Britain Then and Now listing, 10 July to 31 October has the total all causes losses on operations as Spitfire 353, Hurricane 569, Bf109 600, Bf110 248.

Bergstrom reports, July to October, Spitfire 394, Hurricane 603, Bf109 534, Bf110 196

Luftwaffe Quartermaster reports as translated by the RAF, July to October Bf109 600, Bf110 235, plus 18 night fighters.

Williamson Murray, Luftwaffe, table IX says in the July to September period the Luftwaffe single engined fighter units lost 47% of their original strength, the twin engined units 66%. For May and June 1940 Murray reports the Luftwaffe single engined fighter units lost 19% of their original strength, the twin engined units 30%, for May to September, single engined fighter units lost 57% of their original strength, the twin engined units 97%,

Bergstrom's total of confirmed kills by Luftwaffe fighters, at 1,120, is hundreds more than can be confirmed by RAF records and post war investigations, his fighter losses for the RAF higher and Luftwaffe lower than the air force records.

The main reported Bf110 failing was poor acceleration, which would be a big problem on close escort sorties.

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## Zipper730 (Apr 25, 2022)

Snowygrouch
, I remember hearing Capt. Eric M. Brown talking about the aircraft doing quite well when it wasn't tied close to the bombers it was escorting.

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## Zipper730 (Apr 25, 2022)

This is pretty interesting






I transcribed all the numbers and, also rewrote a few terms (permanent fuel was obviously internal fuel). I reposted this because I inadvertently made a typo the first time.






The figures for the modified Tempest Mk.II/V are quite interesting, particularly the ability to squeeze around 25-30 gallons into the aircraft, though it would have still come up short relative to the P-51B/C.

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## Snowygrouch (Apr 26, 2022)

Will post some snippets on the British intellgence files on Me110 evaluation later today.

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## Stig1207 (Apr 26, 2022)

Snowygrouch said:


> danish author
> Christer Bergström,



Swedish actually; I know we look and sound much the same, but still

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## Snowygrouch (Apr 26, 2022)

Stig1207 said:


> Swedish actually; I know we look and sound much the same, but still


Sorry I just copy pasted that text from the linked prevous post by someone else on this forum...

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## drgondog (Apr 26, 2022)

Zipper730 said:


> This is pretty interesting
> View attachment 665818
> 
> 
> ...


Interesting contrast between pre-P-51B and Tempest Range figures. The N-73 through P-51A (internal fuel only at 180gal US) had a straight line range w/no reserve at 10K of about 1050mi. If all the RAF data is in Imperial Gallons, the Tempest II and V straight line ranges of 740 and 790 respectively for 194gal US and 192gal US is 30% less than Allison engined Mustangs with 7% more fuel. The P-51B with no fuselage tank had very slightly less straight line range at 1025mi with 4 gallons more than P-51A

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## Geoffrey Sinclair (Apr 26, 2022)

Zipper730 said:


> This is pretty interesting
> View attachment 665818
> I transcribed all the numbers and, also rewrote a few terms (permanent fuel was obviously internal fuel).
> View attachment 665819


The transcription for the Spitfire IX (cut away fuselage as modified in the U.K.), second and third lines should read 96+62?

The next page in Air 19/286 is interesting, it dates the document to 7 September 1944 and states,

"3. The following progamme has been arranged:-
(i) Spitfire IX (now in production). 800 sets of tanks have been ordered for retrospective fitting and production of these tanks should commence in about 3 months' time. The modification will comprise replacing the existing 85 gallon main fuselage tank by a 96 gallon tank and fitting a 72 gallon self sealed tank in the fuselage behind the pilot.

(ii) Spitfire IX (cut away fuselage). This aircraft comes into production in about 4 months' time and it is hoped to embody the 96 gallon main tank and a 62 gallon rear fuselage tank in the production line from the outset. The cut away fuselage, which gives a considerably improved rear view, prevents the fitting of a 72 gallon tank."

Vickers built 633 LF.IX and 89 HF.IX September to December 1944 and another 475 LF.IX and 100 HF.IX in 1945.

The range figures in Air 19/286 are similar to the proposals from the first half of 1944 reported in AVIA 20/2030 and AIR 20/3312, see messages 228 and 229 in the Spitfire Combat Radius (range) evolution, limitations? topic






Spitfire Combat Radius (range) evolution, limitations?


Well, I guess that depends how good you think the P-47 was in air combat down low, which is where it did have to tangle with German fighters quite a bit. And I don't think it was so good because of all the drag and weight. Both the F4U and F6F were almost as big and heavy as the P-47 and they...



ww2aircraft.net





Also in AIR 19/286 the Spitfire LF.IXE with Merlin 66, maximum weak mixture cruise speed was 328 mph at 20,000 feet, most economical cruise was 220 mph at 20,000 feet, this gives fuel load (85 gallons internal, rest external) / MEC range / MWM range
85 / 434 / 240
130 / 721 / 387
175 / 980 / 520
255 / 1,355 / 765.

The Spitfire XIV with 112 gallons internal range was 460 miles, a 62 gallon rear fuselage tank was predicted to increase this to 770 miles. Mark XIV range with 112 internal and 30 gallon external 610 miles, 112+45 = 680 miles, 112+90 = 850 miles, 112+170 = 1,130 miles. The Spitfire XXI had an extra 8 gallons internal and cruised about 8 mph faster than the XIV. The Mustang III with 150 gallons of fuel range 950 miles, with 221 gallons internal 1,450 miles, with 150 internal and 125 external 1,710 miles, with 221 internal and 125 external 2,210 miles, economic cruise of 253 mph at 20,000 feet.

The RAF standard was ranges of fighters are shown as ranges at maximum economic cruising power on the fuel available, after deducting fuel used in 15 minutes at maximum power at sea level. This allowance is for warming up and climbing to operational height. The Tempest came in at about a short ton heavier than the P-51D.

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## Snowygrouch (Apr 26, 2022)

As promised some pages from the British Air Intelligence files on the Me110. Reading these has significantly warmed me to the aircraft.

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## Conslaw (Apr 27, 2022)

33k in the air said:


> There were numerous bombing missions which flew under 26,000 feet. Of 372 bombing missions of the 303rd Bomb Group, the lowest bombing altitude:
> 
> 
> ```
> ...


Those three missions with minimum bombing altitude over 29,000 must have been interesting.


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## Stig1207 (Apr 27, 2022)

Geoffrey Sinclair said:


> Williamson Murray, Luftwaffe strength 28 June 1940 1,107 Bf109 to 357 Bf110, or about 3 to 1 Bf19 to Bf110
> 
> Wood and Dempster, 10 August 1940, Bf109 1,101 establishment, 934 strength, 805 serviceable, Bf110 301 / 289 / 224, or over 3 to 1 Bf109 to Bf110.
> 
> ...



Andrew Arthy posted the following charts from Luftwaffe Quartermaster reports at some stage, perhaps on this forum?

So the 600 Bf 109's lost are to all causes on operations, 502 to enemy action and 98 without enemy action. Bergström's total losses to enemy action is actually higher for the 109's, by 32 aircraft.

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## Geoffrey Sinclair (Apr 27, 2022)

Stig1207 said:


> Andrew Arthy posted the following charts from Luftwaffe Quartermaster reports at some stage, perhaps on this forum?
> 
> So the 600 Bf 109's lost are to all causes on operations, 502 to enemy action and 98 without enemy action. Bergström's total losses to enemy action is actually higher for the 109's, by 32 aircraft.


Luftwaffe Quartermaster
663 Bf109 and 252 Bf110 total all cause losses
600 Bf109 and 235 Bf110 lost on operations
502 Bf109 and 224 Bf110 lost to enemy action
Bergstrom 534 Bf109 and 196 Bf110 lost. 

Battle of Britain Then and Now
586 Hurricanes and 364 Spitfires lost to all causes on both operations and non operations.
500 Hurricanes and 300 Spitfires in round terms, destroyed by enemy action on operations (including losses to Luftwaffe bomber fire) plus another 18 Spitfires and Hurricanes lost on the ground "enemy action" and 28 to unknown causes on operations.
Bergstrom 603 Hurricanes and 394 Spitfires lost.

What definition is Bergstrom using and should be used? I chose to compare his total to "total all causes losses on operations" as that was the closest match for the aircraft under discussion, the Bf110. Also Bergstrom's 1,300 confirmed Hurricane+Spitfire kills can be compared to the total of 1,000 Luftwaffe aircraft lost to enemy aircraft in the Battle of Britain Then and Now list.


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## Milosh (Apr 27, 2022)

Luftwaffe Quarterly reports, German Order of Battle - Statistics as of Quarter Years, 1938-45

What is interesting is very few of the units were at Est. Strength in June and none in Sept.

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## Zipper730 (Apr 27, 2022)

Geoffrey Sinclair said:


> The transcription for the Spitfire IX (cut away fuselage as modified in the U.K.), second and third lines should read 96+62?


Yeah, I just entered it haphazardly, but I reposted it correctly.


> The next page in Air 19/286 is interesting, it dates the document to 7 September 1944 and states,
> 
> "3. The following progamme has been arranged:-
> (i) Spitfire IX (now in production). 800 sets of tanks have been ordered for retrospective fitting and production of these tanks should commence in about 3 months' time. The modification will comprise replacing the existing 85 gallon main fuselage tank by a 96 gallon tank and fitting a 72 gallon self sealed tank in the fuselage behind the pilot.
> ...


According to that timetable, the 72-gallon aft-tank would have been put into operational service in early December, 1944, and the 62-gallon tank for the cut-away fuselage would be around early January, 1945.


> The range figures in Air 19/286 are similar to the proposals from the first half of 1944 reported in AVIA 20/2030 and AIR 20/3312, see messages 228 and 229 in the Spitfire Combat Radius (range) evolution, limitations? topic


Do you have access to these historical documents? They sound like they'd be very interesting to read. I actually did transcribe much of what you wrote since it's nice to have the data handy (I am curious why some of the figures, such as the Spitfire Mk.VIII/Mk.21 had two ranges listed, since the fuel load was identical).

Was there any proposal to fit the Mustang with a 98 imperial gallon tank? That's the only way I get 346 gallons, unless they meant 246?


> Also in AIR 19/286 the Spitfire LF.IXE with Merlin 66, maximum weak mixture cruise speed was 328 mph at 20,000 feet


I'm surprised the altitude figures were so low. I'm not an expert on the merlin 60 series, but we had versions that we had (V-1650-3/-7) had critical altitudes that were typically around 19000' (V-1650-7) to 24000' (V-1650-3) without ram, and with ram, you'd see around 24000' (V-1650-7), and 29400-29800' (V-1650-3) with ram compression. The Spitfire climbed faster than the P-51's did, so I'd figure they'd have had better AMPG up high.


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## Stig1207 (Apr 28, 2022)

Geoffrey Sinclair said:


> Luftwaffe Quartermaster
> 663 Bf109 and 252 Bf110 total all cause losses
> 600 Bf109 and 235 Bf110 lost on operations
> 502 Bf109 and 224 Bf110 lost to enemy action
> ...



Looks to me that Bergstrôm is definitely using destroyed by enemy action for the Luftwaffe, while Fighter Command losses are losses to all causes, but I don't know where he gets his figures from. Odd that he has more 109's lost but less 110's by a similar number , +32 109's; -28 110's.
Otoh, his 1300 confirmed Hurricane + Spitfire kills compares well with the 1385 total Luftwaffe losses to enemy action from the Lw Quartermaster.


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## drgondog (Apr 28, 2022)

Zipper730 said:


> Was there any proposal to fit the Mustang with a 98 imperial gallon tank? That's the only way I get 346 gallons, unless they meant 246?


No.


Zipper730 said:


> I'm surprised the altitude figures were so low. I'm not an expert on the merlin 60 series, but we had versions that we had (V-1650-3/-7) had critical altitudes that were typically around 19000' (V-1650-7) to 24000' (V-1650-3) without ram, and with ram, you'd see around 24000' (V-1650-7), and 29400-29800' (V-1650-3) with ram compression. The Spitfire climbed faster than the P-51's did, so I'd figure they'd have had better AMPG up high.


Climb is related to Excess Power and Wing Loading. Range is more dependent on specific fuel consumption per hour and combination of parasite and induced drag and wing loading. The Mustang and Spitfire, with same engine and boost and RPM and altitude, will always find the Mustang with more 'air miles per gallon' per relative Gross weight load out %.

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## Geoffrey Sinclair (Apr 28, 2022)

Zipper730 said:


> Do you have access to these historical documents? They sound like they'd be very interesting to read. I actually did transcribe much of what you wrote since it's nice to have the data handy (I am curious why some of the figures, such as the Spitfire Mk.VIII/Mk.21 had two ranges listed, since the fuel load was identical).
> 
> Was there any proposal to fit the Mustang with a 98 imperial gallon tank? That's the only way I get 346 gallons, unless they meant 246?
> 
> I'm surprised the altitude figures were so low. I'm not an expert on the merlin 60 series, but we had versions that we had (V-1650-3/-7) had critical altitudes that were typically around 19000' (V-1650-7) to 24000' (V-1650-3) without ram, and with ram, you'd see around 24000' (V-1650-7), and 29400-29800' (V-1650-3) with ram compression. The Spitfire climbed faster than the P-51's did, so I'd figure they'd have had better AMPG up high.


I only have 25 pages from AVIA 20/3030 and 6 from Air 20/3312 as at the time I was only after what happened, not what might happen or proposed plans which make up the bulk of those files. Early in the war the RAF standard characteristics cruise height was 15,000 feet, that was changed to 20,000, the performance figures are meant to be standards for basic planning purposes, adjusted according to the mission. The idea Spitfires were retrofitted with the larger tanks helps explain the uncertainties about what capacity individual aircraft had. The two ranges listed are economic versus maximum weak mixture cruise.

Mustang 221 gallons internal 2x62.5 gallon external = 346 gallons


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## EwenS (Apr 28, 2022)

Zipper730 said:


> I'm surprised the altitude figures were so low. I'm not an expert on the merlin 60 series, but we had versions that we had (V-1650-3/-7) had critical altitudes that were typically around 19000' (V-1650-7) to 24000' (V-1650-3) without ram, and with ram, you'd see around 24000' (V-1650-7), and 29400-29800' (V-1650-3) with ram compression. The Spitfire climbed faster than the P-51's did, so I'd figure they'd have had better AMPG up high.


The figures being quoted were for a Sptfire *LF.IX* with a Merlin* 66*.

The Merlin 66 was considered a"low altitude" engine. The *F.IX* got the Merlin *63* which had a higher altitude rating. The difference seems to lie in the superchargers with different rotor sizes and gearing ratios.

Merlin 63 11.5/10.1 rotor dia; 6.39/8.03 gear ratios. combat power low gear @ altitude 1,710 @ 8,500ft; combat power high gear 1,510 @ 21,000ft
Merlin 66 12.0/10.1 rotor dia; 5.79/7.06 gear ratios. combat power low gear @ altitude 1,705 @ 5,750ft; combat power high gear 1,580 @ 16,000ft

V-1650-3 12.0/10.1 rotor dia; 6.39/8.095 gear ratios. combat power low gear @ altitude 1,530 @ 15,750ft; combat power high gear 1,300 @ 26,500ft
V-1650-7 12.0/10.1 rotor dia; 5.80/7.34 gear ratios. combat power low gear @ altitude 1,705 @ 5,100ft; combat power high gear 1,300 @ 26,500ft

The V-1650-7 is often described as nearly the equivalent of the Merlin 66

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## Zipper730 (Apr 28, 2022)

Geoffrey Sinclair said:


> I only have 25 pages from AVIA 20/3030 and 6 from Air 20/3312 as at the time I was only after what happened, not what might happen or proposed plans which make up the bulk of those files.


If I may ask, can you put them up here? Is there any issues regarding copyright?


> Early in the war the RAF standard characteristics cruise height was 15,000 feet, that was changed to 20,000, the performance figures are meant to be standards for basic planning purposes, adjusted according to the mission.


What would be the optimum cruise altitude for the Spitfire Mk.VII/VIII and Mk.IX with the Merlin 63.


> The idea Spitfires were retrofitted with the larger tanks helps explain the uncertainties about what capacity individual aircraft had.


Yeah, I figured they had the tanks available earlier.


> Mustang 221 gallons internal 2x62.5 gallon external = 346 gallons


Okay, that makes sense. It's weird how the conversions that they're using for American aircraft don't perfectly translate across (221 imperial gallons computes out to 265.4099 US gallons and the P-51B/C's had a capacity of 269 gallons).



EwenS said:


> The figures being quoted were for a Sptfire *LF.IX* with a Merlin* 66*.
> 
> The Merlin 66 was considered a"low altitude" engine. The *F.IX* got the Merlin *63* which had a higher altitude rating. The difference seems to lie in the superchargers with different rotor sizes and gearing ratios.


No, the Spitfire cited by Geoffrey Sinclair was the Spitfire F. Mk.IX, and the engine cited was specifically the Merlin 63. The problem was that the RAF seemed to calculate 20000' as a default altitude for basic performance calculations. The calculations are just not accurate unless the plane cruises at 20000'.


> Merlin 63 11.5/10.1 rotor dia; 6.39/8.03 gear ratios. combat power low gear @ altitude 1,710 @ 8,500ft; combat power high gear 1,510 @ 21,000ft
> Merlin 66 12.0/10.1 rotor dia; 5.79/7.06 gear ratios. combat power low gear @ altitude 1,705 @ 5,750ft; combat power high gear 1,580 @ 16,000ft
> 
> V-1650-3 12.0/10.1 rotor dia; 6.39/8.095 gear ratios. combat power low gear @ altitude 1,530 @ 15,750ft; combat power high gear 1,300 @ 26,500ft
> V-1650-7 12.0/10.1 rotor dia; 5.80/7.34 gear ratios. combat power low gear @ altitude 1,705 @ 5,100ft; combat power high gear 1,300 @ 26,500ft


The V-1650-3/-7 figures don't look right (I don't know enough about the Merlin 63 & 66 to even guess).


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## Milosh (Apr 29, 2022)

Zipper730 said:


> 221 imperial gallons computes out to 265.4099 US gallons


*257.1661 gal
1 gal *is equal to *1.1636 gal*


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## ThomasP (Apr 29, 2022)

I am pretty sure 1 Impgal = 1.2 USgal

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## wuzak (Apr 29, 2022)

EwenS said:


> The figures being quoted were for a Sptfire *LF.IX* with a Merlin* 66*.
> 
> The Merlin 66 was considered a"low altitude" engine. The *F.IX* got the Merlin *63* which had a higher altitude rating. The difference seems to lie in the superchargers with different rotor sizes and gearing ratios.
> 
> ...



The V-1650-7 was equivalent to the Merlin 65/66. The gear ratios were slightly different because of the different drive systems (UK built Merlins had Farman type drive, Paclard 2 stage Merlins had Wright epicyclic system).

The Merlin 63 was a strengthened version of the Merlin 61, and retained the 11.5"/10.1" superchargers. Later production 2-stage Merlins had the 12"/10.1" supercharger.

When the Spitfire LF.IX was being built so too was the Spitfire HF.IX, which used the Merlin 70. The Merlin 70 had the same ratios as the 63, but had the 12"/10.1" supercharger.


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## wuzak (Apr 29, 2022)

Admiral Beez said:


> The Germans had a terrible time using twin-engined, two-seater fighters as daylight bomber escorts. Would the British have failed as badly had they sent the Mosquito fighter variant as a daylight bomber escort?



Daylight long range day fighter Mosquitoes would have performed poorly as escorts. Basically the could not compete with single engine interceptors. 

The Mosquito was not designed for the traditional fighter role. It did well at night against other night fighters, and it could have some success against s/e fighters when the circumstances were right.


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## wuzak (Apr 29, 2022)

Zipper730 said:


> While it has some of the following disadvantages
> 
> Critical altitude is lower than the P-51B, topping out at around 19000 feet. While the aircraft seems to retain a good degree of speed all the way up to around 25000', it's climb-rate dips more than speed with altitude. Somewhere between 10000-20000', the P-51B starts to generate a climb-rate that exceeds the Tempest Mk.II, and, by 30000', it has over twice the climb-rate.
> Compared to the Tempest Mk.II, however: It (provided I did my conversions right) does appear to be superior to the Fw 190A across significant portions of the envelope in terms of rate of climb. With the Fw 190D, there appears to be an advantage from 0' to around 195000' with the Fw-190D doing around 40 fpm better around 30000'.



The Tempest II (Centaurus) only started in service in early 1945.


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## EwenS (Apr 29, 2022)

wuzak said:


> The Tempest II (Centaurus) only started in service in early 1945.


The first production Tempest II, MW735 from the Bristol Aeroplane Co production line, first flew on 4 Oct 1944.

183 squadron was the first to receive them in Aug 1945 at Chilbolton. It was renumbered 54 squadron on 15 Nov 1945. The next unit was 247 squadron, again at Chilbolton, beginning late in Aug. The next units to get them were in India in 1946.

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## Zipper730 (Apr 29, 2022)

E
 EwenS


I didn't know they weren't online until the last few weeks of WWII...


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## GregP (Apr 29, 2022)

ThomasP said:


> I am pretty sure 1 Impgal = 1.2 USgal



Technically, 1 Imp Gal = 1.20095 US Gal.

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## Zipper730 (Apr 29, 2022)

*On Imperial to US Gallons,*


M
 Milosh
, no it's not. For most purposes you'd just multiply by 1.2 for simplicity purposes, but if I recall it's technically 1.2009499204287 (I've typed that in so many times on excel due to the faulty arrangement of the sheet that it might very well have embedded itself into my memory ), though I think GregP's figure of 1.20095 is probably good enough for most purposes.

In either way the number doesn't come out to 269 US gallons, which was the correct fuel load the plane could carry (the left & right wings both carry 92 gallons apiece for 184 and the center tank carries 85 gallons).

*On Merlin variants,*

1. What's a Farman-type gear-train like? I know what an epicyclic system sort of looks like...
2. The V-1650-7/Merlin 65/66 hit ACA at 19000' correct?
3. What was the Merlin-63's ACA (I think the V-1650-1 was 24000').

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## pbehn (Apr 29, 2022)

Zipper730 said:


> *On Imperial to US Gallons,*
> 
> 
> M
> ...


Do you realise what you are discussing taking a gallon down to 13 decimal places? Are you discussing the weight of fuel or the volume?

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## Thumpalumpacus (Apr 29, 2022)

pbehn said:


> Do you realise what you are discussing taking a gallon down to 13 decimal places? Are you discussing the weight of fuel or the volume?



The weight (more correctly, mass) doesn't change, but the volume can and does. Anyone who's heard the whoosh of pressurized air escaping your car's fuel-cap when you go to refill can get that. Temperature changes can and do cause fuel to expand or contract. See: https://www.consumerwatchdog.org/resources/DPReportHotFuelUSAJune07.pdf

Is a gallon a measure of volume or mass? I seem to remember it being a measure of volume, but I could being suffering CRS.

Nothing to detract from your point about 13 decimal places being rather silly.


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## pbehn (Apr 29, 2022)

Thumpalumpacus said:


> The weight (more correctly, mass) doesn't change, but the volume can and does. Anyone who's heard the whoosh of pressurized air escaping your car's fuel-cap when you go to refill can get that. Temperature changes can and do cause fuel to expand or contract. See: https://www.consumerwatchdog.org/resources/DPReportHotFuelUSAJune07.pdf
> 
> Is a gallon a measure of volume or mass? I seem to remember it being a measure of volume, but I could being suffering CRS.
> 
> Nothing to detract from your point about 13 decimal places being rather silly.


Down to 13 decimal places you are getting into the realm of moles and groups of molecules and certainly into the realm of standard temperature and pressure Boyles law etc. As per your post, if you take the filler cap off on a hot day your tank of fuel is changing all the time the cap is off, measured to 13 decimal places, and same if you take off in a plane, that is before any discussion of what happens in the carburettor. The problem with the gallon was it came before these issues, there are liquid and dry gallons in the US system. Gallon - Wikipedia

BTW the weight is correct in the discussion, the mass will not change but the weight, to 13 decimal places may do, gravity is taken as a constant, but in the limit, it isnt.


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## Thumpalumpacus (Apr 29, 2022)

pbehn said:


> Down to 13 decimal places you are getting into the realm of moles and groups of molecules and certainly into the realm of standard temperature and pressure Boyles law etc. As per your post, if you take the filler cap off on a hot day your tank of fuel is changing all the time the cap is off, measured to 13 decimal places, and same if you take off in a plane, that is before any discussion of what happens in the carburettor. The problem with the gallon was it came before these issues, there are liquid and dry gallons in the US system. Gallon - Wikipedia



That's exactly why I added the caveat that I wasn't arguing with your point that drilling down to thirteen decimal places is silly.

My understanding is that a gallon is a liquid measure of weight, not volume. Water, for instance, doesn't really expand or contract until it hits a phase-change, but volatiles like petrochemicals can and do change liquid volume IAW ambient temperature, so a gallon of gas takes up marginally more volume on a hot day compared to a cold day.

Again: not significant when you get down to 13 decimal places.

Solids aren't sold by the gallon in America, so I don't know what a gallon of wood might look like.

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## pbehn (Apr 29, 2022)

Thumpalumpacus said:


> The weight (more correctly, mass) doesn't change, but the volume can and does. Anyone who's heard the whoosh of pressurized air escaping your car's fuel-cap when you go to refill can get that. Temperature changes can and do cause fuel to expand or contract. See: https://www.consumerwatchdog.org/resources/DPReportHotFuelUSAJune07.pdf
> 
> Is a gallon a measure of volume or mass? I seem to remember it being a measure of volume, but I could being suffering CRS.
> 
> Nothing to detract from your point about 13 decimal places being rather silly.


I had this discussion (or a similar one) during a pressure test in Scotland. The engineer in charge maintained that water was not compressible so if a valve failed the water coming out would be negligible. I pointed out that all the time the pipeline was being pumped up to pressure the pipes (there were three, 20 inch diameter pipelines, all 7.5 kilometers long connected to each other for the test) were expanding, if a valve failed the water coming out was the same as the water pumped in from the moment pressure started to rise, which turned our to be several hundred gallons. The "volume" of an aircrafts tank will change depending on what you put in it, if you measure to 13 decimal places, put a gas in it has one volume, fill it with fuel it has another and fill it full of Mercury yet another, down to that limit of accuracy the tank itself changes size just by filling it. The smallest measure in metric is a nanolitre (9 decimal places) 750 million nanoliters is less than a US quart.


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## Shortround6 (Apr 29, 2022)

When you are dealing with with aircraft fuel _systems_ you often have to deal with several realities. 
Just like many other parts of aircraft the "tanks" are made to tolerances. Trying to make metal tanks to + or - several even one digit past o in millimeters is silly. In fact on a big tank the tolerance could be + or - single digit mm on left side of decimal point. And that assumes no dents or sags or..........
And that is for a metal tank, wooden tank? 
Self sealing material? It may not fill corners, it swells, it dissolves., etc. 

Then we get into can you even get 100% of the fuel back out, you often cannot and many manuals will often give a number for "usable" gallons. 
It is also not a good idea to use the last few gallons as that is where all the sediments and contaminates are hiding :;
There are fuel tank drains and they usually will take the last dregs of fuel out of the tank for maintenance. 
How well are your fuel tank fittings installed? Right to the fraction of a mm to surface of the tank or a little high?

many manuals will also give a figure for a difference between "dry weight" of an aircraft and an allowance for trapped gas and oil in the_ piping/pumps etc_. 

People have rightly pointed out the difference in temperature.
But not only is gasoline/fuel dispensed by the volume the weight doesn't mean a whole lot because gasoline will vary from batch to batch in weight even for the same volume at the same temperature because different batches are NOT made of exactly the same compounds. 
One of the most important measures of gasoline is how many BTUs per gallon. You get some gas that is several hundred BTUs per gallon low you aren't going to find it by weighing it. You will find out when the plane doesn't go as far. (or when the engine craps out because that lean setting was little leaner than you thought it was).

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## wuzak (Apr 29, 2022)

Zipper730 said:


> *On Merlin variants,*
> 
> 1. What's a Farman-type gear-train like? I know what an epicyclic system sort of looks like...
> 2. The V-1650-7/Merlin 65/66 hit ACA at 19000' correct?
> 3. What was the Merlin-63's ACA (I think the V-1650-1 was 24000').



The epicyclic gear set is what is used in modern automatic transmissions. There is a central gear (the Sun gear) and an outer internal gear (the ring gear) and a number of gears that fit between the two (the planet gears), which are held on a carrier. Depending on which gears are fixed and which are rotating determines the gear ratio and the direction of rotation.

The Farman type gearbox was a set of spur gears - one set for low gear and one for high. 







From Engines

I guess you could say the system is similar to a modern manual gearbox, but with each ratio using its own layshaft. The big central gear drives two layshafts with a pinion on one end and a gear at the other end. These gears drive the gear connected to the supercharger impeller. 

The gears have clutches to determine which gear is driving the supercharger. 

Critical altitude depends on the boost being used. And if ACA means aircraft critical altitude, then the critical altitude depends on the aircraft.

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## wuzak (Apr 29, 2022)

Thumpalumpacus said:


> Solids aren't sold by the gallon in America, so I don't know what a gallon of wood might look like.



About 0.133 cubic feet! Do they sell wood in cubic feet or yards?

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## Thumpalumpacus (Apr 29, 2022)

pbehn said:


> I had this discussion (or a similar one) during a pressure test in Scotland. The engineer in charge maintained that water was not compressible so if a valve failed the water coming out would be negligible. I pointed out that all the time the pipeline was being pumped up to pressure the pipes (there were three, 20 inch diameter pipelines, all 7.5 kilometers long connected to each other for the test) were expanding, if a valve failed the water coming out was the same as the water pumped in from the moment pressure started to rise, which turned our to be several hundred gallons. The "volume" of an aircrafts tank will change depending on what you put in it, if you measure to 13 decimal places, put a gas in it has one volume, fill it with fuel it has another and fill it full of Mercury yet another, down to that limit of accuracy the tank itself changes size just by filling it. The smallest measure in metric is a nanolitre (9 decimal places) 750 million nanoliters is less than a US quart.



Water is compressible -- at about 30,000 psi the water molecules will actually start to squeeze closer. But in comparison to volatiles, it is much less compressible/expansible.

The temperature has more to say than the actual content, and as you pointed out, at 13 decimal places the difference is less than negligible.

Obviously if a valve fails the water coming out the other end is going to have an attitude. A longer lay requires higher pressures, which counterintuitively results in lower gpm, but it's not going to be pretty all the same.


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## GregP (Apr 29, 2022)

A United States unit of liquid capacity equal to four quarts or 231 cubic inches or 3.785 liters = 1 US gallon. 

A British unit of liquid and dry capacity equal to four quarts or 277.42 cubic inches or 4.544 liters. — called also 1 imperial gallon.

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## Shortround6 (Apr 29, 2022)

wuzak said:


> About 0.133 cubic feet! Do they sell wood in cubic feet or yards?


Board feet.

1 foot X 1 foot X 1 inch = 1 board foot

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## Thumpalumpacus (Apr 29, 2022)

GregP said:


> A United States unit of liquid capacity equal to four quarts or 231 cubic inches or 3.785 liters = 1 US gallon.
> 
> A British unit of liquid and dry capacity equal to four quarts or 277.42 cubic inches or 4.544 liters. — called also 1 imperial gallon.



Thanks, Greg. I was sure it was volume.


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## Zipper730 (Apr 30, 2022)

wuzak said:


> The epicyclic gear set is what is used in modern automatic transmissions. There is a central gear (the Sun gear) and an outer internal gear (the ring gear) and a number of gears that fit between the two (the planet gears), which are held on a carrier. Depending on which gears are fixed and which are rotating determines the gear ratio and the direction of rotation.
> 
> The Farman type gearbox was a set of spur gears - one set for low gear and one for high.


Understood



wuzak said:


> Critical altitude depends on the boost being used. And if ACA means aircraft critical altitude, then the critical altitude depends on the aircraft.


Yeah, I screwed up with ACA, I meant uninstalled engine critical altitude. If I recall the US used around 60 inches early on max which l ater increased.


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## Snowygrouch (Apr 30, 2022)

This may be of use. I would note that its likely the consumption was regarded as very important too, which in the case of the P-47 was dramatically higher than he Mustang which would have had a large impact on logistical planning for supply. This is not readily apparent from this particular graph, (although can you infer it from adding up the capacities and dividing by the range) I do have a chart of consumption but I just cant find it this second...

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## Milosh (Apr 30, 2022)

Would be nice if the P-39 and the Spitfire IX were also included.


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## Thumpalumpacus (Apr 30, 2022)

wuzak said:


> About 0.133 cubic feet! Do they sell wood in cubic feet or yards?



My store sells it by the cubic foot. Roadside guys here sell it by the quarter-cord/half-cord etc.


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## Shortround6 (Apr 30, 2022)

Thumpalumpacus said:


> My store sells it by the cubic foot. Roadside guys here sell it by the quarter-cord/half-cord etc.


Firewood or lumber or guitar wood

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## wuzak (Apr 30, 2022)

Thumpalumpacus said:


> My store sells it by the cubic foot. Roadside guys here sell it by the quarter-cord/half-cord etc.



Never heard of that cord unit before!

Here firewood is typically sold by weight (well, mass actually).


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## Thumpalumpacus (Apr 30, 2022)

Shortround6 said:


> Firewood or lumber or guitar wood



Firewood!


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## Milosh (Apr 30, 2022)

Thumpalumpacus said:


> My store sells it by the cubic foot. Roadside guys here sell it by the quarter-cord/half-cord etc.


And face cord.
A face cord is the next most common unit of measurement. It refers to any stack of wood that is 4 feet (1.2 m) high and 8 feet (2.4 m) long. The depth or width of the pile is less than 4 feet (1.2 m), which means that each piece of wood in the pile is less than 4 feet (1.2 m) long.









3 Ways to Measure a Cord of Wood - wikiHow


Wood is sold to consumers by the cord, but if you've never purchased wood before, you might be wondering what a cord of wood actually is. Moreover, since firewood is rarely sold by the full cord, there are certain considerations worth...




www.wikihow.com


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## special ed (Apr 30, 2022)

Quarter cord and half cord. Are those musical measures with out the "H"?
Are we getting into another furlongs per fortnight things?

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## GregP (Apr 30, 2022)

Thumpalumpacus said:


> Thanks, Greg. I was sure it was volume.



If you want to get really technical, I believe it is volume at a particular temperature. Let's look at just above freezing to just below boiling.

At 34°F, the specific volume of water is 0.01602 ft^3/lb.

At 200°F, the specific volume is 0.01663 ft^3/lb.

So, from just above freezing to just below boiling, the volume changes by 3.8%. That's why physics experiments dealing with water are usually done at about 72°F (about 22°C). If they are NOT done at some standard temperature, the temperature is at least noted so corrections can be made for other temperatures.

In aviation, the standard temperature is 59°F (15°C), as we all know. We all know that if we fill our Cessna's tanks with fuel at low temperature and the day warms up, fuel will weep out of the vent as the fuel expands. So, the only time we fill up completely in early morning is when we are going to fly somewhere and be in the air for at least an hour or so. That way, we don't waste fuel. All of us "cheap" guys try to fuel up when the temperature is at its coolest. If we sell fuel, we try to sell during the heat of the day.

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## don4331 (Apr 30, 2022)

GregP said:


> In aviation, the standard temperature is 59°F (15°C), as we all know. We all know that if we fill our Cessna's tanks with fuel at low temperature and the day warms up, fuel will weep out of the vent as the fuel expands. So, the only time we fill up completely in early morning is when we are going to fly somewhere and be in the air for at least an hour or so. That way, we don't waste fuel. All of us "cheap" guys try to fuel up when the temperature is at its coolest. If we sell fuel, we try to sell during the heat of the day.


Up north here, because to the massive temperature difference between the cold of winter and the heat of summer, the pumps have temperature compensation built in, so no real advantage on when you fuel.


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## SaparotRob (Apr 30, 2022)

special ed said:


> Quarter cord and half cord. Are those musical measures with out the "H"?
> Are we getting into another furlongs per fortnight things?


How many furlongs to the hogshead does your car get?

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## special ed (Apr 30, 2022)

I don't have a car. However if I had half of a horse would I have 1/2 horse power?

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## SaparotRob (Apr 30, 2022)

What if it’s a quarter horse?


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## GregP (Apr 30, 2022)

don4331 said:


> Up north here, because to the massive temperature difference between the cold of winter and the heat of summer, the pumps have temperature compensation built in, so no real advantage on when you fuel.



Yes, there is. If you fuel in the morning and fill to the brim, you'll weep fuel out of the vent as it warms up. Not much, but some.

Aviation gasoline has a volume correction factor of 1.0000 at 15°C. At -20°C, it is 1.0450. At 30°C, it is 0.9803.

Let's say you fill up at 15°C and your fuel load in the Cessna is 30 gallons, and late afternoon is 30°C. Then you would lose .0197 * 30 gallons, or you would vent out 0.591 gallons. Granted, .6 gallons isn't much, but if you burn 12 gallons per hour, you vented out 3 minutes of fuel. Not much, to be sure, but worth thinking about over time, particularly if your airplane has a more fuel than 30 gallons. If your plane holds 100 gallons and you burn 25 gallons per hour at cruise, you will vent almost 5 minutes of fuel overboard if you plane just sits on the ramp as temperature rises and you are full to the brim in early morning.

If you do that 30 days out of the year, you vented out 2.4 hours of fuel for no reason other than to be full in the early morning. It likely won't make or break your budget, but that's why flying club aircraft are almost always fueled to about 3/4 full only. You can bet the airlines know all about it since they burn huge amount of fuel. They would have no problem filling up if the plane is going to fly soon but, if it going to sit for a couple of hours, they'll fuel accordingly. They also fuel by weight (pounds or kilograms of Jet-A), not by volume, and they fuel according to the route to be flown and the availability of fuel at various stops along the way.

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## Howard Gibson (Apr 30, 2022)

SaparotRob said:


> How many furlongs to the hogshead does your car get?


What kind of hogshead, beer or wine?

Weights and Measures MDCCCXXXV

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## don4331 (May 1, 2022)

Zipper730 said:


> *On Merlin variants,*
> 
> 1. What's a Farman-type gear-train like? I know what an epicyclic system sort of looks like...


I think (hope) this is a slightly more descriptive picture than 
W
 wuzak
's . The Low speed shafts at the e.g. "6 O'clock" position with High speed shafts are at "3 and 9 O'clock, but in a cutaway, the shafts are rotated for better visibility - low speed at bottom, high speed at top.





Farman's patent is for the multi clutch, separate shaft drive - very similar to Volkswagen's DSG transmission.
By releasing the slow speed clutch while applying the high speed one, Farman is able to accelerate the supercharger impeller to faster speed in a controlled manner.​Rolls Royce tried using an over running freewheel (think bicycle rear hub) in Kestrel to allow faster high ratio (it added less length to engine), but impeller running at 20k rpms, caused heat related issues in the freewheel.​​The low speed has a single shaft as the load is less. The high speed has two shafts as the load is higher and RR wanted to better balance the load on the impeller shaft. They also expected the engine to spend more time at altitude, in high speed. Class 8 trucks, e.g. Kenworth's, transmission also had dual counter shafts to allow acceleration of 80k lbs without needing an overly larger transmission.​​It also allows you to understand why early Griffon Seafire's had issues with the supercharger slipping during takeoff - the single shaft for low speed was designed to hold the load of the crankshaft impeller at constant speed, not that of crankshaft suddenly being accelerated for take off, while impeller needs a moment to catch up.​During normal flight: Crankshaft and Impeller would not be running the same speed - crankshaft would be running a constant 2,700rpm, while impeller would be a constant 15,750rpm in low range (Assuming Griffon 65, 5.84:1 step up gears). At take off, the engine is accelerating from say 1,000 rpms to 2,700 requires the impeller to accelerate from 5,840 to 15,750 (almost 10k rpm increase) with the boost control is fighting the impeller to avoid over boosting. Something had to give.​​For the Griffon 101, with 3 speeds, you have a single shaft in "6 O'clock" for LS, another single shaft at "12 O'clock" for MS, and shafts at "3 & 9 O'clock" for FS. And the cool part is - you can do it all in the thickness of a couple gears. With a little juggling of components, no addition length to engine.​​The rest of 
W
 wuzak
post is bang on.

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## Zipper730 (May 26, 2022)

PAT303 said:


> This is the bit that annoys me the most, one of the reasons Spitfires only had 85G of fuel was to keep the weight down so they could climb fast, the reason they had to climb fast was because they didn't have enough fuel to loiter. By simply putting 20G under the seat as per Sydney Cottons mod...


I've never been able to resolve this, but what PR variant had the 20 IG tank under the pilot?

I can't find anything on that...



pbehn said:


> What is "low speed" the landing speed of a Tempest was 110 MPH


Was there a typical rule of thumb for computing landing speed in those days? Postwar, generally landing speeds seemed to be around 1.15-1.2 Vs and later on, that went up to 1.3 Vs.



GregP said:


> You mean position correction for airspeed?


Correct


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## pbehn (May 26, 2022)

Zipper730 said:


> Was there a typical rule of thumb for computing landing speed in those days? Postwar, generally landing speeds seemed to be around 1.15-1.2 Vs and later on, that went up to 1.3 Vs.


You seem to spend your life looking for rules of thumb. By the time the Tempest was put into service things had long since passed using rules of thumb, except maybe for a test pilots first flights, but test pilots stayed alive by not using such guidance.


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## Zipper730 (May 29, 2022)

Uh, actually the 1.2 VS was pretty common in the post-war period.


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## Reluctant Poster (May 29, 2022)

Zipper730 said:


> I've never been able to resolve this, but what PR variant had the 20 IG tank under the pilot?
> 
> I can't find anything on that...
> 
> ...


I don’t believe it was under the pilot. Spitfire Bs and Cs had a 29 gallon tank in the rear fuselage.

