Another P-38 "what if" thread...

Yep, sorry, and please nuke if this has been discussed-I haven't been able to find it. One thing that hit me reading Bob Johnson's book was the relatively gradual, but steady buildup of P-47s in England, and more importantly the gradual implementation over occupied Europe. He writes about how inexperienced pilots were warned to keep the speed high and not engage in any kind of maneuver fight with German fighters, and how Spit pilots warned them how the '47 would be lunch for the BFs and FWs. The lack of range of the '47 (relative anyway, and at that time of the war, before large drop tanks were sorted) meant that it wasn't doing any long incursions over occupied Europe/Germany, but at the same time, that gave pilots a rather gradual introduction to combat and time to build skills and learn to utilize the plane. At the same time it gave Republic time to work out bugs and get things dialed in. The other issue that struck me is that we had a lot of '47s and they rarely fought badly outnumbered. (Please correct me where I am mistaken-no where near the knowledge of so many here). The other point-in late '42/early '43 much of the Luftwaffe was still at the Eastern front, further improving the odds.

Compare that to the '38. A significant number were in Britain in mid-late '42, at least a portion of which flew over as part of operation Bolero. My understanding is that they flew missions from England, but like the early '47 squadrons, had limited contact with the enemy. In late '42 every '38 in England was flown to N. Africa to support that campaign.

Moving forward to mid/late '43 when it became obvious that long range bomber losses were too great without escort fighters. At that instant, the '38 was the only plane with the range and performance to be considered (the '51B not being available to fly combat missions until December-granted only a few months after the '38s first started escorting). Now, one of the biggest problems of the '38 was limited production-Lockheed was spread pretty thing with other contracts, it was a complex plane to build...and unlike most other fighters there were no other plants building them. In addition they were in great demand in other theaters.

So, we had an unfortunate mix:
1) Newly formed outfits with rookie, poorly trained pilots and ground crews, with little familiarity with the '38.
2) Very limited numbers of planes/pilots available, meaning they were always heavily outnumbered when flying escort.
3) The '38 was being flown in a new environment that it hadn't been refined for. Other planes and outfits had months to "work the bugs out". Not so with the '38 groups who only had a few weeks to sort out the planes and become combat capable.
4) These inexperienced pilots and unsorted aircraft were thrown into the escort mix at the very time the Germans were moving their best pilots and a large number of planes to the Western front.

So-the what if? What if-instead of transferring all the existing squadrons from England to NA in late '42, what if those squadrons had been kept in place? Slowly built up in numbers and more gradually probing deeper into Europe? What if the numbers of aircraft and pilots was at parity with the '47? What if another plant or two was converted to '38 production? Let's say Vultee was able to produce planes in '42, rather than '45, or Bell had been converted to '38 production rather than the P-39?

How much different would those first long range escort missions have gone, with pilots, crews and a manufacturer with a year of experience with the plane in the Northern European environment? Some of the development that took place with the '38 wouldn't have been any, or much, earlier (more powerful engines, core-type intercoolers, maybe dive recovery flaps). But many of the issues could have been addressed quite quickly-as they were in the end of '43. Dual generators, heated flying gear, improved cockpit and gun heaters, detonation/engine failure issues due to fuel distribution/differences. And it certainly would have been figured out that "low boost/high rpm" cruise, against the directions of Lockheed and Allison-was hard on engines.

It probably would have gotten some of the P-38 issues sorted out sooner and helped the bombing campaign.

However, while not causing the allies to loose in North Africa/Sicily/Italy the absence of the P-38 would have resulted in more losses of P-39s and P-40s and quite possible more bomber (medium at least) losses in those campaigns. After the P-38 the P-40F/L was the best American fighter at altitude (which is not saying a whole lot) unless you count some of the reverse lend lease Spitfires.

P-38s could cover the beaches in Sicily from air bases in NA which none of the single engine fighters could do. Which left fighter support to the aircraft carriers.

Bell was making, on average, 200-400 P-39s a month in 1942 (total production 1932) and 43 (4947) and while quite a few went to Russia changing over the Bell factory would have seen a number of months of no production or production in near single digits. Can you afford to build 500 fewer fighters in 1942 for more P-38s in late 1943/44?

