Which jet was better, the Me 262 or the Gloster Meteor? (3 Viewers)

[Magnon]

Some background material on the centrifugal vs axial compressor advantages as at the late forties is attached for information. Surge caused flameout on changing throttle settings and when manoeuvring. Novotny was to lose his life on one such an occasion.

The original source was "Flight" archives http://www.flightglobal.com/FlightPDFArchive/1950/1950 - 2126.PDF

Regards,

Magnon

 

[Colin1]

Some background material...

I don't suppose you could rub that crap off the graph?

 

[FLYBOYJ]

Some background material on the centrifugal vs axial compressor advantages as at the late forties is attached for information. Surge caused flameout on changing throttle settings and when manoeuvring. Novotny was to lose his life on one such an occasion.

The original source was "Flight" archives http://www.flightglobal.com/FlightPDFArchive/1950/1950 - 2126.PDF

Regards,

Magnon

Good information but totally outdated.

 

[Magnon]

Good information but totally outdated.

Great to hear you have access to later data which contradicts it, Flyboy ... Can you post it, or just point us to where we can get it?

Regards,

Magnon

 

[Magnon]

US Air Force Museum - WWII - Messerschmitt Me-262 Swallow
Me 262

The Messerschmitt Me 262 Swallow (or Stormbird) has got to be one of the hottest looking aircraft ever designed. That shark-like fuselage not only looks menacing, it's also an aerodynamically well designed lifting body. Fortunately due to lack of high temperature resistant alloys and quality control problems arising from the Nazi's use of slave labor, the Me 262 had a lot of mechanical problems. Its Junkers Jumo 004 Turbojet engine had a time between overhaul interval of less than 50 hours. Mostly this was due to the wartime shortage of nickel alloys which would have enabled them to manufacture turbine blades that were more heat resistant. The materials used were not much better than common steel and were prone to stretching and cracking. In today's turbine aviation engines if you lose a compressor blade it might take out one or more blades behind it and keep running, although with a good deal of vibration and lessened power. If a Junkers Jumo 004 turbojet lost a compressor blade, it almost invariably led to a catastrophic cascading failure with the turbine shedding more and more blades in a domino effect until the engine literally blew apart. Interestingly enough the Arado 234 bomber which used the same engines had much fewer problems. The difference with the Arado 234 was that after takeoff the throttles were set to a cruise position and generally left there until landing. This made for less variations in operating temperatures and RPMs resulting in fewer compressor blade cracks and failures.

When the Junkers Jumo 004 turbojets were operating properly they were unbeatable and uncatchable. They were most vulnerable at takeoff and landing. The Me 262 did not have the complicated fuel management that today's gas turbine engines have. If the pilot advanced or retarded the throttles too quickly he risked over or underfuelling the engine causing a flame out and total power loss. The engines were also sensitive to angle of attack changes. If the airflow deviated much from coming straight into the intake, such as in abrupt maneuvering, the airflow could be disturbed enough [to] stall the compressor, flaming out the engine.​

Problems with regard to flameout if any aerobatics were tried... maybe that's why they were forbidden in the Me 262 Handbook? There were big problems with restarting the engines after flameout, but that's another story...

Regards,

Magnon

 

[Magnon]

A quote from Stormbirds.com website:

...The Me 262, although a great fighter, had one glaring weakness - it's engines, which remained an early development prototype practically throughout their use. The Jumo 004 was never intended by its designers for front-line service, as it was not yet fully developed. It was pressed into service because of the war situation. That, coupled with the fact that inferior materials were used, at least in the later production, made the engines unreliable. Therefore the Me 262s takeoff and landing was an extremely vulnerable time for the fighter. If a pilot was attacked while the engines weren't yet at full power and attempted to suddenly increase power to maneuver, the engines would flame out and leave the plane a sitting duck. That is, if it didn't crash right away, being so close to the ground...​

Wurger! The piston engine protectors of the Luftwaffes finest.

This is pretty much up to date, and confirms the inferiority of the JUMO as at the time it was pressed into service...

Regards,

Magnon

 

[Magnon]

American raiders: the race to ... - Google Books

Check out:

...The JUMO 004 didn't like radical air intake changes. Doing a maneuver like that could have it flame out. The Me 262 was not a dogfighting airplane like the F86 was later on...​

But it was a good bomber destroyer.

Regards,

Magnon

 

[DerAdlerIstGelandet]

I don't think anyone is arguing that the Me 262 was a dog fighter. I also don't see how that makes it inferior to the Meteor.

 

[Magnon]

I don't think anyone is arguing that the Me 262 was a dog fighter. I also don't see how that makes it inferior to the Meteor.

I agree...

 

[Magnon]

I don't think anyone is arguing that the Me 262 was a dog fighter. I also don't see how that makes it inferior to the Meteor.