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## Reluctant Poster (May 29, 2022)

Reluctant Poster said:


> I don’t believe it was under the pilot. Spitfire Bs and Cs had a 29 gallon tank in the rear fuselage.


A detailed discussion of PR Spifires was posted in this forum a few years back





The Story of the Photographic Reconnaissance Spitfire


The story of the Spitfire as a photographic reconnaissance aeroplane starts at the end of 1939, by which time operational experience with Blenheims and Lysanders used on photographic missions had shown that an aeroplane capable of flying much faster and higher was needed. A special flight...



ww2aircraft.net


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## Zipper730 (May 29, 2022)

I suspect this was a misunderstanding that ended up becoming a myth of history: After awhile it becomes repeated so many times by well-intentioned and reputable people that it ends up becoming established as fact.


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## Zipper730 (Jul 26, 2022)

Shortround6 said:


> But some what seriously the P-38 was conceived as a long endurance interceptor.


That's not exactly right. The P-38's specs were classified as being an interceptor because of the fact that Lt. Saville and Kelsey wanted to circumvent requirements that the USAAF had placed into effect which limited the total load of guns & ammo to 500 lb. (they wanted 1000 lb. as a starting point), they felt that two engines would probably be needed to carry such an armament load with decent performance (particularly since they figured at least 1500 hp would be needed and, given they wanted inlines, and none produced that power, that kind of made it a necessity), and pursuit aircraft were restricted to 2 engines (unless they had multiple crew like the YFM-1).

Since Lieutenants cannot override Majors, Colonels, and Generals, they sidestepped it by classifying the plane as an interceptor (a designation which might have existed in other countries, but did not appear to formally exist here), which allowed them to draw up their own specifications around a new category. With names having power, and being careful in never mentioning the term "pursuit" when referring to their design (they procured the XP-39 probably as an insurance policy in case they couldn't slip the two-engined designs passed the top-brass), they ultimately got their wish.

The aircraft was basically intended to be a fighter with high-altitude performance and heavier armament.


> Granted it got drop tanks before _some_ other US fighters


Ironically, due to Kelsey. He figured they were needed, but there was (at best) little interest in using them for anything other than ferry missions at best.

The USN was using them on the PV's to extend their range over water and, at the risk of his career, he put nothing in writing and managed to get everything in place. His superiors were not impressed at first, but ultimately let it go (there was a need for a photo-reconnaissance aircraft, which the USAAC lacked).



EwenS said:


> Merlin 63 11.5/10.1 rotor dia; 6.39/8.03 gear ratios. combat power low gear @ altitude 1,710 @ 8,500ft; combat power high gear 1,510 @ 21,000ft
> Merlin 66 12.0/10.1 rotor dia; 5.79/7.06 gear ratios. combat power low gear @ altitude 1,705 @ 5,750ft; combat power high gear 1,580 @ 16,000ft
> 
> V-1650-3 12.0/10.1 rotor dia; 6.39/8.095 gear ratios. combat power low gear @ altitude 1,530 @ 15,750ft; combat power high gear 1,300 @ 26,500ft
> V-1650-7 12.0/10.1 rotor dia; 5.80/7.34 gear ratios. combat power low gear @ altitude 1,705 @ 5,100ft; combat power high gear 1,300 @ 26,500ft


I think you made a typo there, the -7's critical altitude was lower than the -3.


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## Zipper730 (Jul 26, 2022)

Regarding the Hawker Tempest, I remember some mention of problems being present with the wing-mounted radiators on the Mk.I and the Sabre IV engine having a tendency to consume excessive oil at higher RPM levels. Does anybody have anything as to why that's the case?


S
 Shortround6

W
 wuzak


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## Shortround6 (Jul 26, 2022)

Zipper730 said:


> That's not exactly right. The P-38's specs were classified as being an interceptor because of the fact that Lt. Saville and Kelsey wanted to circumvent requirements that the USAAF had placed into effect which limited the total load of guns & ammo to 500 lb. (they wanted 1000 lb. as a starting point)................


I may be wrong but somewhere one of the few differences between the X-608 (later P-38) and the X-609 (later P-39) proposals or requirements (and they changed over the years) was that the X-608 was supposed to haven an endurance of 2 hours as opposed to the X-609's endurance of 1 hour. 
Now between 1936 and 1939 the desired speeds at both 20,000ft and sea level changed and there may have been other changes. 
The 1000lbs of armament was a goal as they hadn't actually selected the gun/s and numbers yet. The 37mm was the front runner but there was a 23mm and perhaps a 25mm. Not sure if the Navy 28mm (1.1in ) was any more than a pipe dream. The 1000lb weight may include the bracing, brackets, ammo boxes etc in addition to the gun and ammo weight. 

The "endurance" may have been at high speed (max cruise) rather than most economical and if so a single engine plane was going to need around 100 gallons (600lbs) more fuel for 2 hours of endurance vs one hour. An extra 600lbs of fuel (or even 500lbs) in a 5-6000lb plane (XP-39 was supposed to be well under 6000lbs when still on paper).

In some of these requirements there were minimum speeds listed, desired speeds listed, and the companies replies might give a "guarantee" which if the actual completed airplane didn't meet the company had to pay penalties. (Curtiss XP-46 failed bad enough that the government got back over $14,000.)

There was certainly a lot of room for changes and for short descriptions to leave a lot out. 

But the basic difference between the X-608 and the X-609 seems to be the change in endurance since both planes were supposed to meet the same speed and climb goals the Bell 3 was supposed to carry a much heavier armament than the P-36/P-37. Perhaps the X-608 was supposed to carry more armament but by the the time the XP-39 was on paper the high armament was a given.
Bell has started with an even earlier design that this. 




With the reduction gear on the engine and four (?) machine guns above the extension shaft in 1936. 
Then they moved the reduction gear to just behind the prop and fitted the cannon (with that pan magazine) and finally they moved the engine even further back and put the cockpit between the guns and the engine.




Drawing says four .50cal guns or two .50cal and one 25mm. 

It doesn't matter if they called it a pursuit or an interceptor, if they wanted plane that could fly at 1.75-2 hours at max continuous or close to it (and some of these 1930s specifications were rather unrealistic) you were going to have trouble with a single engine plane.

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## PAT303 (Jul 26, 2022)

Reluctant Poster said:


> I don’t believe it was under the pilot. Spitfire Bs and Cs had a 29 gallon tank in the rear fuselage.


Sydney Cotton put a 20G tank under the pilots seat but the aircraft was a stripped out fighter, the 29G rear fuselage tank was in the first production PR model.


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## ThomasP (Jul 26, 2022)

I could be wrong, but it does not look like a 20 Impgal fuel tank would fit under the seat. The control runs would interfere?








The above photo is from the SpitfireSite.com


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## PAT303 (Jul 27, 2022)

The first two ''proof of concept'' you could call them had 20G tanks, the production versions 29G.


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## Zipper730 (Jul 27, 2022)

P
 PAT303
Okay, so they could put a 20 IG tank under the pilot's seat, but found the 29 IG tank was superior? I'm curious though if that could be added if they wanted some kind of "escort" Spitfire (I think the idea probably isn't a very good one, but we're in what-if territory...).


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## PAT303 (Jul 27, 2022)

Zipper730 said:


> P
> PAT303
> Okay, so they could put a 20 IG tank under the pilot's seat, but found the 29 IG tank was superior? I'm curious though if that could be added if they wanted some kind of "escort" Spitfire (I think the idea probably isn't a very good one, but we're in what-if territory...).


Zipper, Sydney Cotton fell out of favour with the RAF soon after his Cotton specials started flying, I've as yet not been able to find a drawing of the under seat or rear tank, I assume and I have no proof that the 29G tank could also be the same the Malta MkV's used, there's lots of info on the 42G lower 33G upper and 33G lower 33G upper tanks but that's it, I've also found info on the leading edge tanks that say they were 57G but most sources claim 66G, I've been meaning to find a definitive book on the PR Spit's. As for an escort Spit, easy to get to Germany once the MkVII VIII and IX Spits get into service.


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## drgondog (Jul 28, 2022)

PAT303 said:


> Zipper, Sydney Cotton fell out of favour with the RAF soon after his Cotton specials started flying, I've as yet not been able to find a drawing of the under seat or rear tank, I assume and I have no proof that the 29G tank could also be the same the Malta MkV's used, there's lots of info on the 42G lower 33G upper and 33G lower 33G upper tanks but that's it, I've also found info on the leading edge tanks that say they were 57G but most sources claim 66G, I've been meaning to find a definitive book on the PR Spit's. As for an escort Spit, easy to get to Germany once the MkVII VIII and IX Spits get into service.


'Easy to get into Germany'? How about returning after 20 min combat? Did the RAF publish Combat Radius charts similar to AAF?


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## Zipper730 (Jul 28, 2022)

PAT303 said:


> Zipper, Sydney Cotton fell out of favour with the RAF


Why?


> I've as yet not been able to find a drawing of the under seat or rear tank


So, it's still a possibility that's it's one of those historical myths.


> I've also found info on the leading edge tanks that say they were 57G but most sources claim 66G


From what I was told, the prototype/concept had 57 IG, then production models had 66 IG.

I'm curious if the range figures for escort for the Spitfire were based on S-weaving atop the formations or simply flying waves of fighters as long-ranged fighter-sweeps aimed at clearing out the way? Honestly, that seems the best profile for escorts.

In Korea, that seemed to be the norm since jet-fighters had such a speed-difference that it made other methods of escorting B-29's impractical.


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## drgondog (Jul 28, 2022)

Zipper730 said:


> Why?
> So, it's still a possibility that's it's one of those historical myths.
> From what I was told, the prototype/concept had 57 IG, then production models had 66 IG.
> 
> ...


Combat Radius tables (AAF) are straight line travel for taxi to takeoff to climb to cruise to fight to cruise to descend to loiter to land. The extra burn in lowered mpg relatve to straight line, for essing during close escort, was factored by Gp Operations as every escort profile was somewhat different - to very different.

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## Shortround6 (Jul 28, 2022)

drgondog said:


> 'Easy to get into Germany'?



It wasn't that hard to get a Spitfire "into" or even out of Germany. It was about 300 miles to the Ruhr.

The Problem was getting Spitfires into and out of Eastern Germany. Or not even Eastern Germany. 
Granted the Raid on Stuttgart on Sept 6th 1943 took off from west of London but that trip was 525 miles until the northward dog leg/bomb run. 
Again we can grant that the fighters, if there had been any that could go the distance, could fly from air fields close to the coast.

I am sure you you know the numbers much better than I do, it just bothers me when people try to short hand the escort problem (and you were doing a short reply to somebody else) and gloss over the fact that Germany was just over 300 miles wide for much of it's height and the skinny part (Southern Germany) was lower than Britain and need a longer flight path. 

To escort to Eastern Germany needed roughly double the range of escorting to Western Germany.


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## drgondog (Jul 28, 2022)

Shortround6 said:


> It wasn't that hard to get a Spitfire "into" or even out of Germany. It was about 300 miles to the Ruhr.
> 
> The Problem was getting Spitfires into and out of Eastern Germany. Or not even Eastern Germany.
> Granted the Raid on Stuttgart on Sept 6th 1943 took off from west of London but that trip was 525 miles until the northward dog leg/bomb run.
> ...


Actually SR, the P-47 which had inherently more range than Mark IX could barely escort into Germany and return - with the 200gal ferry tank on a straight withdrawal support on July 28 - a little over 200+ miles to RV with no essing. First 8th AF fighter penetration into Germany. The 75 gal combat tank extended combat radius to about 225mi.

That was the point I was making about severe lack of Combat Radius for Spit IX. With the Spit IX, before P-47C conversion, the 4th FG was barely making St. Omer to Ostend on pure sweeps with no essing/escort - 100mi. AFAIK, zero Spitfires (save recon) made it to Germn border until RAF moved some to the Continent post D-Day.

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## Mike Williams (Jul 28, 2022)

drgondog said:


> AFAIK, zero Spitfires (save recon) made it to Germn border until RAF moved some to the Continent post D-Day.



Fwiw, UK based Spitfire IXs and XIV could and did reach into Germany, for example:



http://www.wwiiaircraftperformance.org/150grade/1-squadron-oprep-27aug44.jpg




http://www.wwiiaircraftperformance.org/150grade/1_Sq_ORB_Aug44.jpg




http://www.wwiiaircraftperformance.org/150grade/165_ORB_Aug44.jpg





http://www.wwiiaircraftperformance.org/610-ORB-1sept44.jpg




http://www.wwiiaircraftperformance.org/350-ORB-11Sept44.jpg




http://www.wwiiaircraftperformance.org/130_Oprep-12Sept44.jpg




http://www.wwiiaircraftperformance.org/402-Form541-12Sept44.jpg

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## drgondog (Jul 28, 2022)

Mike Williams said:


> Fwiw, UK based Spitfire IXs and XIV could and did reach into Germany, for example:
> 
> 
> 
> ...


I stand corrected Mike - I did forget about the 90 gal tanks in September 1944. That said, I was focused on 1943 operations. You did notice that the sorties were shallow penetrations and two hour flights? Dad had about 20 in 6.5-7.5 hr duration and one nearly 8 hr to Piryatin/Kiev. Nevertheless I learned something as most Germany penetrations for RAF (and IX AF mediums) were executed w/Mustangs

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## drgondog (Jul 28, 2022)

drgondog said:


> I stand corrected Mik - I did forget about the 90 gal tanks in September 1944. That said, I was focused on 1943 operations.





drgondog said:


> Actually SR, the P-47 which had inherently more range than Mark IX could barely escort into Germany and return - with the 200gal ferry tank on a straight withdrawal support on July 28 - a little over 200+ miles to RV with no essing. First 8th AF fighter penetration into Germany. The 75 gal combat tank extended combat radius to about 225mi.
> 
> That was the point I was making about severe lack of Combat Radius for Spit IX. With the Spit IX, before P-47C conversion, the 4th FG was barely making St. Omer to Ostend on pure sweeps with no essing/escort - 100mi. AFAIK, zero Spitfires (save recon) made it to German border until RAF moved some to the Continent post D-Day.


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## BiffF15 (Jul 28, 2022)

drgondog said:


> I stand corrected Mike - I did forget about the 90 gal tanks in September 1944. That said, I was focused on 1943 operations. You did notice that the sorties were shallow penetrations and two hour flights? Dad had about 20 in 6.5-7.5 hr duration and one nearly 8 hr to Piryatin/Kiev. Nevertheless I learned something as most Germany penetrations for RAF (and IX AF mediums) were executed w/Mustangs


It is no wonder that your Godfather, along with so many others, couldn't hear well. I can't imagine spending that much time behind an unmuffled V12 with 1940 era hearing protection.

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## PAT303 (Jul 28, 2022)

drgondog said:


> 'Easy to get into Germany'? How about returning after 20 min combat? Did the RAF publish Combat Radius charts similar to AAF?


Been over this ad nauseum, the MkVII, VIII and IX could all have 500+ mile combat radius's allowing 15 minutes fuel for take off and climb plus 20 minutes combat, , both Jeffery Quill on behalf of Supermarine and the A&AEE on behave of the RAF did it in two separate tests, MkXIV's did 300 miles with just a 90G drop tank escorting bombers to the Ruhr.


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## PAT303 (Jul 28, 2022)

Zipper730 said:


> So, it's still a possibility that's it's one of those historical myths.


It's mentioned numerous times, apparently there is a drawing in a book called Merlin PR Spitfires in detail, I'm going to chase that book up


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## PAT303 (Jul 28, 2022)

Mike Williams said:


> Fwiw, UK based Spitfire IXs and XIV could and did reach into Germany, for example:
> 
> 
> 
> ...


With rear and leading edge tanks the MkVIII has 196G internal fuel with the 90G dropper, plenty of fuel to range further than they did on those missions.


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## PAT303 (Jul 28, 2022)

drgondog said:


> Actually SR, the P-47 which had inherently more range than Mark IX could barely escort into Germany and return - with the 200gal ferry tank on a straight withdrawal support on July 28 - a little over 200+ miles to RV with no essing. First 8th AF fighter penetration into Germany. The 75 gal combat tank extended combat radius to about 225mi.
> 
> That was the point I was making about severe lack of Combat Radius for Spit IX. With the Spit IX, before P-47C conversion, the 4th FG was barely making St. Omer to Ostend on pure sweeps with no essing/escort - 100mi. AFAIK, zero Spitfires (save recon) made it to Germn border until RAF moved some to the Continent post D-Day.


How about this, you have MkV's and P47's flying out to 200 miles sweeping the sky, MkIX's warm up taxi and take off and climb to 20,000ft on the rear 33G upper tank burning it off to restore combat maneuvers, they are allowed 24G as per the flight books for that they go a bit farther on the extra fuel, they cruise out behind the short range escort at 20,000ft @ 220 miles per hour at most economic cruise on the 90G dropper, at around the 200mile mark which is the limit of the MkV/P47 the Spits speed up to 250miles per hour @ max weak mixture and continue to fly as far as the dropper allows which is around the 500 mile mark, once they get there they have 96G in the main tank, 42G in the rear tank and 26G in the leading edge tanks, or if they use Mareng bags 36G in the leading edge. Depending on time or model you can have 85G or 96G main tank, 75G or 66G rear tanks, 26G or 36G leading edge plus 90G dropper, the consumption is around 5.7 miles per gallon plus there was a 14.5G oil tank developed for the PR spits that was also used the the fighter versions. The Spitfires based in the UK could have made a serious contribution in regards to escorting bombing missions in the darker days of 1943 early '44.


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## 33k in the air (Jul 28, 2022)

PAT303 said:


> How about this, you have MkV's and P47's flying out to 200 miles sweeping the sky, MkIX's warm up taxi and take off and climb to 20,000ft on the rear 33G upper tank burning it off to restore combat



One little problem: that altitude is not high enough. 25,000 feet would be the minimum in order to be a few thousand feet above the bomber formation.


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## PAT303 (Jul 28, 2022)

33k in the air said:


> One little problem: that altitude is not high enough. 25,000 feet would be the minimum in order to be a few thousand feet above the bomber formation.


Well fly at 25,000ft, problem solved.


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## FLYBOYJ (Jul 28, 2022)

PAT303 said:


> Well fly at 25,000ft, problem solved.


And are you going to get the range (and speed) required on "a weak mixture" at 25,000?"


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## 33k in the air (Jul 28, 2022)

PAT303 said:


> Well fly at 25,000ft, problem solved.



How much more fuel is expended in climbing to 25,000 feet compared to 20,000 feet? Also, does the calculation of radius include the distance covered in the climb? It's probably not a good idea to be climbing over enemy territory.

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## PAT303 (Jul 29, 2022)

FLYBOYJ said:


> And are you going to get the range (and speed) required on "a weak mixture" at 25,000?"


It's late 1942 early '43 how many B17 crews would pass on having MkIX's flying escort because they could only go 450 miles instead of 500 running a richer mixture?, remember they were bolting unpressurised ferry tanks under P47's trying to get every last mile out of them at that time.


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## PAT303 (Jul 29, 2022)

33k in the air said:


> How much more fuel is expended in climbing to 25,000 feet compared to 20,000 feet? Also, does the calculation of radius include the distance covered in the climb? It's probably not a good idea to be climbing over enemy territory.


Lets find problems to stop it from working instead of solutions meaning it can. You have 197G internal fuel, 90G external and 5.7 miles to the gallon, nothing else in your fighter inventory has that at the time, make it work.


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## FLYBOYJ (Jul 29, 2022)

PAT303 said:


> It's late 1942 early '43 how many B17 crews would pass on having MkIX's flying escort because they could only go 450 miles instead of 500 running a richer mixture?, remember they were bolting unpressurised ferry tanks under P47's trying to get every last mile out of them at that time.


I really don't have a dog in the fight but until you do some "exact" calculations, you're just guessing this would work.


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## FLYBOYJ (Jul 29, 2022)

PAT303 said:


> Lets find problems to stop it from working instead of solutions meaning it can.


Crack out performance charts and do the math! That will be the proof in the pudding


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## PAT303 (Jul 29, 2022)

FLYBOYJ said:


> I really don't have a dog in the fight but until you do some "exact" calculations, you're just guessing this would work.


I'm not guessing anything, get the thing flying and learn, that's what they did with the P51 at the start, they learnt on the go not only with the plane but tactics and planning, it's better than having the things sitting on the coast with only the single 85G main tank and 175 mile radius.


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## FLYBOYJ (Jul 29, 2022)

PAT303 said:


> I'm not guessing anything, get the thing flying and learn,


How lean? You know when you lean you're raising cylinder head temps? At what RPM? Can you maintain a desired cruise speed and fuel burn? Until you figure this out, you're guessing


PAT303 said:


> that's what they did with the P51 at the start, they learnt on the go not only with the plane but tactics and planning,


Yes they did, that's why I say look in the pilot's manual


PAT303 said:


> it's better than having the things sitting on the coast with only the single 85G main tank and 175 mile radius.


It is, and when you "do the math" you many not be "sitting on the coast with only the single 85G main tank and 175 mile radius."


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## PAT303 (Jul 29, 2022)

Learn not lean, you've missed the ''r'' haha, all I'm saying is do it, they had the plane they had the tanks and knew how the Spit flew from the long range flights they did with the MkV, load the things with fuel and start working out the problems.


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## Thumpalumpacus (Jul 29, 2022)

Not all problems submit to human ingenuity, unfortunately.

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## FLYBOYJ (Jul 29, 2022)

PAT303 said:


> *Learn not lean, you've missed the ''r'' haha*, all I'm saying is do it, they had the plane they had the tanks and knew how the Spit flew from the long range flights they did with the MkV, load the things with fuel and start working out the problems.


No Pat - you *LEAN* a mixture! Or as you say, a "weak mixture" haha



Until you do the math your scenario is a guess. It's that simple just spouting out what you "think" the aircraft will do is meaningless

Food for thought - you bring this up but don't you think someone recognized this 79 years ago? If so, ask yourself why this wasn't done...

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## 33k in the air (Jul 29, 2022)

An article from the Royal Aeronautical Society published in 2017:

Escort Spitfire - a missed opportunity for longer reach?

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## PAT303 (Jul 29, 2022)

Flyboy, we are talking about two different things mate, I don't mean lean the fuel mixture, I mean learn what works once you get the thing flying, load the Spit with fuel and start flying missions, say 350 miles radius and work out real world consumption figures. Like I posted have the long ranged MkIX's escorted out the first 200 miles by MkV's and P47's so they can save fuel, your not getting to Berlin but who's cares in '42-'43, bomb the Ruhr into a waste land instead.


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## PAT303 (Jul 29, 2022)

33k in the air said:


> An article from the Royal Aeronautical Society published in 2017:
> 
> Escort Spitfire - a missed opportunity for longer reach?


Spitfire to Berlin? – Making Supermarine’s Finest an Escort Fighter There are some good idea's in this one too, everyone seems fixated on Berlin, leave it to the RAF at night and bomb everything else within fighter coverage.


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## FLYBOYJ (Jul 29, 2022)

PAT303 said:


> Flyboy, we are talking about two different things mate, I don't mean lean the fuel mixture, I mean learn what works once you get the thing flying, load the Spit with fuel and start flying missions, say 350 miles radius and work out real world consumption figures. Like I posted have the long ranged MkIX's escorted out the first 200 miles by MkV's and P47's so they can save fuel, your not getting to Berlin but who's cares in '42-'43, bomb the Ruhr into a waste land instead.


OK - but this "could have" been calculated before going on missions and relying on "trial and error." These real world fuel consumption figure "should have" been calculated at the factory wayyyy before they hit a front line unit.


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## PAT303 (Jul 29, 2022)

FLYBOYJ said:


> Food for thought - you bring this up but don't you think someone recognized this 79 years ago? If so, ask yourself why this wasn't done...


Same could be said for the 109, you have to ask why they weren't fitted with DT's during the BoB, doesn't make sense either.

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## wuzak (Jul 29, 2022)

FLYBOYJ said:


> And are you going to get the range (and speed) required on "a weak mixture" at 25,000?"



Maximum cruise speed for a PR.XI (similar to a IX) with Merlin 63 was 397mph @ 31,000ft - 2,650rpm, +7psi boost. Maximum cruise speed at 38,000ft was 378mph - 2,650rpm, +1.1psi boost. These were maximum cruise settings.

@ 28,000ft, 2,350rpm, +3.5psi boost, the cruise speed was 351mph.

So, fast enough, but I don't know the fuel consumption at those settings.

Mk.IX fighter will be draggier, so will be a few mph down, Merlin 66 models will have lower critical altitudes, so lower speeds again. Merlin 70 Mk.IXs (HF.IX) would be about the same as the XI.

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## FLYBOYJ (Jul 29, 2022)

wuzak said:


> Maximum cruise speed for a PR.XI (similar to a IX) with Merlin 63 was 397mph @ 31,000ft - 2,650rpm, +7psi boost. Maximum cruise speed at 38,000ft was 378mph - 2,650rpm, +1.1psi boost. These were maximum cruise settings.
> 
> @ 28,000ft, 2,350rpm, +3.5psi boost, the cruise speed was 351mph.
> 
> ...


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## Geoffrey Sinclair (Jul 29, 2022)

If you make up a Spitfire VIII using the various maximum size fuel tanks ever fitted to Merlin Spitfires with the external and/or rear fuselage tanks able to refill the main tanks after take off, the theoretical combat radius comes to around 500 miles, cruising all the way at maximum weak-mixture power setting of 320 mph at 20,000 feet using 66 gallons per hour, corresponding with an engine setting of 2,400 rpm, +4 lbs boost. Which translates to much but not all of Germany when based in England, taking direct courses. The requirements for combat, reserves and the need to burn off some of the rear fuselage fuel before combat means the external fuel limit is about 90 gallons.

When the Ministry of Aircraft Production began reporting external fuel tank production in December 1943 Spitfire 90 gallon tanks were being made at about 500 per month.

The standard Spitfire VIII with a 90 gallon external tank could go about as far as the 1943 P-47, add a 33 gallon rear fuselage tank the ability to fight with it still full and it can go about as far as the 1944 P-47.

There are plenty of reasons why a longer range Spitfire would be nice to have over and above escorting long range bombers but the need for the escort mission in 1944 can be seen from the amount of use made of RAF P-51s, I do not have the numbers but understand some but not a lot of such sorties. Certainly the USAAF would have liked more long range escorts available up to around May 1944. Probably if the RAF had offered the 8th Air Force the equivalent of 1 to 3 fighter groups of long range Spitfires in mid to late 1943 the arrangements would have continued into 1944, but you would expect with the RAF P-51 units replacing the Spitfire ones. The Spitfires then take advantage of their longer range on missions over France then from September 1944 onwards while being based in Britain able to escort Bomber Command day missions over Western Germany, Bomber Command was not going to do deep penetration day raids.

The RAF did not like the way Sidney Cotton was running the reconnaissance unit, more as a collection of civil pilots than a military unit. Also in building up the unit Cotton did what he felt he needed to do, rather than go through the slow official channels, finally a few times Cotton had done what the RAF powers that be had said was not possible, in at least one case to the Admiralty's delight. It also probably did not help he was part of the pre war spying system.

The early Spitfire PR types are a maze of fuel and camera installations, conversions would have further conversions. N3069 and N3071 were the original prototypes, arrived 13 October 1939, they were initially fitted with cameras but no extra fuel. The plans were to have a range of 1,000 miles on internal fuel. N3116 and 3117 arrived 4 February and P9307 to 9310 on 11 February 1940.

When designations were handed out Type A was for N3069 and N3071 as orginally modified, PR IB or type B short range was for them fitted with a 29 gallon under seat tank, PR IC or type C long range was for a new camera fit, along with 30 gallons under the pilot seat and 30 gallons in a fixed blister under the port wing. The type D was for the wing leading edge fuel tanks which did away with the need for the under seat tank. One census says 68 mark I and 27 mark V were converted to the PR types but that includes many of the 32 mark I officially built as PRIII. PR mark III production began in August 1940, PR mark IV in June 1941.

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## drgondog (Jul 29, 2022)

PAT303 said:


> How about this, you have MkV's and P47's flying out to 200 miles sweeping the sky, MkIX's warm up taxi and take off and climb to 20,000ft on the rear 33G upper tank burning it off to restore combat maneuvers, they are allowed 24G as per the flight books for that they go a bit farther on the extra fuel, they cruise out behind the short range escort at 20,000ft @ 220 miles per hour at most economic cruise on the 90G dropper, at around the 200mile mark which is the limit of the MkV/P47 the Spits speed up to 250miles per hour @ max weak mixture and continue to fly as far as the dropper allows which is around the 500 mile mark, once they get there they have 96G in the main tank, 42G in the rear tank and 26G in the leading edge tanks, or if they use Mareng bags 36G in the leading edge. Depending on time or model you can have 85G or 96G main tank, 75G or 66G rear tanks, 26G or 36G leading edge plus 90G dropper, the consumption is around 5.7 miles per gallon plus there was a 14.5G oil tank developed for the PR spits that was also used the the fighter versions. The Spitfires based in the UK could have made a serious contribution in regards to escorting bombing missions in the darker days of 1943 early '44.


Begging he question 'why not'?


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## drgondog (Jul 29, 2022)

PAT303 - If you wish, first get the RPM/Boost and fuel burn rates for warm up, take off, form into squadron, climb to cruies, cruise to RV, fight for 20 minutes, cruise back, descend, loiter reserve for 20 min at low RPM/Boost.

http://www.wwiiaircraftperformance.org/mustang/P-51D_15342_AppendixB.pdf Try this for 1650-7 recognizng that the Spit IX drag is greater and probably not able to achieve same speed for same burn, even with less Induced drag at cruise.

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## PAT303 (Jul 29, 2022)

drgondog said:


> Begging he question 'why not'?


It does doesn't it, let me ask a question, when it comes to ANY Spitfire conversation what is the first thing people say was the Spits biggest problem, lack of range, every single time, lack of range, even the RAF knew it, they even went to all the trouble of making this abomination.



yet it wasn't until the MkXVI, a basic MkIX with a Packard Merlin that it came off the production line with a genuine worthwhile increase in internal fuel, in September 1944, yep it beggars the question.


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## PAT303 (Jul 29, 2022)

We have all seen this chart, a MkIX with 196G internal and 90G dropper would fall between the P47 and P38 but 6-9 months earlier.


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## drgondog (Jul 29, 2022)

PAT303 said:


> View attachment 679539
> 
> We have all seen this chart, a MkIX with 196G internal and 90G dropper would fall between the P47 and P38 but 6-9 months earlier.


That chart s wrong on so many levels. The Combat Radius for the P-47C without belly tank was 125+ mi CR. The Combat Radius of the P-47C/D with 75 gal c/l tank was 230mi (Aug 1943),with 2x150gal pylon tanks was 425mi circa March/April 1944. These values for 25K cruise zone altitude.

To be in ballpark for Spit IX and comparative, you need cruise speed without 90 gal tank (outbound), with 90 gal tank from takeoff through climb through cruise and into combat, need fuel consumtion at at least MP butAAF doctrine specfied 15min MP, 5 min WEP. Then cruise clean with reduced internal weight from fuel consumed. I suspect that optimal cruise stated in miles per gallon are less in a Mark IX than the cleaner Mustang III by at least 1/2mpg.

BUT, the MOST critical variable is Internal fuel available after extended Radius 'projection' is reached and 20 minuts of combat has burned an hour of cruise fuel in 20 minutes.

For the simple answer 'why not', consider the P-51B-7 with 85 ga fuse tank had 269gal internal fuel to the 85 gallon Spit values. AND - same basic engine and about 20% lower total Drag.

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## Shortround6 (Jul 29, 2022)

drgondog said:


> 85 ga fuse tank had *269 US gal* internal fuel to the 85 imp gallon (*102 US gal*) Spit values


Fixed it for you for the nit pickers.


drgondog said:


> same basic engine and about 20% lower total Drag.


So even in the Summer of 1943 (July 1st 1943 date on P-51B manual) the P-51B has 150 imp gallons of internal fuel. Super Spit is going to need an extra 65 gallons of internal fuel to match plus and extra 20 imp gallons to cover the difference in drag (figuring 13.3% more for drag to be generous) or 170 imp gallons internal. P-51B had 125 imp gallons external in the drop tanks (pair of US 75 gallon).

The US later figured that a P-51 without the rear tank and with a pair of 75 US gal drop tanks was good for a 460 mile radius.

US and the RAF may have used slightly different engine limits. US used 2320rpm and 36in (3lbs ?) boost as the _provisional_ limits (July 1943 remember) on the Merlin V1650-3 for lean mixture. The British may have used 2400rpm and 4lbs for lean mixture?

At 2600-2700rpm and 7lbs of boost (rich mixture) the engine can be burning about double the GPH that it did at max lean.

The _provisional _range tables in the July 1943 manual show the P-51B running right on the edge of shifting to rich mixture. 215 IAS at 25,000ft with the pair of 75 US gallon drop tanks require 2350rpm and FT and 65 US GPH.
Running at 210IAS at 25,000ft with tanks requires 2250rpm at FT but only 52 US GPH.

Now the later manuals show some restrictions on the rear fuselage tank. Like at over 1/2 capacity when doing a tight turn or pull out the airplane will under go elevator reversal. Just like it sounds the plane will go in the opposite direction the pilot intends. This tendency gets less as fuel is burned off until at about 1/2 tank it goes away. This why both the Mustang and the Spitfires with rear tanks tried to burn off a fair amount of the rear tank fuel before switching to the drop tanks.
However for the Spitfire this also means that when the drop tank is dropped you only have the remaining fuel in the internal tanks. Which at absolute best ( 96 Imp gal for the two main tanks +26 IMP gal for the wing tanks + about 30 IMP gal for the rear tank (the 2nd rear tank having been used up) and using 54 imp gal for 20 minutes combat leaves about 98 Imp gal to get home.
Now we are arguing over the exact tank fitment. And the amount of fuel the Spitfire can keep in the rear tank/s and still fight for the average pilot.
And arguing about difference the difference is between the Spitfire and the Mustang speed/fuel burn.

PR Spits were not supposed to fight, they were supposed to run.

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## FLYBOYJ (Jul 29, 2022)

Geoffrey Sinclair said:


> If you make up a Spitfire VIII using the various maximum size fuel tanks ever fitted to Merlin Spitfires with the external and/or rear fuselage tanks able to refill the main tanks after take off, *the theoretical combat radius comes to around 500 miles, cruising all the way at maximum weak-mixture power setting of 320 mph at 20,000 feet using 66 gallons per hour, corresponding with an engine setting of 2,400 rpm, +4 lbs boost. * Which translates to much but not all of Germany when based in England, taking direct courses. The requirements for combat, reserves and the need to burn off some of the rear fuselage fuel before combat means the external fuel limit is about 90 gallons.


Is this indicated in any performance chart?


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## Shortround6 (Jul 29, 2022)

Geoffrey Sinclair said:


> theoretical combat radius comes to around 500 miles, cruising all the way at maximum weak-mixture power setting of 320 mph at 20,000 feet using 66 gallons per hour,





Geoffrey Sinclair said:


> The requirements for combat, reserves and the need to burn off some of the rear fuselage fuel before combat means the external fuel limit is about 90 gallons.


It doesn't matter what the external fuel was, It the British wanted they could have come up with a 120 IMP gal drop tank. 

What mattered was the roughly 54 Imp gal for the combat allowance and the 10-15 gal reserve for finding your own (or any) airfield after crossing the coast. Also the wind was usually coming from the west. 
Your operational radius was the distance you could fly at the desired exit speed/s *after* combat and *before* having to hunt for a friendly airfield.

Again _provisional _numbers for the P-51B are 315mph at 20,000ft using 36imp gals GPH clean and 329mph at 20,000ft using 51 GPH with the pair of 75 US gallon drop tanks. 

I am sure the Spit would show a difference with and without the drop tanks. A newer manual could very well show a difference in the P-51 numbers. 

It is going to take 25-30 gallons just to warm up - takeoff - climb to 25,000ft (doesn't include form up on the charts but lets assume it does) so that takes care off most of the burn off of the rear tanks to get close to combat capacity. Warm up/take off is done on the main tank/s but any fuel over flow in cruise is routed back to the main tank/s so they are full or near fuel after a couple of hours.

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## 33k in the air (Jul 29, 2022)

drgondog said:


> That chart s wrong on so many levels. The Combat Radius for the P-47C without belly tank was 125+ mi CR. The Combat Radius of the P-47C/D with 75 gal c/l tank was 230mi (Aug 1943),with 2x150gal pylon tanks was 425mi circa March/April 1944. These values for 25K cruise zone altitude.



That chart appears to be based on the charts published in the document _Eighth Air Force Tactical Development August 1942–May 1945_ (Chart A and B, p.97 of document, p.119 of PDF). Below is what is shown on Chart A for the P-47:

May 1943 = 175 miles
June 1943 = 230 miles
July 1943 = 340 miles (1 x 75-gallon drop tank)
Aug. 1943 = 375 miles (1 x 108-gallon drop tank) (+33 gallons, +35 miles compared to 1 x 75-gallon)
Feb. 1944 = 425 miles (1 x 150-gallon drop tank) (+42 gallons, +50 miles compared to 1 x 108-gallon)
Feb. 1944 = 475 miles (2 x 108-gallon drop tanks) (+66 gallons, +50 miles compared to 1 x 150-gallon)

The increases are roughly one mile per additional gallon carried when drop tanks are used.

The accompanying text which describes the figures shown on the chart, however, says the 475-mile range was achieved with 2 x 150-gallon tanks. I think that text is a typo, as only an additional 50 miles is gained despite carrying an additional 150 gallons, which is out of place with the gains made from the prior drop tanks.

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## Mike Williams (Jul 29, 2022)

Geoffrey Sinclair said:


> When the Ministry of Aircraft Production began reporting external fuel tank production in December 1943 Spitfire 90 gallon tanks were being made at about 500 per month.



That's interesting and has got me curious now as to when the 90 gallon tanks started to be used on Spitfires operationally. I have a few docs on hand and will dig around for others:



http://www.wwiiaircraftperformance.org/111-kennedy-10sept43.jpg

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## drgondog (Jul 29, 2022)

33k in the air said:


> That chart appears to be based on the charts published in the document _Eighth Air Force Tactical Development August 1942–May 1945_ (Chart A and B, p.97 of document, p.119 of PDF). Below is what is shown on Chart A for the P-47:
> 
> May 1943 = 175 miles
> June 1943 = 230 miles
> ...


Dean Published the AAF Combat Radius Tables for several of the conditions above. Reference pp 599-600.Also note the differences between 10K and 25K altiude with 10K cruise achieving a delta of ~+25-50mi for in-line. His source for the 'practical' Combat radius was developed by USAAF at Wright Field 1943-1945.

From a practical standpoint there also was a difference between Wright Field/contractor collaboration Range tables, the Operating Manual Tables and Operations in ETO. Notably the 108gal single went into Operations in September but no VIII FC P-47 penetrations as far as Bremen occurred until November 13, 1943. Strikes Occurred, but without fighter escort at the target. The escorted strike on Bremen , with the 4th penetrating deepest, launching from forward base Shipdam near coast, Direct air miles in 325mi range.

Despite having 108 gal external, the escort was not going past Quackenbruck, Lingen and Munster in October, so AFAIK Bremen Target Escort (optimal as little essing performed) first occurred on November 13th, 1943. The 55th FG (P-38s) got several that day and the 355th performing Withdrawal support at Bremen got several VCs just west of Bremen as B-17s were returning home. The 355th staged at Bungay for the mission, well forward of Steeple Morden, about 325 mi to Bremen w/108 gal tank. .The Only Group level missions in excess of Bremen was when they were able to mount 2x150 'flat tanks' to cross over 400 mi CR in April/May 1944.

To the table/data above the first 108 gal belly tank missions were flown in late September, 1943. To the table above the value '475' for 2x108 tanks in Feb 1944, only a very few P-47C/D had been depot modified with interanal plumbing and racks by February, The -15/-16s were arriving but not operational in squadron levels until late March.

Here is the bottom line between the various and contradictory CR charts. A.) none match up to he Wright Field published charts that Dean drew from, b.) no fighter missions actual combat radius in context of extremes for losses and victory credits in air combat are closely aligned wth the combat radius values specified _Eighth Air Force Tactical Development August 1942–May 1945_ (Chart A and B, p.97 of document, p.119 of PDF). The contradiction doesn't make 'them' wrong but does raise into question the practical standard for operations planning using various sources.

For my book (deathless prose to be sure) I based much of my range tables on Dean and performed my own Breguet calcs using published fuel consumption rates published in various flight tests and bench tests. There were Contradictions requiring judicious application of silver dollar to resolve. The tie breaker wa always, 'so how far did they plan to go, with reserve for weather/winds and combat and loiter time on return'. 

On March 29 the 56th penetrated as far as Dummer Lake in the 390 mi range from Boxted w 1x150s and as far as Stuttgart with 2x150s n late April. (420mi) on a Sweep with no escort duties. Until the P-47s got their 65 gal increase internally they were limited to a Brunswick/Stuttgart radius of operations.

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## 33k in the air (Jul 29, 2022)

drgondog said:


> Dean Published the AAF Combat Radius Tables for several of the conditions above. Reference pp 599-600.Also note the differences between 10K and 25K altiude with 10K cruise achieving a delta of ~+25-50mi for in-line. His source for the 'practical' Combat radius was developed by USAAF at Wright Field 1943-1945.



For what it's worth, _Eighth Air Force Tactical Development August 1942–May 1945_ was prepared by the Eighth Air Force and the Army Air Forces Evaluation Board (European Theater of Operations) and published in July 1945.

So it seems there are different sets of figures from what would seem to be official sources.


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## drgondog (Jul 29, 2022)

Yes - and to be clear all the Wright Field and Contractor Range Tables were established in clear weather in many cases close to STP in controlled conditions and many authors did Not understand even the fundamentals of publishing the boundary conditions to proclaim what a Combat Radius actually was.