Shortround6 said:

It probably would have gotten some of the P-38 issues sorted out sooner and helped the bombing campaign.

However, while not causing the allies to loose in North Africa/Sicily/Italy the absence of the P-38 would have resulted in more losses of P-39s and P-40s and quite possible more bomber (medium at least) losses in those campaigns. After the P-38 the P-40F/L was the best American fighter at altitude (which is not saying a whole lot) unless you count some of the reverse lend lease Spitfires.

P-38s could cover the beaches in Sicily from air bases in NA which none of the single engine fighters could do. Which left fighter support to the aircraft carriers.

Bell was making, on average, 200-400 P-39s a month in 1942 (total production 1932) and 43 (4947) and while quite a few went to Russia changing over the Bell factory would have seen a number of months of no production or production in near single digits. Can you afford to build 500 fewer fighters in 1942 for more P-38s in late 1943/44?

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In NA, perhaps the bigger impact than even the P-39/P-40 losses would be the loss of the only fighter with the range to hit the German resupply lines. IIRC the German army in NA was dependant on transport aircraft for a large share of their supplies. The '38s from what I understood were very effective at disrupting them. Nothing else available in late '42, early '43 had the range. Tough call-but you put your resources where the biggest, most immediate need is. And at the time that was NA, not England.

Ultimately a "what if" thread just opens a different topic for discussion. The '38 is often disparaged for it's performance in the 8th as an escort fighter. And no doubt the plane had some deficiencies, and when first thrown into that role, some significant ones. Point is, many were resolved pretty quickly, and had it been introduced similarly to the '47, a number of them would have likely been resolved before being heavily utilized in that role.

In addition to the aircraft deficiencies, the biggest issue comes back to numbers and other needs. Gen Kenney was screaming for every '38 he could get in the SWPA-the '47s he did receive saw little use due to the range issue. Ditto in NA.

The P-51Bs were rushed into service as escorts just as quickly and aggressively as the '38 was in late '43. It also had some teething problems, but fewer, and fairly quickly resolved. Part of that I'm sure was due to the Merlin already being well sorted at high altitudes in the Spits and Hurricanes.

The other "what if" questions? What if the only prototype hadn't been destroyed in a publicity stunt after only a few hours of flight testing? What if the issue of compressibility had been identified 2 years earlier and rectified before volume production? What if so much of Lockheed's production capacity wasn't tied up building British bombers and the focus had been on '38 development-getting the YPs built sooner?

Another problem the P-38 had in the European theater was its distinctive shape. It was the sole allied fighter that could be readily identified at a very long range, whereas all the single-engined fighters had to be much closer for positive identification. The P-38 screamed American fighter to everybody because nothing else was close.

loreng59 said:

Another problem the P-38 had in the European theater was its distinctive shape. It was the sole allied fighter that could be readily identified at a very long range, whereas all the single-engined fighters had to be much closer for positive identification. The P-38 screamed American fighter to everybody because nothing else was close.

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Yep, and that's mixed news. Not a desirable situation when you're trying to bounce an enemy fighter and a quick glance identifies you. Flip side, when you're escorting 100 bombers, every one equipped with 10 or more .50 machine guns-it's kind of nice to be readily identified. New bomber gunners were noted for firing at any single engine fighter that got close to them. Similar situation when providing cover over your own forces or providing close air support.

IdahoRenegade said:

...
The P-51Bs were rushed into service as escorts just as quickly and aggressively as the '38 was in late '43. It also had some teething problems, but fewer, and fairly quickly resolved. Part of that I'm sure was due to the Merlin already being well sorted at high altitudes in the Spits and Hurricanes.

The other "what if" questions? What if the only prototype hadn't been destroyed in a publicity stunt after only a few hours of flight testing? What if the issue of compressibility had been identified 2 years earlier and rectified before volume production? What if so much of Lockheed's production capacity wasn't tied up building British bombers and the focus had been on '38 development-getting the YPs built sooner?

