WI: NACA Modified P-38

Discussion in 'Alternate History Discussion: After 1900' started by EverKing, Jun 15, 2017.

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  1. Threadmarks: Introduction & Background

    EverKing Well-Known Member

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    WI: NACA Modified P-38 fighter
    -------------------------------------------------------

    Notice to Readers: This TL is still alive but only occasionally updated at this time (Summer 2018). Real life and the greatly expanded scope of detail required to continue advancing the TL at this point (including a fair share of original design and research) has kept me from more regular postings. But, Please, follow along and keep your eyes open for updates when they occur. I really value everyone's input and often the discussion around specific developments has been key to finalizing the next development.

    Cheers!
    E

    Aug. 2018

    -------------------------------------------------------
    (This was something I had planned to post after being on the board longer but a discussion in another thread prompted some discussion of P-38 development so I thought I would go ahead with this for the sake of discussion.)

    I know there have been several discussions over the years surrounding the Lockheed P-38 American Twin-Engine fighter/interceptor of WWII but one part of the equation that I have never heard discussed is the “What If…” the NACA recommended modifications to the airplane had been implemented, especially at or near the beginning of P-38 operations.

    OTL Background:

    Without re-hashing the origin and initial development history of the Lockheed Model 22 / P-38 (all of that information is readily available on numerous on-line sources) I will focus on what led to the NACA studies of the airframe, their proposed solution to the problems encountered, and why these solutions weren’t put in place.

    A record-breaking cross-country flight in early 1939 (which resulted in the loss of the only XP-38) garnered enough attention and excitement that the US Army Air Corp (USAAC) placed orders for pre-production (YP-38) and production (P-38) aircraft in numbers greater than Lockheed had anticipated for the entire Model 22 life. This necessitated a rushed production development and major reconfiguration to accommodate the unintended mass-production.

    Tests in early 1941 of the first pre-production YP-38’s quickly ran into issues when at high speed (around Mach 0.68), especially in dive, where the nose of the aircraft would drop--locking into an often un-recoverable dive accompanied by “buffeting.” The problems getting the production line up and fully operational prevented Lockheed from directing any engineering resources to these problems until November 1941, but they were unable to identify the cause or provide any solutions until Gen. Hap Arnold, head of the by then renamed Army Air Forces (USAAF), ordered the National Advisory Committee for Aeronautics (NACA—predecessor of NASA) to analyze the YP-38 in their full-scale wind-tunnel in December 1941 – January 1942 which resulted in the report “Full-Scale Wind-Tunnel Investigation of Buffeting and Diving Tendencies of the YP-38 Airplane.”

    This report was finally able to identify that the control lock and diving difficulties were the result of a high-speed pressure wake developing over the wing and fuselage resulting is loss of lift to the central wing and buffeting of the tail as the turbulent wake passes over it, a phenomenon just recently discovered at the time which led the idea of the “sound barrier.” This is often referred to a “Compressibility” problem as it related the change of aerodynamics at high speed from a traditional non-compressible fluid to a compressible one. The specific behavior of the P-38 is now better known as “Mach Tuck.”

    NACA tested several solutions to the problem including wing filleting, partial flap deployment, three different inboard (between the engine booms and the center gondola) wing designs, two revised canopy designs, and an extension to the trailing edge of the gondola. They found the best performance gain (delay of up to 64 mph in the formation of the shock-wave) resulted from a simple 0.2c (20% of chord) leading edge extension to the center wing section and using their second canopy revision. They also noted that although the gondola extension did not increase the Critical Mach number, it did reduce the turbulence of the wake re-joining the airstream and smoothed out the air flow over the tail surfaces.

    One aspect which I find very interesting with these design modifications was that the extended leading edge moved the center of lift forward causing the plane to become unbalanced. They recommended moving the coolant radiators from the mid-boom into the extended leading edge of the wing to rebalance the aircraft with the added benefit of reducing drag and further streamlining the aircraft. I will address this again in the ATL discussion to follow.

