P-47 Turbo super charger

[Tony Drago]

 Get and engine and a supercharger. Build the plane around it. A beast is born.

[Dan McEntee]

   You look at that, and even with the knowledge that you know what it's for, and you just say, "How??" Well, you just need enough sheet  metal!!  It kind of looks like the duct work coming off the old Bryant furnace at Grandma's house!!
   But I think that is how they really did it!! Engineer the minimum ducting for max output, then stretch the Seversky P-35 enough to fit around it!!
 
  Type at you later,
   Dan McEntee
 
   

[Brett Buck]

Get and engine and a supercharger. Build the plane around it. A beast is born.

   P-38 was pretty much the same deal, it was completely built around the Allison with the full-up turbosupercharger system. It more-or-less had to have twin booms to fit it all in. As installed, it had *much* more power than the Merlin at all altitudes. It was really complicated to operate, but the higher performance exacerbated the compressibility issue - which would have been an issue with a lot of other airplanes, but they didn't have the performance.

    The other Allison applications (P-40, A-36/P-51A, and particularly the P-39) had partial systems without the turbo and the single-speed supercharger, and were dogs.

    I note that they looked at replacing the Allisons with Merlins for the P-38, but while it was lighter, it gave up an amazing amount of power at high altitudes, far more than it gained by better aerodynamics.

    Brett

[Paul Smith]

I could have gotten the P-38 from 450 MPH to 575 MPH with an hydraulic stabilator.
The company that developed the SR-71 did not know anything about transonic flight in the 1940's.  Like Tim Allen they thought that MORE POWER was the answer to everything.

[Brett Buck]

I could have gotten the P-38 from 450 MPH to 575 MPH with an hydraulic stabilator.
The company that developed the SR-71 did not know anything about transonic flight in the 1940's.  Like Tim Allen they thought that MORE POWER was the answer to everything.

   They knew, there was a long article in the late, lamented, "Lockheed Horizons" where Kelly was talking about it in 1940. The issue was that while it was good enough for any level flight speed it could reach, any sort of dive at high altitudes quickly got it in trouble. What it needed was a thinner wing section, which was part of the plan for the P-58, but that was killed by engine development failures, like a lot of other airplanes at the time. Redesigning the P-38 was more-or-less out of the question by that point, clearly it was neither required nor cost-effective. Instead, Kelly proposed the P-80 in an unsolicited bid with a typical Skunk Works availability schedule, far better than any piston-engine fighter at the time.

   I have heard compelling arguments that had the USAAF not been run by the Bomber Mafia (who prevented the development of drop tanks for the P-47 and P-38 for a very long time on doctrinal grounds), both airplanes could have been decisive in the daylight bombing campaign, which was more-or-less a disaster until the P-51 with internal extra tank and drop tanks showed up in 1944.  Very shortly afterwards, the Luftwaffe was decisively defeated. The P-38 had the range to cover almost all the missions just with the internal fuel, the problem being that managing the engines was proving too difficult with a lot of reliability issues. By the time they sorted that out, and the Bomber Mafia had to admit they had been wrong, the time had passed. The P-51 was plenty good enough, it was far cheaper. The "good enough" factor is why they never used the Corsair in Europe in any numbers - it was marginally better but not required if you already had hundreds of P-51s.

  The P-38 did very well in the Pacific where it was used at low-medium altitude and many of the pilots in the Pacific preferred it over the Mustang.

      Brett

     

[Bill Schluckbier]

It is true that the P-51 gets a lot of credit but something that gets forgotten about the bombing campaign is that at the start, the P-47 also faced a more capable German air-force.  By the time the P-51s arrived, the German force was less capable due to attrition losses of experienced pilots mostly thanks to the P-47. Even with the drop tanks, the P-47 range was limited by its internal fuel capacity; you could only go as far away from the base as long as your internal fuel could carry you back.  Once you dropped the external tanks; the fight and the ride home was going to be fully dependent on your internal fuel.  I have Gabrieski's book and his first impression of the P-47 after having flown Spitfires was rather interesting.

[Steve Helmick]

"The other Allison applications (P-40, A-36/P-51A, and particularly the P-39) had partial systems without the turbo and the single-speed supercharger, and were dogs."  (from Brett's post)

Regarding the P-39, I recall reading someplace that after WWII was over, somebody (probably an air racer) got a P-39 and fitted a P-51 propeller to it, radically improving performance. Looking at the propellers on a lot of WWII fighters is interesting. Some look to me like they'd be terrible, such as the P-39 and Bf-109.  Steve 

[Brett Buck]

"The other Allison applications (P-40, A-36/P-51A, and particularly the P-39) had partial systems without the turbo and the single-speed supercharger, and were dogs."  (from Brett's post)

Regarding the P-39, I recall reading someplace that after WWII was over, somebody (probably an air racer) got a P-39 and fitted a P-51 propeller to it, radically improving performance. Looking at the propellers on a lot of WWII fighters is interesting. Some look to me like they'd be terrible, such as the P-39 and Bf-109.  Steve

    The single-stage supercharger version of the Allison was more powerful than the Merlin at low altitudes. What killed it in the P-40, P-39, and A-36/P-51 was that it couldn't keep up at higher altitudes. This was fine for the P-40 and A-36 applications and those were fast airplanes for relatively low-altitude attack and China/Burma fights with the Japanese. It was hopeless at high altitudes typical of European theater fighter applications. The P-39 originally had the turbocharger, too, and the prototype was excellent at all altitudes. What killed was a very bad decision by the USAAF at Wright Field. They decided that they didn't want the turbocharger because it required a scoop and exhaust exit, and they somehow imagined that reducing the drag would make up for the lack of power. That might have been truish at low altitudes but was insanely wrong even at moderate altitudes (like above 15,000 feet), so, same problem. The P-39 worked very well on the Eastern Front for the Russians, which was mostly low-altitude combat, where it was used for air superiority - not tank-busting as sometimes stated - since it was better than most of the other airplanes in all respects. The Russians also found it to be a *vast* improvement over what they were used to in terms of comfort, equipment, the radios worked, etc., like a lot of the lend-lease stuff they got from the USA (Studebaker trucks, Sherman tanks (until they got T-34s) and a lot of other stuff).

     They figured it out for the P-63 with a 2-stage supercharger (still not the turbo) or a Merlin, but as with a lot of those sorts of things, it was surpassed by many other airplanes and not really needed. It was another big upgrade for the Russians who made good use of it but not for the US.

      Brett