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Have Ben Kesley not to attempt the trans-continental record, but ship the XP-38 without much of fanfare to Wright Field, and then to the NACA full-scale wind tunel. Plenty of problems/issues would've been unearthed and probably solved in less time than it was historically the case.
Lockheed Hudons were very useful aircraft, that, along with other marine partol aircraft, were keeping UK supplied and thus in the war. Hudsons were perhaps unsung heros of the ww2.
WIth that said - second source for the P-38 early enough would've done miracles not just for a steady supplies of very good fighters, but also enabled easier implementation of the improvements to the type.

IdahoRenegade said:

Yep, and that's mixed news. Not a desirable situation when you're trying to bounce an enemy fighter and a quick glance identifies you. Flip side, when you're escorting 100 bombers, every one equipped with 10 or more .50 machine guns-it's kind of nice to be readily identified. New bomber gunners were noted for firing at any single engine fighter that got close to them. Similar situation when providing cover over your own forces or providing close air support.

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It was not just the shape, it was also the size - P-38 was almost twice the size of the Bf 109, or 70-80 bigger than the Fw 190. Thus the pilots of LW were in position to spot the P-38s (or P-47s, for that matter; P-51 was in-between the LW fighters and P-47) at far longer distance that it was the other way around. That will give them tactical advantage -> surprise -> 1st shot advantage.
P-38 will be easier to disecern for the bomber gunners while doing close escort, however the LR fighters were better used for freijagd, or ranging well ahed the bomber stream to hit the defenders. Close escort also means that escort fighters are flying at low-ish speed, and interceptors can choose time and location of attack, plus ability to concentrate on the area of choosing thus owervhelming both escorts and bombers. As it happened during the BoB.

My understanding was that the P-38 was distinctly unsuited for the high altitude escort role.
Its supercharger system had very long ducting which allowed fuel to fall out of suspension at low throttle settings and pool.
Its maximum speed was very very close to its Mach limit for compressibility at high altitude.
I have also read that it took longer for the a pilot to go from cruise settings to combat in a P-38 than other American fighters but I don' know the specifics.

I know that dive recovery flaps eventually allowed the late P-38J and all of the L models to recover from compressibility, but it still had the speed limitation.
Was there ever a successful solution to raise the compressibility Mach limit?
Was the fuel falling out of suspension ever really solved? If so, how was it done and what were the results?

Maybe it is important and maybe it is not, but a P-38 cost about twice what a P-51 cost in money and also needed two engines to be manufactured instead of just one.

- Ivan.

There were several reasons to why fuel reverted from 'mist' to droplets after the air-fuel mixture exited engine-stage supercharger (not turbo supercharger) and entered intake manifold, the problem that was most acute on the J version. Like wrong engine setting used in cruise (high rpm, low boost, instead of low rpm, higer boost) - that kept the temperature of air-fuel mixture too low thus easing forrming of droplets. That was further bolstered by now very much improved intercoolers the P-38J got. The engine-related issue was the design of intake manifold, a problem that Allison have had already by 1940-41, while in 1943 it got another internal modification that 'swooped' any droplets that formed inside and 're-atomized' those droplets back. The change in intake and more care for cruise setting improved reliablity of engines.
P-38's cockpit was perhaps a worst part of the aircraft, with levers and switches located at any possible place, even under the seat. Being a 2-engined aircraft just made the things worse for newly baked pilots, and there was plenty of those in 1943.
The YP-38 was tested at NACA full-scale wind tunel. There it was suggested to either increase the chord of the inboard wing (where the compressibility was mostly experienced) by 10% or by 20% in front of the front spar, or to make that wing section in new low-drag air foil, the NACA 66-115. The 20% increas of chord moved the centre of lift too much forward, that was to be countered by relocation of radiators in the new section. Major reduction of drag was measured with such A/C, ditto for improving compressibility limit.
Another improvement was on the central pod, where several suggestions to improve Mach limit were also done.
NACA report: link
What-if about such P-38 actually making it in production, plus plenty re-P-38: link
Money was no problem for the USA in ww2, it was lack of capability sometimes, as it was the case for long range, high altitude escort before 1944.

