1942 and on: RAF fields 'proper' P-38s - consequences?

Standard fit on the Mk.IX was the 45 gallon 'slipper' tank, and later, the larger 'cigar-shaped' tank, the capacity of which I can't remember at the moment, without checking my references.
Both were used on 'sweeps', and jettisoned once over the Continental coast.

The production changes to the Spit IX which included the rear fuselage tank were as follows:-
a) The original 85 Gallon tank was replaced by a 96 Gallon tank
b) A rear fuselage tank was fitted, this was a 72 gallon tank on Spits with the 'traditional' cockpit and a 62 gallon tank on new production aircraft with a cut down rear fuselage
c) Clipped wing was introduced in early 1945 as Spitfires with a full bomb load and the increased fuel tanks sometimes suffered skin wrinkling when pulling out of dive bombing attacks. Clipping the wing effectively added 10% to the strength of the wing and clipping wing at that time, had nothing to do with trying to increase the roll rate.
d) Metal elevators and a slight repositioning of the Gyro gun sight were also needed to allow for the extra fuel.
e) The extra range required an extra oxygen bottle

The Official Still Air range of a Spit IX cut back cockpit carrying a 90 gallon DT was 1,420 miles. The paper recognises that this isn't an operational range stating that for base planning purposes 75% of the still air range is used which in this case gives an operational range of just over 1,000 miles. The paper also states that each mission will have it's own factors which is of course correct and a point often forgotten in these debates.

The paper is attached and I think you can just read it.

Re the use of 90 gallon Drop Tanks on operations. The problem wasn't the use of the tanks, the problem in Italy was that they were running out of tanks to use.

Glider said:

. The paper also states that each mission will have it's own factors which is of course correct and a point often forgotten in these debates.

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100%

Consider weather factors and performance degradation due to operational factors (repairs). Many here will utilize flight test and flight manual data as gospel but in the real world those numbers sometimes don't pan out.

Glider said:

The production changes to the Spit IX which included the rear fuselage tank were as follows:-
a) The original 85 Gallon tank was replaced by a 96 Gallon tank
b) A rear fuselage tank was fitted, this was a 72 gallon tank on Spits with the 'traditional' cockpit and a 62 gallon tank on new production aircraft with a cut down rear fuselage
c) Clipped wing was introduced in early 1945 as Spitfires with a full bomb load and the increased fuel tanks sometimes suffered skin wrinkling when pulling out of dive bombing attacks. Clipping the wing effectively added 10% to the strength of the wing and clipping wing at that time, had nothing to do with trying to increase the roll rate.
d) Metal elevators and a slight repositioning of the Gyro gun sight were also needed to allow for the extra fuel.
e) The extra range required an extra oxygen bottle

The Official Still Air range of a Spit IX cut back cockpit carrying a 90 gallon DT was 1,420 miles. The paper recognises that this isn't an operational range stating that for base planning purposes 75% of the still air range is used which in this case gives an operational range of just over 1,000 miles. The paper also states that each mission will have it's own factors which is of course correct and a point often forgotten in these debates.

The paper is attached and I think you can just read it.
View attachment 549173

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On a Seafire III, combat radius was 100 miles on internal fuel of 85 gals and 185 with a 60 gal drop tank.

The problem with Spitfires flying around with 72 gallons (86.5 US gallons) or 62 gallons (74.5 US gallons) in the rear fuselage is that they couldn't fight very well with that load.
Much like P-51s had stability problems with a full 85 gallon tank and it was prefered (if possible) to burn some of the fuel out of the P-51s rear tank before combat was joined.

Some planes may have had only one tank fitted?



From Spitfire performance.

Post war the US (different standards of air safety or airworthiness) continued to use the rear tanks although with some restrictions. The British stopped just about completely using the rear tanks in the Spitfires.

It is one thing to fly a plane 1500 miles, it is another thing to perform violent maneuvers in an aircraft that is carrying about double the amount of fuel it was designed for and that extra fuel in a poor place in regards to the center of gravity.

