Why not a jet driven P-38?

A P-38 called the Black Pearl?

Kilroy Jack Sparrow wasn't around in WWII. <[:{0

kool kitty89 said:

I'm pretty sure the airforce regected the design because of its radical desicn. (as they perfered a more conservative approach and Lockheed had a hard enough time getting them to accept the P-38 design)

Earlier you posted that the P-80 used the P-38's wing, later you said it used the L133's, so which is it?

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The P-80 used the L133's wing - the P-80 also used the wingtips from the P-38 as well as the nose (although it was turned upside down)

Oh, thanks for the clarification.
Still, does anyone have coments on the impoved compressibillity and buffeting characteristics of the later models I mentioned a few posts back?

I know we've reasoned-out all the reasons of why the P-38 was not converted to jet propultion but here's a website full of alternate configurations of the Lightning just for fun: Translated version of http://www.kristofmeunier.fr/

Impressive site, what an imagination and effort this guy put in! Some of his designs are really fantastic.

Kris

And based on some of them a configuration of jet engines slung under the booms looks feasible, and it might have been useful as such as an intrim measure for the P-80, though fuel load might still be insuficent.

GE J-31 engines could be used as there were a surplus after the Airacomet was canceled, and from the figures I've seen several hundred J-31 engines were produced (around 300 from what I remember) and with less than 60 production Airacomets this would have left a good amount of spare engines.

With the late model J-31 producing 2000 lbf thrust each this would give a decent thrust-to-weight ratio. Assuming you subtract the diference beween the conventional engines an coresponding equipment (radiators turbochargers, etc), which were, with both engines, over 4000 lbs (compared to the J-31 with only 850lbs each) this would bring the empty weight down to about 10,000 lbs, so a respectable loaded weight would be around 15000 lbs. This would give a thrust/weight of 0.27 which is decent, considdering the Me 262's was 0.28 (it compensated with its good aerodynamics). Assuming max weight is arround 17,000 lbs the thrust/weight would still be over 0.20. But drop-tanks would be a must to provide adequit range, but as said before most of the high-speed problems with the P-38 had been remeded and such a plane wouldn't be going much more than 500mph aniway.

If mounting the jet-engines under the booms, it would be necessary to angle the jet exaust pipes slightly outward as to eliminate jet-wash on the tail-section.

The P-38 also had a better ammo capacity than the P-80, especially in early models.

I found this on wikipedia: "Buffeting was another early aerodynamic problem, difficult to sort out from compressibility as both were reported by test pilots as 'tail shake'. Buffeting came about from airflow disturbances ahead of the tail; the airplane would shake at high speed. Leading edge wing slots were tried as were combinations of filleting between the wing, cockpit and engine nacelles. Air tunnel test number 15 solved the buffeting completely and its fillet solution was fitted to every subsequent P-38 airframe. The problem was traced to a 40% increase in air speed at the wing-fuselage junction where the chord/thickness ratio was highest. An airspeed of 500 mph at 25,000 feet could push airflow at the wing-fuselage junction close to the speed of sound. Filleting forever solved the buffeting problem for the P-38E and later models."

So since they solved buffeting and compressability problems at speeds of 500+mph (which the P-38 could manage in a dive) maby a jet version would have been workable. Even if you slimmed down the (now engineless) nacelles and booms for less drag there'd still be plenty of room for fuel to increase capasity which could bring range up to acceptable standards. Still, it probably wouldn't reach 600mph, but even the P-80A barely made it past 550mph in level flight.

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I wouldn't rely on Wikipedia too much. The P-38 was restricted to 460 TAS at 20,000 ft, 440 TAS at 30,000 ft. The manual notes that these speeds could be exceeded by 20 mph if the dive recovery flaps were deployed.

That's a pretty low limit for a jet fighter. The ME 262 or Meteor III could exceed that in level flight, let alone a dive.

I'll agree with that, though there were many better alernateves to the P-38 airframe and the XP-80 was already in the works in 1943 so redesigning the Lightning was pointless. Also the F-84 Thunderjet was originally designed around the Thunderbolt airframe, though in the end it shared few, though some similarities.

Also what units are those TAS measurements in?

It's too bad Bell didn't modify the wings of the P-59 as they were the main problem. Even without altering the thickness the wings could have bees shortened by 2ft each (preferably at the roots) bringing the span down to 41ft. This would inprove roll rate, maneuverabillity, and decrease drag (increasing top-speed). Shortened wings would decrease glide capability, but this was only useful for testing unreliable engines. They would also lessen float on landing. The shortened flaps could be redesigned to double as airbrakes, further improving landing and controll characteristics. The thick wings could have also been used to hold fuel, which I dont think was ever done.

Without the wing modifications, the P-59 had a very high flight ceiling (over 46,000 ft) and could have made a good high altitude recon plane, though the poor visibility through the canopy would be a drawback. Mayby it could have performed Photo recon.

A P-59B converted for high-altitude recon could have prooved to be symilar, if somewhat inferrior, to the Ar-234B (in recon configuration) though I think the P-59 had better low altitude performance (especially in terms of fuel consumption).
The P-59 also had a better offensive armament, though with only 200 rounds in each of its 3x .50 caliber guns gave it only ~10 sec of firing time (same as the P-80A but with half the firepower). It also had a 37mm M4 cannon, but with only 44 rounds and a rof of only 150 rpm it had limited usefulness. The overall armament was sumilar to Bell's P-39 and P-63, though their firepower was suplimented by underwung gun pods (a total of 4 .50 cal guns), their guns had slightly more ammo, while the cannon generally had less.

It also had a decent bomb/rocket load of 2x 1000lb bombs or 8x 60lb rockets, though I'm not sure these could be carried with the drop tanks but I think they could. With drop tanks the P-59B had a respectable range of 950 miles, but without the droptanks the range was less than 500 miles, limiting its usefulness as a fighter-bomber.

Is the TAS in mph or knots?

Sorry, missed the question first time. MPH.