tomo pauk said:

There were several reasons to why fuel reverted from 'mist' to droplets after the air-fuel mixture exited engine-stage supercharger (not turbo supercharger) and entered intake manifold, the problem that was most acute on the J version. Like wrong engine setting used in cruise (high rpm, low boost, instead of low rpm, higer boost) - that kept the temperature of air-fuel mixture too low thus easing forrming of droplets. That was further bolstered by now very much improved intercoolers the P-38J got. The engine-related issue was the design of intake manifold, a problem that Allison have had already by 1940-41, while in 1943 it got another internal modification that 'swooped' any droplets that formed inside and 're-atomized' those droplets back. The change in intake and more care for cruise setting improved reliablity of engines.
P-38's cockpit was perhaps a worst part of the aircraft, with levers and switches located at any possible place, even under the seat. Being a 2-engined aircraft just made the things worse for newly baked pilots, and there was plenty of those in 1943.
The YP-38 was tested at NACA full-scale wind tunel. There it was suggested to either increase the chord of the inboard wing (where the compressibility was mostly experienced) by 10% or by 20% in front of the front spar, or to make that wing section in new low-drag air foil, the NACA 66-115. The 20% increas of chord moved the centre of lift too much forward, that was to be countered by relocation of radiators in the new section. Major reduction of drag was measured with such A/C, ditto for improving compressibility limit.
Another improvement was on the central pod, where several suggestions to improve Mach limit were also done.
NACA report: link
What-if about such P-38 actually making it in production, plus plenty re-P-38: link
Money was no problem for the USA in ww2, it was lack of capability sometimes, as it was the case for long range, high altitude escort before 1944.

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Thanks for the links-that is first I've seen of the actual NACA report and post in the other forum was very interesting. I had been wondering much the same-the wing shape is very blunt and thick in the inner wing section. Can't readily thin it out without reducing structural strength and more importantly fuel capacity. But the leading edge extension makes sense. The other question I always had was about using a liquid heat exchanger for the intercooler. Seems like it's a lot more efficient to put a compact liquid HE in the airstream between the turbo and SC, rather than ducting the intake air to the IC and back. In addition the other HE could could be mounted wherever it was most efficient and contributed the least to increased drag. IIRC the J and L models only showed a modest speed increase over the G and H models, in spite of a significant increase in HP, due to the added drag of the chin-type intercooler.

Bodie's book shows some pretty radical experiments conducted with the '38. I'm actually surprised they never built a configuration based on the input from the NACA report with those leading edge and nacelle revisions.

The testing was undertaken during the winter of 1941/42 - exactly in the time Lockheed is trying very hard to produce the Lightnings both for USA and UK (order was for some 550 pcs for the RAF). It was probabaly judged that changes to the shape & structure would've meant a several setback for the production.
Wing profile was not that thick - 16% at root - but the problem was that naceles and central pod created venturi, that increased the speed of local airflow thus 'invoking' compressibility problems, along with increase of drag. Add the, indeed, additional drag made by new intercoolers and the result was barely faster J/L vs. F/G. Jand L were also heavier, that will knock out a few mph, too.
So, again - have Kesley doesn't crash the XP-38, NACA tests it during the 1940, suggested improvements are incorporated on the last half of YP-38 series and subsequent non-prototype versions. Have the second source of P-38s in order to have subsequent modifications introduced without much interrupting the flow of P-38s to the units.
Having the coolers between the engines and pod allows for easier improvement of cockpit heating, reduces the length of coolant pipes (+ for survivability), reduces weight of cooling system.

I don't know how accurate it is but without big leading edge extensions there is no real room for radiators in the leading edge of the inner wing.
Leading edge extensions are going to cut into the pilots downward view. Not good as it is?
Cockpit heating could be solved (somewhat) by a 2nd generator sooner and an electric heater?