It was - and is - a planning document for a pilot or operations officer to understand an ideal flight plan to go from A to B - then draw conclusions for the group CO/Squadron CO to evaluate adverse winds aloft encountered contrary to briefed weather, loiter for early R/V, seein a bomber force in trouble past the 'point of no return' based on the 20 minute combat burn. 

AFAIK, there was no single document in which the 'Bible' was collectively agreed until 1945. Additionally the individul Pilot Operating Manual Tables exhibited straight line travel for the selected assumptions. including fuel burn rate vaues baked for each MP/RPM recommendation, internal/external tanks and altitudes based on their own flight tests. That said, Materiel Command was in the approval cycle.

I also recall that in our earlier discussion n this subject months ago, one of the 8th AF radius charts WAS accompanied by some boundary conditions very much like the AAFMC 1945 chart values (in some cases) but not referencing MC or Contractor charts. 

I will state unequivocally that the optimistic CRs were composed by Brequet equations which are reasonably sohisticated and far easier with computers to integrate each leg with sfc values for propsed RPM/Boost per leg (withut having to worry about wingman jockying throttle trying to stay on element leader's wing who in turn is trying to stay with the boss). Actual ETO/Combat variables took a chunk out of each segment thus calculated.

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## Glider (Jul 29, 2022)

The following couple of pages may be of interest as the describe the use of 90 gallon tanks as a routine operation from around December 1943. The problem being the shortage of the tanks.

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## Geoffrey Sinclair (Jul 30, 2022)

FLYBOYJ said:


> Is this indicated in any performance chart?


Yes if you are referring to the fuel consumption. Cruise 320 mph TAS at 20,000 ft, corresponds with an engine setting of 2,400 rpm, +4 lbs boost, consumption 66 gallons per hour. In the following I will add 20 gallons for a reserve, which would be around 30 minutes at 170 mph IAS. And ignore the obvious consumption penalties for carrying external loads, hauling a heavier load to altitude, penalties for formation flying, variations between individual aircraft and pilots when it came to fuel consumption, or an allowance for faulty navigation. Or the gains from using economic cruise for part of the outbound and return


Shortround6 said:


> It doesn't matter what the external fuel was, ... It the British wanted they could have come up with a 120 IMP gal drop tank.What mattered was the roughly 54 Imp gal for the combat allowance and the 10-15 gal reserve for finding your own (or any) airfield after crossing the coast. Also the wind was usually coming from the west. ... It is going to take 25-30 gallons just to warm up - takeoff - climb to 25,000ft


The RAF allocation was 23 gallons for take-off and climb to 20,000 ft and 36 gallons for 15 minutes of combat, where do the figures quoted above come from?


Shortround6 said:


> Your operational radius was the distance you could fly at the desired exit speed/s *after* combat and *before* having to hunt for a friendly airfield.


As I have been using. Spitfire VIII 124 gallons internal.

Spitfire VIII in 1945 with 75 gallon rear fuselage tank, 40 gallons need to be used before it is considered safe to enter combat leaving 35, giving 124+35 = 161 -36 -20 = 105 for return, 40 internal + 90 external -23 = 107 gallons outbound.

The early 1943 Spifire VIII 124-36-20 = 68 gallons for return, 90 external -23 = 67 gallons outbound. That gives a nominal combat radius of around 300 miles.

Therefore the comment about an external fuel limit of around 90 gallons.

The what if later 1943 Spifire VIII equipped and able to enter combat with a full 33 gallon rear fuselage tank, that adds 80 miles to the nominal combat radius.

Roger Freeman combat radius, 8th Air Force,
P-47 280 miles 84 gallon external tank, August 1943
P-47 325 miles 108 gallon external tank, September 1943
P-47 375 miles 165 gallon external tank, February 1944

Keeping the Spitfire able to reach about as far as the P-47 as the aim, given how much combat the P-47 saw in the time period.

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## PAT303 (Jul 30, 2022)

Geoffrey Sinclair said:


> Keeping the Spitfire able to reach about as far as the P-47 as the aim, given how much combat the P-47 saw in the time period.


Exactly, we don't need to fly to Berlin or do anything fancy, just get the Spit into Germany late '42 onwards, P47's saw continuous air combat with the limited range they had, the Spit could have joined them.


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## drgondog (Jul 30, 2022)

33k in the air said:


> For what it's worth, _Eighth Air Force Tactical Development August 1942–May 1945_ was prepared by the Eighth Air Force and the Army Air Forces Evaluation Board (European Theater of Operations) and published in July 1945.
> 
> So it seems there are different sets of figures from what would seem to be official sources.


As long as the subject has been beaten to death, the primary issue is that the Combat Radius as defined, is a straight line optimal climb from take off to cruise, cruise, fight and return. 

ETO added much longer engine start and taxi for 48+ airplanes, staged take off usually in pairs, forming up fights, squadrons into group before climb, fly essentialy straight line to coast, branch to R/V - with weather always a wild card.

The P-47 ops were even more complicated because much of its history in ETO was close escort, requiring 'essing' for at least one squadron from R/V to R/V,then return. With the long range role, both the Mustang and P-38 flew many missions picking p the baton from the jug groups much farther away from base before any 'essing' required - usually much closer to target. 

Another consideration for you in your own analysis - is to look at the encounter reports and note that almost zero P-47 Victory credits and MACRS were beyond the target for their escorted bombers. These docs paint a clearer picture of the radius of action to return to base on remaining internal fuel after a fight. Those reports are a clearer Practical marker for the mission planning application of 'real Combat Radius' vs 8th AF or MC publications.

Only when the P-47D-25 with 370gal internal were the 'extended CR' feasible.

The longet mission I found in 1944 for P-47D-25+ (with 370 gal + 2x150s) was Oct 7, 1944 when the 78th swept to Leipzig and Dec 4 when 56th swept to W/Brandenburg.

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## GregP (Jul 30, 2022)

Shortround6 said:


> It doesn't matter what the external fuel was, It the British wanted they could have come up with a 120 IMP gal drop tank.
> 
> What mattered was the roughly 54 Imp gal for the combat allowance and the 10-15 gal reserve for finding your own (or any) airfield after crossing the coast. Also the wind was usually coming from the west.
> Your operational radius was the distance you could fly at the desired exit speed/s *after* combat and *before* having to hunt for a friendly airfield.
> ...



I don't think you will see 315 mph @ 36 gph @ 20,000 feet. Maybe 56 gph, but not 36 gph unless you are at sea level, 1600 rpm, and 220 mph.


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## 33k in the air (Jul 30, 2022)

drgondog said:


> As long as the subject has been beaten to death . . .



Perhaps so, but I still find the discussion useful precisely because the sources differ on the figures, and only by discussing it can such differences be sorted out and the truth, however imperfectly, approached.



drgondog said:


> Another consideration for you in your own analysis - is to look at the encounter reports and note that almost zero P-47 Victory credits and MACRS were beyond the target for their escorted bombers. These docs paint a clearer picture of the radius of action to return to base on remaining internal fuel after a fight. Those reports are a clearer Practical marker for the mission planning application of 'real Combat Radius' vs 8th AF or MC publications.



Alas, I don't have access to archives I can visit in person, so I'm limited to what has been digitized and posted online. This is both great and frustrating. It's great in that I can view information I'd probably never be able to see otherwise, but it's frustrating because there is still so much material that has yet to be digitized. That said, I'm thankful for everything that has been digitized and made more readily accessible.



drgondog said:


> Only when the P-47D-25 with 370gal internal were the 'extended CR' feasible.
> 
> The longet mission I found in 1944 for P-47D-25+ (with 370 gal + 2x150s) was Oct 7, 1944 when the 78th swept to Leipzig and Dec 4 when 56th swept to W/Brandenburg.



Were these the 'flat' 150-gallon tanks or the P-38's teardrop-shaped tanks? The 150/165-gallon P-38 tanks were definitely used in the Pacific by P-47s, based on photos of wartime P-47 units in the PTO.


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## drgondog (Jul 30, 2022)

33k in the air said:


> Perhaps so, but I still find the discussion useful precisely because the sources differ on the figures, and only by discussing it can such differences be sorted out and the truth, however imperfectly, approached.
> 
> 
> 
> ...


Both but mostly 'flat' because it could be attached to C/L ack, whereas the round crosssection 150 was a potential hazard. Kenney was 'different' from Eaker/Doolittle in command style,


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## drgondog (Jul 30, 2022)

GregP said:


> I don't think you will see 315 mph @ 36 gph @ 20,000 feet. Maybe 56 gph, but not 36 gph unless you are at sea level, 1600 rpm, and 220 mph.


 I think this is best chart. Racks only Cruise - 2050RPM 29" 52gph 303mph for 25K http://www.wwiiaircraftperformance.org/mustang/P-51D_15342_AppendixB.pdf

May 1945 Flight tests for range in P-51D-15


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## PAT303 (Jul 31, 2022)

drgondog said:


> Despite having 108 gal external, the escort was not going past Quackenbruck, Lingen and Munster in October, so AFAIK Bremen Target Escort (optimal as little essing performed


He's another idea, lets forget the escorting in 1942-43, just send Spit V's and P47's out as far as they can go, say 200 miles and let MkIX's go as far as they can go which will be over 400 miles, instead of escorting per say lets make them fighter sweeps so they can fly at their best altitude an speed, the Luftwaffe are going to engage if there is a bomber mission going on so the fighters can engage independently of they are doing.


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## 33k in the air (Jul 31, 2022)

PAT303 said:


> He's another idea, lets forget the escorting in 1942-43, just send Spit V's and P47's out as far as they can go, say 200 miles and let MkIX's go as far as they can go which will be over 400 miles, instead of escorting per say lets make them fighter sweeps so they can fly at their best altitude an speed, the Luftwaffe are going to engage if there is a bomber mission going on so the fighters can engage independently of they are doing.



Here's a better idea: put a Merlin into a P-51 airframe in early 1941 instead of late 1942.

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## Shortround6 (Jul 31, 2022)

33k in the air said:


> Here's a better idea: put a Merlin into a P-51 airframe in early 1941 instead of late 1942.


About the 42nd time somebody has suggested this

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## Shortround6 (Jul 31, 2022)

PAT303 said:


> just send Spit V's and P47's out as far as they can go, say 200 miles and let MkIX's go as far as they can go which will be over 400 miles, instead of escorting per say lets make them fighter sweeps so they can fly at their best altitude an speed,



And this would work so much better than the whole "lean to France" thing why?

The Germans had had almost 2 years of experience in avoiding fighter sweeps and trying to bounce small pockets of bombers (used as bait) and small pockets of fighters (disconnected from the main groups). 

A fighter sweep that is even 10 minutes off in timing is going to be 50 miles from the bombers. (assuming the fighters are doing 300mph). 
The Germans had radar, they had the ability to plot tracks. Maybe not as well as the British but this was 1942-43 and not 1940.


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## 33k in the air (Jul 31, 2022)

Shortround6 said:


> About the 42nd time somebody has suggested this



Great minds think alike (and with the benefit of hindsight)!


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## Shortround6 (Jul 31, 2022)

33k in the air said:


> Great minds think alike (and with the benefit of hindsight)!


Some basic problems with the idea are
1. the US (Packard) only made about 42 Merlin engines in all of 1941. and 2/3rds of them are for the British.
2. Those engines are the equivalent of the Merin XX (as used in Hurricane IIs), and if stuffed into a P-51 Airframe it may give you a better airplane than a P-40F (in the summer of 1942), but it won't give you an airplane that can escort B-17s and B-24s.


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## drgondog (Jul 31, 2022)

PAT303 said:


> He's another idea, lets forget the escorting in 1942-43, just send Spit V's and P47's out as far as they can go, say 200 miles and let MkIX's go as far as they can go which will be over 400 miles, instead of escorting per say lets make them fighter sweeps so they can fly at their best altitude an speed, the Luftwaffe are going to engage if there is a bomber mission going on so the fighters can engage independently of they are doing.


LW basically ignored 8th AF Fighter Sweeps in 1943. Only the bombers drew their undivded attention. P-47s didn't make a straight line penetration of 200 miles until 4th, 78th and 56th first tried draggy 200 gal Ferry Tank.

Internal fuel is THE Boundary condition for max combat range.

When you compare (or fantasize) about LR escort role for Spitfire, compare your visionary Spit internal fuel to even Mustang I with 170 gal internally or P-51B/C w/269gal. It took the 85 gal fuse tank inst'l for P-51B and upgrade on P-38J to add 2x55gal LE tanks to get either one operational over Berlin.

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## 33k in the air (Jul 31, 2022)

Shortround6 said:


> Some basic problems with the idea are
> 1. the US (Packard) only made about 42 Merlin engines in all of 1941. and 2/3rds of them are for the British.
> 2. Those engines are the equivalent of the Merin XX (as used in Hurricane IIs), and if stuffed into a P-51 Airframe it may give you a better airplane than a P-40F (in the summer of 1942), but it won't give you an airplane that can escort B-17s and B-24s.



Perhaps not, but it does demonstrate the promise of the combination, and that might provide an earlier impetus to more aggressively develop the combination.


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## tomo pauk (Jul 31, 2022)

Shortround6 said:


> 2. Those engines are the equivalent of the Merin XX (as used in Hurricane IIs), and if stuffed into a P-51 Airframe it may give you a better airplane than a P-40F (in the summer of 1942), *but it won't give you an airplane that can escort B-17s and B-24s.*



(my bold)
The P-51/Merlin XX combo will certainly produce a far better airplane than it was the P-40F. 
Why it will not be able to escort the B-17s and B-24s?


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## Shortround6 (Jul 31, 2022)

33k in the air said:


> Perhaps not, but it does demonstrate the promise of the combination, and that might provide an earlier impetus to more aggressively develop the combination.


The two stage Merlin didn't show up in production until the spring of 1942 (in England), there were about 4 squadrons of MK IX Spits at Dieppe in Aug of 1942 and RR was already working on drawings to fit the engine into the Mustang in England and NA was working on their version in the US in Aug (didn't fly until oct/nov?) 

So there was no "combination" in early 1941. You might have been able to work on the engine mounts but you didn't know how big the radiator was going to be, you didn't know how big the oil cooler was going to be, and you didn't know how big the intercooler on the engine (the Merlin XX didn't have an intercooler) or how big the intercooler in the radiator duct/s was going to be. 
You didn't know were everything was going to be under the cowling or how big the ducts were going to be and you didn't know how far in front of the firewall the engine was going to be or how much the engine weighed or were the center of gravity was going to be (making final design of the engine mounts (more than just laying out the bolt holes) a bit difficult.) 
The bare and dry (no fluids) 2 stage engine weight just 200lbs more than the bare and dry 2 speed engine. The extra cooling arrangements (radiator and fluid, oil system without oil and intercooler ) added over 300lbs to the Merlin XX installation. And you needed a bigger propeller. 

The early 2 stage engine offered around the same power as the 2 speed engine did but it offered it at 27-29,000ft instead of 18,500ft. 

That is what made the possibility of a Merlin powered escort fighter for US turbo charged bombers become attractive. 
A two speed supercharged plane was never going to operated at the altitudes necessary to provide top cover to the bombers. Flying several thousand feet below the bombers was not going to work. 

Stuffing a 2 speed Merlin into a Mustang I airframe could have been done, but it wasn't going to give you an escort fighter for the US and the whole engine installation is going to have to be redone anyway for the 2 stage engine/s.

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## Shortround6 (Jul 31, 2022)

tomo pauk said:


> (my bold)
> The P-51/Merlin XX combo will certainly produce a far better airplane than it was the P-40F.
> Why it will not be able to escort the B-17s and B-24s?



Because the engine hits it's FTH between 18,500ft and 20,000ft, by the time you get to 25,000ft you have lost at least 10% of you power.
The Turbo B-17s and B-24s can maintain sea level power to 25,000 (roughly).

Now in the summer of 1942 nobody knew exactly what altitudes the bombers would be operating at. It took quite a while to figure that out (also what cruising speeds). 

However, with hindsight,  we can see that a P-51B could reach 30,000ft in just under 10 minutes and being climbing at 2175fpm. The engine was making 1075hp and could make 51.6in of boost.

Our P-40F needed 21 minutes to reach 30,000ft and in fact it needed just over 10 minutes to get from 20,000ft to 30,000ft. 
Granted it was running at 2850 rpm and not 3000rpm.
But the engine was only making 680hp and the plane was climbing at 530fpm. In fact the plane was only climbing at 1000ftm at 25,000ft. 
That was about the minimum for combat maneuvers. 
Other charts show some improvement. like 1070fpm at 28,000ft. 



The Mustang airframe is going to allow the plane to go faster, it isn't going to do as much for climb, better than the P40F but not the same difference that the speed shows. And climb shows you how well the plane can maintain speed in turn or other maneuvers. 

An early P-47 (tooth pick prop and no water injection) will outclimb the 2 speed Merlin Mustang by several thousand feet (be several thousand feet higher at any given climb rate). 
The Early P-47 was making about 1600hp at 30,000ft or over double what the Merlin XX engine could give you and your early Merlin Mustang was going to weigh at around 2/3rds not 1/2. 

You can fly at 25,000ft and up, but you are not going to be able to fight well. 
Just showing up isn't going to be the solution. You are going to have to fighter above where the bombers are in order to keep the Germans from booming and zooming the bombers.

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## drgondog (Jul 31, 2022)

tomo pauk said:


> (my bold)
> The P-51/Merlin XX combo will certainly produce a far better airplane than it was the P-40F.
> Why it will not be able to escort the B-17s and B-24s?


First, NAA tried to strike relationship with Rolls in 1941, was shut down by General Motors parent company (on behalf of subsidiary Allison). Second the AAC/AAF didn't want the Mustang with any engine combo in 1941. Third, the deal betwen Packard and R-R was 50-50 production split and the P-40F/L consumed all of FY 42 Priority and funding for the Merlin XX (1650-1). Those are the practical reasons that prohibited the 'early bird'.

Most Important Reason? The first Mustang to be delivered with plumbing and external rack was NA-97 delivered at the same time as the last of NA-91 Mustang IA - and that only because NAA was allowed to propose to NAA specification - not Materiel Command after a hard poiltical fight or the A-36.

Other important reasons: 
Arnold prioritized external fuel tanks for extended Range use in Jan 1942, but MC moved like molasses on the execution of the prioity and had to be kicked in the ass in April, and still did't deliver a tested prototype for 60gal ad 75 gal combat tank until summer. 
NONE of the US fighters had a tank pressurization feature for fighters delivered in 1942 and deep into 1943 with P-38J and P-51B.
Despite intense pressure by Gen Barney Giles on Materiel Command and NAA/Republic/Lockheed/Bell/GM (XP-75) work on prototype schemes to increase inernal fuel the prototypes (NAA and Lockheed) first flew in July 1943 and kits were not designed, fabricated and shipped to Depots until Oct 1943.

Conclusions:
Even if 8th AF changed doctrine of tactical deployment of high altitude B-17/B-24 which had excellent speed at 22-25K, down to say 18K, the Merlin XX equipped airframe could not go to Berlin until the actual P-51B/P-38J. 
Wheteher XX or 1650-3 The Mustang design changes for engine and radiator changes, the bomb rack/internal plumbing, the aft fuselage fuel tank - all needed to be in production six months to field One Fighter Group for mid altitude operations in ETO. Better than P-40F? Yes but it needed the above range features and 8th AF doctrine change for lower altitude to be considered over the P-38G/H with 300gal and external 300 gal tanks - for Stuttgart/Hamburg range targets. 

But, to make the question "why not" into an early 1943 P-51B reality with Merlin XX? No sooner than Merlin 60 series save a little less time sorting out the radiator/rumble due to lower heat loads. 

To extrapolate earlier mandates necessary for mid 1943 Merlin XX operations:
prescience on part of B-17 Hq Acolytes that disaster was looming in 1943; 
full knowledge of the future is 'bright' for NAA by Oliver Echols in Feb 1940, throwing his energy into introducing NAA as a better choice for Britain and France than a two year re-tooling nightmare for P-40 -in Jan 1940; 
willingness to re-commit Merlin XX from Curtiss to NAA - when R-R Packard cut their deal; 
immediate vision that internal fuel needed priority increase based on 'unheard of' 2200 mi ferry range;
approval by GM Board to abandon sales of Allisons to NAA fighter production; Incremental funding from MC 'with no strings attached', leaving NAA to develop 'best solution' vs 'XP-75, XP-46, P-60 solutions' driven by MC.

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## Shortround6 (Jul 31, 2022)

drgondog said:


> the deal betwen Packard and R-R was 50-50 production split and the P-40F/L consumed all of FY 42 Priority and funding for the Merlin XX (1650-1).


I don't know what the deal started out as but it wound up as an initial contract for 9000 engines, 1/3 for the US and 2/3rds for the UK with peak production at 800 engines per month. 
aside from that I have no argument with anything in you post. 


Follow up contracts and changes to contracts get short shrift in most common accounts. 
It took Packard until March of 1943 to complete the original contract but I don't know when the follow up contracts were signed or what the details were. 
We do know that Packard built almost exactly 800 engines a month for the last 6 months of 1942. 
The US may not have taken delivery of the full 3000 engines from the first contract. 
Packard did build over 26,750 two speed engines by the end of 1944 and just under 18,600 two stage engines by the end of 1944. 

By the summer of 1944 Packard was building over 2000 engines a month. 

That is from the historical production perspective. Changing the numbers of engines built in 1942 requires more factory space, more machine tools and more employees. 
In some cases expanding Packard production may mean something else may not get built, tank engines? Landing craft engines? a different aircraft engine? 


perhaps somebody could have beaten some sense into a few officers in material command to allow drop tanks and the needed plumbing and pumps sooner. 

What you can't make somebody do is make a significant change in the rate of climb of a well over 8000lb airplane that was using the single stage Merlin engine at the higher altitudes (over 20,000ft). That is more physics. 
Once you specify a certain amount of weight for guns and ammo, and the desired fuel and protection and the structural strength and so one, you are going to wind up with a over 8,000lb airplane for US service. And if your available engine only offers 1100hp at the crank at 18,500ft in climb you don't have lot of options to change the climb performance. 

see. http://www.wwiiaircraftperformance.org/mustang/Power_required_available_P-51A_P-51B_P-47B.pdf

Yes this report was from late 1943 but engineers could have done (and probably did ) similar studies earlier. In fact teh P-47Ds were in production when this report was issued. 
Please note that the power curves are for thrust HP and figure in the efficacy of the propellers. 
Similar curves could have been done for higher altitudes. 

The power you have to climb is the surplus power you have between the required power to actually fly at the desired speed and the max power of the engine. 
In the case of the 3 planes shown the P-51A at 180mph needs about 250hp to fly and has 800hp available so it has 550hp thrust to climb with. 
The P-51B needs 275hp to fly but has1150hp available so it has 875 hp thrust with. 
The P-47B needs 435hp to fly ( a lot more drag and weight) but has 1600hp available and has 1375 hp thrust to climb with, however that horsepower needs to deal with almost 50% more weight. 

engineers and engineering officers could make charts and predictions on performance based on charts/formulas like these. 
A Merlin V-1650-1 is going to fall in between the P-51A and the P-51B in both needed power (only a small change) and the available power. 
The problem for this question is that the available power at 20-25,000ft is not going to be enough to give the plane the performance it needs. And they could figure that out without actually building the plane. 
Now as used in 1943-44 the B-17s and B-24s often did not fly at 25,000ft but flew 2-5,000ft lower but they didn't know that in 1941-42, they were planning on 25,000ft (or close) altitudes and in the US only the P-38 and P-47 offered the desired performance at altitude,_ *until *_The two stage Merlin showed up.

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## PAT303 (Jul 31, 2022)

33k in the air said:


> Here's a better idea: put a Merlin into a P-51 airframe in early 1941 instead of late 1942.


You may be better off using your time machine for better purposes.

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## PAT303 (Jul 31, 2022)

Shortround6 said:


> The Germans had had almost 2 years of experience in avoiding fighter sweeps and trying to bounce small pockets of bombers (used as bait) and small pockets of fighters (disconnected from the main groups).


Why don't we use the fighter sweeps to orbit fighter bases which is what the 2 TAF actually did so the German fighters can't get off the ground, support the bombers that way, we don't have P51's, lets use the planes and tactics that we do have.


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## 33k in the air (Jul 31, 2022)

PAT303 said:


> You may be better off using your time machine for better purposes.



(1) My comment was mostly tongue-in-cheek (though it did spur good comments from Shortound6 and drgondog).

(2) As has been pointed out, the Spitfire was not developed into a long-range escort fighter, so claiming it could have been one would also involve a time machine.

There was no pressure on the RAF to develop a long-range escort because Bomber Command had long before switched to nighttime bombing. The USAAF was only forced to develop a long-range escort because it was firmly committed to daytime bombing and unescorted daylight raids had proved too costly no matter how good the formations and heavily armed the bombers.

I'm not sure how you convince the RAF to develop something that its own tactics say its doesn't need.

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## PAT303 (Jul 31, 2022)

33k in the air said:


> I'm not sure how you convince the RAF to develop something that its own tactics say its doesn't need.


The Spit needed range regardless of what theater it flew in, the lack of it was it's biggest drawback.


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## Thumpalumpacus (Jul 31, 2022)

PAT303 said:


> Why don't we use the fighter sweeps to orbit fighter bases which is what the 2 TAF actually did so the German fighters can't get off the ground, support the bombers that way, we don't have P51's, lets use the planes and tactics that we do have.



Well, the obvious answer is that you can't keep fighters over a German base forever. They're going to run low on fuel. So you want to cab-rank them then? Great. Let's see how many Tiffies y'all can produce, and pilots, and fuel, and repair facilities, and so on.

Good luck doing that in 1941-42.

No, the bombers were the bait that drew up the fighters, and I'm pretty sure German radar could tell the difference between 50 bombers escorted by 100 fighters, and 500 bombers escorted by 250 or so fighters.

During the height of Pointblank, German fighters flew to attack bombers, day and night. It was only when Doolittle had 1) a fighter that could do long-range escort in the Mustang and 2) had so many bombers that the LW fighters _had_ to come up and play that he could actually set fighters loose ahead of bomber formations. 

Until then, Eaker had to husband his fighters. But once Doolittle took over, fighter numbers were such that they could operate in relays, and be loosened from the bombers:

_Available evidence demonstrates that Doolittle had a direct influence on changing fighter tactics in the Eighth Air Force. In his memoirs, he claimed responsibility for changing the fighter tactics, which he considered "the most important and far-reaching military decision I made during the war."21 Minutes from a 21 January commanders meeting show that Doolittle "emphasized that the fighter role of protecting the bombardment formation should not be minimized, but our fighter aircraft should be encouraged to meet the enemy and destroy him rather than be content to keep him away."22 Moreover, in a postwar interview, Gen Pat Partridge confirmed that the offensive fighter posture was Doolittle's idea.23 The decision to "let the fighters loose" marked an innovation in fighter tactics. The prevailing AAF doctrine discouraged escort fighters from pursuing enemy aircraft. AAF Field Manual 1-15, Tactics and Technique of Air Fighting, dated 10 April 1942, stated the mission of close escorts "precludes their seeking to impose combat on other forces except as necessary to carry out their defensive role." The Eighth Air Force under Eaker's command had TACTICAL AND TECHNICAL INNOVATION 62 closely followed this guidance. To conserve his bomber force, Eaker prohibited his fighters from pursuing the Luftwaffe.24 Discussion held during an Eighth Air Force commanders meeting in September 1943 illustrates this bomber-centric philosophy. The commanders agreed that the fighters' priority was escorting the bombers, not destroying German fighters.25 The defensive policy frustrated fighter pilots. It ceded the initiative to German fighter pilots and wasted the escorts' offensive potential.26 For example, on 3 November 1943, P-38s achieved their first aerial victories in the European theater with no losses. However, the number of kills was limited to three because strict rules of engagement prevented the fighters from pursing enemy aircraft.27 Doolittle's pursuit policy changed the Eighth's fighter philosophy and "stood official doctrine on its head."28 Fighter escorts were transformed from passive defenders to aggressive attackers. The offensive tactics also optimized the use of fighter escorts. Fighters performing close escort had previously rendezvoused with bomber formations and followed them to the target or to the limits of their range. Because fighters cruised at a higher speed than bombers, the "little friends" weaved to stay in position. These maneuvers wasted fuel and reduced the fighter's escort range. Shortly after Doolittle arrived, the Eighth implemented a relay escort system. Under the new policy, a fighter group rendezvoused with bomber formations and escorted them for 150–200 miles until they transferred escort responsibilities to another group. The new tactic optimized the use of the three different types of fighters in the Eighth Air Force: P-47s escorted the formations during the shallow-penetration portions of the mission, P-38s during the medium-penetration, and the P-51s assumed escort duties for the deepest portion of the route.29 The new tactic also enabled a new role for fighter aircraft—strafing ground targets. Returning fighters, free from their escort duties, began to drop to low altitude in search of targets of opportunity._

This was certainly not the case in 1942. You didn't have the numbers of fighters, they didn't have the fuel to do much free-ranging, and an aggressive strategy like that requires the ability to take losses that frankly couldn't be absorbed in 1942.

Rodeos over France got shot up. Put up 400 bombers, yeah, they will need to come up and play, but 40 Havocs or what-have-you? The LW can pick and choose the fight, and they certainly did.

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## PAT303 (Jul 31, 2022)

Okay I give up, the Spit is stuck with it's 85G of fuel.


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## Thumpalumpacus (Jul 31, 2022)

PAT303 said:


> Okay I give up, the Spit is stuck with it's 85G of fuel.



Brits were and are clever. If they could've have had it doing Rodeos over the Rhine, don't you think they would have? Whatcha got? Why'd they pass up what appears to be a golden opportunity in you eyes? What are you seeing that they missed?


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## Shortround6 (Jul 31, 2022)

The Spit evolved in certain ways for real reasons. 
Sometimes the reason may not what we think of as good looking back but the reasons were at least valid at the time.

Both the Spit and Hurricane were literally shacked with the the wooden propellers, They made the planes have long take offs and slow climbs and that was with small fuel tanks.
The two pitch props were better but the constant speed prop cut several minutes off the climb to 20,000ft and improved the climb at all altitudes. 

Unfortunately by the time they short out the propeller problem it is the summer of 1940 and they are trying to get Castle Bromwich to actually produce Spitfires and a not piles of parts. 
Supermarine can introduce modifications in short order but Castle Bromwich needs everything standardized with few changes as they mass produce things. the fastest production they can manage is the the order during the BoB and not too many experiments with long range fighters which aren't really needed in the summer and early fall of 1940. The Raids on South Hampton at the end of Sept also totally screw things up. It takes a number of months to get production up and running in the dispersal scheme. Supermarine is introducing the MK IIB (with cannon) and the Mk V over the winter. The MK Vb makes it appearance. These improve the hitting power of the Spitfire and improve the performance as the Germans start to introduce the 109F. RR is allowing higher boost limits but for carry increased loads needs the changes in climb settings and in max cruise settings. 

Unfortunately the Spitfire took several hits to performance during 1940-41. The IFF, crucial to the battle, added a bit of weight and added two antennas for more drag, the 20mm guns added drag with the big gun barrels and the blisters on the wing to hide the cannon drums. Depending on canopy the external BP glass cost about 6mph of speed. The Spit was more capable but if you want to start adding fuel the increase in performance gets even smaller. In June of 1941 the Spit VB was being tested using 9lbs of boost. By Jan 1942 they were rating the engine at 15lbs for combat. So sometime in 1941 they could have decided they had the performance to handle a bigger fuel load. Of course during 1941 the 109F came into wider use and in June of 1941 the F-4 started to show up with it's improved engine.

So when do you want start adding the fuel tanks to the Spitfire in 1941?

In Jan of 1942 two stage Merlin had passed it's type test but they weren't expecting production until the summer. 

RR had tried to improve altitude performance with the Merlin 46 engine. While this increased altitude performance by several thousand feet it also cost 100hp or more at lower altitudes. This was the engine used in the Darwin Spits and the idea of adding 300lbs or more to Spitfires powered by these engines flying over the France and low countries? 
In 1941 the only way to justify making the Hurricane was to stuff the Merlin XX engine into it so the Spitfire got the 2nd choice engine. 

The British had ideas, but they were limited by trying to keep numbers up by keeping changes to a minimum. 


As far as trying to orbit German fighter fields? 
The bombers often flew dog leg courses to throw of German plotters and to both cause the Germans to take-off and burn fuel as the bombers turned away or cause mad scrambles as the bombers changed course and crossed behind what appeared to be a bypassed group of fighter fields. Dog legs were also used to avoid Flak guns. The exit routes were also planned to be a good distance sideways from the entry routes to keep the German guessing.

How long before the Germans start figuring out that visits from orbiting fighters means they will soon be within striking distance of an allied bomber group? Germans can start plotting the bomber group's course by plotting which German airfields are getting attention from the Allied fighters. 
How long before the Germans start bring up fighters from other airfields to clear the Allied fighters off and allow the fighters on the ground to take off with full fuel to go after the bombers? 

This is not 1944-45. The Germans have a lot more distance/time to set things up than the Germans had when Allied fighters were based in France and the low countries.

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## Shortround6 (Jul 31, 2022)

I would also note that the engine in the Spitfire IX was about 200lbs heavier than the engine in the Spitfire V and the propeller was heavier which makes sticking a fuel tank behind the seat a whole lot easier from a CG standpoint.


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## 33k in the air (Jul 31, 2022)

PAT303 said:


> The Spit needed range regardless of what theater it flew in, the lack of it was it's biggest drawback.



Range for what? Unless it's accompanying bombers to a distant target, where is the pressing need for range?


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## Milosh (Aug 1, 2022)

33k in the air said:


> Range for what? Unless it's accompanying bombers to a distant target, where is the pressing need for range?


Range equals time in the air.


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## PAT303 (Aug 1, 2022)

Thumpalumpacus said:


> Brits were and are clever. If they could've have had it doing Rodeos over the Rhine, don't you think they would have? Whatcha got? Why'd they pass up what appears to be a golden opportunity in you eyes? What are you seeing that they missed?


They did do rodeo's out to 300 miles with just a 90G drop tank in 1944, why couldn't they do it in '43?.


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## Geoffrey Sinclair (Aug 1, 2022)

From mid 1941 until the end of 1942 and early 1943 the Luftwaffe day fighters in the west could pick when to engage, since the amount of damage the raiders could inflict on anything important was minimal, as the 8th Air Force built up it was realised that had to change but the priority for the first half of 1943 was the defence of Tunisia then Sicily and the Kursk offensive. The experience of the 1941/42 fighting had given the Luftwaffe a good ability to ignore fighter only operations, given the bombers cruised slower than the fighters it was a clue, and generally avoid poor tactical situations.

In July and August 1943 the Luftwaffe received a series of significant wake up calls, in date order, the "overnight success"
1) On July 5 the Kursk offensive begins, for the first time in the east the Luftwaffe is unable to secure air superiority where it wants it, the Red Air Force is able to intervene effectively. The air force needs to become bigger, given the Red Air Force largely ignores its opposite number the Luftwaffe can usually still operate.
2) 10 July the allied invasion of Sicily, in the air fighting before and during the invasion the Luftwaffe discovers the more aircraft it commits the higher the casualties without changing the overall situation. The air force needs to become much bigger or leave.
3) 27 July the firestorm at Hamburg.
4) 17 August the strikes on Schweinfurt and Peenemunde.
The next day the Luftwaffe chief of staff committed suicide.

Starting in July, after the failures of the Kursk and Sicily operations and with increased pressure on the home defences the Luftwaffe focus day fighters shifted to defending Germany, enabling the defeat of the unescorted day bomber but also making it easier for the allied forces in the "tactical" field. While the bomb damage started to really hurt the war economy.

Fighter Command did not change size much in the 1942/43 period in terms of number of day fighter squadrons, the quality went up but not the quantity. The big change in terms of pressure on the Luftwaffe was the USAAF, since it was totally dedicated to offensive operations while the RAF defended Britain as well, including the US airbases. As well as the numbers comes the availability and size of external tanks for the fighters. The British economy was fully stretched in 1943, getting a production line set up and quantity output was difficult even for something as relatively simple as the external tanks. First mission with a new size is one thing, adequate supply so all the fighters have access to them is another thing. From July 1943 and definitely after mid October 1943 the 8th Air Force stayed within the range of adequate fighter cover, operations in the period to around end February 1944 limited by the problems the P-38 and P-51 were having, plus there only being 2 P-38 and 1 P-51 groups operational end January, up to 2 and 3 by end February, so it meant staying mostly where the P-47 could go.

The Spitfire IX cannot go out to 400 miles without a major fuel tank upgrade, even the VIII needs more internal fuel. It is a false comparison to consider the Spitfire a long range fighter if the Mustang is present, it is medium range, like the P-47, if the mark VIII is used. What I do not have is the mission profile for the 8th Air Force combat range calculations, hence why the Spitfire ranges are nominal, until it can be compared with the actual profile the 8th Air Force was using.

In 1942 there are effectively no USAAF fighters in Britain and what drop tanks available were in the 30 to 60 imperial gallon range, assuming the Spitfires and P-47s could carry them. Sitting on enemy airbases requires numbers and range while France had plenty of fighter capable airfields. The 8th Air Force had a part operational fighter group in March 1943, up to 3 groups in April, 4 in August, 6 in September, by D-Day it had 15 groups. The 9th Air Force had 1 fighter group in November 1943, up to 18 groups by D-Day.

Put it another way for every 3 fighter sorties the USAAF could put up in April 1943 they could put up 33 in June 1944 and that is before the general expansion of fighter group strength. A 10 fold increase in offensive strength was far more than the Luftwaffe could handle even after concentrating forces in theatre.

Merlin Mustang time line, Rolls Royce began work on the two stage Merlin in 1940, expected late 1941.

N3297 the ex mark III prototype first flew with a Merlin 61 on 20 September 1941. Tests were so successful the call for production was being made before the type tests were done. On 12 November 1941 came the call to cancel all but Merlin 61 Spitfires. Merlin 60 production began in November 1941 according to Rolls Royce, 13 made that month and 13 more in December, 47 engines built by end February. Merlin 62 production from April 1942, Merlin 61 from May 1942.

Spitfire IX production from June 1942, mark VII from September, mark VIII from November.

The first Mustang arrived in Britain in October 1941, so airframe and engine are finally in the same area, 7 more in November, 24 in December. By 24 January the plan was to equip 10 Army Co-Operation squadrons. 

Rolls Royce performance estimates, April 1942.
Air Vice Marshall Linnell informs the US that Merlin Mustangs a good idea, 9 June 1942.
3 Merlin Mustang conversions were ordered on 15 June 1942.
US/UK agreement for 1,200 Merlin Mustangs built January to October 1943, split half each, with the RAF releasing Packard Merlins from its order to the USAAF, 20 July 1942.

British order request for 120 engineless Mustang airframes a month for Britain and up to 200 a month for overseas theatres 27 August 1942. RAF talks about an order for 3,000 Merlin Mustangs, half for the RAF.

2 P-51 airframes officially accepted as XP-51B prototypes, August 1942, to await engines.
British request for bulk Merlin Mustangs 8 October 1942.
Mustang X first flight, 13 October 1942.
Churchill request to Harry Hopkins for Merlin Mustangs 16 October 1942, after 6 Mustang X test flights.
British request for 400 engineless Mustang airframes to be sent and converted to use Merlins. 5 November 1942.
XP-51B first flight 30 November 1942.

A Merlin XX engined Mustang would be one of the better 1942 fighters, but with the Merlin 61 so superior and in production why bother?

By 1943 the self defending bomber idea had an explicit in numbers added to it. The 8th Air Force considered 300 would be a big enough force to keep losses to acceptable levels, and it took until August and October for it to be abandoned. Until then there was little call for longer range fighters, nice to have but the priority was proving the bomber ideas. The everything that could fly mission on 24 December 1944 lost 12 bombers MIA and 23 written off, around half the 1943 long distance raids, but from 1,884 effective sorties. Even 30 lost from the 300 in 1943 would have been way too much, in 1945 thirty losses were well within acceptable levels. Also the early B-17F range as used by the 8th Air Force their radius of action was German border sort of distance and there was a certain make what you have work, the 3 fighter groups available April to August 1943 watched the bomber force grow from 5 to 16 groups, and that is with the B-24 groups on detached duty, end September the 6 fighter groups had 20 bomber groups to escort. 

The allies firstly had to have the fighters in theatre, then a supply of tanks then enough pilot capable of being able to fly the distances, fight and return without many getting lost. Then use good tactics, like the 1944 escort ones As noted in Britain in 1943 but also in the US making changes in production came at a cost, both in terms of time to production and what had to be stopped to enable the new production.

As of mid 1943 only the Spitfire had shown to be able to match the best German fighter performance, and that required the latest versions after nearly a year where the German fighters were superior. Everyone was after the Spitfire, cutting production would be very unpopular.

To the Spitfire what if,

The allies have to decide the self defending day bomber is wrong earlier. The RAF have to decide the P-51 schedules are too optimistic both in time and numbers and increasing the Spitfire range is needed for bomber escort and general usefulness for the 1943 and 1944 operations. Furthermore the idea increasing efforts against Germany would pay off, the need for allied high performance fighters in the Mediterranean would drop as the Luftwaffe withdrew for example.

As part of mark XIV development, with a heavier thirster engine, specify a 30 to 40 gallon rear fuselage tank which the heavier engine should make an easier engineering task but also have the tank able to be used by the mark VIII, available about the time the mark XIV enters production in October 1943. Then during the Castle Bromwich mark V to IX change over, first IX in February 1943, last Vc in August, specify the Spitfire VIII internal fuel tankage, then later the rear fuselage tank, accepting the loss of production, using spare 60 series Merlins to convert more mark V to IX if necessary.

In early 1943, if the 90 gallon tank is available, the Spitfire can nominally match the August 1943 P-47 range, adding a 33 gallon tank nominally matches the February 1944 P-47 range.


