XP-39 II - The Groundhog Day Thread

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Your comment on there being other units and Axis allies that need to be taken into account was well founded and prudent; I would have done the same. Fortunately Kaminsky seems to have applied due diligence.
 
Briefly from the book "P-80/F-80 Shooting Star" by David R. McLaren. The Lockheed Aircraft Corporation indicated that they were interested in the "jet propelled aircraft program" but was officially discouraged by the War Department wanting Lockheed to continue on with the P-38 and other projects. Verbatim from the book..."Finally, in 1943, their Chief Research Engineer, Clarence "Kelly" Johnson was approached by Army Air Force officials while he was observing some P-38 armament trials at Elgin Field, Fl. and was informed that the Air Force was now interested in seeing a proposal from Lockheed for a new jet propelled fighter. The idea for which had never been far from Johnson's mind to begin with, and on the way back to California, Johnson roughed out his thoughts on foolscap. Johnson then presented his sketches to Lockheed's Vice President and Chief Engineer, Hall L. Hibbard, and other Lockheed representatives, and with their blessings, he flew back to Wright Field, Ohio later in the month to present a rough draft of what Lockheed had in mind, their Model L-140, to the Air Force.
 
Mad Dog said:
Oh no, someone else is repeating that "completely and utterly false" story! How dare they! Quick, Flyboy, go sort 'em out!
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Yep, saw that on several other sites, I'll raise the ante, utter BS! So run with that! Wright Pat asked Lockheed to come up with another turbine design. As Lockheed was already working on the L-133, the course changed after Kelly Johnson met with AAF officials and promised an airframe in 180 days. As stated, the XP-80 was ready in 143 days.

If you look at the L-133, it's wings are similar to the XP-80 (and P-38). There is a slight resemblance to the XP-59B concept drawing but that's where it stopped. The XP-80's design began around the dimensions of the H-1 engines and other production components were adopted where and when possible.

As stated, the XP-80's nose was based on the P-38 nose section. With the P-38 already in production, there was tooling available for fabrication. Although the nose sections were similar, IIRC they were not interchangeable.
 
P-39 Expert said:
Well, a Spitfire V weighed 6600lbs and had a 1200hp engine. A 109G weighed 7000lbs and had a 1475hp engine. An early P-39D/F/K/L weighed 7650lbs and had a 1150hp engine. See the power/weight ratios? EarlyP-39 was overweight.
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Again, based on what? Yes, we have power to weight ratios and we can compare them to the contemporizes of the day so where's the "line" to consider these aircraft were "overweight"?
 
Must admit I'm a bit confused by the whole "power to weight" comparison given that propulsive power for a given engine hp will vary depending on the gearing and propeller, while the weight component really only becomes a factor as a proportion of available lift generated by the flying surfaces.

Or am I missing something?
 
When the AAF said that the L-133 was a bit too much for them and asked Lockheed to build something more conventional without canards, Kelly Johnson designed a new single-engine fuselage and took the complete L-133 wing set and grafted them onto the new fuselage. He had already expended the effort to design the L-133 wings, they were still "current," as far as airfoil went, and wasn't about to do it again.

In hindsight, they may have been better off with the L-133 airplane. It would have been at least interesting to see how it would have performed. I seriously doubt the L-133 would have been a turkey like the XP-55 Ascender was. Alas, it never got built. The only real innovation we saw from the L-133 design was the production of the first axial-flow turbojet designed in the United States, the L-100 / J-37. Below is a pic of one we have at the Planes of Fame Museum.



It was actually built only as a mockup and never ran, but it definitely DID get the U.S.A. into axial-flow turbojet engine design. The test engine could not be made to start running on its own, and only actually turned over on the power of the starter. Nobody has gone back with some engineering talent to see what the issue was because engine development passed the L-1000 rather rapidly.
 
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When was development started on L-1000 engine?
 
I would say power to weight is entirely based on what the other guys are building. The Wildcat would have had a fine power to weight ratio if the Zero had weighed 9,000 pounds, but as it was the Wildcat and P39 and P40 were all a bit porky
 
FLYBOYJ said:
Again, based on what? Yes, we have power to weight ratios and we can compare them to the contemporizes of the day so where's the "line" to consider these aircraft were "overweight"?
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pinsog said:
I would say power to weight is entirely based on what the other guys are building. The Wildcat would have had a fine power to weight ratio if the Zero had weighed 9,000 pounds, but as it was the Wildcat and P39 and P40 were all a bit porky
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Exactly. Power to weight will affect climb more than any other measurement. Early P-39D/F/K/L P/W ratio was 18% higher than Spitfire V and 29% higher than 109G. Was quite overweight. Less weight improved climb, which was what the early P-39D/F/K/L needed most. Later N model with more powerful engine climbed very well.
 
Sorry, but please go look at the P-80 then look at the L-133 - not only is the P-80 wing much, much smaller (38ft 9in vs 46ft 8in), it is completely different shape. The P-80's wing is narrow and straight with slight double taper, whereas the L133's wing is a conformal double triangle with engines buried in the roots. I suspect the idea that anything was carried over from the L-133 came out of the Lockheed marketing department. The idea that Lockheed miraculously converted the L-133 into a new design that was nothing like the L-133, but a lot like the XP-59B proposal they claim they ignored, all in 143 days, is a massive pile of male bovine manure.
 

Are you basing this on your highly calibrated eyeballs or are you really good at guessing loft dimensions based on professional experience.
Mad Dog said:
The idea that Lockheed miraculously converted the L-133 into a new design that was nothing like the L-133, but a lot like the XP-59B proposal they claim they ignored, all in 143 days, is a massive pile of male bovine manure.
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Well go get your shovel - I worked with people in the mid 1980s who were on the XP-80 program and it was designed from the ground up. The only thing Lockheed got from Bell was a great opportunity based on their failure to further their basic design. Had Lockheed actually used a Bell design or any engineering data there would have been a paper trail documenting this and the AAF would have had to approve it, so since you're talking about "male bovine manure," "SHOW US THE BEEF"!!!
 
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