Perhaps somebody with the manuals for the Spitfire fitted with these tanks can tell us what the manual says, In peace time the Seafire 46 with a 32 gallon tank in the rear fuselage (and under wing tanks in addition to the belly drop tank) was always supposed to the rear tank first regardless of whatever combination of external tanks was carried. Warm up and take off done on the lower main (with the upper draining into it) until a safe height was reached (2,000ft is in the manual but is crossed out). while the extra 32 gallons does extend the range ti doesn't do much for the internal fuel if the belly drop tank has to be dropped early

Please note the Seafire 45 with a Griffon 61 engine and a 5 bladed Rotol propeller did not get the rear fuselage tank but the Seafire 46 with a Griffon 87 using a 6 blade counter rotating propeller did. The reduction gear and propshaft for the Griffon 87 added about 100lbs to the weight of the Griffon engine weight of the counter-rotating propeller was ????
The MK 46 did get a larger tail.

Edit, the pilots notes for the MK IX, XI and XVI from Sept 1946 says that acrobatics are prohibited when carrying any external stores except the 30 gallon blister tank and when carrying more than 30 gallons in the rear fuselage tanks, and are not recommended when the rear fuselage tanks are carrying any fuel (italics are in the manual)

Later it says that acrobatics or combat maneuvers are prohibited when the rear tanks have more than 30 gallons if fuel.

It also says the except in an emergency landings should not be attempted with more than 30 gallons in the rear tanks. If a landing with more than 30 gallons is to be made and a drop tank is being carried the drop tank should be jettisoned.

Sorry, but it looks like that while the Spitfire could have been improved the possibility of converting it to a really long ranged fighter was going to take a lot more work than some people want to believe.

As you correctly state post was standards are different from wartime standards and this was common practice in a number of airforces. To include the rear tanks in the standard build and to order hundreds of tanks for retrofitting into current operational Spitfires shows (to me anyway) that this extra risk had been accepted.

I do not doubt that pilots were instructed to use these tanks in a certain order, that's common practice no doubt today where drop tanks are normally identified as being the first to be emptied. Besides if you are going to fly approx. 1,000 miles there is plenty of time to use whatever tank first that you desire.

Glider said:

I do not doubt that pilots were instructed to use these tanks in a certain order, that's common practice no doubt today where drop tanks are normally identified as being the first to be emptied. Besides if you are going to fly approx. 1,000 miles there is plenty of time to use whatever tank first that you desire.

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If all you want to do is fly 1000 miles you are right, but if you want to fly 400-450 miles fight and return home things get a bit more difficult.

assuming you are getting near the 400 mile mark of the 500 mile radius (1000 mile mission and numbers are for illustrating the point, not real numbers) and enemy aircraft show up to attack your fighters or the bombers you are escorting. Most fighters have to jettison all external tanks in order to engage in combat (a few Spitfires using 30 gal tanks and Japanese fighters excepted) leaving them with only internal fuel to fight for 10-20 minutes with and then the flight home. Combat can burn fuel 2-3 times faster than even a fast cruise (Spit V using 15lbs boost could burn fuel 5 times faster than most economical). Using up 25% of your internal fuel to get the CG (and gross weight) of the aircraft in the right place for effective combat may leave you short of fuel after the external tank/s are punched off even if you had a surplus of fuel to make the flight if combat had not been joined.

That is the whole trouble with most of these schemes to turn the Spitfire into a long range fighter, there is no doubt whatsoever that you could stuff enough fuel somewhere into a Spitfire to make very long flights. The Problem is getting enough fuel into the plane while still maintaining combat maneuverability and not depending on external tanks for the return leg.

Please note that several American fighters sometimes suggested for 8th air force escorts have a similar problem. They don't have enough internal fuel to fight over central/eastern germany and make it home regardless of how much fuel they can hold in drop tanks or how far they can fly with the drop tanks attached.