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## PAT303 (Aug 1, 2022)

Shortround6 said:


> As far as trying to orbit German fighter fields?
> The bombers often flew dog leg courses to throw of German plotters and to both cause the Germans to take-off and burn fuel as the bombers turned away or cause mad scrambles as the bombers changed course and crossed behind what appeared to be a bypassed group of fighter fields. Dog legs were also used to avoid Flak guns.


They did all that because they didn't have fighters, it's the same argument as to why they didn't add more fuel in the BoB, they wanted less fuel so the Spit climbed faster, if it had more fuel it didn't need to, another 20G behind the seat has it at 20,000ft with a full main tank. 2nd TAF orbited fighter fields later in the war, once they got more fuel, don't know about you but I see a pattern emerging.


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## Shortround6 (Aug 1, 2022)

PAT303 said:


> it's the same argument as to why they didn't add more fuel in the BoB, they wanted less fuel so the Spit climbed faster, if it had more fuel it didn't need to, another 20G behind the seat has it at 20,000ft with a full main tank.





PAT303 said:


> 2nd TAF orbited fighter fields later in the war, once they got more fuel,



I do see that the later fighters had more power=better power to weight ratio. 

Hmmmm, I do see a pattern.

Climb isn't just about reaching 20,000ft quicker, it is about having better climb in combat at 20,000ft and above.
Less weight/more power means better turn performance. Not in absolute turn rate but in being able to maintain (or not loose as rapidly) height in a turn. It also means being able to get back in fight quicker after loosing altitude. 

Now _when _should they have stuck the 20 gallon tanks in???
before or after they were scrabbling around in late June and into July refitting hundreds of fighters with constant speed props from the 2 pitch props.
Change was good for 2-3 minutes off the climb time to 20,000ft. 
Might have added a bit to the endurance. 

Adding weight when they were still using the crappy propellers may have been a cost they were unwilling to pay. 

And not all constant speed props were equal. The Rotol offered 30-35 degrees of pitch change. The converted DeHavillands may have offered 20 degrees of pitch change. 

Worry about being able to fight effectively with 85 gal of fuel for take off before you worry about adding more fuel to try to make up for crappy equipment.

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## drgondog (Aug 1, 2022)

In the 1930s both AAC/AAF and RAF heavy bomber doctrine argued that the bomber did not need escort. Further, in te case of the RAF, bomber mission profile was low (attack) to medium altitudes. Ditto Germany. Fighters, with exception of Bf 110 and P-38 were single engine interceptors with high rate of climb and speed attributes. The P-38 was designed as an interceptor - and at the time was a 'one off' requirement for AAC. The rest of AAC fleet were Pursuit with same basic mission as the RAF and LW programs. Note that XP-39 was desgned as S/E Interceptor also but relegated to Pursuit when Turbo stripped and easily fell into category of Spit and Bf 109. So, when WWII started, only the P-38 and to a degree the Bf 110, was a big airframe with easy capability to extend range.

Further, to the point of the Spitfire (and Bf 109) design features, the focus was climb and maneuverability - primarily home defense but also battlefied air superiority. Internal fuel capacity and engine were two major factors in juggling weight vs performance and neither Germany nor Britain envisioned the respective designs to require long range at the sacrifice of point defense performance.

Fuel fraction is probably the hardest to increase Post producton.

Therefore both were tethered to relative short combat radius because of lack of ease to dramatically increase internal fuel. Only the three major AAF fighters had the design attributes to stuff significant additional internal fuel to meet the requirements of Long Range escort. The key USN fighters had significant internal fuel but their mission was twofold - Carrier CAP and intermediate escort ranges for Dive Bomber and Torpedo Bomber carrier strike escort.

Fuel was the dominant consideration pointing to the larger US designs over European and Japan built fighters. The A6M was an exception but the compensating decision to keep airframe GW low and fuel fraction high was to strip excess (armor plate, self sealing tanks, etc) weight in the original design.

When mission expansion was desired, to include much larger tactical footprint, neither the Spitfire nor Bf 109 presented 'easy to find and design' space for extra tankage, nor solutions simple with respect to ease of incorporation - either for contiguous volume or ease of production changes.

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## Thumpalumpacus (Aug 1, 2022)

PAT303 said:


> They did do rodeo's out to 300 miles with just a 90G drop tank in 1944, why couldn't they do it in '43?.



After the beating they took over France they may not have thought it worthwhile.

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## Thumpalumpacus (Aug 1, 2022)

PAT303 said:


> They did all that because they didn't have fighters [...]



It was more to avoid concentrations of flak.


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## Reluctant Poster (Aug 1, 2022)

Shortround6 said:


> I don't know what the deal started out as but it wound up as an initial contract for 9000 engines, 1/3 for the US and 2/3rds for the UK with peak production at 800 engines per month.
> aside from that I have no argument with anything in you post.
> 
> 
> ...


Robert Neal lists the Packard production contracts placed by the US in this paper


https://www.enginehistory.org/members/articles/PackardMerlin.pdf

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## drgondog (Aug 1, 2022)

Reluctant Poster said:


> Robert Neal lists the Packard production contracts placed by the US in this paper
> 
> 
> https://www.enginehistory.org/members/articles/PackardMerlin.pdf


Thanks - the 50-50 split was long held from some no loner remembered source.


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## 33k in the air (Aug 1, 2022)

Milosh said:


> Range equals time in the air.



Sure, but a shorter-range Spitfire is still more than capable of successfully fighting for air superiority within the limits of its endurance.

Long-range fighters were spurred by the need to escort the bombers in daylight.


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## Reluctant Poster (Aug 1, 2022)

drgondog said:


> Thanks - the 50-50 split was long held from some no loner remembered source.


The Packard Merlin program was first and foremost intended to produce Merlins for British bombers, in particular the Lancaster. The Lancaster was in fact the biggest single users of Packard Merlins although the P-51 was a close second. The US tagged along with the initial order by adding 3,000 for their own use but I don't think they had any intentions of continuing until the success of the P-51 Merlin conversion.


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## Reluctant Poster (Aug 1, 2022)

EwenS said:


> The figures being quoted were for a Sptfire *LF.IX* with a Merlin* 66*.
> 
> The Merlin 66 was considered a"low altitude" engine. The *F.IX* got the Merlin *63* which had a higher altitude rating. The difference seems to lie in the superchargers with different rotor sizes and gearing ratios.
> 
> ...


The Merlin 63 was superseded by the Merlin 70 which had the improved supercharger (much more than a simple enlargement. See my previous post in another thread) with the higher gear ratios. It was therefore the equivalent of the V-1650-3. This went into the Spitfire HF IX. The Merlin 63 was somewhat of an expedient to get 2 stage Merlins into service as soon as possible. Since Packard came into production a little later, they were able to incorporate the improved supercharger from the beginning of their 2 stage production.
The figures given for the V-1650-3 and -7 are puzzling as I don't see how the -7 can have the same performance at 26,500 feet as the -3 with the lower supercharger speed. 

Its interesting to note that the USAAF chose to sacrifice high altitude performance for better performance at lower levels during the P-51 B/C production run.


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## Reluctant Poster (Aug 1, 2022)

Any discussion of long-range fighters is incomplete without mention of the ME 110 Dachshund belly.








File:Me 110D-0 with Dackelbauch tank 1940.jpg - Wikipedia







en.wikipedia.org

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## Reluctant Poster (Aug 1, 2022)

Reluctant Poster said:


> The Merlin 63 was superseded by the Merlin 70 which had the improved supercharger (much more than a simple enlargement. See my previous post in another thread) with the higher gear ratios. It was therefore the equivalent of the V-1650-3. This went into the Spitfire HF IX. The Merlin 63 was somewhat of an expedient to get 2 stage Merlins into service as soon as possible. Since Packard came into production a little later, they were able to incorporate the improved supercharger from the beginning of their 2 stage production.
> The figures given for the V-1650-3 and -7 are puzzling as I don't see how the -7 can have the same performance at 26,500 feet as the -3 with the lower supercharger speed.
> 
> Its interesting to note that the USAAF chose to sacrifice high altitude performance for better performance at lower levels during the P-51 B/C production run.


One important point that I neglected to mention, which Snowygroch would never forgive me for, is that the Merlin 63 had an SU carburetor whereas the other 4 used the Bendix Stromberg


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## PAT303 (Aug 1, 2022)

Geoffrey Sinclair said:


> The Spitfire IX cannot go out to 400 miles without a major fuel tank upgrade, even the VIII needs more internal fuel


That's been my argument from day dot, there's no reason after the MkIX came into service and helped turn the tide over France, Africa and the Med that they couldn't have started on immediately addressing the range issue

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## GregP (Aug 2, 2022)

You talk like you know more than the military planners who guided and won WWII. After D-Day, the airfields moved toward Germany and the Spit could play.

They got the performance out of the Spitfire that they wanted it to have. It was one of the best fighter-interceptors of the war. They left the long-range escort stuff to the U.S.A. and got on with their mission. The British were quite satisfied with it. Can't you be?


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## nuuumannn (Aug 2, 2022)

GregP said:


> The British were quite satisfied with it.



It's not that simple, really. Portal, C-in-C Air Staff was convinced the RAF did not need a long range escort a for its bombers, the issue arising during discussions about increasing Bomber Command's presence over enemy territory with the re-introduction of daylight bombing raids, this is before the US arrived in the UK. He was vociferous in his criticism of the concept, which was discussed in that context. He argued that a long range fighter could never match a short range fighter in performance which beggars belief in hindsight, but he held sway over operations. Churchill remarked that Portal's dogged refusal to examine the long range fighter escort for RAF bombers, "closed many doors..."

Quill, Supermarine test pilot mentions extending the range of the Spitfire it in his book and there was plenty of experimentation operationally that confirmed that with modification the Spitfire could become a long range escort fighter, but for Portal. From Spitfire, a test-pilot's story:

"In the meantime a 75-gallon tank was fitted in the fuselage of a Mk.IX (ML186) behind the pilot and we also fitted a bob-weight in the elevator circuit, so what with this and the large horn balance on the elevator we hoped for the best. However the best and most expeditious way to test this aeroplane was to fly it a good long way and see how everything worked out.

So I took off from High Post on Salisbury Plain with all tanks full, carrying a 45-gallon drop tank in addition, and set off at economical cruising boost and RPM in the general direction of Scotland. The weather was unsettled, so I decided to fly at a low altitude which, was not, of course a favourable height for optimum air miles per gallon; but I thought that if I could fly at a distance equivalent to John O'Groats and back non-stop at the rather unfavourable height, keeping to the east of the Pennines and the Grampians, it would be a useful demonstration.

The aeroplane was unstable to start with, but as soon as I had used up the rear fuselage fuel the handling was back to normal and I settled down to a long and enjoyable flight over a great variety of countryside from Salisbury Plain to the Moray Firth and back again, all below 1,000 ft. In distance, and not taking into account the various diversions for weather and terrain, it was roughly equivalent to flying from East Anglia to Berlin and back. It took five hours."

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## PAT303 (Aug 2, 2022)

Thumpalumpacus said:


> After the beating they took over France they may not have thought it worthwhile.


They took a beating because they MkV was outclassed by the FW190 and 109F, they did fit 30G slippers to extend range but the pilots instead use it to cruise at a higher speed, the MkIX re-addressed the balance


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## PAT303 (Aug 2, 2022)

GregP said:


> The British were quite satisfied with it. Can't you be?


If they were satisfied with it why did they try to increase the range of them as far back as the MkII?


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## PAT303 (Aug 2, 2022)

Nuuumannn thanks for posting that, I'm not home so can't cite my books, did he have a drop tank also?.


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## PAT303 (Aug 2, 2022)

GregP said:


> They left the long-range escort stuff to the U.S.A. and got on with their mission.


Don't want a long range escort, I just want the Spit to have the fuel to range deeper than just the coast taking the fight to the Luftwaffe, once the MkIX and especially the LF MkIX came into service mid 1942 early '43 they had the plane that could go toe to toe with the best German aircraft, in doing so also supporting the US bomber operations as much as possible 6-9 months before their own LR fighters came on the scene.


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## Geoffrey Sinclair (Aug 2, 2022)

PAT303 said:


> That's been my argument from day dot, there's no reason after the MkIX came into service and helped turn the tide over France, Africa and the Med that they couldn't have started on immediately addressing the range issue


The Spitfire range issue had been addressed, the mark VIII upped fuel capacity from 87 to 124 gallons, the mark I range was 575 miles, the IX 434 miles and the VIII 660 miles on internal fuel using the RAF measuring system. In late 1942 and through mid 1943 the requests were for more Spitfires, not longer range, the fighting over France, Tunisia and Sicily had the Luftwaffe coming at the allied air forces around the front line. After that the bulk of the Luftwaffe day fighter force kept pulling back to where the western allied fighters could not reach or to at least cut the number of allied fighters likely to be encountered.

There were two technical issues that had to be addressed, the Spitfire was more sensitive to CoG issues than the Mustang, the Westland elevator design improved that, then comes the general strengthening required, at 7.11 pounds per imperial gallon for 100 octane, plus a rule of thumb 1 pound of self sealing tank weight per imperial gallon capacity a 75 gallon tank means 533.33 pounds of fuel plus 75 for that tank, 610 pounds. Given the heavy bomber escort mission extra oxygen will be needed as well. The 90 gallon external tank at 0.5 pounds per gallon of capacity plus fuel is 685 pounds. As far as I know the VIII was cleared to carry 1,000 pounds of bombs, even so this full fuel load adds another 300 pounds to the take off weight versus a full bomb load.

From an incomplete list of Spitfire Modification orders, the date is of course the order date, not the actual implementation date and the modifications were not always for all marks. Numbers 1293 and 1383 are present to help date 1335 and 1414, the rear fuselage tanks installations.

437 29-Aug-41 Introduce 90 gallon drop tank
729 22-Sep-42 Introduce rear fuselage 29 gal tank for ferrying
743 20-Oct-42 Fit Westland convex elevator
814 15-Dec-42 Trial installation mock up torpedo 50 gal o/ld tank
1099 19-Oct-43 Introduce 45gal o/ld tank
1231 02-May-44 Modify 90gal o/ld tank for use on any mark
1293 21-Mar-44 T.I. Lightweight air system
1363 20-May-44 Strengthen cannon fairings. Cancelled
1377 27-Jun-44 Introduce Mk VII bottom fuel tank
1436 22-Aug-44 Gyro gunsight Mk IID


drgondog said:


> So, when WWII started, only the P-38 and to a degree the Bf 110, was a big airframe with easy capability to extend range.


The P-38 started with 400 or 410 US gallons unprotected, dropped to 300 gallons protected, then went to 410 gallons protected with the wing leading edge tanks, around a 37% increase in capacity. The Spitfire VIII went to 124 gallons from 87, a 42.5% increase. A difference being the Spitfire had gained over 50% more power and so more fuel consumption, the P-38 increase in power was less, 1,150 to 1,425 HP take off. The P-47D managed a 21% upgrade in internal fuel, the P-47N an 82% versus the original P-47, the P-51B a 46% increase versus the P-51A but with an upgrade in take off power from 1,200 (V-1710-81) to 1,490 HP (V-1650-7).


drgondog said:


> When mission expansion was desired, to include much larger tactical footprint, neither the Spitfire nor Bf 109 presented 'easy to find and design' space for extra tankage, nor solutions simple with respect to ease of incorporation - either for contiguous volume or ease of production changes.


Yet by late 1944 and into 1945 the use of wing and rear fuselage tanks meant the Spitfire came with approaching 200 gallons of internal fuel, versus the 87 in the mark I, with much of the design work done earlier, for example to handle the heavier Griffon engine, 1,980 pounds for the Griffon 61 versus 1,640 pounds for the Merlin 61. The wing tanks were around in 1942, the rear fuselage in 1944/45, and earlier than that in a smaller size as a ferry option.

In 1943 the Spitfire VIII coming with the internal fuel capacity able to fully exploit the 90 gallon external tank was considered adequate. The needs of the moment were higher performance, the Griffon, and numbers of the latest Spitfires both for 1943 and the expected major air fight that Overlord would provoke in May 1944. There was a major fight, Fighter Command's 4th and 5th highest kill claims in a month were June and July 1944, but no one, even in mid 1944, was willing to build into the plan the loss of quality and quantity the Luftwaffe had actually suffered by June 1944.

The expected performance and availability of the Merlin Mustang was a factor in decisions about the Spitfire range, why make the effort when an off the shelf solution was available. That there were not as many Mustangs made available to the RAF as initially expected (and when) meant increasing the Spitfire range became more useful. The liberation of France opened up the possibility of Bomber Command day raids on Germany, which would need escorts. In the fourth quarter of 1944 Spitfires based in Britain could escort Bomber Command day raids on Western Germany, though given the RAF bomber armament and formation flying, plus the caution of their commander, those raids were not going deep. With the production pressure easing the chances to introduce more and larger modifications increased.

The Spitfire VIII with 30 to 75 gallons of rear fuselage fuel would be a useful addition to the 8th Air Force operations in the 1943 to early/mid 1944 period, and the 15th Air Force for a couple of months longer, as the headline operations. The ability to carry more internal fuel plus bombs would be a bonus but not make a major difference to the missions most Merlin Spitfires spent 1944/45 doing, fighter bomber operations and sweeps.

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## drgondog (Aug 2, 2022)

Reluctant Poster said:


> The figures given for the V-1650-3 and -7 are puzzling as I don't see how the -7 can have the same performance at 26,500 feet as the -3 with the lower supercharger speed.
> 
> Its interesting to note that the USAAF chose to sacrifice high altitude performance for better performance at lower levels during the P-51 B/C production run.


I didn't look at your figures for 1650-3 and -7. IIRC the FTH for Bench (Static) runs was 24K+ and 19K+ respectively for Military [email protected] RPM. 

The difference in P-51B/D Altitude FTH Performance for Speed/level flight runs is Ram Air to attain FTH of ~4500 ft over Bench FTH. Ram air delta is result of iterative solution approach. 

Look to Reports NA-5534 and NA-8449 for the respective charts to display both Static and Ram air HP vs alitude.


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## Thumpalumpacus (Aug 2, 2022)

PAT303 said:


> They took a beating because they MkV was outclassed by the FW190 and 109F, they did fit 30G slippers to extend range but the pilots instead use it to cruise at a higher speed, the MkIX re-addressed the balance



So plumbing the thing for more fuel doesn't necessarily improve performance. And I'd imagine that with the deep-penetration sweeps you're envisioning, you're going to need a higher cruising speed anyway unless you want to be caught stooging around, no?

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## Shortround6 (Aug 2, 2022)

When planes changed the ability to modify the planes changed.

As an example of this the P-36/Hawk carried a tank behind the pilots seat. On the radial engine airplanes the tank was used as an over load (ferry) tank and most maneuvers were prohibited. French crashed a few trying to dogfight with fuel in the rear tank.
On the Allison P-40s the same tanks (self sealing but same location) allowed for maneuvering with fuel in the rear tank but the rear tank was supposed to be starting after take off.
On the Merlin engined P-40s the rear tank was supposed to taken down to 20 gallons and the other tanks emptied and the 20 gallons in the rear tank were kept as a reserve and used for landing or landed in the tank if not needed.

P-51s with the rear tank varied a bit depending on the time and manual. with around 55-85 gallons the elevators could go into reversal in high G turns. With around 25-55 gallons the plane handled normally and in post war fling manuals the last 20-25 gallons were supposed to kept for reserve and the plane was supposed to handle for landing with that amount of fuel in the rear tank.

We know that the rear fuel tanks in the Spitfire were taken out of service after the end of the war. Granted different air forces have different standards and have different standards during wartime and peace time (RAF accident rates with Meteor were horrific even in the 19590s though).

Now what was the max gross weight the plane was "supposed" to operate at without any restrictions in flight envelope or maneuvers. 

Could the Spitfires operated with the 90 gallon drop tank installed? and it was close to the center of gravity.
Sticking 60-70 Imp gallons in the rear fuselage may be much like the Mustang (25-30 gallon need to be burned off before combat) 

For some reason the MK VIIIs didn't seem to get the rear tanks ? or only got one tank instead of two? 
MK VIIIs had 120-123 gallons of internal.
MK XIVs went back to 85 gallons in fuselage tanks instead of the 96 in the MK VIII. 

How many MK XIVs got rear fuselage tanks?

Spits could carry a bigger load than they could maneuver with, so could most other fighters, drop tanks and bombs could overload the structure. 

For the Long range Spitfire what was the load limit it had when maneuvering and then what would the load limit have been with 450-600lbs in the rear fuselage?


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## nuuumannn (Aug 2, 2022)

PAT303 said:


> Nuuumannn thanks for posting that, I'm not home so can't cite my books, did he have a drop tank also?.



No worries Pat, yes it did have a drop tank during that flight. What it does prove is that the idea of improving the Spitfire's range was taken seriously by the manufacturer at least and at high level within the RAF the idea of a long range escort fighter was discussed and seen as a potential fix against bomber losses during daylight ops. A pity Portal was so dogged in his determination not to pursue the idea, but it could have been done, as you've stated.

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## PAT303 (Aug 2, 2022)

Thumpalumpacus said:


> So plumbing the thing for more fuel doesn't necessarily improve performance. And I'd imagine that with the deep-penetration sweeps you're envisioning, you're going to need a higher cruising speed anyway unless you want to be caught stooging around, no?


They used the extra fuel to cruise at a higher speed making it harder for them to be bounced and needing less time to accelerate. I would not use the MkV for deep penetration missions.


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## PAT303 (Aug 2, 2022)

Shortround6 said:


> Shortround6 said:
> 
> 
> > For some reason the MK VIIIs didn't seem to get the rear tanks ? or only got one tank instead of two?
> ...


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## PAT303 (Aug 2, 2022)

nuuumannn said:


> A pity Portal was so dogged in his determination not to pursue the idea, but it could have been done, as you've stated.


I supposed there's our answer to why it wasn't done.


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## nuuumannn (Aug 2, 2022)

PAT303 said:


> I supposed there's our answer to why it wasn't done.



As I mentioned earlier, even Churchill saw the limitations of not choosing that option.


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## PAT303 (Aug 2, 2022)

nuuumannn said:


> As I mentioned earlier, even Churchill saw the limitations of not choosing that option.


Maybe they should have left it to the people who built the thing on whether it could have been done before making a decision.


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## Thumpalumpacus (Aug 2, 2022)

PAT303 said:


> They used the extra fuel to cruise at a higher speed making it harder for them to be bounced and needing less time to accelerate. I would not use the MkV for deep penetration missions.



My point was that if you're planning deeper missions into occupied Europe, you'll probably want a faster cruising speed in order to minimize enemy response times where at all possible. After all, those hypothetical deeper missions by Mk IXs are going to be exposed to much more potential enemy response, don't you think?


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## nuuumannn (Aug 2, 2022)

PAT303 said:


> Maybe they should have left it to the people who built the thing on whether it could have been done before making a decision



Quite possibly, but aircraft manufacturers don't establish policy, they produce equipment to enact policy. Of course, manufacturers can offer advice, but it's up to the policy makers to take it or not.


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## PAT303 (Aug 2, 2022)

Thumpalumpacus said:


> My point was that if you're planning deeper missions into occupied Europe, you'll probably want a faster cruising speed in order to minimize enemy response times where at all possible. After all, those hypothetical deeper missions by Mk IXs are going to be exposed to much more potential enemy response, don't you think?


Your arguing against reality, the British did do 300 mile rodeo's in the Spit XIV with just a 90G drop tank, the MkVIII/IX has an extra 100G of internal fuel, that gives them the flexibility to fly faster or further or both, I don't understand the fierce objection to giving the Spit more fuel.


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## Shortround6 (Aug 2, 2022)

PAT303 said:


> I would not use the MkV for deep penetration missions.



as I have noted before (repeatedly) the MK V has a least 300lbs less weight forward of the firewall compared to a MK IX and would have more trouble with weight in the rear fuselage than the MK IX.

"_the only Spit that reached it's max take off weight was the Wright field modified MkIX's from what I can find_."

Not quite the same thing. Max take-off weight is not max maneuver weight.

Max take-off weight for the Spits in the Manual was 8700lbs but that required a hard smooth runway and only gentile maneuvers.
all forms of flying had a limit of 7,800lbs. 
A MK IX with 85 gal of fuel weighed 7445lbs. ?
The MK VIII was limited to 7900lbs. 


In the 1946 manual for the Spitfire IX, XI and XVI acrobatics are prohibited when carrying *any* external stores except the 30 gal "blister" drop tank nor when the rear fuselage tanks contain more than 30 gallons of fuel._ and are not recommended when the rear fuselage tanks contain any fuel._

Italics are in the manual. Yes it is a peacetime manual. 

Tests of a MK IX using experimental metal covered elevators and an inertia weight in Jan/Feb 1945 showed an improvement with the metal elevators but the inertia made no difference.
With 74 gallons of fuel in the rear tanks the CG was 12.2in aft of the datum point. With 34 gallons used the CG was 9.9in aft of the datum point and with the tanks empty the CG was 7.4in aft of the datum point. 

Basically it seems that the Spitfire VIII/XI could hold about an extra 35 ? gallons of fuel for use in combat. 120-123 for the MK VIII with larger fuselage tanks and wing tanks. 
MK IX with 85 gallon forward fuselage and 30-40 gallons in the rear tank/s = 115-125 gal. 

Spits with 40 gallons in the rear tanks were tightening up turns even at two Gs but could be held. Mustangs at 55 US gallons in the rear tank were pretty much handling normally. 


With 34 gallons used the fuel load is about 10 gallons more than the post war manual wants but then many of the left over Spits had fabric covered elevators.


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## Shortround6 (Aug 2, 2022)

From a test dated Oct 1942. 



Spitfire F Mk IX BF274 Test



Difference in speed and climb with and without a 30 gallon drop tank. 
Putting 30 gallons inside the plane is going to improve the *speed* performance substantially. 

the climb performance isn't going to change a whole lot from the drop tank. If the plane is climbing at 203-240mph (best climb speed from 15,000 to 30,000ft) the change in drag by getting rid of the drop tank is nothing like the change in drag when trying to fly at 350MPH +.

The loss of about 200fpm in climb stays pretty constant no matter what the altitude. 
You want 150 Imp gal in the Spitfire for combat you loose another 200fpm climb over the loss from 120 gallons. 

The Spit is about 30-40mph slower than a P-51B, it does climb better but now you want to cut some the Spits climb rate ( and ability to turn).


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## Thumpalumpacus (Aug 2, 2022)

PAT303 said:


> Your arguing against reality, the British did do 300 mile rodeo's in the Spit XIV with just a 90G drop tank, the MkVIII/IX has an extra 100G of internal fuel, that gives them the flexibility to fly faster or further or both, I don't understand the fierce objection to giving the Spit more fuel.



I don't object to giving the Spit more fuel, I'm wondering what the objections were and trying to understand why your suggestion wasn't taken up. Apparently Portal and Churchill were against it, but did they actually have grounds?

Apparently


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## 33k in the air (Aug 2, 2022)

PAT303 said:


> Your arguing against reality, the British did do 300 mile rodeo's in the Spit XIV with just a 90G drop tank, the MkVIII/IX has an extra 100G of internal fuel, that gives them the flexibility to fly faster or further or both, I don't understand the fierce objection to giving the Spit more fuel.



You are operating with the benefit of hindsight.

To those at the time, with no RAF bombers making deep penetration raids in daylight, there is no reason to greatly extend the Spitfire's range. Indeed, the expectation was the American insistence to do deep raids in daylight would result in disaster. Which they did, enough so that there was an effort made to convince the USAAF to switch over to nighttime bombing.

A long-range fighter is not necessary to win air superiority. You do not need to fly into the enemy's airspace; you can just control the air over your own forces.

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## PAT303 (Aug 3, 2022)

Shortround6 said:


> In the 1946 manual for the Spitfire IX, XI and XVI acrobatics are prohibited when carrying *any* external stores except the 30 gal "blister" drop tank nor when the rear fuselage tanks contain more than 30 gallons of fuel._ and are not recommended when the rear fuselage tanks contain any fuel._


I'm not suggesting the Spit goes into combat with any external stores such as a drop tank, no plane could except the MkXIV with the 90G combat tank so I don't understand what you are saying here, the Spit had the same restrictions put on it as the Mustang in regards to maneuvers with rear tanks and drop tanks, RAF mustangs had their rear tanks wired shut post war also, is there a report on their flight restrictions in 1946?.


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## PAT303 (Aug 3, 2022)

33k in the air said:


> A long-range fighter is not necessary to win air superiority. You do not need to fly into the enemy's airspace; you can just control the air over your own forces.


That's like being in a car race with the fastest car but with not enough fuel to make it to the end.


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## PAT303 (Aug 3, 2022)

Shortround6 said:


> The loss of about 200fpm in climb stays pretty constant no matter what the altitude.
> You want 150 Imp gal in the Spitfire for combat you loose another 200fpm climb over the loss from 120 gallons.
> 
> The Spit is about 30-40mph slower than a P-51B, it does climb better but now you want to cut some the Spits climb rate ( and ability to turn).


So if that's your logic they shouldn't have put rear tanks or drop tanks on the P51 because it couldn't climb turn or fight with full rear tanks and drop tanks either.


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## PAT303 (Aug 3, 2022)

33k in the air said:


> there is no reason to greatly extend the Spitfire's range.


So why did they develop drop tanks, slipper tanks, leading edge tanks, larger main tanks and rear tanks if it didn't need more range?. What was the biggest drawback of the Spit again?, that's right, lack of endurance.


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## PAT303 (Aug 3, 2022)

Shortround6 said:


> Spits with 40 gallons in the rear tanks were tightening up turns even at two Gs but could be held. Mustangs at 55 US gallons in the rear tank were pretty much handling normally.


The Spit IX was deemed satisfactory to perform combat maneuvers once 34G ha been burnt off, the P51 was required to have no more than 40G in the rear tank an preferably 35G if going into combat. You will notice in both reports that it states that pilots need to get experience with the changes in handling when the rear tanks are use. 


http://www.spitfireperformance.com/Spitfire_IX_ML-186_Handling.pdf




http://www.wwiiaircraftperformance.org/mustang/P-51B_Fuselage_Tank_4-43-23-1.pdf


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## Shortround6 (Aug 3, 2022)

PAT303 said:


> I'm not suggesting the Spit goes into combat with any external stores such as a drop tank, no plane was except the MkXIV with the 90G combat tank so I don't understand what you are saying here, the Spit had the same restrictions put on it as the Mustang in regards to maneuvers with rear tanks an drop tanks, RAF mustangs had their rear tanks wired shut post war.


It simply shows the performance loss in climb.



PAT303 said:


> The Spit IX was deemed satisfactory to perform combat maneuvers once 34G ha been burnt off, the P51 was required to have no more than 40G in the rear tank if going into combat.
> http://www.spitfireperformance.com/Spitfire_IX_ML-186_Handling.pdf   http://www.wwiiaircraftperformance.org/mustang/P-51B_Fuselage_Tank_4-43-23-1.pdf



The two reports don't measure quite the same thing, as I pointed out earlier the Test on the Spit IX was for an experimental plane with all metal ailerons in Jan 1945.
The P-51B test was done in Dec 1943, and the handling of the P-51B was better at 1/2 tank than the Spitfire was at 1/2 tank.


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## Shortround6 (Aug 3, 2022)

PAT303 said:


> So if that's your logic they shouldn't have put rear tanks or drop tanks on the P51 because it couldn't climb turn or fight with full rear tanks and drop tanks either.


The P-51 was about 30-40mph faster than the Spitfire. 
The P-51B was almost 2,000lbs heavier than the Spitfire, a similar increase in fuel load is going to have a proportionally smaller change in performance. 

The P-51B has a way of fighting that is different than the Spitfire, it can use it's speed (and low drag) to compensate for it's poorer climb and turn.
Since the Spitfire is already slower sacrificing climb and turning ability may not be the way you want to go. 

Think about what happens if both planes are doing 360mph, the Spitfire has only a limited amount of excess power, the difference between 360mph and 400mph.
The P-51s is heavier but it has the difference between 360mph and 440mph and since the P-51 doesn't need as much power to fly at 360mph it has even more power to use for climb or turning.

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## 33k in the air (Aug 3, 2022)

PAT303 said:


> That's like being in a car race with the fastest car but with not enough fuel to make it to the end.



The Soviets gained air superiority over their own forces without long-range aircraft like the P-51 and without a large, four-engine strategic bomber force.


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## 33k in the air (Aug 3, 2022)

PAT303 said:


> So why did they develop drop tanks, slipper tanks, leading edge tanks, larger main tanks and rear tanks if it didn't need more range?. What was the biggest drawback of the Spit again?, that's right, lack of endurance.



Improving endurance for more localized air superiority duties -- or a better range for fighter-bomber work -- is not quite the same thing as flying 600+ miles to fight over the enemy's capital while your heavy bombers are hitting it.


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## PAT303 (Aug 3, 2022)

Shortround6 said:


> The P-51 was about 30-40mph faster than the Spitfire.
> The P-51B was almost 2,000lbs heavier than the Spitfire, a similar increase in fuel load is going to have a proportionally smaller change in performance.


I'm going to say it again for the dozenth time, I don't want to make the Spit a P51, I want it to be able to range deeper into Europe before the P51 came on scene and compliment it after.


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## PAT303 (Aug 3, 2022)

Shortround6 said:


> Think about what happens if both planes are doing 360mph, the Spitfire has only a limited amount of excess power, the difference between 360mph and 400mph.
> The P-51s is heavier but it has the difference between 360mph and 440mph and since the P-51 doesn't need as much power to fly at 360mph it has even more power to use for climb or turning.


Okay you win, instead of finding ways to give the B17's crews some support in 1942-'43 even if it's doing fighter sweeps causing the Luftewaffe to redirect their fighters around them taking away their ability to dictate when to attack your think a better suggestion is to do a Portal and say it can't be done?.


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## PAT303 (Aug 3, 2022)

33k in the air said:


> The Soviets gained air superiority over their own forces without long-range aircraft like the P-51 and without a large, four-engine strategic bomber force.


They didn't bomb Germany's industrial base.


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## PAT303 (Aug 3, 2022)

33k in the air said:


> Improving endurance for more localized air superiority duties -- or a better range for fighter-bomber work -- is not quite the same thing as flying 600+ miles to fight over the enemy's capital while your heavy bombers are hitting it.


Maybe some of you need to actually read posts before replying, for the upteanth time, I don't want to fly to Berlin in 1942, I just want to use the fighters on hand to support the bombers as much as possible, in 1942-43 on average B17 crews didn't make it to their 10th mission before being lost, maybe you all should have asked them if they wanted help, any help, even if it's half way out and half way back, do you think they would say, no thanks, Berlin or nothing?. Seeing what those crews had to endure I would have done anything to help, the naysayers be damned.


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## PAT303 (Aug 3, 2022)

Shortround6 said:


> The P-51 was about 30-40mph faster than the Spitfire.


Those P51A pilots are going to have sore necks constantly looking up as they watch the fighting going on above them.


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## Shortround6 (Aug 3, 2022)

PAT303 said:


> I'm going to say it again for the dozenth time, I don't want to make the Spit a P51, I want it to be able to range deeper into Europe before the P51 came on scene and compliment it after.


Just point out (for the dozenth time) that were differences between the Spitfire and P-51 that affected how they were used and what you could do with them.

A Spitfire IX was NOT a Mustang with less fuel. 
It had some definite limitations.
The MK VIII was supposed to be the longer range version. 
However it was not produced at Castle Bromwich in order not to affect production. 
The MK VIII got a strengthen fuselage and a retractable tail wheel and a few other minor changes. 

The MK IX only appeared in numbers (4 squadrons) at Dieppe and a lot of the early ones were built on MK V airframes with less than ideal outfits. 
The whole program was rush job to counter the Fw 190. and long range was not desired. They had the MK VIIIs in the works but they wouldn't show up until 1943 so the MK IX was the interim rush job. Turns out it was very close to the MK VIII in performance (except for range) so they kept building them with further refinements. One of which was the modified extended elevator horns. Probably not a good idea to put rear fuselage tanks in the early MK IXs.
By the time you get the new elevators and bit of streamlining (like stop using the VC wings with double cannon blisters) it is the fall of 1942 and RR and NA are both working on the Merlin Mustangs and the MK VIII is closer to production. There isn't a lot of opportunity to build long range MK IXs (and by long range I mean 150 Imp gallons internal).
You could build a plane with more range than the MK IX but how much is it really going to get you and are you willing to screw up production of the MK IX in the fall/winter of 1942 to get it?
Please note that several of test Spitfires used at Boscombe down were converted from MK Vs in October of 1942. 
Also note that the Mustang MK X with Merlin was flown by RR on Oct 13th 1942. 3-4 more were in the shop being worked on. 
Basically the MK IX was Flown with about 120 Imp gallons of internal fuel after the drop tanks were gone. Better than the standard MK IXs but we are talking about an extra 40-45 minutes of flight time? A lot this depends on the speed used when exiting. 

you only have a few months to make any major difference difference 

I would also note that the 8th Air Force was not doing a large number of raids into Germany in 1942 early 1943.

The 303rd Bomb Group made it's 50th mission flight on July 14th 1943 after starting on Nov 17th 1942. 
14 of those missions were into Germany. 

It might have been quite possible to make a long (or longer) ranged version of the Spitfire, but it might have required more engineering changes. Supermarine was also busy designing the MK XII Griffon Spitfire in the summer/fall of 1942 and the "prototype" MK XIV (MK VIIIG) flew in Jan 1943 although actual production aircraft didn't reach squadron service until Dec 1943. 
What version of the Spitfire do you want to stop in order to free up engineering staff (and workers for prototypes ) for the "somewhat" longer ranged MK IX Spitfires. 

There is no real reason they couldn't have built a Merlin powered Spitfire with 150 or more gallons of internal fuel, however you may very well need a slightly stronger fuselage, You may want the larger rudder, vertical fin of later versions, you may want a bit different elevator (or metal covered one) You may want a bit stronger landing gear to handle the higher take-off loads on non-paved runways. 
It was also a question of priorities. They didn't have the staff to handle all the different versions, perhaps they made some wrong choices, but in 1942 (and early 1941) they were handling a lot of projects (versions) all at once. A new version may have required another version to be canceled. 

A lot of 1942 was spent trying to catch-up/get ahead of the Fw 190. It didn't help that the Spitfires replacement (the Typhoon) was failing in rather spectacular fashion in 1942. 
Perhaps if the Typhoon had been able to make more of the load in 1942 the Spitfire might have been able to shift to other roles..

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## nuuumannn (Aug 4, 2022)

33k in the air said:


> To those at the time, with no RAF bombers making deep penetration raids in daylight, there is no reason to greatly extend the Spitfire's range. Indeed, the expectation was the American insistence to do deep raids in daylight would result in disaster. Which they did, enough so that there was an effort made to convince the USAAF to switch over to nighttime bombing.



There _was _discussion at high levels about increasing the Spitfire's range and we'll get to that in a second, but there was discussion about long range fighter escorts for the RAF surrounding the ineffectiveness of Bomber Command night raids, which took place in 1941 following the release of the Butt Report that included the suggestion of reverting back to daylight raids, although these could only be carried out with a long range escort fighter, something that even the Prime Minister had suggested. Again, as mentioned, it was Portal, Chief of the Air Staff who pooh pooed the idea, believing that a long range fighter would not be effective against existing short range fighters. Also in these discussions were bombing accuracy and successfully reaching the target area, both of which Bomber Command was bad at. Even before the war, there was discussion about bomber escort fighters, Edgar Ludlow-Hewitt, C-in-C Bomber Command in 1938 wrote, 

"Experience in China and Spain seems clearly to indicate that with the aircraft in use in two theatres of war at present, fighter escorts are considered absolutely essential for the protection of bomber aircraft. So far as I'm aware this policy runs counter to the view long held by the Air Staff".

That view remained entrenched within the Air Staff under Portal. 

Increasing the Spitfire's range was deemed necessary for ferry purposes and with this in mind, throughout 1941 and 1942 Supermarine did much work in researching the fitting of extra internal tankage and external tankage, either fixed or drop tanks with the intent of increasing the Spitfire V's range. Sholto Douglas, head of Fighter Command was keen on doing so, pushing for increased internal range rather than external tanks. In an Air Staff Requirement dated August 1941 there was a request to increase the tropical (yup) Spitfire's range to not less than 1,000 miles, which resulted in the demand for an additional 90 gallons of fuel. Following trials by the A&AEE with Spit V AB320, the aircraft had flown a distance of 1,035 air miles with a slipper tank under the fuselage. This was done at 15,000 ft at a speed of 170 IAS.

In the Big Book of Spitfires by Morgan and Shacklady there is ample reference to this work and on page 150 in the chapter about the Spitfire V marks there is a curious map, out of context with the text on that page, which shows projected ranges of a bomber escort Spitfire in circles from the UK, the caption reading "Maximum long range bomber escort shown as shaded areas - UK Berlin ferry range, full overload tanks". This shaded area shows transit range of 540 miles from fixed points in the UK, with sufficient fuel to return again puts the cities of Hamburg, Hanover, Berlin, Munich, Prague and Milan in range, there's even an outer ring where the range is extended for a one-way operation to 1,140 miles, which puts Leningrad and Belgrade in reach. The key to the map has the following,

"Fuel Basis, Escorting - 5 min take off, 10 min climb, 15 min max power, remainder max cruise at 240 mph. Enforcing - 5 min take off, remainder cruise at 240 mph with 20% fuel reserve."

Unfortunately there's no date nor clue as to who produced the map, but I'm guessing Supermarine.

In the book there is a page, 311, on efforts to increase the IX's range by Vickers and by the Americans at Wright Patterson, where Spitfire IXs MK210 and MK317 were sent for that purpose. Following modification and subsequent trials, the Vickers mods increased the Spitfire's range to 1,400 miles, the American efforts yielded increases over this to 1,600 miles, although handling unsurprisingly suffered. The American system was more efficient and handled better, although the Vickers system could be modified to increase the aircraft's range to 1,650 miles.