    The problem is that the report wasn’t completed until March 31, 1942, by which time the US was at war and Lockheed was ramping up to start production on the combat-ready P-38F (beginning in April 1942) at war-time production rates. With the P-38 the most capable fighter then in inventory there simply was not the opportunity to re-design and re-tool for the modifications NACA recommended and the P-38 was sent into combat while still suffering numerous problems, not least of which was the issues with compressibility.

    The results are well known and documented: the P-38 in the ETO struggled the first 18 months of combat prompting 8th Fighter Command to pre-emptively phase them out in favor of the new P-51 as they became available at the end of 1943 and through the first half of 1944 which prevented Lockheed and the USAAF from implementing a number of fixes for the problems and delayed others until it was too late to have much impact in the reputation of the P-38 in Europe. It was not until the P-38J-25-LO and P-38L-5-LO/VN the airplane really came into its own and that was realized almost entirely in the Pacific.

    ATL Discussion:

    For this examination of a “What If…” I have decided to place the POD with the NACA study. Specifically, that Gen. Arnold did not wait for Lockheed to tackle the dive issues first and instead ordered the NACA study to take place in June-July of 1941 with the final report completed September 30, 1941 (six months earlier than OTL). This updated timeline would allow Lockheed engineers to immediately go to work implementing the NACA design changes in fall 1941 prior to US entry into the War and the corresponding production pressures which prevented it from happening in OTL. The first production P-38’s with the NACA modifications would then roll out either as late block P-38E’s in early ’42 or, more likely, as the finalized P-38F in April 1942.

    OTL, the P-38F/G/H continued to use the enclosed intercooler in the leading edge of the outboard wings, which provided adequate cooling for the early model engines and low-boost ratings but which, by the P-38G and even more so the P-38H, limited engine power to lower settings due to in-adequate cooling. This was a problem that was not anticipated so it wasn’t until the P-38J in August 1943 that the intercoolers were switched to the core-type, chin-mounted position—squeezed between and behind the oil radiators. However, in my ATL, with the oil radiators moved adjacent the coolant radiators in the leading edge extension the space in the chin of the nacelles is completely freed up which allows the core-type intercoolers to be installed in the space previously occupied by the oil radiators as soon as it becomes apparent it is needed without re-designing the nacelles themselves. This means that the engine power limitations of the G either never occurs (because the intercoolers have already been moved) or are quickly overcome by sending field modification kits in early 1943 with full integration on the assembly line taking place with the P-38H in the spring of 1943.

    Additionally, moving the intercoolers in these earlier models (G or H) would allow a matching earlier installation of the leading edge fuel tanks in the outer wings, increasing the range and combat radius in 1943 sufficient to provide full escort coverage to 8th AF Bombers even to deep penetration targets.

    Another advantage of moving the Prestone (engine coolant) radiators to the inboard position in the extended leading edge is that the heated coolant can be run through a heater core close to the cockpit cupola, increasing available cockpit heat as soon as it becomes apparent the existing heat is insufficient for high-altitude or cold weather operations. Again, this is something I expect would be utilized no later than early-mid 1943.

    One final advantage of this layout is that frees up a large amount of space in the tail booms which could be utilized in later production models. With engine weight increases in the F/G and again in the H/J models the Center of Gravity could potentially have been moved forward enough to justify installation of either additional small fuel tanks in the booms where the radiators used to be, or—perhaps a better option—small water/alcohol tanks which would permit the use the Water Injection under War Emergency Power, further increasing performances and reducing the risks of detonation under high manifold pressure (> 60 in/Hg).

    The estimated (conservative according to NACA documents) dive performance gains of this P-38 redesign are impressive:

    upload_2017-6-15_16-44-45.png

    To put this in perspective, the P-51D had an absolute Critical Mach of around 0.80, depending on the source, but was normally limited to less than 0.73 because of extreme vibrations beyond those speeds. Even if pushing the ’51 to Mach 0.8 or beyond is considered acceptable these NACA estimates for the modified ’38 show a similar diving capability considering a margin for error of the conservative estimate, especially if using Dive Recovery Flaps in addition to the NACA modifications. In these cases the P-38 would be favorable because it can accelerate to max speed faster than the P-51 allowing to either pull-away faster or to gain faster on a diving E/A. Combine that with the faster climb of the P-38, higher peak turning rate, and—in later airplanes—faster roll, there would be nothing that the P-51 could do that the P-38 couldn’t do better. All while bringing a heavier weight of fire on target (128 oz/sec vs 111 oz/sec).