BTW you are quite correct in pilots using the fuel tanks in a certain order. P-40E and P-40F pilots were instructed to use their internal tanks in a different order in order to maximize the flying characteristics of the P-40 with the heavier Merlin in the nose. P-40E pilots were to drain the rear tank right after the drop tank while P-40F pilots were instructed to use a bit more than 1/2 and then drain every other tank on plane before going back to the rear tank, this level of fuel in the rear tank was the "reserve" on the P-40F to be used when lost and trying to find an airfield or in case of adverse winds or other unplanned circumstance. On the P-40E (and later Allison powered planes) this reserve fuel was held in the most forward tank on the airplane.

Before I go into my reply I am not and never had advocated the Spit in whatever configuration as a substitute for the P51. As far as I am concerned it was the supreme escort fighter of the war barr none.

However the Spit in its final modification clearly had a useful range and one that would have been extremely valuable if the UK had developed it 12 months earlier. Looking at the paper the Spit with the larger front tank has a still air range of about 500 mile equalling approx. an operational range of 375 miles. With internal fuel tanks the numbers are 900 and 675 which is more than sufficient to get you home with room to spare from any likely mission.

The point about the COG is a good one but one that I believe the RAF had considered a risk worth taking during war time, or it wouldn't have been a standard fit. The wings were clipped because of the wing wrinkling with full fuel in both tanks or a full bomb load.

This extra caution when comparing war to peacetime operations is common. IIRC the post war pilots notes for a P51D give a VNE speed approx. 50mph less than the pilots notes from wartime.

In May 1944 Tempests with 90 gallon DT's were used to escort Halifax's on a daylight raid to the Ruhr. Imagine the increased flexibility this would have given the planners let alone the difference it would have made in the air war against the Japanese if the hundreds of Spitfires had an increased range.

Interestingly the Spit modified in the USA had a bigger problem as it basically relied on two 60 gallon drop tanks to get the range.

On factor that chart misses is the number of bombers sent to target.

In mid-to-late 1943 the 8thAF could send 250-300 aircraft on a raid. By early 1944 they could send 1,000+.

Raids in mid-to-late 1943 saw losses of up to 60 aircraft, raids in early 1944 saw losses of up to about 60 aircraft. The loss rate in 1944 was much less than 1943 because the attacking force was 3 times the size, or more.

Sorry, but it looks like that while the Spitfire could have been improved the possibility of converting it to a really long ranged fighter was going to take a lot more work than some people want to believe.

http://www.spitfireperformance.com/Spitfire_IX_ML-186_Handling.pdf
http://www.wwiiaircraftperformance.org/mustang/P-51B_Fuselage_Tank_4-43-23-1.pdf

Seems to me that the handling problem with the Spit is no worse than the Stang with rear tanks.

wuzak said:

On factor that chart misses is the number of bombers sent to target.

In mid-to-late 1943 the 8thAF could send 250-300 aircraft on a raid. By early 1944 they could send 1,000+.

Raids in mid-to-late 1943 saw losses of up to 60 aircraft, raids in early 1944 saw losses of up to about 60 aircraft. The loss rate in 1944 was much less than 1943 because the attacking force was 3 times the size, or more.

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Your statement is correct, but..

The point of the graph was to show that the introduction of the P-38 as a long range escort had two main effects.
1. The loss rate dropped to acceptable levels
2. The Luftwaffe had lost the airwar over Europe by March of 44. Months before the P-51 was introduced in numbers equal to the P-38.

The fact that the loss rate further decreased is testament to how badly hurt the Germans were by the introduction of the Lightning as an escort.

The P-38 flew against the best the Luftwaffe had to offer, they were not allowed to stray from close escort, they were outnumbered and mechanical problems were rampant due to various factors. Yet, because the Lightning was such a great plane, the pilots who flew them, were able to overcome those challenges and won.

I would argue that the Lightning was the most strategically significant fighter of WWII, making a vital contribution to winning the battle for the skies of Europe, the Med and the Pacific. It would have done the same for the RAF.

Hairog said:

Your statement is correct, but..

The point of the graph was to show that the introduction of the P-38 as a long range escort had two main effects.
1. The loss rate dropped to acceptable levels
2. The Luftwaffe had lost the airwar over Europe by March of 44. Months before the P-51 was introduced in numbers equal to the P-38.