All this talk here about not needing to increase the Spitfire's range runs contrary to what actually happened and what was investigated by both the manufacturer and the RAF air staff.



Shortround6 said:


> There is no real reason they couldn't have built a Merlin powered Spitfire with 150 or more gallons of internal fuel, however you may very well need a slightly stronger fuselage, You may want the larger rudder, vertical fin of later versions, you may want a bit different elevator (or metal covered one) You may want a bit stronger landing gear to handle the higher take-off loads on non-paved runways.



This is true, but these changes would certainly not have been insurmountable. As mentioned above, range trials were carried out by Spitfires without these modifications that yielded ranges in excess of 1,000 miles, though. For anyone that doubts the Spitfire could have been modified to carry out the escort fighter role, get a copy of the Morgan and Shacklady book and read the sections on the Spitfire V and IX which both include information on efforts to increase its range. Much work was done and, as mentioned, the Spitfire's range _could be _and _was_ increased to (well) over 1,000 miles without too much modification.

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## 33k in the air (Aug 4, 2022)

nuuumannn said:


> There _was _discussion at high levels about increasing the Spitfire's range and we'll get to that in a second, but there was discussion about long range fighter escorts for the RAF surrounding the ineffectiveness of Bomber Command night raids, which took place in 1941 following the release of the Butt Report that included the suggestion of reverting back to daylight raids, although these could only be carried out with a long range escort fighter, something that even the Prime Minister had suggested. Again, as mentioned, it was Portal, Chief of the Air Staff who pooh pooed the idea, believing that a long range fighter would not be effective against existing short range fighters. Also in these discussions were bombing accuracy and successfully reaching the target area, both of which Bomber Command was bad at. Even before the war, there was discussion about bomber escort fighters, Edgar Ludlow-Hewitt, C-in-C Bomber Command in 1938 wrote,
> 
> "Experience in China and Spain seems clearly to indicate that with the aircraft in use in two theatres of war at present, fighter escorts are considered absolutely essential for the protection of bomber aircraft. So far as I'm aware this policy runs counter to the view long held by the Air Staff".
> 
> That view remained entrenched within the Air Staff under Portal.



I yield to your more thorough knowledge.

I do wonder though what Harris would have made of going back to daylight bombing in late 1942/early 1943.

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## PAT303 (Aug 4, 2022)

33k in the air said:


> I yield to your more thorough knowledge.
> 
> I do wonder though what Harris would have made of going back to daylight bombing in late 1942/early 1943.


It would be interesting trying to control 100's of miles of bomber stream made up of 1000's of individual bombers transiting in and out of the UK at the same time, it would certainly overwhelm the day defences not to mention saving a lot of black paint.


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## drgondog (Aug 4, 2022)

PAT303 said:


> Okay you win, instead of finding ways to give the B17's crews some support in 1942-'43 even if it's doing fighter sweeps causing the Luftewaffe to redirect their fighters around them taking away their ability to dictate when to attack your think a better suggestion is to do a Portal and say it can't be done?.


The better way was for Eisenhower to be satisfied with P-40s in abundance for North Africa and leave the P-38s in England, all three operational August to October 1942. Secondly, the LW in Luftflotte 3 were not shy about bouncing Spits, includng Spit IX. from the time the B-17s were making penetrations in November-December, 1943 and January,1944 when there were't enough Spit IXs for critical RAF missions. 

You may recall that in that timeframe - and beyond - though January 1944 the LW wisely chose to conserve the t/e fighters at the threshold of maximum penetration for the P-47s which in January 1944 was beyond Spit IX CR w/90 gal tanks. At that time, the RAF had given up the October thru December 1943 delivered Mustang III and were receiving Mustang III replacements for the reverse Lend Lease.

You might recall that RAF was Hugely influential in pushing the Merlin conversion in June 1942 timframe at R-R - which offered the promise or potential of a neary equal combat aircraft to the Spit IX in the same relative operational window as the Spit IX, by converting in-hand' Mustang I's.

To Portal being a 'short-sighted meanie' for not pushing major additional changes to the Spitfire airframe for additional internal fuel? 

Maybe he was doing some pretty good replacement planning to extend RAF operational footprint ) like escorting Mosquitoes to Norway, etc and let the Americans 'do what they do'? At the time the great R-R and NA experiment proceeded, RAF was getting butt kicked by the FW 190 and not enough airframe conversion capacity to make a difference until late Fall for series 60 Merlin powered Spits. The request by RAF and War Ministry for NA to ship P-51B airframe to Britain began before the first flight of the Mustang X in October 1942.

As an additional observation, thank God for Portal instead of Leigh-Mallory.

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## PAT303 (Aug 4, 2022)

drgondog said:


> leave the P-38s in England





drgondog said:


> LW in Luftflotte 3 were not shy about bouncing Spits, includng Spit IX.


Was the P38 working in 1942?, the Luftwaffe were keen to bounce MkV's but the MkIX took them very much by surprise, it's nearly impossible to tell them apart from a distance so at first they might have jumped in but caution soon prevaled once the MkIX starting being the predominate fighter.


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## Geoffrey Sinclair (Aug 4, 2022)

Shortround6 said:


> Just point out (for the dozenth time) that were differences between the Spitfire and P-51 that affected how they were used and what you could do with them.


Maybe if you took yes for an answer you would not need to repeat. No one here is trying to turn the Spitfire into the Mustang. They are trying to keep the Spitfire range comparable to the 1943/44 P-47, in a similar time frame.


Shortround6 said:


> The MK VIII was supposed to be the longer range version.


So it did not have the longest range on internal fuel of any Merlin version until the 1944 upgrades?


Shortround6 said:


> Probably not a good idea to put rear fuselage tanks in the early MK IXs.


Even with the extra forward weight you note? You are now in 1942, when no one else is thinking of or proposing rear fuselage tanks.


Shortround6 said:


> There isn't a lot of opportunity to build long range MK IXs (and by long range I mean 150 Imp gallons internal).
> You could build a plane with more range than the MK IX but how much is it really going to get you and are you willing to screw up production of the MK IX in the fall/winter of 1942 to get it?


That is the mark VIII plus 33 gallon rear fuselage tank. Why require it in 1942 to early 1943 after noting even the USAAF did not need that sort of range escorts given its operations at the time?


Shortround6 said:


> What version of the Spitfire do you want to stop in order to free up engineering staff (and workers for prototypes ) for the "somewhat" longer ranged MK IX Spitfires.


Why the somewhat and supposed ranges? How about two things, fit the larger internal fuel tanks into the Castle Bromwich Spitfires as it switches to mark IX, then add the 33 gallon rear fuselage tank in say October 1943, the 12th month of mark VIII production and the 14th month of mark VII. Given the exchanges about fighter ranges and drop tanks between the USAAF and RAF in mid 1943?


Shortround6 said:


> "It might have been quite possible to make a long (or longer) ranged version of the Spitfire, but it might have required more engineering change"
> " however you may very well need, ... You may want ... you may want ... You may want ..."


Have you noticed your Spitfires tend to turn up later, thirstier, more fragile, harder to fly and modify than the ones the British built? 

The time line is clear enough, the mark VIII with 90 gallon external tank as built has a longer range than the P-47 to July 1943, matches the P-47 range in August 1943, becomes less in September and much less in early 1944. Add a 33 gallon rear fuselage tank and it matches the early 1944 P-47. Pushing the Spitfire to the edge of its stability envelope and weights would take a lot of resources and time, to come up with something with less range than the off the shelf P-51B and later could supply. Adding a 33 gallon rear fuselage tank to remain competitive with the P-47 range in 1943/44 was clearly possible. Historically none of the 1943 Spitfires came with rear fuselage tanks, cut down rear fuselages or E wings, they were all 1944 changes, the XIV was (just) a 1943 production aircraft, the F.21 was a 1943 design one.

At 66 gallons per hour, 320 mph, translates to 4.85 miles per gallon, the Spitfire VIII had 660-434 = 226 miles more range than the Spitfire IX by having 124-85 = 39 gallons more fuel, 226/39 = 5.8 miles per gallon at economic cruise. So to reach 320 miles at fast cruise cost 66 gallons, at economic cruise 55.2 gallons. Looking at the map on page 8 here and knowing where the front line was in September 1944 it was possible for aircraft in Britain heading for the Ruhr to avoid hostile airspace until the German border, including flying direct courses, no need for high speed cruise until quite near the target, anyway the Germans were not contesting Netherlands airspace with fighters very often, if at all. That was the profile for the Spitfire longer range escort missions in 1944/45 and there were open continental airfields if something went wrong. Spitfire IX 85 gallons, add the 28 gallons of wing tanks and 66 gallons in the rear fuselage, total 179, deduct 103.5 for 300 miles of range, 23 for take off and climb, 36 gallons for combat leaves 16.5 gallons, you could almost do the trip on internal fuel with adequate reserves, alternatively have 113 gallons internal less 52 for return and 36 for combat leaves 27 gallons, the 90 gallon external tank handling the 52 for outward and 23 for climb. The Big Ben anti V-2 operations consisted of Spitfire fighter bombers from Britain making an attack, landing in Belgium, rearming and refuelling and doing another attack on the return journey.

As far as anyone can find the RAF did not run a single mission with a Spitfire VIII/IX/XVI formation using 66/75 gallons of rear fuselage plus wing tanks and a 90 gallon external tank. So there is no evidence for how well the combination went in service use, only the test pilot's reports. As noted that sort of fuel load is about 300 pounds heavier than the standard Spitfire VIII carrying 1,000 pounds of bombs, so at the least that needs to be engineered. To bring it back to the weights actually flown means a reduction of around 40 gallons. So say the 33 gallon rear fuselage tank and 90 external or the 75 internal and 50 external. While the usual rule is better to carry things internally the effects on handling by that much rear fuselage fuel means I suspect many pilots would have preferred the larger external tank. The test pilot's reports make it clear 33 gallons in the rear fuselage was completely acceptable, going beyond that caused increasingly difficult handling problems. Also having two smaller tanks in the rear fuselage was better than one big one because of the way the fuel would move during things like turns when the tank was part filled.

A Spitfire VIII with a 33 gallon rear fuselage tank and 90 gallon overload tank by end 1943 is not an engineering problem, it is whether it was asked for. Similar for taking the hit to production and switching Castle Bromwich to using the bigger fuselage and the wing tanks in 1943. Going beyond 33 gallons in the rear fuselage is an engineering issue, both in terms of handling and weight, it would not be a 1943 aircraft without a lot of work starting in 1942 and probably luck in coming up with the right answers early, if there actually were answers that could be implemented within the constraints of the time (Spiteful tail cure for F.21 series problems for example). Post war rules meant the RAF only used the rear fuselage tanks in the Merlin Spitfires at least with special permission, similarly post war Mosquitoes were flown at maximum weights of at least a couple of tons less than routine wartime weights and even during the war the RAF was wary about filling the rear fuselage tank of its Mustangs.

The various changes made to the Spitfire in 1944 are not well documented, even things like the cut down rear fuselage and E wing which are visible in photographs still have uncertainties. The internal fuel arrangements more so. Add the ongoing monthly quota for Spitfire IX to Russia, which would not want most of the longer range and which prolonged the mark IX production.

The Portal comments about long range were made in 1941, by then or at latest the end of 1941 the PR Spitfires had proved the range could be extended and the pilots could handle the flying hours and navigation loads. The early 1942 P-51 showed the combination of long range and high performance was quite possible. The Spitfire mark VII and VIII were the considered redesign starting in 1941 to make the best use of the Merlin 60 series engines and included adding another 37 gallons of fuel which combined with the 90 gallon external tank meant being able to reach out to around 300 miles at fast cruise and towards 400 at economic. In any case with its world wide commitments adding a long range fighter force in Britain plus associated long range day bombers would require reallocation of resources on a major scale to be effective. As we know the US supplied the bomber force but that was all plans in 1942 and into 1943, taking much longer than the timetables said and not asking for fighter escorts.

The Spitfire XIV as introduced was considered weight limited, not surprising given the engine change and the need for a larger tail, it reverted to the mark IX forward fuselage tanks, 87 versus 96 in the VII and VIII, but kept the wing tanks, the FR version did add rear fuselage cameras. The XIVE added a 33 gallon rear fuselage tank, the FR XIVE added cameras as well. The XIV was considered an interim version with the XVIII the definite one, it had more strengthening and a pair of 33 gallon rear fuselage tanks plus things like a wing that eliminated the residual support for the outboard 0.303 inch machine guns.

On top of the evolution of the original airframe and wing came the redesign for the F.21 and later series, the F.21 began production at Castle Bromwich in April 1944, with the probable aim of shifting all production to the new model, but handling problems kept the F.21 out of the war until just near the end, in fact until after the F.22 started production began, the F.21 came with 124.5 gallons of internal fuel, forward fuselage and wings. The F.22 introduced the rear fuselage tanks during production, the much later F.24 came with a pair of 33 gallon rear fuselage tanks.

Packard Merlin production was was quite consistent July to December 1942, 801, 800, 800, 800, 796, 849, not so consistent January to June 1944, 1,564, 1,490, 2,000, 1,905, 1,275, 2,239

Supermarine Spitfire output July 1940 to April 1941, 137, 127, 100, 61, 74, 42, 49, 66, 67, 74. The mark V began series production in March, mark I ended in April. Overlaying the September damage there was usually a reduction in output during winter, harder to make test flights, plus there was the chance for the staff to recover from the major efforts during the Battle of Britain. January to June 1940 production was 37, 51, 40, 60, 77, 93

Weights, Merlin III 1,375 pounds, Merlin 46 1,425 pounds, Merlin 61 1,640 pounds, Griffon 61 1,980 pounds.

As a final note the British economy was tightly stretched in 1943, even simple things like putting drop tanks into series production involved time lags and trade offs where production of other items was cut and this continued into 1944. The US histories note the required resources for Operation Overlord had world wide effects, they also note some of the effects on the British economy, like cutting steel production. The invasion force was taking over ports for holding its shipping and then for moving to France, reducing the port's ability to handle normal economic traffic, while generating large scale moves to handle the supplies and equipment arriving, then departing from different ports. In the first half of 1944 the British added 28,300 more people or 13.1% more labour to the railway system, including Italians. Despite this in May restrictions were placed on civil rail traffic.

Overlord needed plenty of coasters but the US had been very successfully building largely ocean going tonnage. The rather busy British coaster fleet would need to be used, which meant withdrawal from service for modifications then withdrawal as part of the invasion. Initially some 396 coasters totaling 623,000 DWT were considered suitable and each used underwent an on average 3 month refit (extra armament, accommodation, strengthened masts and smoke making equipment) the refit program began in October 1943 just before the railways began having their usual winter problems. As it turned out the reduction in war damage to the coaster fleet meant the tonnage available in the winter of 1943-4 was about the same as the previous year. Despite agreements to hand back ships after the initial invasion it turned out that between December 1943 and the end of 1944 another 64 coasters of 100,000 DWT were added to the invasion fleet. The US helped by allowing use in Britain of locomotives and rolling stock meant for France. This resulted in post invasion exchanges of we want our Coasters/Trains back, you first.

The real world restrictions on what ifs.

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## drgondog (Aug 4, 2022)

PAT303 said:


> Was the P38 working in 1942?, the Luftwaffe were keen to bounce MkV's but the MkIX took them very much by surprise, it's nearly impossible to tell them apart from a distance so at first they might have jumped in but caution soon prevaled once the MkIX starting being the predominate fighter.


The P-38F and G were operational in 1942, early 1943 - and likely to experience the same issues encountered in fall 1943 with P-38H's. That said, the experiences gained with early identification of issues a year earlier would have been fortuitous by summer 1943 when penetrations to Hamburg and Shweinfurt occurred. 

The heavy loss issues experienced by 14th FG in Africa were more due to inadequate training time in type as well as zero combat experience aganst LW pros.


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## Shortround6 (Aug 4, 2022)

PAT303 said:


> Was the P38 working in 1942?


Define working.

There were 4 fighter groups in England in Sept 1942, 3 were sent to North Africa for Torch. 
There is a very high attrition rate (or low serviceability?) of the P-38s in North Africa. The 78th fighter group in England is stripped of pilots and planes for NA but the 78th stays in England as a unit. The 1st and 14th groups do most of flying in NA. the 82nd group gives most of it's planes to the 1st and 14th groups after flying to NA and gets replacement planes from the US. 

In Jan 1943 the 3 fighter groups in NA have about 90 planes operational between the 3 of them. The 78th back in England has to send most of it's replacement planes to NA. 

Obviously there are some problems but P-38s are the E, F and G versions but mostly F and G. They have different problems from the P-38s used in Europe in late 1943 although the cold cockpit would be common to all. 

Lockheed built 1264 P-38s in 1942, In Dec alone 475 P-38s were shipped to England by sea.

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## Shortround6 (Aug 4, 2022)

Geoffrey Sinclair said:


> Have you noticed your Spitfires tend to turn up later, thirstier, more fragile, harder to fly and modify than the ones the British built?


Some of the modifications don't seem that difficult. 
But the whole rear tank set up seems a bit dodgy compared to the Mustang. 
Mustangs in US service were allowed to keep using their rear tanks for years after the war (I don't know if the shifted anything else. like radios or got ballast or????) 
High back Spitfires were allowed to fill the rear tanks with special permission, otherwise wired shut. 
Low back Spitfires were prohibited from using the rear tanks under any circumstances. 
The test of the Spitfire in Jan 1945 used metal covered elevators. A relatively simple change but not done on service aircraft even post war? 
This is the plane with evaluation of burning down the fuel by 30 gals leaving 43 in the tank/s.
What was the recommendation for fabric covered elevators? 
Post war Manual says 30 gallons remaining was dividing line between what you could do and what you couldn't.
Extra insurance in peacetime or different elevator required a different limit or both. 

Low back Spits (at least MK XVIs ) might have benefited from a broader tail/rudder like the Griffon powered XIV. when trying to fly with a rearward CG? 

As far as thirstier goes, I don't go with best estimates for the Mustang either. The Manual for the P-51B was all estimates and provisional and said so, twice. It does not line up with the charts for the P-51D. 

US radius charts were done at 25,000ft. The advocates of the Spit want to use 20,000ft. How do you want to cover the difference? 
The US also figured the exit speed at 215 IAS. I am not saying they were right but we do need to use a common speed to compare planes.


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## 33k in the air (Aug 4, 2022)

PAT303 said:


> It would be interesting trying to control 100's of miles of bomber stream made up of 1000's of individual bombers transiting in and out of the UK at the same time, it would certainly overwhelm the day defences not to mention saving a lot of black paint.



It would require a lot of retraining of Bomber Command crews. Its aircraft flew to and aimed at the target individually in nighttime bombing, a sharp contrast to the USAAF approach of large, tight formations and the aiming done by lead crews. (The retraining matter was something which the USAAF cited as one of the reasons to not switch to nighttime bombing.)

As it was historically, when Bomber Command did do daytime bombing in 1944, it had to come up with its own tactics since its crews were not trained in tight formation flying. The target marking methods used at night also didn't work as well in daylight and required modification.

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## drgondog (Aug 4, 2022)

33k in the air said:


> It would require a lot of retraining of Bomber Command crews. Its aircraft flew to and aimed at the target individually in nighttime bombing, a sharp contrast to the USAAF approach of large, tight formations and the aiming done by lead crews. (The retraining matter was something which the USAAF cited as one of the reasons to not switch to nighttime bombing.)


100% correct. The ENTIRE US Heavy Bomber crew training pipeline was dedicated to learning the B-24 and B-17 systems, charateristics, daylight (primary) navigation and bomb aiming. It would have deeply impacted expectations for POINTBLANK objectives to be achieved before D-Day. In October, then the brief experience of setting up RAF linked operational training for night operations during November 1943 made it abundantly clear there was no turning away from daylight ops.


33k in the air said:


> As it was historically, when Bomber Command did do daytime bombing in 1944, it had to come up with its own tactics since its crews were not trained in tight formation flying. The target marking methods used at night also didn't work as well in daylight and required modification.


The AAF problem in reverse.

Additionally, no one or unit devoted any significant time understanding the consequences of hearing many airborne collisions over Britain...as two enormous Air Forces competed for airspace at night.

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## nuuumannn (Aug 4, 2022)

33k in the air said:


> I yield to your more thorough knowledge.
> 
> I do wonder though what Harris would have made of going back to daylight bombing in late 1942/early 1943.



Aww shucks, I don't do this to prove my superiority, but because of the reading I've done I know the RAF and Supermarine discussed the idea. The issues that were raised, in reality and here on this thread were/are not insurmountable and if the desire to do it had been there, it would have been done. The work that was done proves that it could have been if there was a need to do it. After all, they turned the Spitfire into a naval fighter, which required a huge amount of structural modification, probably more than what would have been required to turn it into a long range escort fighter.

Harris might have grumbled and groaned, but he wasn't beyond reason. On his watch was the introduction of sophisticated nav aids, which he expressed dismay about, the panacea targets he despised were targeted and so forth. One of his underlying beliefs was that his bomber boys should have the best equipment and ability to do their jobs. If he could have been convinced that having escort fighters along for the ride on daylight ops would have prevented bomber and crew losses, he would have supported the idea. Who knows, he could have thrown his weight behind their development - that might have yielded results. Harris could be very persuasive when he wanted to be.



drgondog said:


> 100% correct.



Yup, agree. When the 8th AF first arrived in Britain, their operational training was done there, including gunnery training, as power turrets were still very new on US bombers even into mid-1942. It wasn't until some bright spark realised the US has acres of uninterrupted sky so training should take place there.

US 8th units did embark on night operations with Bomber Command and to all intents and purposes they were successful, so the Americans could have done night bombing, but the joint chiefs of the 8th and BC came to the conclusion that round-the-clock bombing was a better way of bringing the Reich to its knees.

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## 33k in the air (Aug 4, 2022)

nuuumannn said:


> US 8th units did embark on night operations with Bomber Command and to all intents and purposes they were successful, so the Americans could have done night bombing, but the joint chiefs of the 8th and BC came to the conclusion that round-the-clock bombing was a better way of bringing the Reich to its knees.



Quoting from Roger Freeman's _Mighty Eighth War Manual_ (p.93-94):

In July [1943] it was planned to equip and train six B-17 groups, three in each Division initially, the 92nd, 94th, 96th, 305th, 306th and 385th, to join in raids by RAF Bomber Command. Thirty aircraft in each were to be modified for the task, receiving resin lights, engine exhaust flame dampers and blackout curtains for the navigator's compartment. Gun barrels would need flash eliminators to prevent gunners from being temporarily blinded when firing. Additionally, night adaption goggles had to be supplied for the crews. It was also desirable that the B-17s involved had Gee and Standard Beam Approach equipment, while it was essential that only those with long-range wing tanks were selected.

On 20 July the 422nd Bomb Squadron of 305th Group was selected to act as a trials squadron to co-operate in RAF night bombing attacks. An RAF Bomber Command liaison officer was later attached to the unit at Chelveston where night flying training began on 2 August 1943 . . . This squadron attacked coastal defences near Boulogne on 8 September for its first night bombing mission and during the following four weeks flew seven more to targets with RAF Bomber Command . . . No more than five aircraft were despatched on any one night and the total effective sorties for the eight raids was 32 . . .

Throughout September the six groups assigned to night bombing preparations had been carrying out modifications and training and by October several crews were considered ready to participate in operations. However, all night training was stopped when, following a conference at VIII BC, the decision was made to not proceed with the plans for night bombing. Factors influencing this move were: despite heavy losses the day bombing brought positive destruction of industrial targets while there was no immediate hope of any such accuracy in the night attacks; 422nd's performance had shown that losses would not be substantially reduced by operating in darkness; if night bombing was continued the assigned groups would have to practise this exclusively thus weakening the daylight effort; the anticipated availability of long-range fighters for escort should reduce day bomber losses.

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## Howard Gibson (Aug 5, 2022)

33k in the air said:


> I yield to your more thorough knowledge.
> 
> I do wonder though what Harris would have made of going back to daylight bombing in late 1942/early 1943.


The American heavy bombers had turbochargers. The British heavy bombers did not. American bombers flew high enough that to attack them, the Germans had to climb up above 30,000ft, which suited the escorting P-47s, also turbocharged, perfectly. At 30,000ft, P-47s had a huge speed advantage over the Germans, something like 50mph. In combat, this is not manageable. Escorting Lancasters in daylight would have placed Spitfires at altitudes that suited Fw-190s. The Spitfires could escort American bombers, and they would be faster at 30,000ft, but not as much faster as the P-47s.

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## PAT303 (Aug 5, 2022)

Howard Gibson said:


> The British heavy bombers did not


They had superchargers instead.


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## Milosh (Aug 6, 2022)

PAT303 said:


> They had superchargers instead.


2 speed superchargers that had the engine producing it max HP at 6000ft.


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## PAT303 (Aug 6, 2022)

Milosh said:


> 2 speed superchargers that had the engine producing it max HP at 6000ft.


The Merlin XX had just under 1300hp @ 10,000ft and just under 1200 @ 17,500. If the need arose to fly higher there's no reason high altitude merlins couldn't be fitted.


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## EwenS (Aug 6, 2022)

PAT303 said:


> The Merlin XX had just under 1300hp @ 10,000ft and just under 1200 @ 17,500. If the need arose to fly higher there's no reason high altitude merlins couldn't be fitted.


The RAF did experiment with two stage Merlin engined Lancasters.

Rolls Royce converted 9 Lancaster III into Mk.VI with two speed, two stage Merlin 85/87 in annular cowlings. 7 were used by 4 of the 8 Group Pathfinder squadrons often as Master Bomber aircraft and the other pair for trials. Withdrawn from operational use in Nov 1944. The engines proved difficult for ground crews to maintain however. Probably nothing that could not have been overcome, especially in light of the engines fitted to the Lincoln.

313mph at 18,200ft at take off weight of 65,000lbs. Service ceiling 28,500 ft at same weight.









AIRCRAFT OF THE ROYAL AIR FORCE, 1939-1945: AVRO 683 LANCASTER.


Lancaster B Mark VI, JB675 at Hucknall, Nottinghamshire, after conversion from a B Mark III by Rolls-Royce Ltd, who installed 1,635 hp Merlin 85 engines and four-bladed propellers.




www.iwm.org.uk





Merlin 85 & 68A were used on the Lincoln I & II respectively (originally designated Lancaster IV & V) which reached the first squadrons in Sept 1945.

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## Geoffrey Sinclair (Aug 6, 2022)

Shortround6 said:


> Some of the modifications don't seem that difficult.


Which ones? As so far it comes across as all too hard


Shortround6 said:


> But the whole rear tank set up seems a bit dodgy compared to the Mustang.


If you changed that to had more problems you would join everyone else.


Shortround6 said:


> Mustangs in US service were allowed to keep using their rear tanks for years after the war (I don't know if the shifted anything else. like radios or got ballast or????) High back Spitfires were allowed to fill the rear tanks with special permission, otherwise wired shut. Low back Spitfires were prohibited from using the rear tanks under any circumstances.


As has been reported many times, add the RAF was wary about operating wartime Mustangs using the rear tank. The post war pilot's notes for the Mustang say carrying under wing loads made the handling better and caution about the effects of dropping the loads with the rear tank still full. So putting a 90 gallon external tank on the Spitfire should to the same sort of thing. As the cut down fuselages on the P-47 and P-51 caused handling issues, requiring a dorsal fin extension, you would expect the same for the Spitfire. 


Shortround6 said:


> The test of the Spitfire in Jan 1945 used metal covered elevators. A relatively simple change but not done on service aircraft even post war? This is the plane with evaluation of burning down the fuel by 30 gals leaving 43 in the tank/s.


Actually wrong, the early 1945 tests used a standard Spitfire that was also given hand made metal covered elevators for *some* of the tests, they made handling better. There were July 1944 tests on a mark VIII with a 75 gallon rear fuselage tank. The 30 odd gallons level had been worked out some time previously. Not sure if the 1945 tests made it official or not. The post war Spitfire IX and XVI notes state all XVI and some late model IX had the rear fuselage tanks, the effective start of XVI production was September 1944.


Shortround6 said:


> Post war Manual says 30 gallons remaining was dividing line between what you could do and what you couldn't. Extra insurance in peacetime or different elevator required a different limit or both.


Whatever. It is clear you consider the rear tank in a Spitfire a bad idea, you are just having trouble finding a good reason why, trialing various thoughts like reaching back to 1942. The US mark IX modification was adding 43 gallons in the rear fuselage, plus 16.5 gallons in each wing and plumbing the wings to allow a pair of 62.5 gallon drop tanks, similar to the Mustang. The Spitfire VIII pilot's notes have a 26 gallon rear fuselage tank


Shortround6 said:


> Low back Spits (at least MK XVIs ) might have benefited from a broader tail/rudder like the Griffon powered XIV. when trying to fly with a rearward CG?


As a first problem that adds weight aft, which makes the CoG issues worse. A post war trial with a 58% bigger tail on the mark IX had a mixture of handling advantages and disadvantages.


Shortround6 said:


> US radius charts were done at 25,000ft. The advocates of the Spit want to use 20,000ft. How do you want to cover the difference?


The one data point we have for calculating the Spitfire is at 20,000 feet and "advocates" is an interesting adjective, does that make you a detractor, anti advocate? As for the altitude correction the post war Mustang notes on fuel consumption with altitude have the datum point as 10,000 feet, and say consumption increases over datum by 4.5% at 20,000 feet and 5.5% at 25,000 feet.


Shortround6 said:


> The US also figured the exit speed at 215 IAS. I am not saying they were right but we do need to use a common speed to compare planes.


So the P-38 and P-47 combat radius figures require them to use the same speed as the Mustang? Remembering that being slower than the Mustang they would have the same reserve power issues you brought up about the Spitfire.

We have no idea how the 8th Air Force calculated combat radius, how much allowance for formation flying, for the inevitable difference between aircraft and pilots, whether it was a fast climb to operational height or a steady one, the climb fuel allowance, if economic cruise was employed between base and a given distance from hostile airspace or further and probably other factors. Until that is clarified no one can apply similar adjustments to the Spitfire.

According to Roger Freeman adding an 84 gallon external tank gave the P-47 a combat radius of 280 miles, 108 gallons external increased the radius to 325 miles, so around 90 more miles at a mile a gallon. Upping the external load to 165 gallons increased radius to 375 miles, so 190 more miles from 81 gallons, over 2 miles per gallon. The different external loads 165-108 = 57 gallons for 100 more miles. At 2 miles per gallon going out and back to 280 miles requires 280 gallons, leaving 305-280+84 = 109 for combat and reserves for the earlier P-47D, going out to 325 miles leaves 108-20 = 88 for combat and reserves, to 375 miles leaves 165-70 = 95 gallons for combat and reserves.

According to Francis Dean the yardstick range for a P-47 with 305 gallons was pushing 1,000 miles, so over 3 miles per gallon but adding another 65 gallons internal does not raise the range by around 200 miles. His combat radius with 370 gallons internal is 225 miles, adding 300 gallons of external fuel pushes that to 670 miles, so over 3 miles per gallon. Mission profile is 5 minutes warm up and take off climb to 25,000 feet covering no horizontal distance, cruise (but not at what setting), drop tanks 5 minutes combat and 15 minutes military power for combat, 30 minutes reserves at economic cruise.

Essentially keeping the Spitfire VIII range comparable to the P-47D was possible for much of 1943 as built and required around 33 gallons of rear fuselage fuel to remain so in early 1944, and the engineering issues for the additional tank were historically largely solved in 1942/43 given things like the rear fuselage ferry tank for the mark V and we know that the issues were not major for that fuel load.

Arthur Harris turned down an offer from James Doolittle to mount a combined day mission to Berlin in 1944 citing the lack of fighters available. Eaker had the 1943 problem of a lack of fighter range but also a lack of fighters compared with his bomber strength, it meant running unescorted raids or an underemployed bomber force.


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## PAT303 (Aug 6, 2022)

I've posted this before but simply increasing the size of the leading edge tanks is also a viable option, for reasons unknown the tanks were only between ribs 7 and 5, the PR spits had the tanks from rib 2 outwards, making the MkVIII tanks from rib 2 to 7 doubles their capacity to 50G combined with the added bonus of keeping it on the COG.

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## drgondog (Aug 7, 2022)

PAT303 said:


> I've posted this before but simply increasing the size of the leading edge tanks is also a viable option, for reasons unknown the tanks were only between ribs 7 and 5, the PR spits had the tanks from rib 2 outwards, making the MkVIII tanks from rib 2 to 7 doubles their capacity to 50G combined with the added bonus of keeping it on the COG.
> View attachment 680836


Something about flying an unarmed Spit, maybe. Additionally, complicated to fill multiple tanks, as well as complicating plumbing outboard of the guns as well as screwing up oll inertia as you move outboard. The Mustang was delivered with two auxilary tanks (total 26 gal) in each wing gun and ammo bays. RAF had choice of Very long range (for that time) Recon with only the two fuseage cowl guns. A similar approach leaves a Spitfire defenseless.

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## Shortround6 (Aug 7, 2022)

Most of the swo stage PR Spits got enlarged oil tanks. 

Many of the PR Spits were allowed to fly (or take-off) hundreds of pounds heavier than the combat versions.
Some of the PR Spits had no BP glass.

Most of the PR Spit pilots were instructed to get the pictures back, not muck about with German fighters, even if they had a few guns. 

going back to the P-51 for moment. 




Two different tails and two different rear fuselages for 3 different combinations. 
A Pilots manual may have to cover all three.

The British may have been able to build a longer range Spitfire. 
But what version shouldn't' they have built and what do you need to t do ( I am assuming it could have been done, eventually) to get the Performance you want.

Performance includes climb, turn, roll rate, etc. 
Perhaps they set the Performance standard too high (weren't willing to accept the loss in handling/flying qualities) ? 
Perhaps they didn't have the engineering staff to handle too many changes at once and other projects (Stuffing Griffons in the airframe) took priority.


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## NevadaK (Aug 7, 2022)

Well, a different take would be that a longer range Spitfire would have hurt the daylight bomber offensive. 

My understanding (albeit a little under informed) is that bomber escort was conducted in zones, or waves. The first zone, or wave, was conducted by Spitfires and P-47 ranging our about 250 miles (rough memory here), after that a second zone with P-47's and P-51's out to about 400 miles, and after that P-51's. The planning was for each escort fighter group to be at optimal fighting weight in its area of coverage, not carrying too much fuel to be a liability. On return, bomber groups would be picked up by different escort groups at optimal ranges. 

The Spitfire was being used in its best range and performance. Trying to extend the range, duplicates the capabilities of an already excellent aircraft (Mustang) and creates a void in the shorter coverage area.

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## drgondog (Aug 7, 2022)

Shortround6 said:


> Most of the swo stage PR Spits got enlarged oil tanks.
> 
> Many of the PR Spits were allowed to fly (or take-off) hundreds of pounds heavier than the combat versions.
> Some of the PR Spits had no BP glass.
> ...


Better comparison perhaps is same basic wing/fuselage/empennage for all three 'combinations' - different afterdeck and cockpit enclosure - requiring slightly different DF. Same fuel capacity. Same basic engine, but different supercharger stage variation for different performance envelope. The Dorsal Fin and reverse rudder boost kits added to B/C/D/K until they became production articles. Most of the fuselage and wing from firewall aft, save cooling scoop and radiators to handle heavier load than NA-73 through NA-99 (P-51A).

The only significant changes were related to visibility (cockpit enclosure) and Reduced manueverability through additions of DF and RRB to both B and D. 

The handling qualities reduced with each successive model from A to H, where B and D were less 'pilot natural'than A, until the redesign of the H restored 'handling quality' - the only exception is that B/D rolled better with +/- 15 degree and H matched with +/ 10 but larger ailerons.

The growth of the Spitfire variations from Spit V through Spit XIV are analogous to P-51A through P-51D with diffrent and heavier engines, more weight/torque and design compensations of new rudder and GW without dramatic changes to fuselage/wing. For my, I like to think of the Mark XIV/XVI (and 109K) were top of the line muscle cars similar to P-51D, when compared to Mark V (and Bf 109F) and P-51A as the Gran Prix 'nimble and fun' types.

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## PAT303 (Aug 7, 2022)

drgondog said:


> Something about flying an unarmed Spit, maybe


Huh?.


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## PAT303 (Aug 7, 2022)

drgondog said:


> A similar approach leaves a Spitfire defenseless.


Why would making the tank from rib 2 to rib 7 leave the Spit defenceless?, your not taking the guns out.


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## PAT303 (Aug 7, 2022)

NevadaK said:


> The Spitfire was being used in its best range and performance. Trying to extend the range, duplicates the capabilities of an already excellent aircraft (Mustang) and creates a void in the shorter coverage area.


We are not trying to make the Spit a Mustang, we are trying to extend the range of the Spit before the Mustang comes into service.

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## PAT303 (Aug 7, 2022)

Shortround6 said:


> The British may have been able to build a longer range Spitfire.
> But what version shouldn't' they have built and what do you need to t do ( I am assuming it could have been done, eventually) to get the Performance you want.


Which version should they have built, the one with more than 175 mile radius, why don't we start with that. Seriously we are going around in circles.


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## NevadaK (Aug 7, 2022)

PAT303 said:


> We are not trying to make the Spit a Mustang, we are trying to extend the range of the Spit before the Mustang comes into service.


I understand that, but I'm a little confused as to why? In 1943, the P-47 and P-38 were already in use. The big missing piece is the Mustang which has the range necessary to provide coverage at the full range of the bomber force. The failures of the USAAC bombing campaign in 1943 are due to more than just the lack of escort fighters beyond the 400 mile range arc. The small size of the force itself contributed to the high loss rates. If you take a look at the graphic I added to my earlier post and the ones below, escort fighter coverage occurred in a series of zones. The Spitfire and P-47 were well used in the 200 and 400 mile arcs (ok, slightly shorter). Beyond that required a plane with really long range and that was the P-38 and Mustang. It seems to me that trying to give a Spitfire that kind of range is, in essence, trying to make it a Mustang.

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## Shortround6 (Aug 7, 2022)

You are adding almost 200lbs of fuel plus the weight of the tanks. over the weight of MK VIII with the existing tanks. 

Why didn't they do themselves? 

Some of the early MK VIIIs had a fuel cooler added in the port wing root. It may have depended on which engine and when the plane was built. 
Some planes had a gun camera in the wing root/leading edge. That seems to have bounced back and forth Between sides? 

When the MK VIII was being designed (not when they were built) what was the promised power out put of the Merlin engine?
The Merlin 61 had been cleared for 60.5in, they were testing for 66.5in for emergency use.
The Merlin 45 was cleared for 60.5 but when they went for 66.5in they had to reinforce the supercharger drive. 

What was the Performance they were going after? 

The point of the PR Spits is that they would load them down with more fuel because they didn't expect them to perform violent maneuvers. They expected them to run at high speed and gentle maneuvers. 

You can reinforce the wings to handle more weight (if you have the time to do the calculations and the change the production drawings).

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## PAT303 (Aug 7, 2022)

Shortround6 said:


> The point of the PR Spits is that they would load them down with more fuel because they didn't expect them to perform violent maneuvers. They expected them to run at high speed and gentle maneuvers.
> 
> You can reinforce the wings to handle more weight (if you have the time to do the calculations and the change the production drawings).


And again I will say NO plane including the much vaunted P51 can do combat maneuvers when loaded with fuel, I have already posted evidence of this, why is it okay for the P51 to have to drop it's tanks and have no more than 35G in the rear tank before combat but it's a major issue with the Spit?. I will repeat myself again, by the time the Spit gets into combat the rear upper 41G tank will be empty because it's burnt off in warm up, taxing and climb to altitude, the bottom 33G is it's reserve, the IDENTICAL procedure used by the P51.


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## PAT303 (Aug 7, 2022)

NevadaK said:


> I understand that, but I'm a little confused as to why?


Look at the diagram you posted, there's your answer.


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## NevadaK (Aug 7, 2022)

PAT303 said:


> Look at the diagram you posted, there's your answer.


Correct, that the P-47 and P-38 were already providing coverage for all but the longest missions. 

To your point that you aren’t trying to make the Spitfire into the Mustang, that is exactly what you are arguing for, a plane that can provide coverage for the longest missions. In other words a P-51.


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## PAT303 (Aug 7, 2022)

NevadaK said:


> Correct, that the P-47 and P-38 were already providing coverage for all but the longest missions.
> 
> To your point that you aren’t trying to make the Spitfire into the Mustang, that is exactly what you are arguing for, a plane that can provide coverage for the longest missions. In other words a P-51.


Actually no, go back and read through the thread, what I'm asking for is a Spit with increased fuel capacity that could have been flying 300+ mile missions late 1942 early '43 before the P47-P38 were available.


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## Shortround6 (Aug 7, 2022)

You are adding almost 200lbs of fuel plus the weight of the tanks.

Why didn't they do themselbes?


PAT303 said:


> And again I will say NO plane including the much vaunted P51 can do combat maneuvers when loaded with fuel, I have already posted evidence of this, why is it okay for the P51 to have to drop it's tanks and have no more than 35G in the rear tank before combat but it's a major issue with the Spit?. I will repeat myself again, by the time the Spit gets into combat the rear upper 41G tank will be empty because it's burnt off in warm up, taxing and climb to altitude, the bottom 33G is it's reserve, the IDENTICAL procedure used by the P51.


The much vaunted P-51 was used with 55 US gallons (45 Imp) in the rear tank, plus the 180 US (150 imp) gallons in the wing tanks. 

the Mustang rear tank was worth 240 miles of radius. 460 miles with the wing tanks and a pair of 75 gallon drop tanks, 700 miles with the wing tanks, the rear fuselage tank and the pair of 75 gallon drop tanks. 55 gallons was getting them 4.36 gallons (US) per mile which is perfectly reasonable for a Mustang. 

