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The P-39 was the 'next gen' fighter, that was to sport a big firepower, along with great altitude performance. The later part didn't pan out, the installation of the turbo was bugged, the drag was too big, so the Bell company was suggested (told?) to ditch the turbo, do some rearranging so the USAF can have a new timely strea of 'good enough fighters, rather than to wait several years for might-have-been turbo P-39s.
Without the P-39, U.S. forces may have lost Henderson field to the Japanese, who were determined to take it back. The fierce ground attack by the P-39 gave U.S. ground forces the edge they needed to hold their ground and force the Japanese back.OK, there's a lot here, let's pick one for now...
At this point, what if the Bell company is told - this thing bites...
Make licensed P-40's, P-38's, P-51's, etc.
Without the P-39, U.S. forces may have lost Henderson field to the Japanese, who were determined to take it back. The fierce ground attack by the P-39 gave U.S. ground forces the edge they needed to hold their ground and force the Japanese back.
I honestly don't think that the P-40 could have replaced the P-39. The P-39 was a capable adversary to the Japanese fighters, like the A6M...it wasn't better, but it was well armored and could at least hold it's own in a fight AND the P-39 had the firepower to rip a KI-43 or A6M to shreds. The only shortcoming to the P-39 in early 1942, was that the Japanese had experinced pilots while the American pilots were green, yet the early encounters between the two were standoffs.Perhaps the US would have fared better with more P-40's.
Did the US spread its resources too thin on four (five including the P-51) fighters?
Should the US have concentrated resources on one or two, rather than four/five?
The P-51 probably fits into this equation as well.
The P-51 probably could have have accomplished the work of all four/five.
After the XP-39's heavy redesign, there were no further attempts in a tightly integrated turbo installation on the P-39 at all. (there were some dorsal 'saddle' pack modules tested that apparently weren't worth the low altitude performance loss and weight gain, but nothing akin to the turbo embedded in the belly as on the XP-39)The P-39 was the 'next gen' fighter, that was to sport a big firepower, along with great altitude performance. The later part didn't pan out, the installation of the turbo was bugged, the drag was too big, so the Bell company was suggested (told?) to ditch the turbo, do some rearranging so the USAF can have a new timely strea of 'good enough fighters, rather than to wait several years for might-have-been turbo P-39s.
The P-51 seems to have been solely held back by perception and bureaucratic issues. Compared to the P-39 and P-40 it had obvious value from the start in all around performance and range using the same engines. And the Army may not have shown excessive interest of funded the project when it was on the drawing board, but once the prototypes were flying, interest and production orders were pretty forthcoming. (going so far as to use the A-36 derivative to expand production beyond available 'fighter' allocation)The P-51 came out of a blue, the story is well known, and initially it did not offered anything to the USAF, at least they though it. The capability to accept the 2-stage Merlin (along with other advantages over existing fighters) quickly moved the P-51 in priority list, with new Merlin to be produced also by Packard.
I may be mistaken here, but it seems the US Army was more interested in big, powerful, potent heavy fighters than most other air forces, with less concern on production cost.
Indeed, though the P-39 and P-40 themselves weren't really in a different class of design/engineering/airframe performance than the likes of the Spitfire or Bf 109. The difference being the RAF HAD no P-47 equivalent (or F4U equivalent -but that was more an engine than airframe issue given the R-2800 MADE the Corsair and Thunderbolt and might have made the Typhoon as well -or say Bristol Centaurus being serviceable at 2000 HP in 1941 with altitude performance on par with the F4U-1's engine).Giving up on the P-47 and P-51 and trying to upgrade the P-39 and P-40 would have been flogging already dead horses by the time you get to 1943. NOT building P-39s and P-40s in 1941-42 and some of 1943 leaves with not enough planes to cover the areas of combat you are involved in. Late production P-39s and P-40s were pretty much lend lease aircraft.