    Here are some roughly done drawings of how these modifications would appear (done in MS Paint):
    NACA-P38.png

    All told, these NACA modifications solve three of the biggest issues with the early combat performance of the P-38 with the 8th Air Force: Limited Dive, Engine Cooling/Reliability, and Cockpit heating. In addition, the lack of the radiator ducts in the booms reduces drag and would likely result in a better level-flight top-speed (I would expect a gain of 10-20 mph from this) and improved/decreased fuel consumption. This leaves only two big problems to solve with later models.

    The first of these remaining problems was that the Fuel Mixture, Propeller RPM, and Throttle controls were independent and never had an implemented solution in OTL. For those not familiar with what those are, it means that to change from a “Cruising” condition to a “Combat” condition, the pilot needed to adjust three different levers for each engine (a total of six adjustments): Move Fuel Mixture from Auto-Lean to Auto-Rich; Increase Propeller RPMs; Increase manifold pressure (throttle). I have read some anecdotal evidence* that Lockheed had developed an “automatic manifold pressure regulator” which automated all of these adjustments into a single lever per engine but that the Air Force deemed it “unnecessary” and never authorized its implementation (Allison, the engine manufacturer, implemented this system on the post-war “G” series V-1710 engines). Supposing, with the “big three” problems solved due to the NACA redesign early in the combat life of the airplane the 8th AF decided to keep the P-38’s in primary service longer it is reasonable, I think, to assume this modification would become “necessary” and it could be implemented by late 1943/early 1944 models of the airplane (OTL P-38J, but in ATL, probably be considered second or third block P-38H).

    The second remaining issue was that the ailerons became heavy at high speeds and the so the airplane’s roll rate was quite slow, limiting its use as a dog-fighter. In OTL this was fixed in June 1944 with the P-38J-25-LO which introduced hydraulically boosted ailerons. These exponentially increased the force on the ailerons when turning the yoke and allowed the P-38 to flick-roll faster than most other fighters of the time. I am not certain how much more quickly these would be introduced in ATL vs. OTL as the slow-roll performance wouldn’t be altered by the NACA modifications nor was its solution delayed or prevented by AF brass. So, let’s say that this modification is introduced as it was in OTL, i.e. June 1944.

    Finally, with the 8th AF decision to keep the P-38 as the primary long-range escort fighter I believe it is reasonable to presume that they would have dedicated more time and resources to addressing the basic and tactical training for the pilots that was largely ignored in OTL, possibly even to the extant to sharing information with the P-38 FGs in the PTO—although that is uncertain.

    The result is, that when the 55th FG is transferred to the 8th AF with P-38H’s in September 1943 they have an aircraft capable of escorting bombers, at high-altitude, comfortably, reliably, and with significantly improved performance over most Axis fighters. This would reduce the demand for P-51’s and while I still expect them to come in theatre I would expect the P-38 Fighter Groups to keep the P-38’s rather than switching to P-47’s and P-51’s resulting in a near even three-way split between the fighter types by war’s end.

    I don’t know that this would have any significant impact on the eventual course or outcome of the war but improved long-range escort earlier in the war could have had a large positive impact on bomber-loss rates and morale. The reduction in bomber-losses in turn could mean a faster buildup of US Bomber forces and an earlier launch of major 1000+ raids perhaps even increasing the time-table for the Normandy Invasion, although other logistical problems likely lock that in no earlier than May ’44.