I agree... The uncontestable fact is that the Me 262 was the prototype of the modern fighter. But as Voltaire once said:

Le mieux est l'ennemi du bien​

The perfect is the enemy of the good​

Regards,

Magnon

 

[Magnon]

I don't suppose you could rub that crap off the graph?

Sorry, it was a PDF file. Pretty hard to change electronically.

WYSIWYG.

Regards,

Magnon

 

[drgondog]

US Air Force Museum - WWII - Messerschmitt Me-262 Swallow
Me 262

The engines were also sensitive to angle of attack changes. If the airflow deviated much from coming straight into the intake, such as in abrupt maneuvering, the airflow could be disturbed enough [to] stall the compressor, flaming out the engine[/B].​

Problems with regard to flameout if any aerobatics were tried... maybe that's why they were forbidden in the Me 262 Handbook? There were big problems with restarting the engines after flameout, but that's another story...

Regards,

Magnon

Magnon - ALL jet engines are sensitive to AoA changes - some moreso than others... restart not always fun either.

 

[riacrato]

This still going? Magnon you must be at least on page 300+ of the "why the Me 262 sucks" google results page now

 

[FLYBOYJ]

Great to hear you have access to later data which contradicts it, Flyboy ... Can you post it, or just point us to where we can get it?

Regards,

Magnon

Jet engine 101 - Axial flow engines are going to produce more power and be more efficient than centrifugal flow engines for high speed applications. I've worked on Turbomeccas, J-33s, M701s, T-56s, and more recently RR Vipers and I can tell you with 33 years working on aircraft this is a fact. Centrifigual engines are good for helicopters or for applications where space is at a minimum and where there will be a lot of load on the turbine (PT-6 for example). I can list about a dozen text books that go into this, probably the most prominent being FAA Advisory 65-12A and Aircraft Gas Turbine Engine Technology by Treager. It was evident after the first generation of jet fighter aircraft what was going to be the standard jet propulsion configuration.

 

[Magnon]

Jet engine 101 - Axial flow engines are going to produce more power and be more efficient than centrifugal flow engines for high speed applications. I've worked on Turbomeccas, J-33s, M701s, T-56s, and more recently RR Vipers and I can tell you with 33 years working on aircraft this is a fact. Centrifigual engines are good for helicopters or for applications where space is at a minimum and where there will be a lot of load on the turbine (PT-6 for example). I can list about a dozen text books that go into this, probably the most prominent being FAA Advisory 65-12A and Aircraft Gas Turbine Engine Technology by Treager. It was evident after the first generation of jet fighter aircraft what was going to be the standard jet propulsion configuration.

You might have missed that I put the caveat "best for the late forties." The big advantages of the axial jets are low frotal area and a much higher potential pressure ratio. However, at the time, for development during wartime, the centrifugals got to 3.9:1 pressure ratio vs 3.12 for the axials. The high frontal area of the Derwent was negated by embedding the engine in the wing. The Meteor nacelles had lower drag than the Me 262s.

There's no dispute that the axial was better in the long term, but the Allies were developing them in parallel with centrifugals.

Regards,

Magnon

 

[Magnon]

This still going? Magnon you must be at least on page 300+ of the "why the Me 262 sucks" google results page now

Thanks for the reality check, Riacrato... three or four pages would have been enough...

 

[FLYBOYJ]

You might have missed that I put the caveat "best for the late forties." The big advantages of the axial jets are low frotal area and a much higher potential pressure ratio. However, at the time, for development during wartime, the centrifugals got to 3.9:1 pressure ratio vs 3.12 for the axials. The high frontal area of the Derwent was negated by embedding the engine in the wing. The Meteor nacelles had lower drag than the Me 262s.

No I didn't miss the caveat, and my original quote "Good information but totally outdated

There's no dispute that the axial was better in the long term, but the Allies were developing them in parallel with centrifugals.

Regards,

Magnon

Agree....

 

[DerAdlerIstGelandet]

Thanks for the reality check, Riacrato... three or four pages would have been enough...

Yeah most people would have given up after 3 or 4 pages of not proving their point...

 

[Messy1]

Kind of like this?

 

[Civettone]

Good point on the centrifugal jet engines: they were indeed the better choice that early on.

A quote from Stormbirds.com website:

...The Me 262, although a great fighter, had one glaring weakness - it's engines, which remained an early development prototype practically throughout their use. The Jumo 004 was never intended by its designers for front-line service, as it was not yet fully developed. It was pressed into service because of the war situation. ​

I wonder what this is based on. Never intended for front-line service?? They were working on it for 4 years straight and they knew it would be the main engine of the Me 262 since 1942.

Let me also add that the Jumo 004 was improved at the end of 1944 reaching an overhaul time of 25 hours which was not all that bad. Also it would get a regulator like on the BMW 003 which would take care of most of the accidental flame outs.
So we should also take this into account when judging the Me 262: the 1944 or the 1945 version?

Kris