Yes, and even in some alternate reality where the XP-38 never crashes and the entire program progresses a full year sooner (Lockheed tooling and production capacity expansion included), you at very least would want the P-40 in production though the C model until volume production of the P-38E/F could meet service demands (possibly along with supplemental un-turbocharged models -probably using F3R/F3L engines in place of similar engines being allocated to P-39D and P-40D/E production)The timeline for the P-47, P-51 and P-38 was within months of entry date had the AAF killed the P-39 and P-40 before Pearl harbor which would not been a very good idea
The P-39 'saddle' mount turbos seem far from the attractive option compared to more embedded arrangements, especially with a liquid intercooler. (short of that, it's not going to be practical without excess drag) Same goes for the P-40: you could certainly do better than the configuration on the YP-37, but short of a compact water-to-air intercooler the increase in drag is simply going to be too much.The weight of the turbo is not a big problem. The Problem is the size of the intercooler and the size of the ducts needed to carry the intake air and the cooling air for the intercooler. It just won't fit without some major surgery.
The extra drag on the P-39 mock ups cost around 40mph below 15,000ft. A P-39 could outrun a Zero at low altitude rather easily. With the turbo the new P-39T or P-40T may be able to out run them at high altitude but they will loose the ability to out run them at low altitude.
OK, there's a lot here, let's pick one for now...
At this point, what if the Bell company is told - this thing bites...
Make licensed P-40's, P-38's, P-51's, etc.
...
A bunch of aerodynamic problems with the basic airframe got addressed due to the XP-39 tests, and it wasn't the turbocharger but the intercooler installation that was the problematic portion of the system. (too much drag, poor location and not enough cooling capacity) That issue probably wouldn't be effectively solved without developing a water-air intercooler to replace the bulky air-to-air arrangement.
...
The P-39 is several years newer than the Spitfire or 109, and had NACA testing to help refine it, so drag improvements aren't that surprising. It's more of the same vintage as the Fw 190 though the latter is closer in size/weight to the P-36/P-40. The P-36/P-40 itself is a pretty well streamlined design for being the same age as the 109 and Hurricane, and slightly older than the Spitfire. Both the P-40 and P-39 also had better high-speed handling than the other aircraft and better all-around visibility (prior to the hooded spit) and the P-40 in particular had a slightly roomier cockpit and I believe a better heating system than the spitfire. (the P-36 also had a heater before the spitfire)
With Bell producing P-38s (and no production P-39s/P-400s), IF they could get the tooling patterns in a timely manner, expecting exactly half the production volume of individual fighters would seem realistic. Overall monetary expenditure may have been somewhat less (P-38 was not quite 2x the cost of the P-39 at similar volumes, and omitting the turbo/intercooler systems should help) but overall man-hours, material, and especially engines would be major limiting factors. If they couldn't get the tooling set up quickly, it may have been somewhat worse than that.Bell producing the P-40 instead of P-39 does not add much IMO. The P-51 is too late, the 1st non-turbo XP-39B is delivered in Nov 1939; Bell producing P-51s instead the P-63s would've make plenty of sense, though. Bell produced 939 P-39s before 1942, vs. only 208 of P-38s by Lockheed in the same time, so we'd probably see a deficit of some 500+ US-produced fighters prior 1942 with Bell producing the P-38.
You'd definitely want boundary layer separators, or similar overlapping ducting on the intercooler and any external radiators (like the P-38's tail radiators and the P-40's chin radiator) reducing turbulence and improving airflow over the radiator surfaces. (at least part of it relates to the venturi effect and has a good deal in common with NACA cowling and duct research, including those applied to thrust augmentation for rocket/jet exhaust)The turbocharger, along with 4 waste gates was a draggy affair, all sticking out in the slipstream. The intercoolers were without boundary layer separator, and without any means to control the cooling air passage - it means drag and low capacity for intercooling.