    The biggest difference would be in the reception and memory of the P-38 and its potential for a continued career post-war, similar to the P-51. The possibility of keeping them in service longer could also lead to the late-war approval for the adoption of the P-38K-1 with the F15 (Allison V-1710-75/77) engines and Hamilton-Standard Hydromatic high-activity propellers. In OTL only one of these was made using the large P-38J style chin and retaining the high-drag boom radiators. Even with all that drag it was able to achieve 432mph in level flight using Military Power and was expected to make 450mph with War Emergency Power with matching improvements in range and fuel consumption (about 10%). It also had a ceiling of 46,000 feet, a max climb of 4,800 ft/minute and could make it to 20,000 feet in only five minutes. Without the full coat of pain and with the reduced drag of the NACA design modification I can only image what its performance could be. In this case the P-38K would likely replace the F/P-82 Twin-Mustang of OTL and see continued service into the early 1950’s including limited combat in Korea as bomber-escorts and Close Air Support.

    So, any thoughts on this, its feasibility, and any effects I may have missed?

    -----------------------
    * http://www.ausairpower.net/P-38-Analysis.html (Pertinent section about 45% down in the italicized letter from Col. Harold J. Rau to “Commanding General, VIII Fighter Command, APO 637, U.S. Army”)
     
    Last edited: Aug 21, 2018
  2. Carl Schwamberger Well-Known Member

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    I've seen some less expert proposals for the P38. Mostly involving turbocharger upgrades.
     
  3. EverKing Well-Known Member

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    The problem with all the turbo upgrade arguments is that they generally fail to consider the state of metallurgy at the time. Sure, if you were to build a P-38 using modern technology and metals you could dramatically reduce turbo size while increasing boost and efficiency but in 1940 the alloys available really limited this.

    I wanted to take a more historically based direction for P-38 improvement. At first I considered a "What if K.A. Kawalki" had defected to the US in 1940 and brought his wing design with him (an early version of what we now call a Supercritical wing) and NACA was able to use that to improve the crit.mach of the P-38, but when researching it I stumbled upon the linked NACA report on the YP-38 and everything fell into place.
     
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  4. Carl Schwamberger Well-Known Member

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    Yes, a earlier PoD is necessary to improve performance via turbochargers.

    In another direction I wonder if high octane fuels were easily available in the 1930s engine performance would have been any better? Dolittle had some comment on that.
     
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  5. TonyA Curmudgeon like, but nastier

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    Impressive summary!
     
  6. EverKing Well-Known Member

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  7. Musketeer513 Member

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    Can't wait for more.
     
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  8. Carl Schwamberger Well-Known Member

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    The 1944 Report clarifies some things I'd heard elsewhere. Thanks for that. All I have for the 1940-41 period is Dolittles commentary, but since he had worked some years as a aircraft engineer for a fuel manufactor his account has some small weight. The short version is through the 1930s commercially available gasoline fuels had a very low octane rating by post WWII standards. 65 Octane is the number I recall. Dolittle & his peers were trying to persuade the corporate suits to develop and market higher octane fuels, up into the 80 & possiblly 90 octane range. The refusal was based on the lack of market since the engine manufactors provided nothing that could use such fuels. To complete the circle the motors that could use high octane fuel were not built because the fuels were not being made.

    Dolittle did make clear that custom built engines were common for fuels in the 70 to 90 and higher octane ranges. Additives and custom fuel mixes were available in small batches to those who could pay. Dolittle like other knowledgeable pilots carried a witches brew of additives in his aircraft for boosting the commercial fuels of the aircraft he used. Later in 1940-41 Dolittle observed the same problem in plotting the development of the Army Air Corps engines beyond 41. At one point the head of the Quartermasters Corps informed the Air Corps that only 65 octane fuel would be provided across the board to simplify logisitcs. Fortunately the reorganization of early 1942 gave the Army Air force control of its own material supply & development went ahead.
     
  9. EverKing Well-Known Member

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    I wasn't aware of Doolittle's work on this. I do know that, afaik, 100 grade fuel was the rated fuel for the Air Corp but their manuals do provide operating standards to run on 90 grade fuel as well.
    Would you like me to continue this as a narrative story rather than pure technical discussion? That could actually be fun...start with the Lockheed design team, move on to flight testing, then into early combat operations from the pilot's POV, and so on.
     