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The point of the introduction of the P-38 also coincides with a slowing of operations by the 8th AF, mainly due to the weather. Depends on whether monthly loss rates is bombers lost per sortie whether that shows up in the stats. Shorter range missions would also benefit from P-47 involvement.

You will also notice that the loss rates increased to higher rates in the few months after the P-38 introduction.

Hairog said:

I would argue that the Lightning was the most strategically significant fighter of WWII, making a vital contribution to winning the battle for the skies of Europe, the Med and the Pacific. It would have done the same for the RAF.

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I'm not sure the P-38 could have done a lot for the RAF in 1942/43. It wasn't as long ranged as its late 1943/1944 versions and had other issues. And I doubt it would have been available in sufficient numbers to provide protection for daylight bombing, given that the USAAF needed them as well

The Lightning was a plane plagued with problems.
Forced into a combat environment ill equipped.
Not going to get past the huge logistics problems.
Their presence did help but it was costly and time consuming to get them in the air.
Plus pilots suffering badly with no poor functioning heaters.
The crafty understated mechanics found a way to keep them in the air to earn a credible combat record.

The Mustang was a far more reliable aircraft, far less costly to deploy.
Took less training time to certify a make a competent combat pilot.
Most all became successful and survived the war.

Once the problems were sorted out the Lightning took its fair share of targets.
But then again required a lot more training, logistics and maintenance to keep them flying.
In war time you don't have time for sorting out chronic long term problems.
But you do it anyway !

After WW2 the Lightning got parked and cut up.
More countries took the fat boy Thunderbolt before the Lightning.
Heck the P63 was more desirable after WW2.

Where are people getting the idea that the Lightning couldn't climb, turn or roll?

Dan Fahey said:

The Lightning was a plane plagued with problems.
Forced into a combat environment ill equipped.

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Well if you will recall the Mustang needed a whole new engine that was not an American design and then there was the problem of their tails coming off. So the P-51 had a lot more problems than most recall. The prototype flew in Oct. 1940, in 1942 it was rejected by the RAF and didn't equal the Lightning in escort duty until May of 1944. That's a long time to work out the bugs and get it to the frontline. Meanwhile the Luftwaffe was being decisively defeated and their best pilots being shot down by the undertrained pilots flying the P-38 and P-47.

Not going to get past the huge logistics problems.

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I suggest that the logistics problems in the Med and Pacific were multiple times what they were in Britain. Imagine trying to fly out of a jungle island thousands of miles away from the closest flush toilet or how about from a sand dune in Africa. They managed in both of those theatres, so I believe they would have in Europe as well.

Their presence did help but it was costly and time consuming to get them in the air.

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It more than helped. Their introduction saved the American daylight bombing effort. They were available and should have been used much earlier and would have saved many a bomber crew. It was a huge failure by the "Bomber will always get through" mentality of the US Army Air Corps.

Another failure was keeping them tied to the bombers in close escort. If they would have been let loose like the P-47 and P-51 from close escort earlier you would have seen some real carnage at Luftwaffe airfields.

As for stats, in Europe an enemy plane destroyed on the ground counted as a kill. In the Pacific it didn't. Many a German plane was caught on the ground after 1944.

The Mustang was a far more reliable aircraft, far less costly to deploy.
Took less training time to certify a make a competent combat pilot.

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People seem to forget about the cost of training a pilot. How many more pilots were lost due to their one engine being damaged? How many P-38 pilots were saved by having that second engine? Not to mention the planes themselves. How many twin engine P-38s flew again after having their engine repaired. thus saving the cost of building another plane transporting it to the front and having to train another pilot?

How many excellent pilots were lost? Bong came home on one engine I believe 3 times during his career.

Then you have to take into account the cost of building or retrofitting factories to build the Mustang compared to increasing the build rate of the Lightning. Add in the cost of R&R, retraining flight instructors and mechanics, retooling machine tools, switching to manufacturing a new tire design , retrofitting the tail so it didn't fall off, switching engines, etc. I don't think the P-51 was such a bargain when you include all the overhead that went into getting it into combat. The phrase "Penny wise, pound foolish" comes to mind.