The Manual for the Spit says to have no more than 30 Imp gallons in the rear tanks (post war manual does not say 33 IMP, it says 30.) the handling trial from Jan 1945 used the metal covered elevator. I would very hesitant to use that recommendation on a normal MK IX and we do know that not all MK IXs used the same elevators. 

If they had wanted to they might have changed things (they sure changed the horizontal stabilizers/elevators on the Typhoon to carry 1000lb bombs.) 

The Spitfire needs more fuel per mile, It will only old about 2/3rds the fuel in the rear tank for combat. It won't hold as much as the Mustang without jumping through some more hoops in the forward/wing tankage. 

Now as a sort of Benchmark the Mustang without drop tanks had a radius of 150miles without the rear tank and 375 miles without drop tanks and with the rear tank filled. 
269 gallons vs 334 gallons for the wing tanks (184) and drop tanks (150) for the 460 mile radius. 

Warm up, take-off, and climb to 25,000ft can take a fair amount of fuel and combat allowance of 5 minutes WEP and 15 minutes military can also suck up fuel. 

A Mustang with wing tanks and 75 US gallon drop tanks and no rear fuselage was carrying close to 2000lbs of fuel for take off. 

A Spitfire needs to lift over 270 Imp gallons of fuel for that weight. 
That is part of the problem for a long range Spitfire, you have to get the weight off the ground not on a special one off mission but for every mission for weeks on end, without breaking the planes or having a high accident rate.


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## PAT303 (Aug 7, 2022)

Shortround6 said:


> That is part of the problem for a long range Spitfire, you have to get the weight off the ground not on a special one off mission but for every mission for weeks on end, without breaking the planes or having a high accident rate.


And yet they did it, go figure. http://www.spitfireperformance.com/spitfire9-fuelsystem-lr.jpg


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## PAT303 (Aug 7, 2022)

Shortround6 said:


> The Spitfire needs more fuel per mile, It will only old about 2/3rds the fuel in the rear tank for combat. It won't hold as much as the Mustang without jumping through some more hoops in the forward/wing tankage.
> 
> Now as a sort of Benchmark the Mustang without drop tanks had a radius of 150miles without the rear tank and 375 miles without drop tanks and with the rear tank filled.
> 269 gallons vs 334 gallons for the wing tanks (184) and drop tanks (150) for the 460 mile radius.


What part of I'm not trying to make the Spitfire a P51 don't you understand?. MkXIV's did 300 mile missions with just a 90G drop tank so lets stop pretending it can't be done.


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## Shortround6 (Aug 7, 2022)

PAT303 said:


> What part of I'm not trying to make the Spitfire a P51 don't you understand?,



You need a MK VIII. 
It should make it back at the desired speed over 300miles after burning the 20 minutes of combat time fuel and with 30 minutes of reserve. 

You just need about 116 gallons of fuel when you drop the external tank. 
Play games with your tank size and a bit of juggling with the internal fuel (use 30 gallons in the rear, it will work)

The problem comes with the 300* plus.*

Like trying to make it much past Cologne. 

You are going to need about 1 imp gallon for every 5 miles you go in and 1 imp gallon for every 5 miles you come out. 
350 mile radius is going to need and extra 20 gallons. 

And with even a 90imp gallon drop tank you are over the normal max gross weight and may be restricted as to what runways you can use.

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## PAT303 (Aug 8, 2022)

And again they got 1,000 mile ranges out of them as per posts a page or so back, your determined to find reasons why it couldn't be done when it clearly was.


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## drgondog (Aug 8, 2022)

NevadaK said:


> Well, a different take would be that a longer range Spitfire would have hurt the daylight bomber offensive.
> 
> My understanding (albeit a little under informed) is that bomber escort was conducted in zones, or waves. The first zone, or wave, was conducted by Spitfires and P-47 ranging our about 250 miles (rough memory here), after that a second zone with P-47's and P-51's out to about 400 miles, and after that P-51's. The planning was for each escort fighter group to be at optimal fighting weight in its area of coverage, not carrying too much fuel to be a liability. On return, bomber groups would be picked up by different escort groups at optimal ranges.
> 
> ...


The ranges depicted for the P-47s are approximately 108gal C/L ranges in the January-February timeframe. The lack of 357FG Mustang assignment (mid Feb) and inclusion of 20th FG P-38 implies very late 1943 though January. The inclusion of 358FG specifically ties from early Jan to very late January, 1944. 

It was traded for 357FG to 9th AF and its last Op for 8th was end of January. That said all 9th AF P-47 FGs (and P-51/P-38) flew escort per 8th AF operational control well into May 1944.

The P-47 assignments for Penertration, Withdrawal escort legs are interchangable. The only Only) Target escort denoted by 354FG Mustangs are joined after bombing with R/V to pick up the trailing two BD.

Loger range Penetration and Withdrawal escort from Spit IX would have duplicated only the legs depicted by 355th, 359th, 78th (B) - would augment but not replace the P-47D intermediate legs.

The key to this document is that just providing ONE LR escort FG per BD (354 P-51, 20&55 P-38s) to Brunswick was possible at the time depicted.

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## drgondog (Aug 8, 2022)

PAT303 said:


> And again they got 1,000 mile ranges out of them as per posts a page or so back, your determined to find reasons why it couldn't be done when it clearly was.


A Range is Not a Combat Radius. The Internal fuel remaining after droping external tanks, fighting for 20 minutes - then cruising at optimum (clean) from that Radius point back to base with ~ 30gal for loiter - controls your planning 'maximum'.

For comparison, the CR of a Mustang I with 170gal internal fuel - with same combat burn off and loiter asumptions, no external tanks possible, was about 120 mi. But the Range (max) for Ferry conditions was ~ 1000 miles. 

Your loiter assumptions are crucial for bad weather and adverse headwinds.

Rough rule of calc for Merlin 60 series is 5mi/gal (as good as cleaner - less drag- Mustang) = 60 gallons for 300 miles at 300mph, plus 30 gal for loiter = 90 gallons internal required to make it back to base. You can complicate all you wish to account for decent leg, but trivial differences in total internal fuel required.

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## NevadaK (Aug 8, 2022)

drgondog said:


> The ranges depicted for the P-47s are approximately 108gal C/L ranges in the January-February timeframe. The lack of 357FG Mustang assignment (mid Feb) and inclusion of 20th FG P-38 implies very late 1943 though January. The inclusion of 358FG specifically ties to very late January, 1944 It was traded for 357FG to 9th AF and its last Op for 8th was end of January. That said all 9th AF P-47 FGs (and P-51/P-38) flew escort per 8th AF operational control well into May 1944.
> 
> The P-47 assignments for Penertration, Withdrawal escort legs are interchangable. The only Only) Target escort denoted by 354FG Mustangs are joined after bombing with R/V to pick up the trailing two BD.
> 
> ...


Thank you, drgondog.

The mission profile is from January 11, 1944. I was using the image to illustrate escort practices for longer range bomber operations. I recognize that as US squadrons shifted to the P-51 we would see fewer P-47/38, but I believe that we would still see multiple squadron/groups handling different outbound and return legs.

I’ll see if I can find a graphic illustrating this.


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## drgondog (Aug 8, 2022)

NevadaK said:


> hank you, drgondog.
> 
> The mission profile is from January 11, 1944. I was using the image to illustrate escort practices for longer range bomber operations. I recognize that as US squadrons shifted to the P-51 we would see fewer P-47/38, but I believe that we would still see multiple squadron/groups handling different outbound and return legs.
> 
> I’ll see if I can find a graphic illustrating this.


Actually, in context of 8th AF assets for escorts, including P-47 and P-38, the number of P-38FG increased to 5 or six and the P-47D asset base expanded slightly even as they were converting from P-47D to P-51B through May, 1944. The 9th AF P-47D and P-38J forces expanded as P-51B equipped FG shed their P-47s and P-38s. That said the P-38 FG 20/55/364 didn't convert until Summer with the 470th last at end of September, 1944.

The effect was to enable 8th AF planners to plan more complex missions in which individual BD and Task Forces branched to distant targets, but because there were more P-51s and P-38s, the actual Target escort force grew from 'one' LR FG per Target group, to two+ per target group while maintaining P-47D forces for Penetration and Withdrawal of the main stream before 'branches'

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## GregP (Aug 8, 2022)

PAT303 said:


> And again I will say NO plane including the much vaunted P51 can do combat maneuvers when loaded with fuel, I have already posted evidence of this, why is it okay for the P51 to have to drop it's tanks and have no more than 35G in the rear tank before combat but it's a major issue with the Spit?. I will repeat myself again, by the time the Spit gets into combat the rear upper 41G tank will be empty because it's burnt off in warm up, taxing and climb to altitude, the bottom 33G is it's reserve, the IDENTICAL procedure used by the P51.



Again I say there is nothing wrong with the Spitfire as it existed. 

You keep trying to improve on something that doesn't need improvement except for development of more engine power and performance. Performance, it had in abundance, as it was designed to have. I'll have to give you good marks for persistence, but the SPitfire was just fine the way it was.

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## NevadaK (Aug 8, 2022)

drgondog said:


> Actually, in context of 8th AF assets for escorts, including P-47 and P-38, the number of P-38FG increased to 5 or six and the P-47D asset base expanded slightly even as they were converting from P-47D to P-51B through May, 1944. The 9th AF P-47D and P-38J forces expanded as P-51B equipped FG shed their P-47s and P-38s. That said the P-38 FG 20/55/364 didn't convert until Summer with the 470th last at end of September, 1944.
> 
> The effect was to enable 8th AF planners to plan more complex missions in which individual BD and Task Forces branched to distant targets, but because there were more P-51s and P-38s, the actual Target escort force grew from 'one' LR FG per Target group, to two+ per target group while maintaining P-47D forces for Penetration and Withdrawal of the main stream before 'branches'


Thank you drgondog,

I always appreciate the quality and clarity of your responses.

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## NevadaK (Aug 8, 2022)

PAT303 said:


> Actually no, go back and read through the thread, what I'm asking for is a Spit with increased fuel capacity that could have been flying 300+ mile missions late 1942 early '43 before the P47-P38 were available.


Greetings PAT303,

I appreciate your argument about extending the range of the Spitfire in 1942, but I think there are a number of factors working against you. First, I think the engineering to make a LR Spitfire is greater and more involved than adding gas tanks where possible. I'm not an aviation engineer, but from what I was able to read my guess is that you are looking at a fairly substantial redesign of parts of the aircraft to make it sounder that role. Second, in 1942 the majority of USAAC/RAF leadership didn't believe in long range escort and there was a general lack of interest in seeing it developed. The conversion of the Mustang to a Merlin engine wasn't about range, but flying higher. Range was a bonus. Also, it was the US that was committed to daylight bombing not the British and the US was bringing its own fighter aircraft, the P-47 and P-38. We can debate the relative merits of each of these, but in the P-47 the US had the preeminent high altitude fighter of the war and the P-38 had the longest legs until the P-51. It's unlikely that the US would have been advocating for a long range Spitfire. Lastly, the RAF needed every fighter it could get and it would have been a drain on the RAF to redirect fighter production to an aircraft designed around long range escort. That production capacity would have to come from the US and that production capacity was dedicated to the P-47, P-38, and later P-51.

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## PAT303 (Aug 8, 2022)

GregP said:


> You keep trying to improve on something that doesn't need improvement


So you would have it fight the entire war with nothing more than an 85G tank?, you may as well not bother building them if that's the case.


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## Shortround6 (Aug 8, 2022)

Well, they did go to 120-123 gallons when they had the chance, but that was one factory while an other factory stayed with 85 and 96 gallon set up. 

When they went to the Griffon engine even on the Mk 21 and MK 22 they stayed with 120 gal of internal fuel despite increasing gross weight by 1300-1400lbs. 
They went for more performance (a bigger engine) and more firepower (four 20mm guns) rather than range. 

Had they had more production facilities they might have have gone for a long range version with extra fuel instead of the bigger engine.

One reason the Spitfire has trouble being turned into a long range fighter (IMHO) is that a Merlin 60 series airplane was a just under 8000lb airplane and that includes a belly tank of some sort. The P-51D went 9600lbs without drop tanks and without the rear tank. The rear tank brought it to 1020lbs and a pair of 75 SU G drop tanks brought it over 11200lbs. 

The P-51D was about 1 ton heavier when clean. You can do better than a MK IX, they did it with the MK VIII. 
The question we have been arguing over for over 12 pages is, while you can't equal the Mustang, how close can you get with a plane that was around 77% as heavy when clean (neither using rear tanks)?
Both are using the same engine for all practical purposes. 

The Mustang started larger/heavier and was easier to add weight to especially considering that the American fighter was built to different standards. 

As you increase the "overload" the Mustang can absorb more overload simply because it was larger/heavier to begin with. 

The MK VIIIs went to NA/Italy and the Far east because that is where they needed the extra range. 
Had they needed the extra range over Europe more in early/mid 1943 they might have changed their priorities or changed production.

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## EwenS (Aug 8, 2022)

Shortround6 said:


> The MK VIIIs went to NA/Italy and the Far east because that is where they needed the extra range.


Well that statement is open to question, at least so far as North Africa/Italy is concerned.

Both the Mk.VIII and IX turned up in the Med around the same time in early 1943. They were used alongside each other there until the end of the war. And sometimes, particularly in 1943 and early 1944 in the same squadrons simultaneously.

IIRC the first Mk.VIII deployed to the Far East (India/Burma) was a rush job and belonged to 81 squadron. It was withdrawn from Italy to Egypt in Nov 1943, re-equipped with brand new Mk.VIII straight from the MU and flown from Cairo to Calcutta arriving at the beginning of Dec.

The first Mk.VIII had arrived in Australia in Oct 1943.


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## wuzak (Aug 9, 2022)

drgondog said:


> A Range is Not a Combat Radius. The Internal fuel remaining after droping external tanks, fighting for 20 minutes - then cruising at optimum (clean) from that Radius point back to base with ~ 30gal for loiter - controls your planning 'maximum'.
> 
> For comparison, the CR of a Mustang I with 170gal internal fuel - with same combat burn off and loiter asumptions, no external tanks possible, was about 120 mi. But the Range (max) for Ferry conditions was ~ 1000 miles.
> 
> Rough rule of calc for Merlin 60 series is 5mi/gal (as good as cleaner - less drag- Mustang) = 60 gallons for 300 miles at 300mph, plus 30 gal for loiter = 90 gallons internal required to make it back to base. You can complicate all you wish to account for decent leg, but trivial differences in total internal fuel required.





Shortround6 said:


> Well, they did go to 120-123 gallons when they had the chance, but that was one factory while an other factory stayed with 85 and 96 gallon set up.



Perhaps when comparing British and American aircraft fuel volumes should be listed in LITRES?

The 170 US gallons internal fuel is 141 UK gallons, 17% more than the 120 UK gallons in the Spitfire.


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## Warbirdnutball (Aug 9, 2022)

PAT303 said:


> The P51 was the quintessential escort fighter but it really didn't come into it's own until 1944, the Spitfire, if the MkIII with two stage Merlin was developed could have escorted bombers out to the Ruhr from the end of the BoB, from the 60 series onwards models, (MkVIII, IX) could have been handy out to around 400 Miles radius from 1942 but it was really maxed out at around 500-550 miles. The P47 was in my opinion too much of a fuel pig to be seriously considered, it could carry lots of fuel but it wasn't efficient by any means and the N/M series got their range by simply carry vast amounts of it, a fantastic fighter if used to it's advantages, the P38 had serious range but it's performance was not up to par until the L series which made it a later war aircraft but once it's issue's were sorted it was a top class fighter, the A6M compromised everything for range, it's slow speed and nil protection made it useful only in the Pacific against weaker opponents and I personally do not like the Zero at all, it's without doubt the most overrated aircraft of the war for me and I would not want to fight in it. I don't think anything else fits the bill.


If you really feel that way about the P-47 them maybe you should read about Hub Zemke and his wolfpack and the tactics they developed for range and tactics. Their scores were so high because of it. Now I will admit that the 47 was a had hog. That being said, at altitude where their super charger kicked in they performed awesomely. Gave the mustytang a run for it's money.


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## PAT303 (Aug 9, 2022)

Warbirdnutball said:


> If you really feel that way about the P-47 them maybe you should read about Hub Zemke and his wolfpack and the tactics they developed for range and tactics. Their scores were so high because of it. Now I will admit that the 47 was a had hog. That being said, at altitude where their super charger kicked in they performed awesomely. Gave the mustytang a run for it's money.


Funny what happens when you give a plane more endurance isn't it.

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## Milosh (Aug 9, 2022)

Warbirdnutball said:


> If you really feel that way about the P-47 them maybe you should read about Hub Zemke and his wolfpack and the tactics they developed for range and tactics. Their scores were so high because of it. Now I will admit that the 47 was a had hog. That being said, at altitude where their *super charger* kicked in they performed awesomely. Gave the mustytang a run for it's money.


Do you mean turbocharger?


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## Shortround6 (Aug 9, 2022)

wuzak said:


> Perhaps when comparing British and American aircraft fuel volumes should be listed in LITRES?
> 
> The 170 US gallons internal fuel is 141 UK gallons, 17% more than the 120 UK gallons in the Spitfire.


 The idea of liters is both good and bad.

Yes everything _should_ be the same, bad is that we already making typos and rounding off errors. 
Since all the original documents/manuals were in gallons (and sometimes don't agree) going to liters may just add errors. 

Most sources say the Merlin Mustang held 180 US gallons in the wing tanks, some say 184 (?). In manuals that give capacity in both US and Imp they say 180 and 150 respectively. 

perhaps the 170 is a typo. perhaps it is the amount of fuel that the range chart says is available after start-up, warm up and take off? There are charts that do say that. 
However then you have to take 10 gallons (US) away from the Spitfire so it is pretty much a wash. 

And some manuals/data sheets have typos on them.


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## Shortround6 (Aug 9, 2022)

EwenS said:


> Both the Mk.VIII and IX turned up in the Med around the same time in early 1943. They were used alongside each other there until the end of the war. And sometimes, particularly in 1943 and early 1944 in the same squadrons simultaneously.


Unfortunately planned allocations and actual use often didn't line up. Mainly because planned allocations wee often done months before the planes actual saw action in theater. 

P-38s were pulled from operations in Europe (England) in Oct of 1942 for operation Torch and some of them didn't get to NA until Dec. 

When did the Med get opened to shipping in 1943? 

Which Type of Spitfire did they _think_ they were going to need for the end of the NA campaign and the invasion of Sicily and Italy? 

The Italian campaign bogged down and they often didn't make very fast advances making the air war somewhat static and perhaps they weren't getting the supplies of aircraft that they wanted and had to make do with substitutes?


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## EwenS (Aug 9, 2022)

Shortround6 said:


> When did the Med get opened to shipping in 1943?


The first through convoy from Gibraltar to Alexandia, GTX1, sailed on 24 May 1943 and arrived 4 June. The first through return convoy, XTG1, sailed from Alexandria on 3rd June and arrived at Gib on 17th June. The Axis surrender in NA occurred on 13 May. But that is not relevant to the matter in hand.

The RAF, having been assembling Spitfires & Hurricanes at Gibraltar before and after Operation Torch, set up a number of MU in North Africa to assemble aircraft that arrived in crates from Britain. 145 MU was formed at Casablanca in March 1943 specifically to handle Hurricanes and Spitfires. It continued in that role and location until March 1945. There is a series of photos of their work on the IWM website dating to the last quarter of 1943, one of which is below.








ROYAL AIR FORCE OPERATIONS IN THE MIDDLE EAST AND NORTH AFRICA, 1939-1943.


Civilian workers running the wing of a Supermarine Spitfire Mark VIII out of its crate prior to assembly of the aircraft (JF672, seen in the foreground) by No.145 Maintenance Unit at Cazès Airport, Casablanca, Morocco. Most of the civilians employed at 145 MU were Spanish refugees who fled to...




www.iwm.org.uk





The earliest Mk.IX in the Med were being assembled at Gib in Feb 1943 before going to join 92 and 145 squadrons alongside the Mk.V. This is a Mk.IX from the Polish Combat (sometimes referred to as the Fighting) Team attached to 145 squadron in North Africa between March and June 1943. Mk.VIII were a few months behind that it arriving in theatre with the first going to 601 in June alongside Mk.V.






The front line in Italy didn't bog down until the winter weather really set in and the Allies ran into the German defences of the Winter Line. That wasn't until the end of 1943. By then around 750 Mk.VIII had been produced and yet squadrons were still not fully re-equipped from the Mk.V and some were still flying a mix of VIII/IX.

If you want a better reason for the MK.VIII being sent to the Middle & Far East, take a look at the air filters rather than the fuel tanks. The Mk.VIII was fitted with the streamlined Vokes Aero-Vee from the outset. The Mk.IX only gained it part way through the production run.

I'm not sure what your point about the P-38s is. Of course they had to be pulled from operations in Britain before going to North Africa. They had to pack up all their kit get it on board ship for transportation to Africa then reverse the process when they got their. So 14th FG:-

Last operation in Britain was 21st Oct 1942.
Ground echelon left Britain on 30th Oct from Liverpool. It arrived at Oran on 10th Nov.
Air echelon moved to Portreath in Cornwall on 6th Nov to prepare for the flight to North Africa. They flew out between 10th & 14th Nov. Followed by further moves to reach their operational base and catch up with the ground echelon.

The 1st FG took more than two weeks after arriving in Africa before flying its first mission on 29 Nov.

The 82nd FG was the last of the initial P-38 Groups to arrive in Britain in Sept/Oct 1942 and did not fly operationally as it was sent for additional training in Northern Ireland. It was therefore the last to leave for North Africa in Dec 1942, flying its first missions between Xmas and New Year.

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## drgondog (Aug 9, 2022)

Duplicate


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## Shortround6 (Aug 9, 2022)

EwenS said:


> I'm not sure what your point about the P-38s is.


Just pointing out that it took time to actually plan deployments and circumstances on the ground could change between plans being made and combat starting. 
Likewise trying to stop things in midstream could take a bit of doing. 

Aircraft sent in crates to North Africa need shipping space allocated and transport to and from the ships. And it was not just the aircraft themselves but the logistics train that went with them. 

Sometimes plans overlapped and sometimes plans needed be modified but some people (not you) think that supplies, aircraft and weapons can be shifted about with just a few days notice with changes of thousands of miles in destinations. 

I do thank you for providing the information for both the Spitfires and the P-38s. 

In late 1942 were do the British plan to send the MK VIII Spitfires? They won't be ready for a number of months but plans have to start being made.


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## Warbirdnutball (Aug 9, 2022)

Milosh said:


> Do you mean turbocharger?


Yes. Sorry. Of all the things I've lost...... Lol.


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## Mike Williams (Aug 9, 2022)

EwenS said:


> The earliest Mk.IX in the Med were being assembled at Gib in Feb 1943 before going to join 92 and 145 squadrons alongside the Mk.V. This is a Mk.IX from the Polish Combat (sometimes referred to as the Fighting) Team attached to 145 squadron in North Africa between March and June 1943. Mk.VIII were a few months behind that it arriving in theatre with the first going to 601 in June alongside Mk.V.


Fleshing that out a bit:

81 Squadron converted to Spitfire IX in North Africa during January 1943.

72 Squadron converted to Spitfire IX's in North Africa in February 1943 and they were immediately successful on operations.

As you mentioned, 145 and 92 Squadron were supplied with Spitfire IX's in North Africa in March 1943.

126 Squadron was using Spitfire IX's on Malta in March 1943.

126 Squadron was using Spitfire VIII's on Malta in June 1943.

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## Warbirdnutball (Aug 9, 2022)

PAT303 said:


> Funny what happens when you give a plane more endurance isn't it.


You mean the paddle blades? Those came out after the Famed Zemke Fan developed to catch the Luftwaffe before the bombers were even sighted. I've met and talked to both Hub Zemke and Gabby Gabreski. They explained to me about things in Europe in the early 90s. We talked for hours and explained a lot about what they went through from first hand experience. Also, those eight 50s had a bigger punch and could handle a LOT more punishment than that 51, no matter which wartime versions were used.

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## drgondog (Aug 9, 2022)

Warbirdnutball said:


> You mean the paddle blades? Those came out after the Famed Zemke Fan developed to catch the Luftwaffe before the bombers were even sighted. I've met and talked to both Hub Zemke and Gabby Gabreski. They explained to me about things in Europe in the early 90s. We talked for hours and explained a lot about what they went through from first hand experience. Also, those eight 50s had a bigger punch and could handle a LOT more punishment than that 51, no matter which wartime versions were used.


IIRC - P-47D-11 were first to get the WI and Paddle blade installs in Jan 1944 timeframe. The 'Fan' was experimented with in May an by that time the 56th, 78th and 353rd had a sample of the bubble top P-47D-25 with the 370gal internal fuel capacity.

The Gabreski's lived next door to us when dad and gabby were at War College class together in 1955 at Maxwell. All true about more firepower but one of Zemke's bitterest disappointments was Landry/Schilling refusing P-51B at 56th FG when he (Zemke) was home on leave.? The 56th would have been selected earlier than 4th FG for conversion. That means the 56th would have had the range to get in ALL of the long range target fights in February. 

He later went on to say that the P-51 was the better air combat choice over P-47 and P-38, when he transitioned the 479th FG from P-38s to P-51s in late September 1944.

Did Gabby tell you how much he liked the P-51H in CA NG post WWII?

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## Geoffrey Sinclair (Aug 9, 2022)

NevadaK said:


> Well, a different take would be that a longer range Spitfire would have hurt the daylight bomber offensive.
> 
> My understanding (albeit a little under informed) is that bomber escort was conducted in zones, or waves. The first zone, or wave, was conducted by Spitfires and P-47 ranging our about 250 miles (rough memory here), after that a second zone with P-47's and P-51's out to about 400 miles, and after that P-51's.
> 
> The Spitfire was being used in its best range and performance. Trying to extend the range, duplicates the capabilities of an already excellent aircraft (Mustang) and creates a void in the shorter coverage area.


Fighter Command was underemployed in 1943 in daylight, lots of areas to cover but few raids. The advantage of a longer range Spitfire works for insertion cover, it enables airfields further back from the coast to be used for that task. And again no one is trying come up with a second Mustang, rather a second 1943 P-47 range wise.


NevadaK said:


> IIn 1943, the P-47 and P-38 were already in use. The Spitfire and P-47 were well used in the 200 and 400 mile arcs (ok, slightly shorter). Beyond that required a plane with really long range and that was the P-38 and Mustang. ... It seems to me that trying to give a Spitfire that kind of range is, in essence, trying to make it a Mustang.


The P-47 was in use in 1943 but without external tanks until the second half, the P-38 first mission, ignoring the units that went to North Africa from England, was 15 October 1943, first bomber escort on the 20th, it took until 28 December before a second P-38 group flew its first mission. First P-51 mission on 1 December, first escort mission on 5 December. Using first mission date, 3 operational P-47 groups on 13 April 1943, 4 on 12 August, 5 on 9 September, 6 on 14 September, 7 on 15 October, 8 on 13 December, 9 on 22 December.

In April 1943 the 8th Air Force had 6 Heavy Bomber Groups operational to 3 Fighter Groups, or 2 to 1, it was 4 to 1 by end May, 5 to 1 mid July to early August, 4 to 1 mid August, 3.3 to 1 on 9 October before finally dropping to 2.5 to 1 in mid October, it spent early 1944 under this, as low as 2.1 to 1 in late January before climbing to 2.5 to 1 in May and staying around this ratio for the rest of the war. Figures exclude the 9th Air Force fighter units, while the July and August 1943 figures benefit from 3 B-24 groups being in the Mediterranean.

Eaker had a fighter numbers as well as range problem.

The Spitfire VIII with a 90 gallon drop tank, vertical climb, fast cruise from airfield, similar return can make around 300 miles radius after allowances for combat and reserves. Does that make it a Mustang? Add a 33 gallon rear tank and you add another 80 miles to the radius. Now is it a Mustang? Increasingly after mid 1943 and certainly after mid October the 8th stayed within fighter escort range. The record of the P-47 in the 1943 and early 1944 period shows an aircraft matching its range should see a lot of combat. Roger Freeman reports the P-47 radius with an 84 gallon external tank as 280 miles in July 1943, then 325 miles with 108 gallons of external fuel in August then 375 miles with 165 gallons of external fuel in February 1944.

What we do not know is how the P-47 radius was calculated, so we can use the same profile for the Spitfire.


NevadaK said:


> I appreciate your argument about extending the range of the Spitfire in 1942, but I think there are a number of factors working against you. First, I think the engineering to make a LR Spitfire is greater and more involved than adding gas tanks where possible. I'm not an aviation engineer, but from what I was able to read my guess is that you are looking at a fairly substantial redesign of parts of the aircraft to make it sounder that role.


The idea is an increase in 1943 over and above that the mark VIII achieved in 1942. Can you please provide the references make it clear fitting a 33 gallon rear fuselage tank into Spitfire VIII/IX/XVI would require substantial redesign, perhaps with examples drawn by the fitting of 1x75 or 2x33 gallon rear fuselage tanks into the mark XVI and IX in 1944/45 which would presumably have cause more substantial redesign problems?

It is generally agreed the longer range Spitfire did not happen in 1943 partly because no one was asking for it, until mid 1943 the Luftwaffe could generally still be encountered around the front line and while the P-47 was working its bugs out only the Merlin 60 series Spitfires had been shown to match German fighter performance. Result was a great demand for the latest Spitfires. Equipping existing underemployed Fighter Command squadrons with longer ranged fighters would not be a drain on the RAF.


Shortround6 said:


> You are adding almost 200lbs of fuel plus the weight of the tanks. over the weight of MK VIII with the existing tanks.
> Why didn't they do themselves?
> Some of the early MK VIIIs had a fuel cooler added in the port wing root. It may have depended on which engine and when the plane was built.
> Some planes had a gun camera in the wing root/leading edge. That seems to have bounced back and forth Between sides?
> ...


And the Spitfire VIII ended up cleared for 1,000 pounds of bombs or about the weight of a 33 gallon rear tank plus 90 gallon external. They actually did do it, in fact more than did it, by putting 2x33 or 1x75 gallon tanks in the IX and XVI rear fuselages, but in the second half of 1944. Here the requirement is 1x33 in the second half of 1943, using things like the results of the December 1942 trials and the use of the 29 gallon rear fuselage ferry tank for the mark V, the one that had less weight forward so was not as able to carry rear fuselage loads.

As for engine power as designed does the same apply to the P-51? After all the D gained over 100 pounds empty and 300 pounds gross, so the D should be predicated on the 1942 Merlin power, since the Spitfire is 1941? Or can both designs do modifications in 1943 and 1944 based on the available engine power at the time? Did the P-51D "reinforce the wings to handle more weight (if you have the time to do the calculations and the change the production drawings)."?

Gun camera location? This is becoming very funny.


Shortround6 said:


> The Manual for the Spit says to have no more than 30 Imp gallons in the rear tanks (post war manual does not say 33 IMP, it says 30.) the handling trial from Jan 1945 used the metal covered elevator. I would very hesitant to use that recommendation on a normal MK IX and we do know that not all MK IXs used the same elevators.


You see when you simply post simple to check falsities it is hard to believe anything claimed. Morgan and Shacklady can be checked to show the early 1945 tests used a standard Spitfire that was also given hand made metal covered elevators for *some* of the tests, they made handling better. There were July 1944 tests on a mark VIII with a 75 gallon rear fuselage tank.

The proposal is a 33 gallon rear fuselage tank, the 75 gallon tank would have weighed about 42 pounds more, or 5 to 6 imperial gallons worth, secondly the pair of 33 gallon rear tanks was preferred because of fuel movement in the part filled 75 gallon tank when the aircraft moved. We know you are rather hesitant from your concerns about 1941 power levels, 1942 production numbers, gun camera position, fuel coolers, elevator coverings and the continued insistence on comparing the Spitfire to the Mustang, not the P-47 and a whole lot more negative ideas.


Shortround6 said:


> The much vaunted P-51 was used with 55 US gallons (45 Imp) in the rear tank, plus the 180 US (150 imp) gallons in the wing tanks.


Why do you think the P-51 was over rated? The proposed Spitfire with P-47 range has 124 imperial gallons front fuselage and wings, plus 33 imperial gallons rear fuselage, total 157 imperial, 188.5 US Gallons (or 17.444 British Firkins if you are firking around) when entering combat. No one expects the Spitfire to go out as far as the Mustang, even if it had the same drag. They do expect it to go out about as far as the P-47.


Shortround6 said:


> Warm up, take-off, and climb to 25,000ft can take a fair amount of fuel and combat allowance of 5 minutes WEP and 15 minutes military can also suck up fuel.
> A Mustang with wing tanks and 75 US gallon drop tanks and no rear fuselage was carrying close to 2000lbs of fuel for take off.
> A Spitfire needs to lift over 270 Imp gallons of fuel for that weight.


Of course the Spitfire allowances for take off etc. have been given several times, but somehow we need to be told how expensive climb and combat are, for the Mustang plus apparently the Spitfire needs to carry 270 imperial gallons, no idea why. The extra weight of the Mustang would mean maybe a third more fuel to climb to the same altitude as the Spitfire.

Imperial (British) gallons in 1 long ton, 2,240 pounds, 100 octane avgas 315, other grade avgas and motor spirit (petroleum/gasoline MT80) 300, Diesel 259, marine diesel 250, RN oil fuel 238. A Slug is 1 Geepound or 14.594 kilograms, if overweight consider quoting yourself in gee what big pounds, though not sure saying you are so many slugs would work as well, unless knocking back whisky perhaps.


Shortround6 said:


> The problem comes with the 300* plus.*
> 
> You are going to need about 1 imp gallon for every 5 miles you go in and 1 imp gallon for every 5 miles you come out.
> 350 mile radius is going to need and extra 20 gallons.
> ...


As has been pointed out the profile is fast cruise from airfield to return to airfield and 33 gallons adds 80 miles to the combat radius. Add possible problems with runways to the longer range Spitfire what a disaster list.


Shortround6 said:


> Well, they did go to 120-123 gallons when they had the chance, but that was one factory while an other factory stayed with 85 and 96 gallon set up.


124 gallons, and 85 gallons.


Shortround6 said:


> The question we have been arguing over for over 12 pages is, while you can't equal the Mustang, how close can you get with a plane that was around 77% as heavy when clean (neither using rear tanks)?
> The MK VIIIs went to NA/Italy and the Far east because that is where they needed the extra range.


The mark VIII was meant for overseas service, dust filters as standard. And actually much of the last many pages has been about keeping the Spitfire range the same as the P-47 in 1943/44, answer take a slight production hit at Supermarine and use the 1942 data about rear fuselage ferry tanks to fit a 33 gallon tank in the final quarter of 1943, take a bigger production hit at Castle Bromwich to increase fuel tankage to the 124 gallon mark when it switches to Merlin 60 series Spitfires in mid 1943, then later add the 33 gallon tank. The reason it has gone on for so many pages is the continual erasing of the P-47, replaced by the P-51 for comparisons and one of the biggest efforts in a long time to throw everything and anything against an idea considered bad in the hope something sticks.

As the calculations show, the need for 75 or 66 gallons in the rear fuselage was actually close to zero for the missions the RAF did in 1944/45, including escorting Bomber Command to the Ruhr, as by that stage most of the route was in friendly airspace, no need for fast cruise until near the target. The Spitfire 21 was on a different development track and being a 1943 design was not expected to have the reach Germany range, though of course the XIV did it, add the F.21 handling problems and no one was going to increase them with more weight to the rear. The F.22 added a 33 gallon tank, the F.24 2x33.


Shortround6 said:


> Which Type of Spitfire did they _think_ they were going to need for the end of the NA campaign and the invasion of Sicily and Italy?
> 
> The Italian campaign bogged down and they often didn't make very fast advances making the air war somewhat static and perhaps they weren't getting the supplies of aircraft that they wanted and had to make do with substitutes?


Initially the mark V, which had its troubles with the Bf109G, followed by the mark VIII, but then the Fw190 turned up and the VIII was late. So Fighter Command gave up some of its mark IX as a result. The Italian campaign first bog down was around October 1943, mainly as the Germans did not defend southern Italy against 8th Army, there was a slow advance October to January.

Thanks for an amusing way to spend an hour.


drgondog said:


> Rough rule of calc for Merlin 60 series is 5mi/gal (as good as cleaner - less drag- Mustang) = 60 gallons for 300 miles at 300mph, plus 30 gal for loiter = 90 gallons internal required to make it back to base.


Spitfire VIII 320 mph 66 gallons per hour consumption. Is loiter in addition to reserves?

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## Warbirdnutball (Aug 9, 2022)

drgondog said:


> IIRC - P-47D-11 were first to get the WI and Paddle blade installs in Jan 1944 timeframe. The 'Fan' was experimented with in May an by that time the 56th, 78th and 353rd had a sample of the bubble top P-47D-25 with the 370gal internal fuel capacity.
> 
> The Gabreski's lived next door to us when dad and gabby were at War College class together in 1955 at Maxwell. All true about more firepower but one of Zemke's bitterest disappointments was Landry/Schilling refusing P-51B at 56th FG when he (Zemke) was home on leave.? The 56th would have been selected earlier than 4th FG for conversion. That means the 56th would have had the range to get in ALL of the long range target fights in February.
> 
> ...


We talked about their books and their experiences in WWII and Korea (with Gabby). Neither talked to me about the P-51 either way. Maybe they sensed I didn't like it. The only plane from Korea we discussed was his F-86. We're were only able to talk for 3 days when they were visiting. It was for a release of one of the art pictures of their exploits. Maybe I was just starstruck with actually meeting them. I do know my memory isn't the greatest anymore due to a car accident. All I do know is we discussed their history with the 56th and Korea. I couldn't monopolize their time as to the circumstances. You obviously had more interaction with them thereby have a deeper knowledge of them. I apologize for stepping on toes. I'll just leave.


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## drgondog (Aug 9, 2022)

Warbirdnutball said:


> We talked about their books and their experiences in WWII and Korea (with Gabby). Neither talked to me about the P-51 either way. Maybe they sensed I didn't like it. The only plane from Korea we discussed was his F-86. We're were only able to talk for 3 days when they were visiting. It was for a release of one of the art pictures of their exploits. Maybe I was just starstruck with actually meeting them. I do know my memory isn't the greatest anymore due to a car accident. All I do know is we discussed their history with the 56th and Korea. I couldn't monopolize their time as to the circumstances. You obviously had more interaction with them thereby have a deeper knowledge of them. I apologize for stepping on toes. I'll just leave.


You didn't step on my toes. Folks have different opinions about every subject on this site and you sure as hell have nothing to either apologize or leave for.

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## WARSPITER (Aug 9, 2022)

drgondog said:


> You didn't step on my toes. Folks have different opinions about every subject on this site and you sure as hell have nothing to either apologize or leave for.


I agree fully. Seeing posts from people who have had interaction with 'those on the spot' is invaluable. Recollections can differ over time and there are things
that will never be clear cut but the more we all get to see the better the understanding. 

I am far less likely to 'reverse armchair' and say what should have or could have happened as I now know there are so many factors involved even down to
personality clashes that caused huge cock ups to occur. It's not all numbers and stats.

So yes, keep them cards and letters coming folks. Very much appreciated.

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## drgondog (Aug 9, 2022)

WARSPITER said:


> I agree fully. Seeing posts from people who have had interaction with 'those on the spot' is invaluable. Recollections can differ over time and there are things
> that will never be clear cut but the more we all get to see the better the understanding.
> 
> I am far less likely to 'reverse armchair' and say what should have or could have happened as I now know there are so many factors involved even down to
> ...


Lol - well you are conversing with one involved in a few 'cock ups' or two.


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## WARSPITER (Aug 9, 2022)

Well, we learn from our mistakes and we learn even more from others. 

It's when the mistakes are not acknowledged that we all suffer the process of repeating them.

I know this from my repeated attempts at wargaming.

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## PAT303 (Aug 9, 2022)

Warbirdnutball said:


> I apologize for stepping on toes. I'll just leave.


No chance your leaving mate, you only have to look at this thread to see the quality of the blokes on here, even though we are having a very stout discussion everyone is treating everyone else with respect, no name calling or personal attacks, this is the best aircraft site on the net and it's all down to the the members, go your hardest and say what you want to say.

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## glennasher (Aug 9, 2022)

Warbirdnutball said:


> We talked about their books and their experiences in WWII and Korea (with Gabby). Neither talked to me about the P-51 either way. Maybe they sensed I didn't like it. The only plane from Korea we discussed was his F-86. We're were only able to talk for 3 days when they were visiting. It was for a release of one of the art pictures of their exploits. Maybe I was just starstruck with actually meeting them. I do know my memory isn't the greatest anymore due to a car accident. All I do know is we discussed their history with the 56th and Korea. I couldn't monopolize their time as to the circumstances. You obviously had more interaction with them thereby have a deeper knowledge of them. I apologize for stepping on toes. I'll just leave.


Don't run off, I learn a lot from everyone here, and anyone leaving is bound to take something with them that could help me learn "stuff". I tend to avoid disagreements, but those are few and far between here. Most folks here are out-and-out gentlemen and conduct themselves that way. I have learned a helluva lot here, and have had more than a few things fleshed out that skewered my previous assumptions. I learn from that. I like learning new information (to me). 
Not all of us are experts by any means, we're all students in our own ways. Hang around, it's fun.

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## GregP (Aug 9, 2022)

PAT303 said:


> So you would have it fight the entire war with nothing more than an 85G tank?, you may as well not bother building them if that's the case.



We'll have to agree to disagree here. They actually WERE built in about 20,351 copies and they flew just fine. They actually turned into one of the finest piston fighters ever built.

You're just being dramatic.


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## NevadaK (Aug 9, 2022)

Came across this, thought I would share. Another log on the fire.









