Me262 vs. P-80 (1 Viewer)

[swampyankee]

The training required for flying jets is primarily on approach and landing, where high residual thrust can result in floating down the runway, vs landing, and slow power lever response can convert aborted landings into crashes.

I also think a lot of the vaunted and largely fictitious German technological "superiority" is because they fielded things like jet aircraft at a stage no one else would consider them ready for service. One rather basic example is the Me262, which engine life that was so poor that its level of serviceability was barely acceptable, even in the desperate state Germany was in at the time.
[added in edit]
The P-80 was taking longer to field because the USAAF wasn't desperate; it wasn't having the crap beaten out of it by a functionally infinite number of high-performance aircraft and the US didn't need to worry about its cities being turned into rubble while its army was being ground down in the East, fighting, and losing, a defensive action in Italy, and already lost in North Africa.

 

[drewwizard]

Really? The turbine, especially the early ones required a lot of training. Pushing the throttle too fast stalled the turbine and flamed out the engine. Acceleration was very bad but constant. Really bad when you misjudge the landing approach and the jets higher stall speed.
The Germans found out bomber pilots made the best ME-262 pilots because they had to unlearn less. Tactics were completely different in the original jet fighters because of the way a turbine worked. High angles of attack stalled the engines. That funny nose on the F-86 had a reason. Once you bleed off energy, it was a long time to get speed and altitude back. Killed a lot of early jet pilots in combat trying to play in a turning battle. Engine controls were not automated like it is today.

The original P-59 (an experiment that flew like a dog) was powered like the meteor with a Centrifugal flow turbojet. The British engine. After review of captured ME-262s axial turbojet and with the help of the scientists who made them work, GE resurrected it's origin axial turbojet program and added the fixes. The US had Hastalloy - B, and the Germans created an aluminum coating and were experts on cooling the turbine blades. (The German response to get around limited supply of high temp alloys).

Here is a quote from the P-80 Wiki page.
After the war, the USAAF compared the P-80 and Me 262 concluding, "Despite a difference in gross weight of nearly 2,000 lb (900 kg), the Me 262 was superior to the P-80 in acceleration, speed and approximately the same in climb performance. The Me 262 apparently has a higher critical Mach number, from a drag standpoint, than any current Army Air Force fighter."[6]

and that's with the new GE engine. The swept wing and cleaner lines made the difference. The P-80 was a little more reliable, but killed pilots like Richard Bong just the same. (Bong didn't engage the auxiliary fuel pump, when the primary failed causing the engine to die at low altitude. No engine in a jet and they fall like a rock. Inexperience in an early jet (P-80) killed Bong and a lot of early ME-262 pilots also)

 

[swampyankee]

Really? The turbine, especially the early ones required a lot of training. Pushing the throttle too fast stalled the turbine and flamed out the engine. Acceleration was very bad but constant. Really bad when you misjudge the landing approach and the jets higher stall speed.
The Germans found out bomber pilots made the best ME-262 pilots because they had to unlearn less. Tactics were completely different in the original jet fighters because of the way a turbine worked. High angles of attack stalled the engines. That funny nose on the F-86 had a reason. Once you bleed off energy, it was a long time to get speed and altitude back. Killed a lot of early jet pilots in combat trying to play in a turning battle. Engine controls were not automated like it is today.

The original P-59 (an experiment that flew like a dog) was powered like the meteor with a Centrifugal flow turbojet. The British engine. After review of captured ME-262s axial turbojet and with the help of the scientists who made them work, GE resurrected it's origin axial turbojet program and added the fixes. The US had Hastalloy - B, and the Germans created an aluminum coating and were experts on cooling the turbine blades. (The German response to get around limited supply of high temp alloys).

Here is a quote from the P-80 Wiki page.
After the war, the USAAF compared the P-80 and Me 262 concluding, "Despite a difference in gross weight of nearly 2,000 lb (900 kg), the Me 262 was superior to the P-80 in acceleration, speed and approximately the same in climb performance. The Me 262 apparently has a higher critical Mach number, from a drag standpoint, than any current Army Air Force fighter."[6]

and that's with the new GE engine. The swept wing and cleaner lines made the difference. The P-80 was a little more reliable, but killed pilots like Richard Bong just the same. (Bong didn't engage the auxiliary fuel pump, when the primary failed causing the engine to die at low altitude. No engine in a jet and they fall like a rock. Inexperience in an early jet (P-80) killed Bong and a lot of early ME-262 pilots also)

High performance aircraft tend to have quite high wing loadings, but the first generation jets weren't that much higher than the last generation fighters: the P-80C's wing loading was only about 5% greater than the P-51D's (at MTOW). The P-80 probably had a better glide angle than the P-51 and a comparable sink rate.

The other highlighted text is quite true, and required development of fuel controls, which were -- until FADECS were developed -- analogue computers using fuel (Hamilton Standard a primary proponent), air, cams and gears, or even analogue electronics were required because turbine engine behavior is very non-linear and optimum compressor performance requires being pretty close to the surge line and Fanno flow means the compressor's operating line moves outside of the stable range. It could be a pain to get this to work right, especially pre-FADEC, where a change the fuel vs pressure vs rpm curve would require a cam design and about 2000 hours of engineer time.

 

[wuzak]

The original P-59 (an experiment that flew like a dog) was powered like the meteor with a Centrifugal flow turbojet. The British engine. After review of captured ME-262s axial turbojet and with the help of the scientists who made them work, GE resurrected it's origin axial turbojet program and added the fixes. The US had Hastalloy - B, and the Germans created an aluminum coating and were experts on cooling the turbine blades. (The German response to get around limited supply of high temp alloys).

