Escort Fighter Performance Comparison

[Zipper730]

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

 

[PAT303]

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.

 

[pbehn]

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.

 

[Shortround6]

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.

 

[pbehn]

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.

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.

 

[Zipper730]

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.

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

1. Climb rate appears to be among the best
2. 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
3. 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).
4. 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

1. 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.
2. 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

1. 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.
2. 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.

 

[pbehn]

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.


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

1. Climb rate appears to be among the best
2. 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
3. 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).
4. 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

1. 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.
2. 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'.

There are some unknown areas

1. 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.
2. 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.

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.

 

[tomo pauk]

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.

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.

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

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.

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.

 

[pbehn]

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.

 

[Shortround6]

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

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.

 

[tomo pauk]

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.

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.

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.

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.

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.

 

[Shortround6]

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.

 

[pbehn]

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.

 

[tomo pauk]

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

Okay.

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.

 

[pbehn]

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.

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.

 

[Shortround6]

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.

 

[Shortround6]

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.

 

[pbehn]

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.

 

[SaparotRob]

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.

 

[pbehn]

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