Escort Spitfire - a missed opportunity for longer reach? - Royal Aeronautical Society


Could Supermarine's iconic fighter have been modified to escort US bombers all the way to Berlin and back? Paul Stoddart examines some development options for the Spitfire and suggests what might have been achieved.




www.aerosociety.com


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## PAT303 (Aug 9, 2022)

GregP said:


> We'll have to agree to disagree here. They actually WERE built in about 20,351 copies and they flew just fine. They actually turned into one of the finest piston fighters ever built.
> 
> You're just being dramatic.


I find it completely baffling that so many of you are putting so much effort into finding out reasons why the Spit shouldn't have it's fuel capacity increased, I can't think of any aeroplane that didn't benefit from it. Jeffrey Quill and Winkle Brown both pushed for it, Johnny Johnston lamented the fact it wasn't done until too late in the war, it's the first and generally only criticism the Spit gets in any conversation, I don't understand it.

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## wuzak (Aug 10, 2022)

Warbirdnutball said:


> Also, those eight 50s had a bigger punch and could handle a LOT more punishment than that 51, no matter which wartime versions were used.



I thought the idea was to not get hit. If being able to "handle more punishment" also means you are more likely to be hit, is it worth it?

PS: Not sure if the P-47 was easier to hit than the P-51, but the extra size must help those shooting at it!


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## NevadaK (Aug 10, 2022)

wuzak said:


> I thought the idea was to not get hit. If being able to "handle more punishment" also means you are more likely to be hit, is it worth it?
> 
> PS: Not sure if the P-47 was easier to hit than the P-51, but the extra size must help those shooting at it!


In the words of the great Rocky Balboa

"*It's not about how hard you can hit; it's about how hard you can get hit and keep moving forward."*


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## drgondog (Aug 10, 2022)

PAT303 said:


> I find it completely baffling that so many of you are putting so much effort into finding out reasons why the Spit shouldn't have it's fuel capacity increased, I can't think of any aeroplane that didn't benefit from it. Jeffrey Quill and Winkle Brown both pushed for it, Johnny Johnston lamented the fact it wasn't done until too late in the war, it's the first and generally only criticism the Spit gets in any conversation, I don't understand it.


From My perspective, I understand both airframe design and production. I suspect without proof, that the dictates of lowest risk path to put the best possible assets in the field for the assigned roles were at the top of both Arnold's and Portal's minds - and guided AAF and RAF/BAM priorities accordingly. From my perspective you have argued that the failure to increase internal fuel for the Spitfire - to increase strategic footprint but no better than parity with the shorter range US aircraft available - was a mistakeny 'missed' and misguided decision.

The RAF doctrines of strategic bombers pointed to middle altitudes and attacks at night in loose formations. There were no advocates of long range strategic day light missions arguing at BAM/RAF senior levels to a.) reconsider, and b.) prioritize LR Daylight escort. Nor were there any advocates to change range requirements of the Spitfire to assist AAF in their goal of daylightlight LR escorts.

Nor were there any specifications for such aircraft for RAF.

So, why slow down existing struggle to attain air superiority at Malta or The Channel or Iraly by slowing delivery of planned Spitfire mods and deliveries to introduce new designs and tooling to achieve slightly better range at expense of Performance in air combat? Recall in that interval of the war, Spits were having asses kicked by Fw 190 and not visibly superior to A6M until a re-engined Spit IX STARTED to arrive in very late 1942. That slice of time also included first flights of Mustang 10 and XP-51B. The latter with full promise of US anufacturing muscle to produce and deliver rapidly.

The 'push' to reduce weight for the Mustang began in 1942 just before 1st flight of Merlin Mustangs. Such were contracted immediately afterwards. 1st Delivery (P-51H) in February 1945. Too late for ETO.

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## NevadaK (Aug 10, 2022)

PAT303 said:


> I find it completely baffling that so many of you are putting so much effort into finding out reasons why the Spit shouldn't have it's fuel capacity increased, I can't think of any aeroplane that didn't benefit from it. Jeffrey Quill and Winkle Brown both pushed for it, Johnny Johnston lamented the fact it wasn't done until too late in the war, it's the first and generally only criticism the Spit gets in any conversation, I don't understand it.


Its a classic barber shop GOAT argument. Sometimes they go for decades.

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## NevadaK (Aug 10, 2022)

NevadaK said:


> I appreciate your argument about extending the range of the Spitfire in 1942, but I think there are a number of factors working against you. First, I think the engineering to make a LR Spitfire is greater and more involved than adding gas tanks where possible. I'm not an aviation engineer, but from what I was able to read my guess is that you are looking at a fairly substantial redesign of parts of the aircraft to make it sounder that role.


The idea is an increase in 1943 over and above that the mark VIII achieved in 1942. Can you please provide the references make it clear fitting a 33 gallon rear fuselage tank into Spitfire VIII/IX/XVI would require substantial redesign, perhaps with examples drawn by the fitting of 1x75 or 2x33 gallon rear fuselage tanks into the mark XVI and IX in 1944/45 which would presumably have cause more substantial redesign problems?

It is generally agreed the longer range Spitfire did not happen in 1943 partly because no one was asking for it, until mid 1943 the Luftwaffe could generally still be encountered around the front line and while the P-47 was working its bugs out only the Merlin 60 series Spitfires had been shown to match German fighter performance. Result was a great demand for the latest Spitfires. Equipping existing underemployed Fighter Command squadrons with longer ranged fighters would not be a drain on the RAF.

Greetings Geoffrey,

As I said, I'm no aviation engineer, but my comment was based on the following:

Numerous sources stating that the MKVIII airframe was necessary for heavier fuel loads. Since that airframe wasn't in service until mid-summer 1943, my assumption is that 1942 is overly optimistic.
Greater effort to reduce overall drag in the Spitfire. From the article I link earlier in this thread, there was a proposal to reduce drag by the introduction of a single under body radiator that would have cleaned up the wing and improved speed by up to 30mph. (That alone gets you extended range without more fuel)
And lastly, in keeping with Supermarine's approach to component improvement the development of a new long range wing similar to what was developed for the P-47. (This last is a conjecture on my part)
Personally, with the arrival of the P-47 I have a hard time making an argument for extended range Spitfire unless it exceeds the Thunderbolt's capabilities.

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## Clayton Magnet (Aug 10, 2022)

drgondog said:


> Spits were having asses kicked by Fw 190 and not visibly superior to A6M until a re-engined Spit IX STARTED to arrive in *very late* _*1942*_


The Spitfire Mk.IX entered squadron service in June 1942


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## 33k in the air (Aug 10, 2022)

Clayton Magnet said:


> The Spitfire Mk.IX entered squadron service in June 1942



Is that conducting actual combat missions, or just working up in preparation to entering combat? How many squadrons were so equipped at that time?

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## pbehn (Aug 10, 2022)

33k in the air said:


> Is that conducting actual combat missions, or just working up in preparation to entering combat? How many squadrons were so equipped at that time?


I think Drgondog was talking about combat in the far east.


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## Reluctant Poster (Aug 10, 2022)

33k in the air said:


> Is that conducting actual combat missions, or just working up in preparation to entering combat? How many squadrons were so equipped at that time?


The first Mk IX combat was on July 28, 1942


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## Mike Williams (Aug 10, 2022)

33k in the air said:


> Is that conducting actual combat missions, or just working up in preparation to entering combat? How many squadrons were so equipped at that time?



BR581: FF 9-6-42 33MU 10-6-42 64S 22-6-42
BR592: FF 10-6-42 33MU 11-6-42 64S 8-7-42
BR978: FF 27-6-42 45MU 28-6-42 611S 25-7-42
BR981: FF 29-6-42 39MU 5-7-42 42S 24-7-42

And so on....

72 Squadron received Spitfire IX's in late July but handed them off to 401, according to S/L Bobby Oxsbring when the squadron went north for a rest. On 28 July 1942 64 Squadron, of the Hornchurch Wing, was the first squadron to go operational with Spitfire IX's . 611 squadron began taking deliveries of Spitfire IXs on 23 July 1942 while at Redhill, a satellite field to Kenley. Their first operation took place on 5 August covering the 308th FS USAAF to Le Touquet, with the first success, a FW 190 destroyed and 2 damaged coming on the 17th. 401 (RCAF) squadron started taking deliveries of Spitfire IXs at the end of July, fully converted with the move to Biggin Hill 2 August, performed their first operations with the Spitfire IX on 6 August 1942 and met with their first success on the 17th when they claimed 1 FW190 destroyed, 5 190 probables with 1 damaged. 402 (RCAF) squadron fully converted to Spitfire IXs by 2 August at Redhill with the first operations taking place on 13 August. They moved to Kenley on the 14th with their first claim in the type of 1 damaged coming on the 17th.

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## WARSPITER (Aug 10, 2022)

The Spitfire IX shot down it's first FW190 on 30th July 1942. The IX entered service first with no 64 squadron at Hornchurch in July 1942. That was it's debut in Europe
so use in the Pacific theatre would have been some time after that.

There were two more versions of the IX with the 66 engine (lower altitude performance - highest number built) and the 70 engine (higher altitude performance - not many).


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## GregP (Aug 10, 2022)

PAT303 said:


> I find it completely baffling that so many of you are putting so much effort into finding out reasons why the Spit shouldn't have it's fuel capacity increased, I can't think of any aeroplane that didn't benefit from it. Jeffrey Quill and Winkle Brown both pushed for it, Johnny Johnston lamented the fact it wasn't done until too late in the war, it's the first and generally only criticism the Spit gets in any conversation, I don't understand it.



I find it absolutely baffling that you want to change what is perhaps the finest piston fighter. Have you ever seen one in person? Have you ever worked on one?

A Spitfire is perhaps a ton or more lighter than a P-51. Comparatively speaking, it is almost fragile by comparison. The structure was strong enough, but the Spitfire is much easier to damage by comparison with a P-51D. Adding the extra fuel would reduce structural margins. It is weight the aircraft doesn't need and the longer-range tasks were being done by other aircraft.

For heaven's sake, leave the nice fighter airplane alone and let it be the great fighter that it was. Try dealing with the world as it actually was instead of what you can look back and turn it into. There are no correct or incorrect answers to a "what if," and the long-range Spitfire is a complete "what if." It was a great airplane if ever there was one. Celebrate it, but leave it alone.

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## MikeMeech (Aug 10, 2022)

Hi
No. 64 Sqn. with Spitfire IXs was in action by the end of July 1942. Also during July 1942 No. 72 Sqn. was equipped but handed them back In August (the squadron went to North Africa and used Spitfire Vs again). Nos. 611 and 401 (RCAF) were also equipped, from VBs, that month. In August No. 402 (RCAF) Sqn was equipped from VBs.
During September No. 122 Sqn. was equipped, as was 133 Sqn. however, this latter squadron became the 366th Sqn. 4th FG of the US 8th AF on 29th Sept. taking their Mk. IXs with them. During October Nos. 306 (Pol), 331 (Nor) and 340 (French) Sqns. coverted to IXs. In November Nos. 315 (Pol) and 332 (Nor) also equipped with IXs. At the start of 1943 9 squadrons of Fighter Command had IXs. It is of note that British RAF squadrons did not have priority for the new fighter (before someone says that the British held them back from non-British squadrons).
The first P-47s undertook their first operations in April 43 with RAF Spitfires going along with them. During the second half of 1942 many Fighter Command squadrons were being re-deployed overseas.

Mike

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## Reluctant Poster (Aug 10, 2022)

MikeMeech said:


> Hi
> No. 64 Sqn. with Spitfire IXs was in action by the end of July 1942. Also during July 1942 No. 72 Sqn. was equipped but handed them back In August (the squadron went to North Africa and used Spitfire Vs again). Nos. 611 and 401 (RCAF) were also equipped, from VBs, that month. In August No. 402 (RCAF) Sqn was equipped from VBs.
> During September No. 122 Sqn. was equipped, as was 133 Sqn. however, this latter squadron became the 366th Sqn. 4th FG of the US 8th AF on 29th Sept. taking their Mk. IXs with them. During October Nos. 306 (Pol), 331 (Nor) and 340 (French) Sqns. coverted to IXs. In November Nos. 315 (Pol) and 332 (Nor) also equipped with IXs. At the start of 1943 9 squadrons of Fighter Command had IXs. It is of note that British RAF squadrons did not have priority for the new fighter (before someone says that the British held them back from non-British squadrons).
> The first P-47s undertook their first operations in April 43 with RAF Spitfires going along with them. During the second half of 1942 many Fighter Command squadrons were being re-deployed overseas.
> ...


I don't think 133 squadron still had any IXs when they were transferred to the USAAF. They lost 11 of them on one mission 3 days before transferring to the USAAF. I believe they were given Vs as replacements.


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## drgondog (Aug 10, 2022)

Reluctant Poster said:


> I don't think 133 squadron still had any IXs when they were transferred to the USAAF. They lost 11 of them on one mission 3 days before transferring to the USAAF. I believe they were given Vs as replacements.


IIRC, the 4th FG flew mix of Spit V and IX until they converted. Nor do I recall that any one squadon was completely equipped with Spit IXs

I overstated the operational delays for Spit IX, believing Squadron level sorties beyond a few squadrons did not start until October/November 1942.


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## EwenS (Aug 10, 2022)

After a number of "prototype" and "pre-production" Mk.IX in early 1942 the first 100 conversions from Mk.Vc airframes were authorised on 18th April 1942 for delivery by the end of June. Ultimately 52 of these were converted by Supermarine and 48 by Rolls Royce. More conversions from F.Vc airframes followed through to March 1944. Exact numbers seem to vary but were in the order of 300 (one source I have says 278 by Supermarine & RR and another says nearly 300 by RR alone). The early conversions display a number of odd features to their cowlings displayng the rush nature of the conversion job. There was an article on these variations way back in an issue of Air Enthusiast in Sept/Oct 2001.

When the Mk.IX began to be issued to the squadrons in North Africa from Jan 1943 (yes I forgot about the Torch squadrons!) it was generally alongside the Mk.Vc. Usually it was only one flight to begin with until numbers increased. So 81 squadron for example went to NA fully equipped with the Mk.Vc. In Jan 1943 it, as noted above, got some Mk.IX. But it operated both models until Nov when it was withdrawn to re-equip with the Mk.VIII and transferred to India.

Someone asked about the planned destination of the Mk.VIII. The answer is "overseas". In an effort to maximise production the number of camouflage schemes applied to aircraft was minimised from 1942. AIUI, from discussions on other sites, all Mk.VIII (except perhaps for some early trials aircraft retained in the UK) produced to about March/April 1944 began life with the Desert Camouflage Scheme applied. That policy also applied to other types destined for overseas, like the Hurricane, at this time. If some other scheme was needed when they got somewhere where that was not appropriate then they were repainted. So that is what happened with aircraft sent to India and Australia. After early 1944 they left the factory in the Daylight Fighter Scheme and were again repainted in theatre as required.

The first Spitfire VIII shipped to India and Australia rolled off the production line in Aug 1943, went aboard ships in mid-Sept and arrived at their destinations in late Oct / early Nov 1943. So planning for that must have occurred some months prior.

81 and 152 squadrons were the first Mk.VIII squadrons to become operational in India in Dec 1943. Having been re-equipped with Mk.VIII in Egypt they flew their new aircraft to the Calcutta area. Spitfire squadrons already in theatre began to swap their Mk.Vc for Mk.VIII from Jan 1944.

Mk.VIII began to reach the squadrons in the Darwin area in March 1944.

And again before anyone says anything about priority, the USAAF 31st and 52nd FG equipped with Spitfire Mk.Vc in NA began to receive Mk.VIII and Mk.IX in the same sort of timescale as British squadrons. More detail on this thread





US Spitfires


I have heard that the Spitfires flown by the US Army in late ‘43 and early ‘44, particularly out of Corsica, Sicily, France, were old models and vastly inferior to the newer models given to the RAF. Is there any truth to this?



ww2aircraft.net

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## Milosh (Aug 10, 2022)

I will put this out there as a Spitfire reference source, home

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## GregP (Aug 10, 2022)

Just for fun, here's one of my drawings of a Spitfire XIV:







Cheers.

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## PAT303 (Aug 10, 2022)

GregP said:


> it is almost fragile by comparison.


Ohhh yes very fragile aeroplanes those Spitfires, this one was only in front line service for 4 years, A long-serving Spitfire Mk. Vb — Historic Photographs | 1941 | 1942 | 1943 | Spitfire Mk. V the dear thing, how did it survive so long being so fragile, one of life's mysteries I guess.


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## PAT303 (Aug 10, 2022)

NevadaK said:


> Personally, with the arrival of the P-47 I have a hard time making an argument for extended range Spitfire unless it exceeds the Thunderbolt's capabilities.


That's exactly what we are trying to achieve, if you read through the thread you would have known that the Spit and P47 could have worked together in the desperate first years of the day bomber offensive, late 1942 early 43, that's the whole point of giving the Spit more fuel.

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## Thumpalumpacus (Aug 10, 2022)

GregP said:


> I find it absolutely baffling that you want to change what is perhaps the finest piston fighter. Have you ever seen one in person? Have you ever worked on one?
> 
> A Spitfire is perhaps a ton or more lighter than a P-51. Comparatively speaking, it is almost fragile by comparison. The structure was strong enough, but the Spitfire is much easier to damage by comparison with a P-51D. Adding the extra fuel would reduce structural margins. It is weight the aircraft doesn't need and the longer-range tasks were being done by other aircraft.
> 
> For heaven's sake, leave the nice fighter airplane alone and let it be the great fighter that it was. Try dealing with the world as it actually was instead of what you can look back and turn it into. There are no correct or incorrect answers to a "what if," and the long-range Spitfire is a complete "what if." It was a great airplane if ever there was one. Celebrate it, but leave it alone.



Greg, I think the phrase that could sum up your post here is "the Law of Unintended Consequences."

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## GregP (Aug 10, 2022)

PAT303 said:


> Ohhh yes very fragile aeroplanes those Spitfires, this one was only in front line service for 4 years, A long-serving Spitfire Mk. Vb — Historic Photographs | 1941 | 1942 | 1943 | Spitfire Mk. V the dear thing, how did it survive so long being so fragile, one of life's mysteries I guess.



Fragile means it is MUCH easier to get "hangar rash," nothing more. The Spitfire structure itself is as strong as it needs to be and the ultimate failure load was 12 g when the development started. I am not aware if it maintained the 12 g ultimate rating as the Griffons engine came into service and it got heavier, but the Spitfire and other WWII-era fighters couldn't maintain more than about 3.5 - 4.0 g in a level turn at 10,000 feet ... they just didn't have the excess power. So, I'm pretty sure the Griffon Spits were as strong as they needed to be.

If you are careful with a Spitfire, there is no reason it shouldn't last as long as any other warbird. Just so you know, there were P-51s in front-line service for 30 years. Many Spitfires served longer than 4 years. Nothing wrong with a well-maintained warbird except that new developments overtake it in wartime, so they generally get swapped out for newer ones as they come down the pike in higher-priority theaters (think ETO) and used for a long time as-is in lower-priority theaters (think CBI). But, you should know that.

Your answer tells me you're more interested in snappy answers than information. So, go do as you want. Cheers.


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## GregP (Aug 10, 2022)

Thumpalumpacus said:


> Greg, I think the phrase that could sum up your post here is "the Law of Unintended Consequences."



Probably right. Changing one of the world's best fighter-interceptors so as to make it heavier to change its mission without adding firepower seem like exactly an undesired consequence. The original guys likely thought that way, too, since they didn't do as Mr. Gas Tank wants when they had the chance. Maybe they were smarter than we know.


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## Thumpalumpacus (Aug 10, 2022)

GregP said:


> Probably right. Changing one of the world's best fighter-interceptors so as to make it heavier to change its mission without adding firepower seem like exactly an undesired consequence. The original guys likely thought that way, too, since they didn't do as Mr. Gas Tank wants when they had the chance. Maybe they were smarter than we know.



No doubt they, or someone looking over their shoulders, had something to say about economics and production schedules. Those are two important factors in production, and you gonna trust an engineer with 'em? 

Weapons are not and can not be manufactured in a vacuum. In this case -- and other, worse cases too -- I think the results speak for themselves. They built the right fighter that they needed at the time, other fighters came along with different mission capabilities, and so the smart thing to do, instead of messing with production _per se_ is to simply apply a division of labor and have each airframe assigned to the most suitable mission.

Some airframes tolerated more mods than others, but that does not argue against what it is that they each do the best. Does that make sense or am I just meandering? The Spit was a superlative interceptor/dogfighter. Try to make it something else and court "jack of all trades-master of none" titles.

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## SaparotRob (Aug 10, 2022)

Well, they made 827 marks of Spitfires (correct me if I'm wrong) so they spent a lot of time tinkering around with the things. Improved high altitude performance, improved low altitude performance, extended range photo recon birds (one sounds more authoritative saying "photo recon birds"), etc. With all the time spent on it and all the things tried with it, if they could've improved range or felt a compelling reason to, they would have.

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## Thumpalumpacus (Aug 10, 2022)

SaparotRob said:


> Well, they made 827 marks of Spitfires (correct me if I'm wrong)




They made MMDCXII marks of the plane. Get it right!

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## SaparotRob (Aug 10, 2022)

Thumpalumpacus said:


> They made MMDCXII marks of the plane. Get it right!


This is why I love The Forum. Facts!


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## Thumpalumpacus (Aug 10, 2022)

SaparotRob said:


> This is why I love The Forum. Facts!



*YOU WILL USE ROMAN ENUMERATION AND YOU WILL LIKE IT.*


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## SaparotRob (Aug 10, 2022)

Thumpalumpacus said:


> *YOU WILL USE ROMAN ENUMERATION AND YOU WILL LIKE IT.*


yes, sir.

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## GregP (Aug 11, 2022)

Roman numerals in 2022? 

Oh excuse me, MMXXII? I say, that might be a trifle odd. Then again, mayhaps not.

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## nuuumannn (Aug 11, 2022)

NevadaK said:


> First, I think the engineering to make a LR Spitfire is greater and more involved than adding gas tanks where possible.



I'm gonna jump in here because I think Pat's getting unnecessary flak here. Let's also not forget the engineering difficulties of converting the Spitfire into a naval fighter were far greater than simply increasing its range, yet it was done, through various variants and modifications to the airframe.

As I posted earlier, the Spitfire was modified to increase its range _and_ combat radius with the hope of using it as a long range escort, although firstly it was to ferry the type to the Middle East. Both the manufacturer and the Air Ministry investigated its potential in these roles. As mentioned, someone (not sure who, possibly Supermarine) calculated that as an escort fighter, a Spitfire V could be made to go all the way to Berlin and back to escort British bombers. This was in either 1941 or 1942.

Both the Americans at Wright Pat (Spit IX MK210 was flown non-stop across the Atlantic to the USA) and the British (Vickers) carried out structural modifications to the Spitfire to give it greater endurance. The Vickers mods extended its range to 1,400 miles, the American mods, to 1,600 miles. Although done in 1944, this alone proves it could have been done had the desire been there.

Here's some detail and a picture of MK210:



Spitfire pilots and aircraft database - Spitfire MK210



Again, I'll repeat why it wasn't, Charles Portal, Chief of the RAF Air Staff refused to believe that the RAF needed a fighter with that kind of range because it would be inferior to short ranged fighters, at least that was his argument.

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## nuuumannn (Aug 11, 2022)

SaparotRob said:


> This is why I love The Forum. Facts!



Now, wait just a cotton pickin' minnit with those "facts"...

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## Thumpalumpacus (Aug 11, 2022)

nuuumannn said:


> Now, wait just a cotton pickin' minnit with those "facts"...



You want facts? I got facts. Everyone gets a fact!

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## NevadaK (Aug 11, 2022)

nuuumannn said:


> I'm gonna jump in here because I think Pat's getting unnecessary flak here. Let's also not forget the engineering difficulties of converting the Spitfire into a naval fighter were far greater than simply increasing its range, yet it was done, through various variants and modifications to the airframe.
> 
> As I posted earlier, the Spitfire was modified to increase its range _and_ combat radius with the hope of using it as a long range escort, although firstly it was to ferry the type to the Middle East. Both the manufacturer and the Air Ministry investigated its potential in these roles. As mentioned, someone (not sure who, possibly Supermarine) calculated that as an escort fighter, a Spitfire V could be made to go all the way to Berlin and back to escort British bombers. This was in either 1941 or 1942.
> 
> ...


Now, why am i getting called out for dog piling here? Especially since I also linked an article from the highly esteemed Royal Aeronautical Society covering what had been tried and so forth. Jeez.

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## drgondog (Aug 11, 2022)

GregP said:


> Fragile means it is MUCH easier to get "hangar rash," nothing more. The Spitfire structure itself is as strong as it needs to be and the ultimate failure load was 12 g when the development started. I am not aware if it maintained the 12 g ultimate rating as the Griffons engine came into service and it got heavier, but the Spitfire and other WWII-era fighters couldn't maintain more than about 3.5 - 4.0 g in a level turn at 10,000 feet ... they just didn't have the excess power. So, I'm pretty sure the Griffon Spits were as strong as they needed to be.
> 
> If you are careful with a Spitfire, there is no reason it shouldn't last as long as any other warbird. Just so you know, there were P-51s in front-line service for 30 years. Many Spitfires served longer than 4 years. Nothing wrong with a well-maintained warbird except that new developments overtake it in wartime, so they generally get swapped out for newer ones as they come down the pike in higher-priority theaters (think ETO) and used for a long time as-is in lower-priority theaters (think CBI). But, you should know that.
> 
> Your answer tells me you're more interested in snappy answers than information. So, go do as you want. Cheers.


Greg - I believe, substantiated by the NAA weight comparison Report of 11-42 NA-5567 "Weight Comparison of Spitfire IX with P-51B" That the Spitfre (Spitfire I) was designed for 11G AoA, 1 G side and 4G Landing Loads. That became the standard for the LightWeight Mustangs, including the P-51H.

The XP-51 was designed to USAAC MC Stress Standards of 12G, 2G and 7G respectively at 8,000 pounds GW.

When the weight comparions were laboriously completed the weight Diference between the Spit IX and P-51B was 1450 pounds - each with 100 and 105 gal fuel respectively. The strength comparison noted that the Ultimate G loads for AoA for the Spit IX and P-51B had both been reduced by Gross Weight Growth over time. That said, the P-51H corrected this issue by re-stressing to combat Gross Weight of full internal load of 9600 pounds at 11G Ultimate, whereas the P-51B at full combat Internal Load had reduced from 12G at 8000 pounds of XP-51 to Approx 10G Ultimate for allowable max stress before failure and about 6.6 for Limit Load AoA. (You know this - just citing the Report comparisons)

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## 33k in the air (Aug 11, 2022)

NevadaK said:


> Especially since I also linked an article from the highly esteemed Royal Aeronautical Society covering what had been tried and so forth. Jeez.



Not to rain on your parade too much, but I posted that same article way back in post #147.


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## GregP (Aug 11, 2022)

Hi Nuuumannn.

I have nothing against Pat303 at all. He is suggesting that the Spitfire family have added fuel all around the board. People have told him it isn't exactly easy or necessarily smart to do that. Also, the aircraft was designed with a specific mission in mind, and he wants to change that, too. So, he wants to change the aircraft and the mission.

What I am saying is the missions he envisions for Spitfires as longer-range aircraft were being flown by other aircraft and, if the Brits had wanted the Spitfire to fly them, they likely could have been modified to do so.

But then the shorter missions that were flown by the Spitfires would have to flown by other aircraft that weren't nearly so suited to them as the Spitfire was. It's a case of, "OK, you want the Spitfires, who are flying short-range intercept, to fly longer-range escort and interdiction missions. OK, so who's going to fly the Spitfire missions currently being flown, and will they be as good at it as the Spitfires are? Should we gamble on that? Will the Spitfires be as good at longer-range missions as the other aircraft currently flying them are?"

Since the Spitfires never did get really long legs in large numbers, my take is they never decided to gamble with having the Spitfire missions taken over by other fighters.

I am not suggesting Pat is completely wrong. I am suggesting that it never happened in real life and since it didn't, we can speculate about it, but it is a "what if" that cannot be tried out; we are left with what the Spitfire actually did. I have no objection to a bit of extra tankage in the Spits had they actually done so. But though we might LIKE it if they had longer legs, they really didn't. And there was a reason for that. It likely has something to do with how good the Spitfire was at the missions to which it was assigned.

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## PAT303 (Aug 11, 2022)

GregP said:


> Your answer tells me you're more interested in snappy answers than information. So, go do as you want. Cheers.


All I want is to give the Spit more endurance so it can stay in the fight, there's a reason P47's and P51's racked up big numbers of kills over Europe, they could get to the fight, the Spit couldn't, a MkIX with 300 mile radius from late 42'-early 43' would have been a handy bird.

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## WARSPITER (Aug 11, 2022)

Fuel capacity was increased as the Spitfire marks progressed starting at 85 gallons internal in the MKII to V then going up to 124 gallons for the MK VIII
and 160 gallons for Mk XIV. The MkVIII had quite a good range compared to the II and V so was sent for use in the far East.

The problem for escort range when compared to the Merlin Mustang is drag/boost. The lower drag and Meredith effect? of the Mustang gave it a cruise speed 
around 30MPH greater than the Spitfire while using the same or less fuel. There was a proposal at one stage to shift the radiator system on the Spitfire to the 
lower fuselage to give the same effect as the Mustang but the time and resources used for this would have meant the Merlin Mustang would have been in operation 
first anyway.

MK XIV's were used as escort for USAAF and RAF bomber raids as far across as Switzerland with about a four hour flight time and no problem with fuel but
this still didn't match the Mustang.

A test was done earlier with drop tanks and extra fuel at Wright field in the US but to get an acceptable range with armament still onboard meant the aircraft
was over it's maximum take off weight. To get a range close to the mustang would have meant another belly tank as well putting the MK IX at 10% over it's
MTOW. The MKVIII had a stronger frame and would have been more capable but it's still pushing things.

Another option would have been to have production of the Spitfire carried out in the US as well as Britain earlier in the war. More available production would
have meant more facilities aside to do R&D giving the possibility of a longer range version in late 1942.

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## PAT303 (Aug 11, 2022)

WARSPITER said:


> didn't match the Mustang.


Not trying to match the Mustang, have said this repeatedly.

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## PAT303 (Aug 11, 2022)

WARSPITER said:


> There was a proposal at one stage to shift the radiator system on the Spitfire to the
> lower fuselage to give the same effect as the Mustang but the time and resources used for this would have meant the Merlin Mustang would have been in operation
> first anyway.


Not trying to design a new aeroplane either, just getting rear tanks into the Spit and into service late '42 early 43' is all I'm trying to achieve, MkIX's were already plumbed for drop tanks.


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## PAT303 (Aug 11, 2022)

WARSPITER said:


> Another option would have been


To fit the rear tanks that were available and in service since 1940 and later fitted to all production MkXVI's.


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## PAT303 (Aug 11, 2022)

nuuumannn said:


> Again, I'll repeat why it wasn't, Charles Portal, Chief of the RAF Air Staff refused to believe that the RAF needed a fighter with that kind of range because it would be inferior to short ranged fighters, at least that was his argument.


That's the only valid argument I can see on why it wasn't done in the whole 19 page thread.

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## WARSPITER (Aug 11, 2022)

PAT303 said:


> To fit the rear tanks that were available and in service since 1940 and later fitted to all production MkXVI's.


Varoius marks did get the rear tanks which was the main increase in fuel capacity plus bag tanks in the wings.

Nuuumannn's post is definitely relevant as it goes to the heart of the matter which was bomber doctrine. 

From what I have read there was always a push pull going on as bomber proponents had been influenced by the 'bomber will always get through' 
syndrome. The thing they found out was they don't all come back.

This should have been obvious from the Battle of Britain where the Luftwaffe struggled to escort bombers which were shown to be far more
vulnerable to fighter attack than thought.

When four engined bombers came around with large amounts of machine guns sticking out of them the original theory still held sway.
Again, flak and fighters with 20 and 30mm cannon literally shot that down.

Prejudice and politics does have a bad influence at times.

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## NevadaK (Aug 11, 2022)

33k in the air said:


> Not to rain on your parade too much, but I posted that same article way back in post #147.


I believe post #147 was before I was born........

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## GregP (Aug 12, 2022)

PAT303 said:


> All I want is to give the Spit more endurance so it can stay in the fight, there's a reason P47's and P51's racked up big numbers of kills over Europe, they could get to the fight, the Spit couldn't, a MkIX with 300 mile radius from late 42'-early 43' would have been a handy bird.



OK, so who is going to fly the Spitfire's current missions while your long-range Spits do their new missions? Were these assets assigned to the RAF or were they USAAF fighters that would NEVER be assigned as defense of the UK? US assets were pursuing US missions, not UK missions except where they happened to coincide.

Basic question is if the SPitfires were not defending the country, who WOULD have been doing so and were they available to UK Fighter Command while the Spits were flitting about elsewhere?


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## wuzak (Aug 12, 2022)

GregP said:


> OK, so who is going to fly the Spitfire's current missions while your long-range Spits do their new missions? Were these assets assigned to the RAF or were they USAAF fighters that would NEVER be assigned as defense of the UK? US assets were pursuing US missions, not UK missions except where they happened to coincide.
> 
> Basic question is if the SPitfires were not defending the country, who WOULD have been doing so and were they available to UK Fighter Command while the Spits were flitting about elsewhere?



I'm sure that by mid 1943 there would be enough IXs to perform escort duty and also defend the homeland.

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## EwenS (Aug 12, 2022)

wuzak said:


> I'm sure that by mid 1943 there would be enough IXs to perform escort duty and also defend the homeland.


On D-Day 6 June 1944 there were still 10 squadrons in Air Defence of Great Britain flying Spitfire Mk.V, with 8 of those belonging to 11 Group in the South East of England and 1 each in 12 & 13 Groups further north. There was even still a Hurricane II squadron based in the east of Scotland in a defensive role.

Over coming months these squadrons transitioned to a variety of types including Spitfire IX & XIV, Tempest V and Mustang III as more aircraft became available.

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## PAT303 (Aug 12, 2022)

GregP said:


> OK, so who is going to fly the Spitfire's current missions while your long-range Spits do their new missions?


What new missions?, adding fuel allows the same squadrons already crossing the channel doing escort missions or sweeps more endurance, I'm not inventing a new air force.

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## PAT303 (Aug 12, 2022)

wuzak said:


> I'm sure that by mid 1943 there would be enough IXs to perform escort duty and also defend the homeland.


Taking the fight to the Luftwaffe and pushing them further back from the channel is the best defence.


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## drgondog (Aug 12, 2022)

WARSPITER said:


> Fuel capacity was increased as the Spitfire marks progressed starting at 85 gallons internal in the MKII to V then going up to 124 gallons for the MK VIII
> and 160 gallons for Mk XIV. The MkVIII had quite a good range compared to the II and V so was sent for use in the far East.
> 
> The problem for escort range when compared to the Merlin Mustang is drag/boost. The lower drag and Meredith effect? of the Mustang gave it a cruise speed
> ...


Internal fuel capacity is the determinant - not external tanks. Whatever you have left after dropping externals and a.) fight for 20 in, b.) economy cruise home, c.) loiter for 30 min is central to Combat Radius estimates.

P-51B/D with fuse tank = 269gal.

Spitfire was designed to slightly lower stress limits than Mustang - at the beginning of its life cycle.

Both the wing and the cooling drag attributes contributed to superior cruise and top speed aerodynamics for the Mustang although the thin(er) wing of the Spitfire gave slightly better Cdmach profile than Mustang wing.

Changing the cooling system approach to imbedded Radiator system would have been a huge fuselage re-design (my speculation) due to differences in aft frame volumes and structure to accomodate the new Meredith type system.

Significant is he lack thereof in the later models of Spit after several years experience and knowledge of the 'do/don't do' of Mustang I and evolution of external/internal configuration changes. Even with the original allotment of NA-73/83 airframes for Merlin conversion, no attempt was made to lift the cooling system into a later model Spitfire toimprove aerodynamics. All the major changes were horsepower driven.

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## WARSPITER (Aug 12, 2022)

drgondog said:


> Internal fuel capacity is the determinant - not external tanks. Whatever you have left after dropping externals and a.) fight for 20 in, b.) economy cruise home, c.) loiter for 30 min is central to Combat Radius estimates.
> 
> P-51B/D with fuse tank = 269gal.
> 
> ...


Yes that is why I only referred to increases in internal fuel capacity.

The cooling system change wasn't done during the war due to time and resources and yes, a massive fuselage change. It wasn't done after the war
as the constraints changed to mostly a matter of money and an acceptance that jets would take over.


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## GregP (Aug 12, 2022)

PAT303 said:


> What new missions?, adding fuel allows the same squadrons already crossing the channel doing escort missions or sweeps more endurance, I'm not inventing a new air force.



You still don't see it, Pat.

The Spitfires were assigned short-range missions because that's what they could fly, and they did it very well. If you re-assign them to longer-range missions, then the short-range mission have to be flown by something else. If the Spitfires expend their ammunition still flying the short-range stuff, then there is no point in going on with a longer-range mission if you are largely unarmed. It is risk without potential reward. If the Spitfires hold their ammunition and bypass the short-range targets in favor of longer-range targets, then they have failed to prosecute the shorter-range missions, so somebody else has to then fly the mission objectives that were bypassed. Surely you don't think most missions were lacking an objective. The objective is the entire reason for the mission. Nobody expends fuel, aircraft wear, and potentially pilots without a clear mission objective. Training and repositioning are the exceptions to that.

What do you mean, "what new missions?"The new missions are the longer-range missions that you seem to want the Spitfires to fly and, if they did, then they would have to ignore the shorter-range missions they were actually flying in real life in order to be effective and still retain attack capability at the new longer ranges. There is no point simply flying over longer-range territory without attacking anything. The premise is simple, if they are NOT flying the missions they actually flew during the war, then who will fly them and were those assets available to RAF Fighter Command?

I'm not saying that all Spitfires expended their entire ammunition supply on short-range missions; they didn't. But a large percentage did. If they kept returning without seeing any action, then they would have been reassigned to other missions where they DID see action. Nobody keeps flying non-effective missions for too long. There is no point.

This was Europe, not the Pacific with large section of empty ocean. So, there were targets on EVERY mission and their were enemy aircraft about on most missions.


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## 33k in the air (Aug 12, 2022)

NevadaK said:


> I believe post #147 was before I was born........



Darn you kids! Get off my forum thread lawn!

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## bentwings (Aug 12, 2022)

Shortround6 said:


> Just about any fighter could use a bit more range.
> Just what are you going to have to give up to get it?
> An extra 20-30 gallons in a Spit might be doable, depends on the engine and tactical situation. but an extra 30 gallons is not going to get to the Ruhr and back let alone any futher.
> 
> ...


Greg’s you tube site has a very in depth analysis of nearly every plane that flew during the war years he often compares common pairing so you get to see graphical comparisons . Drop tanks various sizes of internal tanks and even when the super high octane gas became available as well as German use of nitrous and alcohol fuels

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## GregP (Aug 12, 2022)

Just so everyone is clear, the Greg's Aviation site is not mine. It's another Greg. I like some of his stuff, but some of his contentions are a bit suspect, at least to me. Still, pretty good efforts on his part in general. 

I like them WAY more than I dislike or disagree with them.

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## Thumpalumpacus (Aug 12, 2022)

GregP said:


> Just so everyone is clear, the Greg's Aviation site is not mine. It's another Greg. I like some of his stuff, but some of his contentions are a bit suspect, at least to me. Still, pretty good efforts on his part in general.
> 
> I like them WAY more than I dislike or disagree with them.



I like that he isn't afraid to get into the weeds, and does so by way of explanation that even a dolt like me can understand the issue. I still don't know if he's right or wrong much of the time, but his channel is certainly food for thought.

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## Zipper730 (Aug 12, 2022)

PAT303 said:


> I find it completely baffling that so many of you are putting so much effort into finding out reasons why the Spit shouldn't have it's fuel capacity increased, I can't think of any aeroplane that didn't benefit from it. Jeffrey Quill and Winkle Brown both pushed for it


What was Quill & Brown's rationale?

Also did they have any known specific proposals for stuffing more fuel in?

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## PAT303 (Aug 12, 2022)

GregP said:


> I'm not saying that all Spitfires expended their entire ammunition supply on short-range missions; they didn't. But a large percentage did. If they kept returning without seeing any action, then they would have been reassigned to other missions where they DID see action. Nobody keeps flying non-effective missions for too long. There is no point.


Actually that's exactly what happened later in the war, the Spit's lack of range meant they did pointless short range escort missions and saw nothing or pointless fighter sweeps over the low countries also seeing nothing. A fighter that had expended it's ammo is heading home regardless of what it's mission is, giving the Spit more fuel allows more chance of it getting into action, ideally you want them coming home empty, that means they are doing their job.


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## PAT303 (Aug 12, 2022)

Zipper730 said:


> What was Quill & Brown's rationale?
> 
> Also did they have any known specific proposals for stuffing more fuel in?


More endurance, the Spits biggest handicap was it's lack of endurance. Go and read about the Spit in WW2, everything it did was dictated by its range, it's lack of range,


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## glennasher (Aug 12, 2022)

Please Pat, let it go.


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## PAT303 (Aug 12, 2022)

glennasher said:


> Please Pat, let it go.


Okay.


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## GregP (Aug 12, 2022)

PAT303 said:


> Actually that's exactly what happened later in the war, the Spit's lack of range meant they did pointless short range escort missions and saw nothing or pointless fighter sweeps over the low countries also seeing nothing. A fighter that had expended it's ammo is heading home regardless of what it's mission is, giving the Spit more fuel allows more chance of it getting into action, ideally you want them coming home empty, that means they are doing their job.



That only happened after the war was essentially won, when the competent Luftwaffe was getting scarce. When that happens, your range available from your short-range fighters doesn't matter, you have won the war and the enemy only has to realize it and surrender. Any aerial action after that is almost superfluous.

That was mostly after about February 1945. In 1944, the USAAF averaged 869 German airplanes destroyed each month. In Jan - Mar 1945, they averaged 558. In April 1945, the USAAF destroyed 4,257 German aircraft, 3,703 of them on the ground. Can you say "Collapse of the Luftwaffe as a Fighting Force?"