The link Tomo posted discussed a 20% increase in chord-hard to say just what the HE packaging would look like, but that's quite a lot of space. Seems like it might be reasonable from a packaging standpoint. I had the same concern regarding downward visibility looking at the drawings in that link. But when you look at the '38s layout-the cockpit positioning is far forward with respect to the wing and the nose in front of the pilot is both short and slopes away quickly. Extending the wing LE forward still keeps the cockpit (seat) forward of the center of the wing, so visibility should still be better than most single-engine fighters (at least in the forward quadrant). It sure wouldn't be a Corsair with the cockpit located towards the back of the wing.

Shortround6 said:

I don't know how accurate it is but without big leading edge extensions there is no real room for radiators in the leading edge of the inner wing.
Leading edge extensions are going to cut into the pilots downward view. Not good as it is?
Cockpit heating could be solved (somewhat) by a 2nd generator sooner and an electric heater?

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P-38 have had far better wiev donwards than vast majority of ww2 fighters; problem was booms and engines blocking the view to the sides.
The front fuel tanks were not spaning between leading edge and the main spar , but between the front auxiliary spar and main spar. leaves a 'buffer' between that auxiliary spar and leading edge:

You can check out the drawing at pg. 141 of the AHT, though that one looks less precise than this above.

Here is NACA's suggestion, for case the wing chord is increased by 20%:

Hello All,
It seems like most of the points I was about to bring up have already been covered.
The view downward and to the side actually WAS a complaint of the pilots and this leading edge extension would only make it worse.
Although moving the Coolant Radiators to the wing center section LE would certainly reduce drag, it would also most likely increase the vulnerability of the radiators to ground fire and that was a significant weakness of the P-38 at a later stage of the war.
Perhaps moving the center of lift forward would also address the CoG shift as ammunition was expended. This was apparently bad enough that the British manual for the Lightning called for adding ballast if no ammunition was carried.

I still have not finished reading the NACA proposals yet, but the Alternate History site was "interesting". It is fairly obvious that the author of that post is a fan of the P-38 (as am I). It also appears to me that he is trying hard to end up with a certain conclusion.
A couple points that were brought up are worth mentioning here:
Although the NACA improvements would significantly raise the compressibility Mach number, it is still WAY below that of the P-51. There is a big difference between buffeting and loss of control as compressibility effects.
Also worth mentioning is that although the boosted ailerons on the late P-38J and P-38L improved the roll Rate, the response was still very slow according to pilot reports: There was a significant lag between control input and when the aircraft started rolling.
Perhaps a system with improved response could have been designed but there is no way to improve the high lateral inertia that was a characteristic of this design.

Regarding maximum speeds of the early and late P-38, what are the most reliable numbers you all have found for military power and WEP?
I find some of the claims (especially of the late P-38) to be not very credible.

- Ivan.

Ivan1GFP said:

Hello All,
It seems like most of the points I was about to bring up have already been covered.
The view downward and to the side actually WAS a complaint of the pilots and this leading edge extension would only make it worse.
Although moving the Coolant Radiators to the wing center section LE would certainly reduce drag, it would also most likely increase the vulnerability of the radiators to ground fire and that was a significant weakness of the P-38 at a later stage of the war.
Perhaps moving the center of lift forward would also address the CoG shift as ammunition was expended. This was apparently bad enough that the British manual for the Lightning called for adding ballast if no ammunition was carried.

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Closely-coupled radiators have smaller lenght of coolant pipes, so that should hopefully cancel out the possible increase in vulnerability. IIRC the Mosquito, that used svery similar radiator set-up, was not know to be very vulnerable to MG/AAA fire when used in daylight jobs.
Granted, a P-38 that has better hi-altitude behaviour will be gar more used as a hi-alt fighter, rather than mud-mover.

I still have not finished reading the NACA proposals yet, but the Alternate History site was "interesting". It is fairly obvious that the author of that post is a fan of the P-38 (as am I). It also appears to me that he is trying hard to end up with a certain conclusion.
A couple points that were brought up are worth mentioning here:
Although the NACA improvements would significantly raise the compressibility Mach number, it is still WAY below that of the P-51. There is a big difference between buffeting and loss of control as compressibility effects.
Also worth mentioning is that although the boosted ailerons on the late P-38J and P-38L improved the roll Rate, the response was still very slow according to pilot reports: There was a significant lag between control input and when the aircraft started rolling.
Perhaps a system with improved response could have been designed but there is no way to improve the high lateral inertia that was a characteristic of this design.