The spitfire and 109 had the best consistently improving engine upgrades too, and the Americans had better options than the P-40 and P-39, so direct comparisons are a bit more difficult. The P-39 was substantially faster than its similarly powered counterparts, in spite of being heavier. (the P-39N and Q performed better than the Spitfire V in a number of areas in spite of their engines still not quite matching the Merlin 45 ... granted, the Spit IX was in production by that point)The Spitfire aged the best, when compared with P-40, P-39 and Bf 109. We can be sure that early Spitfire (I to V) would've been even better with earlier adoption of fully covered undercarriage, faired mirror, internal armored glass and early installation of 6 exhaust stacks per side. Not sure whether deletion of snow guard on the ram air intake would've be safe for all-weather operation, deleting it gives 8.5 mph on the Spit V.
I was under the impression that the reason the P-38 suffered critical mach issues at lower speeds than contemporary aircraft with similar or thicker airfoils of similar types (including the Corsair) related to the pod/boom arrangement leading to accelerated airflow along the root section of the wings (on top of being the thickest section of the wing), so modifying the airfoil profile there alone could have dramatically impacted initial onset of compressibility problems.The Only way to eliminate the earlier Mcrit for the P-38 would have been to replace the entire wing with a laminar flow wing similar to the P-51. That would have pushed the Mcr from ~.68 to perhaps .72 given a same T/C (the P-38 23018 was a couple of percent fatter and the a/c was at ~ .25C whereas the 45-100 was 16% and a/c was at ~.45C. The immediate nose down pitch phenomena would have been delayed until the full shock at ~45% Chord with complete separation behind it - which in turn would immerse the horizontal stab/elevator in the associated increase of turbulent wake and greatly diminish elevator authority. [/B]
#1 is mostly what I had in mind with the high degree of leading edge taper on the extension intended to avoid decreasing internal volume/strength without totally obliterating the pilot's forward-downward field of view. (the engine nacelles compromised that badly enough as it was) Any delta/sweep effect would have been incidental. (as would any wing fence effect of the nacelles)1.) decrease the T/C ratio either by deepening the cord of the wing while maintain the original max Thickness, or reducing the Max Thickness while retaining the existing plan form (i.e. replace the existing 23018 to 23016 if that derived same basic internal volume required for fuel and did not require extraordinary beefing up of the wing structure (i.e. Spar weight due to requiring greater bending resistance with shallower beam heighth.
2.) replace existing conventional airfoil with Laminar Flow type with Max T/C pushed back from .25 to . 40%+ Chord.
The P-38K is the P-38J/L with modified nacelles accepting larger, broader chord propellers with slightly larger spinners. Improvements in take-of performance, acceleration, turn, and climb would have been more significant than top speed (akin to the P-47 switching to paddle props) but some gain in speed and increase in ceiling were experienced as well.Something that always gets lost in 'what if' discussions of P-38K and P-47N/J is the extraordinary requirements to modify from P-38J (in cost) by adding a Rolls 1650-7 or the change in the wing; and the GW and cost of the redesign of the P-47N over the D - is that it took ALL the evolutions of both airframes to nearly match or slightly exceed (P47N/J to P-51D) of either the P-51D or P-51H if we keep model introduction in parallel - but ALL P-47s were approximately 1.5X in delivery cost plus 1.4-1.5X in operating cost and ALL P-38s were approximately 2X in delivery and 2X+ on Operating cost.
The P-38K is the P-38J/L with modified nacelles accepting larger, broader chord propellers with slightly larger spinners. Improvements in take-of performance, acceleration, turn, and climb would have been more significant than top speed (akin to the P-47 switching to paddle props) but some gain in speed and increase in ceiling were experienced as well.
The same could apply to the exposed hot section of the turbocharger, a duct shrouding that portion may have both aided cooling of the turbine/exhaust and reduced drag. (possibly improved jet thrust from the waste gates and turbine exhaust as well)
I'm actually surprised this wasn't tried on the P-38, including the P-38M where it would have hidden the exhaust glow at night. (or maybe it was tried and omitted from production for other reasons)