I was reading about the Bell P-59), which was the first jet fighter plane developed in the USA. It was a huge disappointment-when tested, it wasn’t as fast or as agile as the regular piston engine fighters.
My question: was aerodynamics a sufficiently developed science (in 1942), such that the design engineers would have know that they were using a bad design?
From what I read, they went directly from a mock-up to a prototype-maybe the development was too rushed? The other amazing thing I learned-the GE-built jet engines (based upon the British Whittle engine) had very short service lives-some of them only lasted 5 hours! When did jet engines appear that had reasonable service lives?
Lots of questions! As a side note, I was an aircraft mechanic for over 20 years and share the same last name as the British inventor of the jet engine, although I can’t find any family relationship.
Anyway, like any new invention, the jet engine had a lot of promise in the long run but wasn’t all that much better at first especially when it came to longevity. One big problem was the lack of proper metals and other materials that could take the heat produced by a jet engine. Plus that particular type of engine faintly resembles the modern jet engine as the airflow was curved around quite a bit through pipes. Modern jets are more of a straight through design. Modern materials and a lot of learning made jet engines more reliable.
As far as aerodynamics, often they basically put a jet engine inside an existing airframe for testing. Then they came up an airframe specifically for the jet engine based on what they discovered. Aerodynamics at the greater speeds allowed by jet engines wasn’t well known especially when they got closer to the sound barrier.
One prime example was the original F-102 in the 1950s. It should have been able to break the sound barrier from what was known at the time. However it barely could. Then a guy named Whitcomb came up with the idea of the wasp-waisted fuselage (AKA area rule). The middle area of the fuselage was narrower than the front of the aircraft. This allowed for the shock waves to diminish which gave the F-102 the ability to go through the transonic region then into supersonic flight.
My understanding, which might be a bit garbled, is that most of the early jet fighters were limited by underpowered engines. Most improved with engines bought from the more-advanced British or with improved US-design engines. Transsonic issues weren’t all that important (as a limiting factor) until the late 1950s.
The P-59 did use two Whittle design engines, made by GE in Lynn, MA. Whittle used a centrifugal-flow system, looking something like a large turbocharger with vaned wheels for both the compressor and turbine. While less of a stretch technically from existing practice than the axial-flow architecture used by BMW and Junkers, it meant a large frontal area and a lot of drag. Plus, thrust growth would mean even larger frontal area and even more drag, defeating the purpose. Even before the Korean War, centrifugal flow had been recognized as an evolutionary dead end, and it is now seen only in the smallest machines.
The P-59 was slow because it was underpowered and draggy, and useless as a fighter because it was too unstable directionally to be a good gun platform (a larger tail might have fixed that, though). So was the Gloster Meteor, its British counterpart. The Me-262 was a much better war maching mainly because it had axial flow engines.
This. The P-59’s engines only produced a total of 4000 pounds of thrust, giving it a max speed of 413 MPH; the P-51, driven by a piston/prop, was actually slightly faster.
Note too that the P-51 was substantially lighter, by a couple thousand pounds, which is probably a big factor in its greater aerobatic agility.
The engines soon got bigger, and the aerodynamics got better. In addition to only having 4000 pounds of thrust, the P-59 did not have swept wings. Compare to the F-86 that came along just a few years later: 5900 pounds of thrust from a single engine, and a swept-wing design that allowed a top speed of nearly 700 MPH.
They really didn’t understand what alloys they needed for early jet engines. The first US operational jet was the P-80 and after 10 hours their engines needed to be rebuilt.
The P-80’s airframe was deliberately absolutely conventional; they wanted to spend their time troubleshooting jet engines, not odd aerodynamic behavior. So to some extent its mediocrity is intentional.
The lack of swept wings was a big part of the problem. The Germans were ahead on that and we learned a lot from them, but it took a while. I have a great article that I’ll try to dig up about Grumman’s struggles in producing their first swept wing plane, the Cougar.
It started as a variant of the Panther, but was pretty much a whole new aircraft by the time they were done. Corky Meyer, their chief test pilot, had a lot of trouble with the Cougar, including nearly spinning one into Long Island Sound near Oyster Bay. Figuring out swept wing aerodynamics kept them very busy.
Interestingly, the F-86 was based on the P-51 Mustang airframe; the main difference was the swept wings (and the power plant).