Regarding maximum speeds of the early and late P-38, what are the most reliable numbers you all have found for military power and WEP?
I find some of the claims (especially of the late P-38) to be not very credible.

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If we believe the test report, the Mach limit will be raised by approx 0.1 Mach, or the onset of compressibility will be delayed, as it was stated, by 50 to 60 mph. That puts the P-38 in league of P-47, if not quite the P-47, or in other words from 'useles' diver into 'useful' one. Or, able to catch LW fighters that attempt to dive, while not putting it's pilots into an unnecessary risk during dives.
With thousands of pounds worth of powerplant, booms, fuel etc that away from centreline, the P-38 was in no position to became a roller champion. My what-if US twin engined fighter would've been a classic twin (a-la Whirlwind, Fw 187, Hornet), not a twin boom A/C - shaves plenty of weight away from centreline, more useful volume, hopefuly easier to produce.
The P-38J/L was supposed to do 425+ mph on war emergency power.

P-38 in many ways had a bad layout. You can't just quick-fix it somehow, the problems are baked in. Imagine if you will the cross-section area graphed along the length. Area rule? Not so much. High roll moment of inertia and lack of internal space, and the wing section, were other baked-in problems. To manage more power (given a merlin 61 or better V1710) it would have need a bigger prop, possibly giving clearance problems, which would have beed solvable but not trivial.

The 8th AF P-38s in 1943 started escorting six weeks before the P-51 and that was in a period when the bombers were recovering from Munster, Schweinfeld and Regensburg. In the spring of that year they might have made a difference but they were in Africa. The US ARMY air forces were bound to support the only place the army was engaged. They weren't wasting their time out there. The war wasn't all about the 8th AF.

Single engine planes did perfectly well. Twin-prop single-seaters are hard to justify in hindsight, in comparison to the best singles.

K5083 said:

P-38 in many ways had a bad layout. You can't just quick-fix it somehow, the problems are baked in. Imagine if you will the cross-section area graphed along the length. Area rule? Not so much. High roll moment of inertia and lack of internal space, and the wing section, were other baked-in problems. To manage more power (given a merlin 61 or better V1710) it would have need a bigger prop, possibly giving clearance problems, which would have beed solvable but not trivial.

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Some problems were slolvable quickly, some will remain. Those are mostly related to the P-38 being a 2-engined 2-boom fighter (big size, many blind spots for the pilot, slow & expensive to manufacture, takes more time to train a pilot than a 1-engined job etc.).
Merlin 61 will not make compressibility problems go away, the NACA report made suggetions what to do, mostly with inner wings and pod/canopy. The P-38 aready used the most powerful V-1710s around, so that point is moot. The better prop would've been a good thing, a nice paddle-blade type, perhaps 4-bladed, would've improved the rate of climb.
The suggestions by NACA to relocate the radiators in-between the naceles and pod frees space to install a core-type intercooler under the engine, thus leaving space for out-board fuel tanks much earlier than ot was done hostorically.

The 8th AF P-38s in 1943 started escorting six weeks before the P-51 and that was in a period when the bombers were recovering from Munster, Schweinfeld and Regensburg. In the spring of that year they might have made a difference but they were in Africa. The US ARMY air forces were bound to support the only place the army was engaged. They weren't wasting their time out there. The war wasn't all about the 8th AF.

Single engine planes did perfectly well. Twin-prop single-seaters are hard to justify in hindsight, in comparison to the best singles.

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US AAF was bombing Germany from late 1942, increasing the tempo in 1943, despite the increase of the commitment in the MTO. Th thing is that USAF was not counting on need for escort fighters, hopint that it's bombers will get through German defences via altitude, speed and defensive guns. They were proven wrong, and by summer of 1943 there was a haste to find out the means to improve the range of possible escorts, predominantly P-47s in the UK. WIth just one, admitedly big factory making P-38s, there was not enough of those to cover Pacific, MTO and ETO in 1943.
P-38, as a twin, was far more suited for long range work than any 1-engined fighter from either Allied or Axis side until late 1944 and advent of Merlin Mustang.
WW2 indeed was not all about 8th AF, but it was about defeating Germany - the 8th AF was directly contributing in that job.