Here is a quote from the P-80 Wiki page.
After the war, the USAAF compared the P-80 and Me 262 concluding, "Despite a difference in gross weight of nearly 2,000 lb (900 kg), the Me 262 was superior to the P-80 in acceleration, speed and approximately the same in climb performance. The Me 262 apparently has a higher critical Mach number, from a drag standpoint, than any current Army Air Force fighter."[6]

and that's with the new GE engine. The swept wing and cleaner lines made the difference. The P-80 was a little more reliable, but killed pilots like Richard Bong just the same. (Bong didn't engage the auxiliary fuel pump, when the primary failed causing the engine to die at low altitude. No engine in a jet and they fall like a rock. Inexperience in an early jet (P-80) killed Bong and a lot of early ME-262 pilots also)

The XP-80 flew with the Halford H-1 (de Havilland Ghost) turbojet borrowed from the de Havilland Vampire program after destroying the first engine that had been given to them.

Production P-80s used the J-3, an improved J-31 (based on the Whittle W2B/23), replacing the reverse flow combustors with straight through type (like the Halford H-1). The J-33 was developed by GE but produced by Allison.

The T33 used the J33, the F-94 Starfire used a J48, built by Pratt & Whitney, but designed by Rolls Royce as an enlarged Nene.

So none of the production versions of the P-80 family used an axial type jet. They all used centrifugal compressor types, essentially based on Whittle and Halford's designs.

I can't see that GE had worked on an axial turbojet prior to being asked to produce the I-16/J31. They did design the T31 and J35 late in the war.

In Britain AA Griffith had produced a paper on using aerodynamic principals to design blades in an axial compressor in 1926, including a proposed turboprop aircraft engine.

In the following years Griffith produced a compressor to test his principals (1928), experimented with axial flow compressors (including a counter rotating example) and worked with Hayne Constant and Metropolitan Vickers (Metrovicks) to design the Metrovicks F.1 (after originally designing a turboprop). This was on the test bed in 1941 and flew suspended beneath a Lancaster in 1943.

The follow-on F.2 series was to fly in the prototype Meteor in late 1943 - before the P-80.

In 1939 Griffith moved to Rolls-Royce in order to work on axial flow jets.

Meanwhile, Armstrong Whitworth were told to stop work on their piston projects (Deerhound and Wolfhound) in order to produce an axial flow jet design, the ASX.

After the war AW took over the Metrovick engine program, developing the F.9 into the Sapphire. The Sapphire was produced in the US as the Wright J65.

Westinghouse made the J30, an axial flow engine of entirely US design. It first ran in 1943, and first flew suspended under an F4U in 1944.

So, neither the British or the Americans had to wait until the defeat of Germany to produce axial flow turbojets or turboprops.

 

[FLYBOYJ]

Really? The turbine, especially the early ones required a lot of training.

And again you're wrong.

There was a minimal ground syllabus and a few hours in the air for most if not all of the early jets that entered service, to include allied aircraft. Read about "Watson Whizzers," they were flying captured German jets with just a briefing from ground crews and some ground instruction from cooperating captured German pilots. There's a few of us here who have flown recip aircraft and jets, yes there are differences but nothing that can't be overcome with just a few hours of training. Yes, the early jets could be a bit squirley and even dangerous it you let the aircraft get ahead of you, especially on landing, and yes, early jet engines were susceptible to flame out if you pushed the throttles up too fast, but guess what? Some 2nd and 3rd generation jet trainers do the same thing and its a matter of learning the aircraft and again a few hours of flight training is all that's needed if you were already a seasoned pilot. It wasn't until 1948 when the T-33 entered service when there was a dedicated jet training and conversion program that had a detained syllabus for both ground and air instruction.

So if you have a reference to show us other then an Osprey book that says "the turbine, especially the early ones required a lot of training," I'd like to know what that training was and how longit took?!?!?

 

[FLYBOYJ]

Inexperience in an early jet (P-80) killed Bong and a lot of early ME-262 pilots also)

No, forgetting to complete a task.

Bong had almost 5 hours (12 flights) in the P-80 when he was killed which by WW2 standards was plenty of time for jet conversion. The aux pump he forgot to turn on was a quick mod Lockheed was just starting to implement as 10 months earlier test pilot Milo Burcham was also killed from the primary fuel pump failing. During this time The P-80A was being modded as quickly was the aircraft was being built and its possible that there wasn't even a written procedure in place on where and when to turn on this pump. Some folks were even cautious about even using it because if recall it was a converted hydraulic pump manufactured by Pesco Aircraft Products. I also read that one of the Lockheed mechanics told some of the AAF acceptance pilots that "it wasn't important." Around 1989 I interviewed Tony LeVier and he told me had he had a chance to initially brief Bong instead of one of the other production test pilots, this accident might not have happened, but with the pace of production and the war still going on, chance briefings were many times a luxury.

Bong "forgot" to do a task that killed him, this wasn't due to JET inexperience as there have been many high time pilots who "forgot" to do a task (or ignored something on a checklist) that got them killed.

From Wikipedia

"At the time of the crash, Bong had accumulated four hours and fifteen minutes of flight time (totaling 12 flights) in the P-80. The I-16 fuel pump was a later addition to the plane (after an earlier fatal crash) and Bong himself was quoted by Captain Ray Crawford (another P-80 test/acceptance flight pilot who flew the day Bong was killed) as saying that he had forgotten to turn on the I-16 pump on an earlier flight"

BTW - plenty of recip aircraft have boost pumps as well!

 

[pbehn]

I think that as far as the early jets were concerned it was the pilots who were writing the manuals reporting back how they recovered from various "scrapes" to the engineers.

 

[FLYBOYJ]

I think that as far as the early jets were concerned it was the pilots who were writing the manuals reporting back how they recovered from various "scrapes" to the engineers.

You got that right!