Speed wasn’t the reason the ME-262’s wings were originally given sweep:
[QUOTE=Wikipedia]
Although the Me 262 is often referred to as a “swept wing” design, the production Me 262 had a leading edge sweep of only 18.5°, too slight to achieve any significant advantage in increasing the critical Mach number.[20] Sweep was added after the initial design of the aircraft, when the engines proved to be heavier than originally expected, primarily to position the center of lift properly relative to the center of mass. On 1 March 1940, instead of moving the wing backward on its mount, the outer wing was repositioned slightly aft; the trailing edge of the midsection of the wing remained unswept.[21] Based on data from the AVA Göttingen and wind tunnel results, the middle section’s leading edge was later swept to the same angle as the outer panels.
[/QUOTE]
Sweep turned out to be advantageous at high speeds, though, and became the norm.
Addressing the thread’s title: keep in mind many, perhaps most, new “secret weapon” technologies were flops in the military sense. Even ones that worked were often unable to affect change in the military situation.
It’s only hindsight and selective reporting that makes certain programs and certain weapons stand out, giving us the illusion that weapons development could be guided smoothly toward a specific and timely outcome if only we were smart enough.
I believe you are mistaking the North American FJ-1 Fury for the F-86. The FJ-1 had wings and empennage derived from the P-51. The XP-86 started out as a land-based FJ-1, but the straight wing and conventional tail surfaces limited its top speed so the whole shootin’ match got redesigned.
What’s the concensus on the ME-262? I hear that it was a wonderful fighter-when is was working (the Jumo jet engines also had a short life).
The Arado fighter bomber was neat though (the pilot had full frontal vision ..why wasn’t this design emulated?
There was a lot of wavering at the highest levels on the role of the ME-262. With some minor modifications, it was capable of being used as a fighter or a bomber. The problem was that as a fighter, it’d be used in a defensive role and to Hitler that would be defeatism. So it got stuck being modified and crews were trained to use it in an offensive (bomber) role. Then circumstances changed enough for Luftwaffe higher ups to convince Hitler that it could be best used, at the time, as a fighter. So they had to modify the planes for an air to air role and retrain the pilots. So much time was lost in deploying them.
As for the Arado, only 210 were built. Engines weren’t all that reliable, they needed RATO boosters to take off, and fuel was only intermittently available. They were used to bomb bridges crossing the Remagen that the allies had captured. They were more often used as fast reconnaissance platforms and there was a radar equipped night fighter varient. They only went operational in the fall of 1944, so they didn’t have much time to make much of a mark in the war.
History Channel program said the F-86 used P-51 design, “but with swept wings” (and eventually a redesigned tail), so I guess they count the “redesign” as just a tweak to the P-51, or perhaps they’re stretching a bit.
The Nazis developed many technologies that could have significantly changed the outcome of the war, and in nearly every case it was AH himself who mismanaged, second-guessed and crippled the programs into uselessness.
Is it fair to say that the Allies (largely the US and England) got every significant technological advance into combat (including back-room combat like breaking Enigma), while the Nazis, who had technological superiority and a running head start, squandered nearly every technical advance they developed?
Quote:
The Germans were ahead on that and we learned a lot from them, but it took a while. I have a great article that I’ll try to dig up about Grumman’s struggles in producing their first swept wing plane, the Cougar.
While it was true that the Germans had some of the best aeronautical engineers (most of them under Prof. Ludwig Prandtl at Goettingen University), the USA also had excellenT designers…we also had Dr. Theodore von Karman, who was tops in the field. Dr. Prandtl was a bit of an odd duck-he was interested in theoretical modelling, and diverted his staff from actual practical application work. Hitler (as noted) also interfered and caused many projects to go awry
I found the article, which is called “Curing Cougar Conniption Fits”, by Corky Meyer. It appeared in the June 2003 issue of Flight Journal, but I can’t find it for online viewing.
Meyer talked about the many problems Grumman had learning swept-wing aerodynamics. One of the first things they did was fly a modified Bell P-63 with swept wings. Then in testing the Cougar they ran into a lot of trouble. Kind of amazing to me that it worked in the end.
Well, there’s your problem!
The History Channel is famous for getting its facts wrong.
P-59. I meant to say P-59. :smack:
Bonus question: When did they stop calling it the P-80, and start calling it the F-80?