  10. Carl Schwamberger Well-Known Member

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    Not clear in his bio what Dolittles exact role was. He mentions that he was involved in one or another project, but does not brag about his specific contribution. He just writes about the issues he witnessed and moves on. He acquired a masters in areonautical engineering in the 1920s while on active service & was involved in a couple of aircraft development projects. During the 1930s he reverted to the reserves while working for the oil company. In 1940 he was recalled to active service and was on several engineering projects until assigned the problem of configuring a B25 bomber for a extreme mission. Originally he was just to make the B25 do the task, but once he learned the mission he managed to gain command of the unit. Post raid he went on to other aircraft engineering tasks and in 1943 was seent to North Africa where he was accelerated to major command after a couple of his peers either failed or were moved up.
     
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  11. Draconis Emperor of the North Pole.

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    "All told, these NACA modifications solve three of the biggest issues with the early combat performance of the P-38 with the 8th Air Force: Limited Dive, Engine Cooling/Reliability, and Cockpit heating. In addition, the lack of the radiator ducts in the booms reduces drag and would likely result in a better level-flight top-speed (I would expect a gain of 10-20 mph from this) and improved/decreased fuel consumption. This leaves only two big problems to solve with later models.

    The first of these remaining problems was that the Fuel Mixture, Propeller RPM, and Throttle controls were independent and never had an implemented solution in OTL. For those not familiar with what those are, it means that to change from a “Cruising” condition to a “Combat” condition, the pilot needed to adjust three different levers for each engine (a total of six adjustments): Move Fuel Mixture from Auto-Lean to Auto-Rich; Increase Propeller RPMs; Increase manifold pressure (throttle). I have read some anecdotal evidence* that Lockheed had developed an “automatic manifold pressure regulator” which automated all of these adjustments into a single lever per engine but that the Air Force deemed it “unnecessary” and never authorized its implementation (Allison, the engine manufacturer, implemented this system on the post-war “G” series V-1710 engines). Supposing, with the “big three” problems solved due to the NACA redesign early in the combat life of the airplane the 8th AF decided to keep the P-38’s in primary service longer it is reasonable, I think, to assume this modification would become “necessary” and it could be implemented by late 1943/early 1944 models of the airplane (OTL P-38J, but in ATL, probably be considered second or third block P-38H).

    The second remaining issue was that the ailerons became heavy at high speeds and the so the airplane’s roll rate was quite slow, limiting its use as a dog-fighter. In OTL this was fixed in June 1944 with the P-38J-25-LO which introduced hydraulically boosted ailerons. These exponentially increased the force on the ailerons when turning the yoke and allowed the P-38 to flick-roll faster than most other fighters of the time. I am not certain how much more quickly these would be introduced in ATL vs. OTL as the slow-roll performance wouldn’t be altered by the NACA modifications nor was its solution delayed or prevented by AF brass. So, let’s say that this modification is introduced as it was in OTL, i.e. June 1944.

    Finally, with the 8th AF decision to keep the P-38 as the primary long-range escort fighter I believe it is reasonable to presume that they would have dedicated more time and resources to addressing the basic and tactical training for the pilots that was largely ignored in OTL, possibly even to the extant to sharing information with the P-38 FGs in the PTO—although that is uncertain.

    The result is, that when the 55th FG is transferred to the 8th AF with P-38H’s in September 1943 they have an aircraft capable of escorting bombers, at high-altitude, comfortably, reliably, and with significantly improved performance over most Axis fighters. This would reduce the demand for P-51’s and while I still expect them to come in theatre I would expect the P-38 Fighter Groups to keep the P-38’s rather than switching to P-47’s and P-51’s resulting in a near even three-way split between the fighter types by war’s end.

    I don’t know that this would have any significant impact on the eventual course or outcome of the war but improved long-range escort earlier in the war could have had a large positive impact on bomber-loss rates and morale. The reduction in bomber-losses in turn could mean a faster buildup of US Bomber forces and an earlier launch of major 1000+ raids perhaps even increasing the time-table for the Normandy Invasion, although other logistical problems likely lock that in no earlier than May ’44.