Hairog said:

Your statement is correct, but..

The point of the graph was to show that the introduction of the P-38 as a long range escort had two main effects.
1. The loss rate dropped to acceptable levels
2. The Luftwaffe had lost the airwar over Europe by March of 44. Months before the P-51 was introduced in numbers equal to the P-38.

The fact that the loss rate further decreased is testament to how badly hurt the Germans were by the introduction of the Lightning as an escort.

The P-38 flew against the best the Luftwaffe had to offer, they were not allowed to stray from close escort, they were outnumbered and mechanical problems were rampant due to various factors. Yet, because the Lightning was such a great plane, the pilots who flew them, were able to overcome those challenges and won.

I would argue that the Lightning was the most strategically significant fighter of WWII, making a vital contribution to winning the battle for the skies of Europe, the Med and the Pacific. It would have done the same for the RAF.

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P-38's (55th FG) flew the first escort missions about 6 weeks before P-51's first escort mission (354th FG, 9th AF). By the end of December '43 the 20th FG begins flying escort missions with P-38's.
During 'Big Week' late February '44 there are more or less equal numbers of P-38's and 8th & 9th AF P-51's escorting the bombers. Early March there are regularly more P-51's than P-38's flying escort missions.

Hairog said:

Well if you will recall the Mustang needed a whole new engine that was not an American design and then there was the problem of their tails coming off. So the P-51 had a lot more problems than most recall. The prototype flew in Oct. 1940, in 1942 it was rejected by the RAF and didn't equal the Lightning in escort duty until May of 1944. That's a long time to work out the bugs and get it to the frontline. Meanwhile the Luftwaffe was being decisively defeated and their best pilots being shot down by the undertrained pilots flying the P-38 and P-47.

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Before the Mustang's first flight there was a contract in place for Packard to build Merlins.

The RAF didn't reject the Mustang I or II. They bought 300+ Mk Is and were to get 150 more under Lend-Lease, but some of these were kept by the USAAF.

It was after initial testing that the suggestion to install the Merlin 61 in the Mustang was made. Had North American not been given the go ahead to develop the P-51B, or Packard production didn't allow it, there was a plan to ship the airframes to Britain and fit the Merlin in a conversion facility.

Production of the P-51/P-51A and Mustang I/IA was delayed, IIRC, by slow delivery of the V-1710 to NAA.

And there were delays to the P-51B program due to the initial slow production of V-1650-3s (Merlin 63).

North American were given approval to convert two P-51As to the Merlin as the XP-78 in July 1942. First flight was in November 1942. The first production P-51B flew in May 1943.

Hairog said:

It more than helped. Their introduction saved the American daylight bombing effort. They were available and should have been used much earlier and would have saved many a bomber crew. It was a huge failure by the "Bomber will always get through" mentality of the US Army Air Corps.

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Earlier P-38s were much less capable, especially in range.

Hairog said:

Then you have to take into account the cost of building or retrofitting factories to build the Mustang compared to increasing the build rate of the Lightning. Add in the cost of R&R, retraining flight instructors and mechanics, retooling machine tools, switching to manufacturing a new tire design , retrofitting the tail so it didn't fall off, switching engines, etc. I don't think the P-51 was such a bargain when you include all the overhead that went into getting it into combat. The phrase "Penny wise, pound foolish" comes to mind.

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Since the P-51 cost half as much as the P-38 it would suggest that the cost to build plus the overheads (which is included in the customer cost) was half as much as the P-38.

Hairog said:

Where are people getting the idea that the Lightning couldn't climb, turn or roll?

View attachment 550286

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Well, until the P-38J-25-LO the P-38 didn't have boosted ailerons. So, until sometime in 1944 (?) the roll rate was 39 degrees per second. Not exactly flash.

The other aspect of roll is inertia. From what I understand from America's Hundred Thousand, two engines offset from the roll axis caused the initial roll to be sluggish.