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## PAT303 (Aug 12, 2022)

GregP said:


> That only happened after the war was essentially won, when the competent Luftwaffe was getting scarce. When that happens, your range available from your short-range fighters doesn't matter, you have won the war and the enemy only has to realize it and surrender. Any aerial action after that is almost superfluous.
> 
> That was mostly after about February 1945. In 1944, the USAAF averaged 869 German airplanes destroyed each month. In Jan - Mar 1945, they averaged 558. In April 1945, the USAAF destroyed 4,257 German aircraft, 3,703 of them on the ground. Can you say "Collapse of the Luftwaffe as a Fighting Force?"


Greg, the Spit had 85G of fuel for one reason and that was because that's all that could be carried aloft with the then available engine power, the airframe had great growth potential and adaptability as shown by the vast number of models and rolls it was developed into which coincided with Merlin/Griffin engine development. The need to limit it's fuel capacity based on 1937-9 engine power was long gone by 1942, anyway I'll take glennashers advice and leave it.


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## GregP (Aug 13, 2022)

Just so we understand each other, I agree there's nothing wrong with extra fuel. It just never materialized until very late and, by then, it didn't really matter. They also didn't allow Grumman to modify the F6F by eliminating the wing dihedral to increase the rate of roll, even though it was needed. They never allowed Messerschmitt to "fix" the main Bf 109 shortcomings, either.

So, the Spitfire wasn't exactly alone in not getting something that would help it out in the field. Nevertheless, it acquitted itself quite well during the war with what it DID have: sparking performance at the mission it was designed for.

Cheers, Pat303.

*Edit*: By the way, the Supermarine Attacker was basically a jet version of the Seafang / Spiteful. It had a Spiteful wing and a new fuselage with a jet engine in it. The Attacker shared the short range with the Spiteful and Spitfire / Seafire. Max range was just 590 miles, meaning less than 300 mile range with no reserve. So, when it was fueled up, oiled up, and ready for engine start, it was basically in a state of fuel emergency. Perhaps they had to get back for tea, scones, and darts?

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## drgondog (Aug 13, 2022)

PAT303 said:


> Actually that's exactly what happened later in the war, the Spit's lack of range meant they did pointless short range escort missions and saw nothing or pointless fighter sweeps over the low countries also seeing nothing. A fighter that had expended it's ammo is heading home regardless of what it's mission is, giving the Spit more fuel allows more chance of it getting into action, ideally you want them coming home empty, that means they are doing their job.


No. 
Later in war, Spit squadrons based in UK did interceptions of V-1s, convoy escort, escort over transports shipping supplies to Invasion forces, escort to Netherlands, general UK air Defense. Nothing 'meaningless'..

Later, based on Continent, Meaningful Escort of TAC Air light and medium bombers, air defense, even tactical CAS type sweeps. 

Your focus seems to be "'I'm sad that the Spitfire didn't get into the big air battles over Germany" - but the Spits were Everywhere else and making major contributions in wresting air superiority from Axis - just deployed in a complimentary fashion with other air assets available.

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## Milosh (Aug 13, 2022)

GregP said:


> Perhaps they had to get back for tea, scones, and darts?


Scones are Scottish. Biscuits are the Brits.

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## SaparotRob (Aug 13, 2022)

..and now I know.

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## pbehn (Aug 13, 2022)

SaparotRob said:


> ..and now I know.


Biscuit is French for "cooked twice" (you may note a little thread drift here)

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## GregP (Aug 13, 2022)

Milosh said:


> Scones are Scottish. Biscuits are the Brits.



Mea culpa, mea maxima culpa. 

Thread drift? Surely you jest! 

Speaking jest, a man walks into a bar with a monkey on his shoulder ...

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## NevadaK (Aug 13, 2022)

pbehn said:


> Biscuit is French for "cooked twice" (you may note a little thread drift here)


The best southern biscuits are made with White Lily Flour.

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## SaparotRob (Aug 13, 2022)

mmmmmmm biscuits.


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## BiffF15 (Aug 13, 2022)

NevadaK said:


> The best southern biscuits are made with White Lily Flour.


And covered in breakfast gravy!

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## BiffF15 (Aug 13, 2022)

PAT303 said:


> A fighter that had expended it's ammo is heading home regardless of what it's mission is, giving the Spit more fuel allows more chance of it getting into action, ideally you want them coming home empty, that means they are doing their job.


Pat,

A fighter without ammo is not without use. He can stay as a flight lead and do battle direction, monitor engaged time and call “bingo” / for the RTB (Return To Base). As a wingman he is probably more useful in that he checks his flight leads six, keeps navigational / fuel SA and doesn’t wander off (he needs a shooter nearby). “Very loyal this wingman is“. 

As for coming home empty meaning their job is done is not always true. Coming home with your weapons can also mean you have done your mission (Air Superiority has been established and no ordinance was expended to do it).

Cheers,
Biff

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## wuzak (Aug 14, 2022)

drgondog said:


> Internal fuel capacity is the determinant - not external tanks. Whatever you have left after dropping externals and a.) fight for 20 in, b.) economy cruise home, c.) loiter for 30 min is central to Combat Radius estimates.
> 
> P-51B/D with fuse tank = 269gal.
> 
> ...



Smith was not allowed to redesign the Spitfire with a embedded fuselage radiator, even though he and Supermarine wanted to. Production was king, and the changes required for a Mustang style radiator would have cost a lot of production time.

Even when Supermarine made improvements it was delayed, or not implemented at all. For example, the changes made to the radiator for the Mk.III were never adopted. Similarly the V was chosen over the III, and the IX over the VIII, for production reasons.

The new wing was delayed, so that the interim Griffon Spitfire (the XIV) was introduced a year before the "definitive" version, the 21. And the laminar flow wing of the Spiteful was delayed even more.

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## Geoffrey Sinclair (Aug 14, 2022)

GregP said:


> OK, so who is going to fly the Spitfire's current missions while your long-range Spits do their new missions? Were these assets assigned to the RAF or were they USAAF fighters that would NEVER be assigned as defense of the UK? US assets were pursuing US missions, not UK missions except where they happened to coincide.
> 
> Basic question is if the SPitfires were not defending the country, who WOULD have been doing so and were they available to UK Fighter Command while the Spits were flitting about elsewhere?


While the USAAF was still accepting Spitfire fighters for its Mediterranean forces it was not doing so in Britain. Next comes the operational tempo.

The Richard Davis spreadsheet of 8th Air Force bomber activities has 5,577 entries of which 432 are by end 1943. Similarly end December 1943 is page 161 out of 503 pages for Mighty Eighth War Diary. Of the 504 days 17 August 1942 to 31 December 1943 the 8th Air Force dropped bombs on 121 days. There are days when targets in more than one country were attacked, but by country Belgium 7 days, France 64 days, Germany 48 days, Netherlands 11 days, Norway 3, Poland 1. Just Germany is 1 in January 1943, 2 in February, 3 in March, 1 in April, 4 in May, 4 in June, 6 in July, 2 in August, 2 in September, 7 in October 9 in November, 7 in December. Giving 10 days in the third and 23 days in the final quarter of 1943. 

Assuming the Spitfire VIII force is not available until end June 1943, reduce the time to the 184 days of the second half of 1943. Belgium 1 day, France 22 days, Germany 33 days, Netherlands 8 days, Norway 3, Poland 1 in 58 days of operations, 1 in 3 and 2 in 11 for Germany.

Fighter Command had something like 48 squadrons of Spitfires on 1 July 1943, rising to 51 by end December and was providing escort to the USAAF heavies to various targets during the time.

Air 20/2001, As of 29 July 1943 the RAF reported 170 Spitfire VIII overseas plus 327 Spitfire IX, along with 179 Spitfire IX in operational squadrons at home, total counting reserves 214 VIII and 579 IX. On 30 September 213 VIII overseas, plus 347 IX, while 307 IX were in home squadrons. Adding reserves, 332 VIII and 1,011 IX.

Spitfire VIII production to end June 1943, 254, halve this 127, at 20 Spitfires per squadron, 6 squadrons. Castle Bromwich, assume the change over to bigger internal tanks costs three months or the 93 that were actually built February to May 1943, the engines being used to convert mark V to IX while waiting. Putting in a three month delay at Castle Bromwich means another 34 Merlin 60 series Spitfires with larger internal fuel from it by end June 1943 on top of the mark VIII from Supermarine as combined production hits over 100 for the month, then combined production is nearly 200 in August, and 300 in November. This leaves 559 Spitfire IX built at Supermarine June 1942 to June 1943, plus conversions, less losses in Britain for the overseas forces before any of the longer range version are allocated.

AIR 16/1036. Dates are 8th Air Force day bombing of targets in Germany.

Date Column is RAF Fighter Command day offensive sorties for the day, 2nd TAF sorties are all types.
17-Jul-43 356
25-Jul-43 680 
26-Jul-43 842 
28-Jul-43 815 
29-Jul-43 742 
30-Jul-43 709 11,360 offensive sorties in July, including 2,326 USAAF, plus 4,450 defensive sorties, plus 2nd TAF 2,730 sorties
12-Aug-43 733 
17-Aug-43 759 11,320 offensive sorties in August, plus 2,217 USAAF fighter sorties, plus 3,801 defensive sorties, plus 2nd TAF 3,801 sorties
06-Sep-43 1003 
27-Sep-43 797 15,898 offensive sorties in September, plus 3,564 USAAF fighter sorties, plus 3,891 defensive sorties, plus 2nd TAF 5,538 sorties
02-Oct-43 448 
04-Oct-43 257 
08-Oct-43 544 
09-Oct-43 483 
10-Oct-43 0 
14-Oct-43 88 
20-Oct-43 482 7,486 offensive sorties in October, plus 3,404 USAAF fighter sorties, plus 2,361 defensive sorties, plus 2nd TAF 2,551 sorties
03-Nov-43 652 
05-Nov-43 967 
07-Nov-43 701 
11-Nov-43 858 
13-Nov-43 79 
19-Nov-43 363 
26-Nov-43 887 
29-Nov-43 478 
30-Nov-43 208 9,593 offensive sorties in November, plus 3,955 USAAF fighter sorties, plus 1,841 defensive sorties, plus 2nd TAF 4,590 sorties
01-Dec-43 300 
11-Dec-43 45 
13-Dec-43 173 
16-Dec-43 12 
20-Dec-43 421 
22-Dec-43 472 
30-Dec-43 343 4,335 offensive sorties in December, plus 1,292 defensive sorties, plus 2nd TAF 3,820 sorties

So finding an extra or redirecting 100 or so offensive sorties per bomber day in July, rising to no more than twice that in December is quite viable.

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## Reluctant Poster (Aug 14, 2022)

drgondog said:


> No.
> Later in war, Spit squadrons based in UK did interceptions of V-1s, convoy escort, escort over transports shipping supplies to Invasion forces, escort to Netherlands, general UK air Defense. Nothing 'meaningless'..
> 
> Later, based on Continent, Meaningful Escort of TAC Air light and medium bombers, air defense, even tactical CAS type sweeps.
> ...


The Spitfire was first and foremost an interceptor and it was arguably the finest interceptor of the war. It should be appreciated that the combination of the Spitfire by day and the Mosquito by night provided an airtight cordon around the British Isles. The Luftwaffe was unable to launch any spoiling attacks on invasion preparations, in fact they couldn't even get recon aircraft over to observe the preparations. 
One of the interesting aspects of AWP-1 was that the fighters the US planned to be sent to the UK along with the bombers were tasked with defending the USSAF airbases. This proved unnecessary as the RAF had it well in hand. Having a secure base to fly from was a very underrated benefit to the 8th AF. It should be noted tha AEPD-1 suggested that aadiotanl fighter units would be required to provide bomber support over Germany and for offensive sweeps
I believe if the Luftwaffe was going to have any meaningful impact it would have been at night, but the Mosquito put an end to that by decimating the German bomber force during operation Steinbock.
Any successful offence requires a secure base to launch from and the Spitfire and Mosquito provided that.

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## Reluctant Poster (Aug 14, 2022)

Thumpalumpacus said:


> I like that he isn't afraid to get into the weeds, and does so by way of explanation that even a dolt like me can understand the issue. I still don't know if he's right or wrong much of the time, but his channel is certainly food for thought.


In my opinion is that he's lost in the weeds. Lots of misinformation

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## GregP (Aug 14, 2022)

Geoffrey Sinclair said:


> While the USAAF was still accepting Spitfire fighters for its Mediterranean forces it was not doing so in Britain. Next comes the operational tempo.
> 
> The Richard Davis spreadsheet of 8th Air Force bomber activities has 5,577 entries of which 432 are by end 1943. Similarly end December 1943 is page 161 out of 503 pages for Mighty Eighth War Diary. Of the 504 days 17 August 1942 to 31 December 1943 the 8th Air Force dropped bombs on 121 days. There are days when targets in more than one country were attacked, but by country Belgium 7 days, France 64 days, Germany 48 days, Netherlands 11 days, Norway 3, Poland 1. Just Germany is 1 in January 1943, 2 in February, 3 in March, 1 in April, 4 in May, 4 in June, 6 in July, 2 in August, 2 in September, 7 in October 9 in November, 7 in December. Giving 10 days in the third and 23 days in the final quarter of 1943.
> 
> ...



Sure it is, if you want to not fly the missions that were flown in real life. That "what if" never happened, and there is no correct response to discussing it. The guys who ordered the real-world missions didn't change them, and you can't either, except in your what if, which would have been possible, but weren't actually flown. Might have been a good idea, might not have been. Unless you can go and try it out, you can't say for sure. But, yes, it was possible.

I AM sure that changing a small percent of the sorties to something else would likely not have changed the course of the war, but it might have made it longer or shorter by a bit. We can't say which.


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## drgondog (Aug 15, 2022)

Thumpalumpacus said:


> I like that he isn't afraid to get into the weeds, and does so by way of explanation that even a dolt like me can understand the issue. I still don't know if he's right or wrong much of the time, but his channel is certainly food for thought.


I respect much of what he has to say on the technical level, but he went off the rails trying to explain why 'the powers that be conspired to keep P-47 range restricted' when hundreds of B-17/24 crew members were dying and POW. His knowledge of Combat Range, and limitations on such with only increasing external fuel, was sadly limited and confused.

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## Reluctant Poster (Aug 15, 2022)

drgondog said:


> I respect much of what he has to say on the technical level, but he went off the rails trying to explain why 'the powers that be conspired to keep P-47 range restricted' when hundreds of B-17/24 crew members were dying and POW. His knowledge of Combat Range, and limitations on such with only increasing external fuel, was sadly limited and confused.


Exactly. I am amazed at how many articles are out there which basically claim "Top Brass" was actively trying to lose the war, (Bodie dips into that territory)

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## drgondog (Aug 15, 2022)

Reluctant Poster said:


> Exactly. I am amazed at how many articles are out there which basically claim "Top Brass" was actively trying to lose the war, (Bodie dips into that territory)


Bodie's primary illness was the 'what if' surrounding the ultimate solution - the mystical Merlin powered P-38K derivative and wailing about the blindness of AAF leaders in failing to see the light. I wonder if he ever realized that Echols was the single most inflential member of the War Production Board, and even he couldn't get behind diverting Packard production in mid 1944 when Kelsey and Hough bootlegged two P-38J and sent them to R-R?

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## 33k in the air (Aug 15, 2022)

drgondog said:


> I respect much of what he has to say on the technical level, but he went off the rails trying to explain why 'the powers that be conspired to keep P-47 range restricted' when hundreds of B-17/24 crew members were dying and POW. His knowledge of Combat Range, and limitations on such with only increasing external fuel, was sadly limited and confused.



It's apparently not an uncommon view in some quarters. I've run into the sentiment in YouTube comments on videos on WWII aviation-related channels.

Greg's Airplanes and Automobiles lost me when he seemed to say that the B-17 could have regularly carried just about as many bombs to targets as the Lancaster by lugging bombs on its external wing racks, but didn't because reasons by the USAAF leadership.

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## GregP (Aug 15, 2022)

33k in the air said:


> It's apparently not an uncommon view in some quarters. I've run into the sentiment in YouTube comments on videos on WWII aviation-related channels.
> 
> Greg's Airplanes and Automobiles lost me when he seemed to say that the B-17 could have regularly carried just about as many bombs to targets as the Lancaster by lugging bombs on its external wing racks, but didn't because reasons by the USAAF leadership.



The main reason was the effect on range. If you wanted to carry more bombs, you had to give up fuel, crew, or ammunition. If you give up fuel, that means basing your B-17s closer to German air power, not something anyone especially wanted yo do. Nobody wanted to fly with less than the full crew and full ammunition for defense, either, The result is a lower payload.


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## Shortround6 (Aug 15, 2022)

And basically the racks were only good for one bomb each. 
You could lift a pair of 4000lb bombs using the racks. 

But you could only lift a pair of 1000lbs using the racks. You could NOT use the racks for four 1000lb bombs.

And the external bombs added drag meaning you needed more fuel to go the same distance.

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## 33k in the air (Aug 15, 2022)

GregP said:


> The main reason was the effect on range. If you wanted to carry more bombs, you had to give up fuel, crew, or ammunition. If you give up fuel, that means basing your B-17s closer to German air power, not something anyone especially wanted yo do. Nobody wanted to fly with less than the full crew and full ammunition for defense, either, The result is a lower payload.



Yes, but Greg's Airplanes and Automobiles apparently missed this. I pointed out in the comments that external bombs on the B-17 came with drag and handling penalties, but this was ignored.


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## GregP (Aug 15, 2022)

33k in the air said:


> Yes, but Greg's Airplanes and Automobiles apparently missed this. I pointed out in the comments that external bombs on the B-17 came with drag and handling penalties, but this was ignored.



I understand. Pointing out things that aren't in agreement with a video is something seemingly usually ignored or, at the least, attacked as "you obviously don't understand." Seems to a characteristic of the internet, where faceless replies can be attacked with impunity.

My theory is that if someone comes into power (as in , "becomes the boss") and becomes a jerk or posts something on the internet and becomes a jerk to challenges and/ or disagreements, then they were ALWAYS a jerk, but simply didn't have the power or audience to be one effectively before.

Sometimes people point out exceptions and then go on to claim they were the usual experience. Disagreement is, again, usually attacked. Being a bit familiar with warbirds, having worked on and with them for some 18 years, I see a LOT of incorrect statements about them. 

I bet FlyboyJ (a maintainer) could disagree with a lot of posts, too. Sometimes, it just isn't worth the time and/or effort to do so.

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## FLYBOYJ (Aug 15, 2022)

GregP said:


> I understand. Pointing out things that aren't in agreement with a video is something seemingly usually ignored or, at the least, attacked as "you obviously don't understand." Seems to a characteristic of the internet, where faceless replies can be attacked with impunity.
> 
> My theory is that if someone comes into power (as in , "becomes the boss") and becomes a jerk or posts something on the internet and becomes a jerk to challenges and/ or disagreements, then they were ALWAYS a jerk, but simply didn't have the power or audience to be one effectively before.
> 
> ...


Agree Greg - 

Oh, I've mellowed a bit in my old age but will still throw the BS flag up on occasion, but sometimes I see things with regards to aircraft maintenance written by folks with no real background in the industry and, well....

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## Reluctant Poster (Aug 15, 2022)

Shortround6 said:


> For some reason the MK VIIIs didn't seem to get the rear tanks ? or only got one tank instead of two?
> MK VIIIs had 120-123 gallons of internal.
> MK XIVs went back to 85 gallons in fuselage tanks instead of the 96 in the MK VIII.
> 
> How many MK XIVs got rear fuselage tanks?


The Mk VIII was out of production before rear tanks started to be fitted. The Supermarine factories switched to the XIV. Castle Bromwich never produced the VIII
The top fuel tank was reduced in capacity to make room for the oil tank which no longer fit under the nose
All FR XIVs had the 33 gallon rear tank. They accounted for something like 1/2 the production.


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## Reluctant Poster (Aug 15, 2022)

NevadaK said:


> I understand that, but I'm a little confused as to why? In 1943, the P-47 and P-38 were already in use. The big missing piece is the Mustang which has the range necessary to provide coverage at the full range of the bomber force. The failures of the USAAC bombing campaign in 1943 are due to more than just the lack of escort fighters beyond the 400 mile range arc. The small size of the force itself contributed to the high loss rates. If you take a look at the graphic I added to my earlier post and the ones below, escort fighter coverage occurred in a series of zones. The Spitfire and P-47 were well used in the 200 and 400 mile arcs (ok, slightly shorter). Beyond that required a plane with really long range and that was the P-38 and Mustang. It seems to me that trying to give a Spitfire that kind of range is, in essence, trying to make it a Mustang.
> View attachment 680993
> View attachment 680994


There is a bit of an error in that graphic. The P-38 was able to reach that far until the leading edge tanks were added in January 1944.

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## wuzak (Aug 15, 2022)

Reluctant Poster said:


> All FR XIs had the 33 gallon rear tank. They accounted for something like 1/2 the production.



FR XI?
Did you mean FR XIV?


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## Reluctant Poster (Aug 15, 2022)

wuzak said:


> FR XI?
> Did you mean FR XIV?


Yes


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## Zipper730 (Aug 16, 2022)

33k in the air said:


> Greg's Airplanes and Automobiles lost me when he seemed to say that the B-17 could have regularly carried just about as many bombs to targets as the Lancaster by lugging bombs on its external wing racks, but didn't because reasons by the USAAF leadership.


I'm not sure how much surplus range the B-17's carried, but the only hope they could have had would have been fitting the plane with Tokyo-tanks, plumbing the wing for a drop-tank on those external pylons; then stuffing as many bombs in the bay as they could and hope the main landing gear legs didn't give out during the takeoff run.








FLYBOYJ said:


> Oh, I've mellowed a bit in my old age but will still throw the BS flag up on occasion


Having a good bullshit detection device is highly important.

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## FLYBOYJ (Aug 16, 2022)

Zipper730 said:


> Having a good bullshit detection device is highly important.

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## nuuumannn (Sep 1, 2022)

NevadaK said:


> Now, why am i getting called out for dog piling here? Especially since I also linked an article from the highly esteemed Royal Aeronautical Society covering what had been tried and so forth. Jeez.



It wasn't aimed specifically at you, NevadaK. Just to add information to the thread and repeat it because it hadn't sunk in...


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## WARSPITER (Sep 1, 2022)

FLYBOYJ said:


> View attachment 682428


It's also helpful to ensure one's moron magnet is turned off at appropriate times.

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## NevadaK (Sep 2, 2022)

nuuumannn said:


> It wasn't aimed specifically at you, NevadaK. Just to add information to the thread and repeat it because it hadn't sunk in...


No worries, Nuuumannn! My tongue was firmly in my cheek when I wrote that.

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## Geoffrey Sinclair (Sep 10, 2022)

For when this starts up again, from "Case History of Fighter Plane Range Extension Program, Parts I and II," USAF Historical Research Document 202.2-11, 22 February 1945, Enclosure 1.

a Fuel Consumed in Gallons for 5 minutes War Emergency Power & 15 minutes Military Power.
b Fuel Consumed in Gallons during Warm-up, Take-off, and Climb.
c Horizontal Distance to Climb to 25,000 feet.

P-38H Internal Tanks Only. 15,900 pounds take off weight, 300 gallons total fuel, 111 (a), 86 (b), 40 miles (c), range 326 miles
P-38H plus 2x150-Gal External Tanks, 18,000 pounds take off weight, 600 gallons total fuel, 111 (a), 98 (b), 50 miles (c), range 1,005 miles

P-47D Internal Tanks Only. 13,500 pounds take off weight, 305 gallons total fuel, 89 (a), 101 (b), 57 miles (c), range 473 miles
P-47D plus 2x150-Gal External Tanks, 15,600 pounds take off weight, 605 gallons total fuel, 89 (a), 125 (b), 81 miles (c), range 1,045 miles

P-51B Internal Tanks Only. 9,050 pounds take off weight, 180 gallons total fuel, 58 (a), 46 (b), 50 miles (c), range 415 miles
P-51B plus 2x150-Gal External Tanks, 11,150 pounds take off weight, 480 gallons total fuel, 58 (a), 59 (b), 80 miles (c), range 1,570 miles

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## drgondog (Sep 10, 2022)

Geoffrey Sinclair said:


> For when this starts up again, from "Case History of Fighter Plane Range Extension Program, Parts I and II," USAF Historical Research Document 202.2-11, 22 February 1945, Enclosure 1.
> 
> a Fuel Consumed in Gallons for 5 minutes War Emergency Power & 15 minutes Military Power.
> b Fuel Consumed in Gallons during Warm-up, Take-off, and Climb.
> ...


The P-51B never used 150 gal tanks, only 75 and 110 in ETO/MTO. Only later in Pacific for VLR missions was the larger tank used on P-51D and only enabled ~25 to 50 miles more combat radius.

Comments regarding the sources: 
The 'range figures' are all over the place with respect to 'Range-ferry', Range - Combat Radius (planning calculations dependent on multitude of take off, assemble, climb, cruise, fight, cruise home loiter. The nature of the escort also crucial to planning - ranging from Sweep greater than 'normal' escort in which the fighter maintained contact with escorted bombers from distant RV from Target, and finally Target Escort in which the escorts flew to R/V reasonable close to the target - in which close escort was 30 to 45 minutes.

The Fuel consumed is accurate for MP and WEP for 130 octane fuel.

For 25,000 feet, Optimal cruise settings for maximum range did not quite achieve the same values as lower altitudes. The reduced drag at 25,000 vs 10,000 feet cruise was offset by the extra fuel consumed to climb the extra 15,000 feet

The P-38H values you referenced are not useful from Q4/43 to Jan/44. The Operating value for H Ferry Range w/300 gal was ~ 850mi. The Combat Radius for the J-5 and early J-10 are similar but the LE 55 gal tanks were installed as kits in the J-10 and early J-15 to significantly extend combat radius. With 2x150gal externals the CR for planning purposes for P-38H/early J was ~ 440mi not 1005 mi. The Ferry Range was ~ 850 mi with 300gal internal only,

The P47D at block level below P-47D-25 (operational in late Q2/44 in small quantities - fuly operational in Q3) was far lower than stated. With internal fuel, no external tanks, the CR was approximately 125mi and Ferry range 830mi. 

Had the P-47C-2 through P-47-23 had only 305gal internally but able to have CR of 473mi, the 8th AF could have escorted all the disastrous 1943 and spring 1944 missions to the target, save Berlin and Munich. Would not have required P-38J with 55gal LE tank or P51B with internal 85 gal tank to rush to ETO in Fall 1943.

Only the P-47N with 556gal internal and 440 gal exteral and the P-51D with 269gal internal and 330gal externally had CR of 1000mi and Ferry rangse of 2300+mi. That said the P-38L could achieve the same Ferry range operating at low speed/low altitude

The P-51B with 180gal wing fuel, no 85 gal fuse tank, and no external tanks had a Ferry Range of about 1,200 miles but a Combat Radius of only150mi. Have zero idea where the author of the study was researching but it wasn't in ETO or NAA Pilot's handbook or Wright Field testing.

This extraction is completely bogus "_P-51B plus 2x150-Gal External Tanks, 11,150 pounds take off weight, 480 gallons total fuel, 58 (a), 59 (b), 80 miles (c), range 1,570 miles._

A P-51B with only internal 180gal plus the aforementioned bogus 2x150 gal externals is cited for 480gal of fuel. That GW would be 9,050 + (300)x6 = 9,050 +1800 = 10, 850 pounds Take off - not 11,150. This config was never used in combat without 85 gal fuselage tank. Doubt that it was tested when the 150gal combat tank was released just before the P-51B w/85 gal internal fuse tank was in production.

A P-51B w/85 gal fuse tank plus 2x110gal externals is 9,132 (NAA) base fuly loaded internally for 180gal wing tank plus ammo plus oil plus pilot @200, Add 85gal (fuse tank) plus 220gal (2x110gal) = 9,132 + 85x6 + 220x6 = 10,962 (per NAA) GW at Take off. The delta for filling wing tanks from 180 to 184gal is 24 more pounds, which is more common load out for P-51B.

*The P-51B with 2x75 gal externals and 184gal + 0 gal Internal ~ had a CR of 470mi, and Ferry range of 1575mi.
The P-51B with 2x75 gal externals and 184gal + 85gal Internal ~ had a CR of 705mi, and Ferry range of 1,800mi.*

It was meaningless for this study not to use Manufacturer Handbooks for foundation references.


Last but not least, any attempt to cite range without specifying cruise settings and altitudes is simply demonstrating ignorance of aircraft performance boundary conditions for conversation context.

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## 33k in the air (Sep 10, 2022)

drgondog said:


> A P-51B with only internal 180gal plus the aforementioned bogus 2x150 gal externals is cited for 480gal of fuel. That GW would be 9,050 + (300)x6 = 9,050 +1800 = 10, 850 pounds Take off - not 11,150. This config was never used in combat without 85 gal fuselage tank.



The weight of two 150-gallon drop tanks would add at least another 158 to 240 lbs, depending on the empty weight of the drop tank (the figures vary). So that would bring the total weight up to 11,008 to 11,090 lbs.

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## Geoffrey Sinclair (Sep 13, 2022)

drgondog said:


> The Fuel consumed is accurate for MP and WEP for 130 octane fuel.


People have been after the breakdown of the consumption figures for quite a while, why wait to issue a confirmation after someone else provides them?


drgondog said:


> Had the P-47C-2 through P-47-23 had only 305gal internally but able to have CR of 473mi,


The figure supplied were 473 miles range, not radius.


drgondog said:


> A P-51B with only internal 180gal plus the aforementioned bogus 2x150 gal externals is cited for 480gal of fuel. That GW would be 9,050 + (300)x6 = 9,050 +1800 = 10, 850 pounds Take off - not 11,150. This config was never used in combat without 85 gal fuselage tank. Doubt that it was tested when the 150gal combat tank was released just before the P-51B w/85 gal internal fuse tank was in production.


Actually it seems there was a 1943 trial of 150 gallon external tanks on a P-51B, a 28 October 1943 memo to General Myer reports on planned trials P-38J, P-47D and P-51B each with a pair of 150 gallon external tanks, the P-38J and P-51B due at Elgin field on 1 November, the P-47D awaiting good weather and will go to Elgin via Wright.

Now this has started up again, it meant going and finding the study, not just a document that quoted one of the tables, results below. Back to the study, from "Case History of Fighter Plane Range Extension Program, Parts I and II," USAF Historical Research Document 202.2-11, 22 February 1945, Inclosure 1.

Timeline

20 February 1942, memo requesting ferry range extension for P-38, P-39, P-40, P-47, P-51 and P-61

25 February 1942, conference in General Arnold's office about range extension of pursuit, dive bomber and light bombers. 

13 March 1942, P-47B 220 gallon belly tank, 100 gallon tank under each wing, gross weight 17,516 pounds including guns and ammunition, take off over 50 foot obstacle estimated as 4,500 feet. P-38 2x175 gallon (inboard) and 2x75 gallon (outboard), gross weight 20,000 pounds including guns and ammunition, take off over 50 foot obstacle estimated as 3,500 feet.

21 March 1942 conference at Wright Field, initial efforts to increase pursuit types range. Priority to ferry operations, range without removal of equipment, non droppable non leak proof tanks, plus combat range extension with non droppable leak proof tanks for missions lasting 6 hours plus a 30 minute reserve allowance.

27 March 1942, state of play, 75 gallon tanks for F-4 being delivered, 150 gallon tanks wind tunnel tested, this size appears to be the limit drag wise, study on P-38 to increase range to 3,000 miles. P-47, Republic to install two 75 gallon droppable tanks installations and design and test belly tanks to increase range to 3,000 miles, to also proceed with 200 gallon leak prof belly tanks and study development of 600 gallon tank for ferrying.

31 October 1942, P-38 with 2x300 gallon tanks flown for 3,000 mph at 10,000 feet, average speed 213 mph. Medical examination of pilot shows normal fatigue after 13.5 hour flight, therefore project considered practicable. P-47 wind tunnel tests ruled out the 600 gallon tank, study made of Lockheed 300 gallon wing tanks. P-39 unsuccessful flight with 350 gallon belly tank, 2,400 miles range, poor directional stability, to make it acceptable an extra 20 gallons external added, removal of nose guns and other items to allow a 57 gallon nose tank, range to 2,800 miles. P-40 trial with 3x170 gallon external tanks had directional instability and too much drag, 2x170 gave 2,255 miles. 4,000x170 gallon tanks on order.

3 July 1943, flight tests, fuel consumption P-51B, 64 gallons per hour over 4 hours and 45 minutes, 184 gallons of internal and 150 gallons external, P-47D 140 gallons per hour over 3 hours, 305 gallons of internal and 165 gallons external, P-38J 144 gallons per hour, over 4 hours, 300 gallons internal, 300 external.

12 August 1943, P-51D to have wing moved further forward, allowing removal of 50 pounds of tail ballast but this will make carrying rear fuselage fuel more difficult.

21 August 1943, tests showed 85 gallon rear fuselage tank the largest that could be fitted to P-51 Test of 269 gallons internal plus 80 gallons in a pair of 75 gallon wing tanks, tanks dropped at 25,000 feet 200 miles from base, another 1,000 miles flown, 4 hours of flight, 35 gallons remained. The rear fuselage tank meant the SCR-274 and IFF could not be carried, the latter change unacceptable. Leading to ideas like the IFF set in the engine compartment.

25 August 1943, drawings for P-51 fuselage tank about ready, 3 hand built tanks expected to be ready mid September, no IFF or provision for IFF.

3 September 1943, General Arnold reports USAAF in Britain states long range fighters must be provided to accompany daylight bomber operations. Given this will increase fighter losses fighter production needs to be increased. The need to stay near the bombers if they are cruising at 160 mph IAS while the fighter is at 220 mph IAS means the P-51B with 180 gallons internal and 75 external has a combat radius as an escort of 250 to 350 miles, but as an offensive fighter 350 to 500 miles, the P-38J with 290 gallons internal and 300 external figures are 200 to 300 miles and 300 to 450 miles respectively. Adding 85 gallons of internal fuel makes the P-51 figures 550 to 700 miles and 700 to 850 miles, adding 120 gallons internal makes the P-38 figures 375 to 475 miles and 550 to 700 miles. Long range pursuit project now has AAA priority.

8 September 1943, P-51D configuration, 6 wing guns, 55 gallons rear fuselage tank. Long range B and C priority ahead of D or at least the 6 gun wings.

17 September 1943, adding an extra 65 gallons of internal fuel to the P-47 requires raising the cockpit floor and changing of all bulkheads and fittings in the front part of the fuselage, 2 months required for a prototype.

20 September, proposal for external 300 gallon self sealing all purpose ferry tank, able to take fuel, personnel or cargo, 2 prototype examples costing $110,000 and 23 prototypes of another design costing $17,825

1 October 1943, order for a pair of each prototype drop tanks of British type paper, 108 and 150 gallon priced at $350 each.

15 October 1943 P-47 were equipped with the B-10 shackle, pressure relief valve and plumbing to carry the 75, 100 and 150 gallon tanks, in addition wing attachments for 150 gallon tanks were provided. As the P-39 and P-40 had the B-7 shackle they could also use the tanks.

19 October 1943, Farmingdale P-47 production fitted with wing attachments for 150 gallon tanks.

23 October 1943, General Arnold personal letter to drop tank making companies, impressing how important their work is.

11 November 1943, P-51 long range modifications top priority except the P-39 delivery schedule to Russia must be maintained.

16 November modification centre installation of P-51 85 gallon rear fuselage tank, first installation to take 1,000 hours, then 600 per additional airframe.

17 November, defects in cowling production are hampering P-47 production. Sub contractor reports army took skilled welders plus engineering difficulties. Evansville not installing wing tank fittings as they do not have engineering data. Farmingdale reports wing tank fitting needed to be done by hand and were working loose during engine testing. Wing subcontractor expected to deliver wings with fittings already installed.

24 November 1943, P-51 modification above all other work except for the C-46 and aircraft for Russia. 

29 November 1943, 220 P-51 and 156 P-38 have been in modification centres for over a month.

November 1943, conference about air to air refuelling of pursuit types by the bombers they were escorting.

4 December 1943, order for nesting type 150 gallon drop tanks for the P-38 at $812 each, designed to be built and shipped in halves to enable much more efficient shipping of the tanks. The USAAF requirements to transport large numbers of empty containers took lots of ship volume.

P-51, the 85 gallon rear fuselage tank reported to have added about 650 pounds when full, with the fuel weighing around 500 pounds. 

Combat Radius, for fighters accompanying B-17 cruising at 185 mph IAS, fighter at 210 mph IAS (300 mph true), warm up 5 minutes rated power, maximum continuous power climb to 25,000 feet, drop tanks when empty or on radius, 15 minutes combat power, 5 minutes war emergency power, 30 minutes reserve at minimum cruise speed. Following read from a graph.

P-51B/C, 180 gallons internal, radius 175 miles, with 2x75 gallon external tanks radius 500 miles. 265 gallons internal, radius 400 miles, with 2x75 gallon external tanks radius 750 miles.

P-47D, 305 gallons internal radius 150 miles, 305 gallons internal +75 external 250 miles, 305 gallons internal +108 external 300 miles, 370 gallons internal radius 250 miles.

P-38J, 300 gallons internal 125 miles, 420 gallons internal 275 miles, 300 internal +300 external 350 miles, 410 internal +300 external 650 miles.

The tactical tests of the P-51B-1 with 180 gallons of internal fuel have 13 minutes to climb to 25,000 feet, then 53 minutes to reach 220 miles out at 225 IAS (around 320 TAS), 20 minutes of combat, 32 minutes to return the 220 miles, landing with 20 gallons remaining. Going out was uphill? Add a pair of 75 gallon external tanks means 19 minutes to climb to 25,000 feet, then 2 hours to reach 600 miles out at 210 IAS (around 295 TAS), 20 minutes of combat, 1 hour and 34 minutes to return the 600 miles at 225 IAS (around 320 TAS), landing with 20 gallons remaining. The external 150 gallon ferry tank can be carried. P-51B-5 has the fuselage fuel tank, requiring the choice between a radio and IFF set.

The published combat radius figures are not consistent, the table being discussed at least gave the US figures for combat, take off and climb and distance covered in the climb, which was the point of posting them, plus since the altitude was given as well as the fuel allowances for combat and climb the range the cruise speed could be estimated from the range. At the moment the Spitfire long range profile has to use vertical climb and descent, the above gave some ideas on a more realistic profile. Data like below provides clues.

Speed 210 IAS at 25,000 feet.
1. Internal fuel only
2. Internal plus 2x150 gallon external.
a. Take off weight
b. Total fuel
c. Fuel Consumed in Gallons for 5 minutes War Emergency Power & 15 minutes Military Power.
d. Fuel Consumed in Gallons during Warm-up, Take-off, and Climb.
e. Horizontal Distance to Climb to 25,000 feet.
f. range

Note lack of fuel reserves. Table probably dated 20 November 1942, calculations, not flight tests.

1. P-39N, 7,500 pounds, 87 gallons, 52 gallons, 40 gallons, no fuel left.
2. P-39N, 9,600 pounds, 387 gallons, 52 gallons, 50 gallons, 58 miles, 848 miles.

Above for unmodified, below for modified P-39N.

1. P-39N, 7,700 pounds, 120 gallons, 52 gallons, 40 gallons, 38 miles, 156 miles.
2. P-39N, 9,800 pounds, 420 gallons, 52 gallons, 51 gallons, 61 miles, 1,078 miles.

1. P-40F, 8,850 pounds, 156 gallons, 45 gallons, 61 gallons, 65 miles, 283 miles.
2. P-40F, 10,950 pounds, 456 gallons, 45 gallons, 72 gallons, power required for 210 MPH exceeds power available.

1. P-38K, 16,900 pounds, 300 gallons, 111 gallons, 90 gallons, 43 miles, 296 miles.
2. P-38K, 18,600 pounds, 600 gallons, 111 gallons, 101 gallons, 54 miles, 958 miles.

1. P-38J, 16,300 pounds, 300 gallons, 111 gallons, 90 gallons, 42 miles, 298 miles.
2. P-38J, 18,400 pounds, 600 gallons, 111 gallons, 100 gallons, 52 miles, 967 miles.

1. P-38H, 15,900 pounds, 300 gallons, 111 gallons, 86 gallons, 40 miles, 326 miles.
2. P-38H, 18,000 pounds, 600 gallons, 111 gallons, 98 gallons, 50 miles, 1,005 miles.

1. P-47D, 13,500 pounds, 305 gallons, 89 gallons, 101 gallons, 57 miles, 473 miles.
2. P-47D, 15,600 pounds, 605 gallons, 89 gallons, 125 gallons, 81 miles, 1,045 miles.

1. P-51B, 9,050 pounds, 180 gallons, 58 gallons, 46 gallons, 50 miles, 415 miles.
2. P-51B, 11,150 pounds, 480 gallons, 58 gallons, 59 gallons, 80 miles, 1,570 miles.

1. P-63A-1, 7,770 pounds, 136 gallons, 53 gallons, 42 gallons, 35 miles, 235 miles.
2. P-63A-1, 7,770 pounds, 436 gallons, 53 gallons, 58 gallons, 64 miles, 1,216 miles.

1. Spitfire IX, 7,480 pounds, 102 gallons, 58 gallons, 29 gallons, 28 miles, 97 miles.
2. Spitfire IX, 9,580 pounds, 402 gallons, 58 gallons, 38 gallons, 43 miles, 1,263 miles.

Using this data the Spitfire VIII would have a range of around 310 miles on 149 gallons of internal fuel, 62 gallons at 4.6 mpg plus 28 miles less the penalty for around 300 pounds of extra fuel and tankage. The RAF figures in imperial/US gallons are 23/27.6 gallons take off and climb to 20,000 feet, 36/43.2 gallons for combat, range 304 miles no reserves.

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