    The biggest difference would be in the reception and memory of the P-38 and its potential for a continued career post-war, similar to the P-51. The possibility of keeping them in service longer could also lead to the late-war approval for the adoption of the P-38K-1 with the F15 (Allison V-1710-75/77) engines and Hamilton-Standard Hydromatic high-activity propellers. In OTL only one of these was made using the large P-38J style chin and retaining the high-drag boom radiators. Even with all that drag it was able to achieve 432mph in level flight using Military Power and was expected to make 450mph with War Emergency Power with matching improvements in range and fuel consumption (about 10%). It also had a ceiling of 46,000 feet, a max climb of 4,800 ft/minute and could make it to 20,000 feet in only five minutes. Without the full coat of pain and with the reduced drag of the NACA design modification I can only image what its performance could be. In this case the P-38K would likely replace the F/P-82 Twin-Mustang of OTL and see continued service into the early 1950’s including limited combat in Korea as bomber-escorts and Close Air Support.

    So, any thoughts on this, its feasibility, and any effects I may have missed?"

    -----------------------
    * http://www.ausairpower.net/P-38-Analysis.html (Pertinent section about 45% down in the italicized letter from Col. Harold J. Rau to “Commanding General, VIII Fighter Command, APO 637, U.S. Army”)[/QUOTE]



    Thank-you, I wasn't aware that this investigation into the P-38 compressibility problem had been conducted. It would have been a very productive and effective modification and I'm inclined to agree if the NACA mod had been developed earlier then it would have made it into production. After Pearl Harbor the pressure to produce what ever was available delayed OTL improvements to the P-38 like for example the high-activity propellers as you mentioned.

    I haven't finished reading the 1942 document yet so I have some questions for you.

    After the NACA mod had been developed the engineers still thought that dive recovery flaps would be required?

    Also with the relocation of the Prestone radiators and oil coolers to the new leading edge did the designers consider the Meredith effect when designing the new installation? Making the assumption they were aware of it at the time.

    The P-38's OTL canopy was one of its' poorer features. If they were redesigning the canopy contours could that also mean replacing it with a bubble type sliding canopy?
     
    Last edited: Jun 15, 2017
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  12. Draconis Emperor of the North Pole.

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    If you could mix both the narrative style and include technical asides on key items that would be great. But it is your story so please do whatever you are most comfortable with. This is a fascinating subject. The P-38. Such a great plane that would have been even greater but for its under developed potential.
     
  13. Draconis Emperor of the North Pole.

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    Yes. I posted one of them. This NACA investigation thread is much more comprehensive and convincing.
     
    Last edited: Jun 15, 2017
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  14. Just Leo Contrarian with a heart of gold

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    de-havilland-dh103-hornet-3.png

    A DH Hornet wing would fill the bill. Also, I was never a fan of the cruciform tail. The Swordfish fuselage proved that they knew how to build a body with an improved fineness ratio, but not for production. The aircraft was designed to fly towards 40,000 feet, but the pressurized cockpit remained an unfulfilled dream. The P-49 and P-58 were wasted endeavors. There were many improvements possible for the -38, but precious little effort to implement them. The lack of effort to implement the dive flap installation was fairly criminal. There was some discussion on second source production, but too little too late by both Lockheed and the USAAF.
     
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  15. Musketeer513 Member

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    Personally, I would like both but do what is best for you.
     
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  16. EverKing Well-Known Member

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    1) There is no explicit mention of the Dive Recovery Flaps in the NACA report, however the information about the airflow under the wing at different flap possitions is what ultimately led to their development so it is possible that they could have still been developed although they would have been by no means neccesary (assuming the NACA estimates are accurate).
    2) I haven't read any specific refereces to it but it is possible they were aware of the Meredith effect. However, if memory serves, the radiator installations in the P-38 were not well suited or designed for it producing more drag than thrust. The NACA installation would likely also be poor canidatea for Meredith thrust so it is likely a dead end for the sake of this exploration.

    3) Indeed the canopy was junk. While it never happened OTL I may explore better canopy options in the ATL.

    I think this is likely the direction I would go anyway. Some narrative, some ATL technical evaluation reports, maybe even some Encounter Reports when the shooting starts.