Hello Tomo Pauk,

The expectation of greater vulnerability was in comparison the F4U Corsair which had its oil cooler in a similar location and was quite vulnerable to ground fire. The new arrangement for Coolant Radiators, Oil Coolers, etc. would create a much larger area of vulnerability and the Lightning already had issues of vulnerability to ground fire as they found out later in the war.

The standard P-38 had compressibility issues beginning at Mach 0.68. It was placarded at Mach 0.65.
The NACA P-38 would have had issues at Mach 0.77 and presumably would have been placarded a bit below that.
I believe you are a bit optimistic in the view that it would be useful in a diving to pursue a target but perhaps it could dive to evade pursuit.
At least it would have a better chance of surviving a Split-S and not becoming a lawn dart in the process.

- Ivan.

Hi,
I've commented before that ground fire problem will be non-issue for 1942 and 1943 when the improved P-38 will be serving predominantly as hi-altitude fighter. For 1944-45, use the P-47s as ground attack aircraft - horses for courses.

A lot of thoughtful replies.
There were several Drivers toward P-38 technology adjustments from YP-38/P-38E in 1941.

The first experimental external tank/bomb rack and associated plumbing for fuel management to extend Ferry Range substantially.
Compressibility and wake turbulence were experienced consistently but were separate phenomena and difficult to unravel. NACA recommendations notwithstanding, the choices available to Lockheed to produce a new model, new tooling, for inner wing to try to solve became impossible after December 7. Even the P-38K with large diameter props was rejected by War production Board despite a relatively small impact design wise - because of re-tooling issue and allocation of plant space for change over.
The Intercooler/turbo issues have been hashed to death but simply, after the first test on P-38E test bed, the design/tooling/fabrication issues to change to P-38J skipped two model changes before the Change could be integrated in mid/late 1943. In fairness, this also was complicated by unanticipated high altitude temperature issues in ETO as well as complicated and slow (relatively) processing of advancing throttle and RPM in combat engagement. The solution was in hand for intercooler but unavailable when it was really required, namely when the 55th FG began operations through the 20th FG in mid December 1943.
The Lessons learned in combat for both the dive flap and boosted ailerons were incorporated into satisfactory designs, but again - Lockheed was slower (IMO) than other major airframe manufacturers at a.) designing kits forward of production incorporation into a model break, and b.) fabricating kits for field Depot modifications. This cycle (again IMO) critically harmed early P-38J-5 and -10 air to air capability in high altitude ETO combat achievement during THE critical period of POINTBLANK operations to defeat LW before Overlord.

I would summarize the barriers to What If, to point to the lack of Manufacturing/Production nimbleness of a New airframe company (Lockheed) that for, example, did not have the equivalent talent in Production that NAA had in 1942-1943. The funding for the Prototype was immediately increased to 13 P-38s following the crash but look how long it took Lockheed to produce the fist one. Complicate that existing restriction to produce on-hand in 1939 with not getting near enough funding above the YP-38 to truly build for airframe mass production layout.

The issue with the P-38 contrasted with P-51 was that the P-38 was far more complicated internally than the P-51, and b.) that NAA developed very advanced processes to move into mass production. The second major impediment to slowing down production, as mentioned above, was that the P-38G/H was the Only high altitude/high speed/long range fighter on paper that the US had in 1942/1943 until the P-51B-1 entered combat - and neither AAF nor WPD were happy to 'Pause' in draining the swamp while the alligator air forces were chewing our ass in Pacific and Africa.

If we pause to think about the major changes made to the P-51, they boil down to switching from Allison to Merlin engine and never have to contemplate turbo for high altitude, never having to change basic wing or empennage, single seat/control systems/simplicity of maintenance and repair w/respect to P-38