    Yeah, several of the British twin wing designs could be good but are beyond the scope of the PoD and this ATL. The issue with the dive flaps was that the first shipment in a C-54 was shot down by the British and they never bothered sending replacements. Then they didn't want to slow down production to integrate them into the line until all the planned blocks werw complete which meant they weren't factory installed until the P-38J-25 starting June 6, 1944...what a day! And yes, the treatment of the P-38 in the 8th AF was criminal because their disdain led directly to lost aircrew.

    Edit: sorry for all the typoes...I am on my phone instead computer at the moment.
     
  17. Archibald space jockey ! Banned

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    There is an unnerving story about the P-38 dive recovery flaps. They were loaded into a DC-4 that went across the Atlantic... only to be shot down after being mistaken for a FW-200 Condor.
     
  18. Archibald space jockey ! Banned

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    Nice TL, interesting. With a little luck, a different early P-38 history might butterfly away Antoine de Saint Exupéry disaperance and death in July 1944...
     
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  19. Shevek23 Spherical Cow-poke

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    As a lover of the P-38, a believer in its unrealized superior potential, a person saddened that it was not properly appreciated and thus its potential to escort early US bomber raids and save the lives of countless bomber crew members (not to mention recovering and reusing their OTL shot-down planes)--let me play a bit of Devil's Advocate here.

    I've seen some of the online wars between P-38 fans and their detractors, and come away more convinced by the former, especially after this most informative OP!

    But one simple point the naysayers have is clearly true...P-38 was a two-engine plane, while its eventual successor (if we assume the -38 were improved and permitted to do the escort mission) the P-51 was single engine. Thus Lightnings were inherently more costly than any single engine plane, good, bad or mediocre. If the choice was between an excellent two engine job and terrible to mediocre single engine, we just pay the higher price as part of the necessary cost of doing business with the best--except that in Jan 1942, the USAAF needed aircraft in numbers, and soon. If single engine alternatives existed that would be cost-effective, then clearly the Army would prefer that.

    I don't mean to mention this as some sort of trump card killing the -38's prospects, just as pointing out a factor that was relevant in decision making. The fact is I believe the P-38 was originally authorized under the impression it would be a superstar, just as the B-17 was hoped to be a super bomber the P-38 was to be the star fighter. But that was when war was hypothetical; once it started a panic for sheer numbers set in, and the question of whether one P-38 was worth 2 of another type--or less than 2, or more--was not transparent.

    One big advantage the P-38 offered, especially if it had indeed been modified to remove its worst drawbacks, and more appreciated hence ordered in more numbers, is that though it used twin engines, those engines were not Merlins! Not to say anything was wrong with Merlins, quite the contrary--though I do seem to recall some comparisons over ranges of altitude wherein the Allison engines, due to being turbosupercharged, had superior perfomance, while the Merlins had a mechanical supercharger. But the point here is, Merlins were good--but in severe demand therefore, so it was most excellent that the Lightning did not require them.

    I particularly like the way the twin engine layout leaves the central command nacelle to be loaded with heavy and reconfigurable arms.
     
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  20. phx1138 Bocagiste troll

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    Jun 20, 2009
    Location:
    Charlie Townsend's guest house
    TTL, it seems likely the dive-recovery spoiler (even assuming it takes OTL's duration to find the answer, which seems less probable; IMO, it'd be quicker TTL) would be on a different C-54, so not shot down. (Might be soon enough to get to production directly, in the *P-38E or -F TTL.)

    Other improvements? Turbos are hard, but without new materials, there's still reducing the rotating mass (drill the blades, so they look a bit like Swiss cheese), & (possibly) sizing issues (boost lag).

    Direct improvements to the aircraft itself? Cockpit heat is a must. Adding the wing leading-edge fuel tanks sooner would be good, but TTL, better fuel economy might butterfly them away...

    Flipside, tho: more P-38s means more headaches, with pilots who don't like twins & aren't trained in them correctly getting themselves in trouble. There was a myth going around England: if a P-38 lost an engine on takeoff, it'd kill you. It would--because the pilots weren't trained how to recover. Tony LeVier showed 'em: kill one engine, boot the rudder hard over against the dead one, crank on full power to the other & climb out to go around...
     
    Last edited: Jun 16, 2017
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