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Guys, all great info, but remember all this doesn't preclude the fact that all these early jets were not great "accelerators" and flew into combat with high power settings. The Meteor was fast for its day but wasn't a great "roller." The Vampire, had a slow responding engine typical of the period, but built up speed quicker because of its lighter weight and was more maneuverable - but here's the key - the amount of energy these aircraft could maintain and develop during combat. The extra 5 or 6 mph difference in speed is not going to mean too much if one aircraft can use energy to accelerate away.
I think in reality the Me 163 was a rocket-plane that regularly dissolved its pilots in T-stoff * and C-stoff
Wrong.Granted the Sten was not pretty - and the MP40 was nicely machined and fitted.
First of all the 003 was abandoned for the Me 262 relatively early on simply for the fact that it was clear the engine was nowhere near as close to being serial production ready as the Jumo. Only the very first prototypes used the 003. And it wasn't "lousy" it was simply not ready. The J33 also had lousy reliability in pre-production. this is the first jet generation afterall. When the 003 entered true service with Ar 234 and He 162 it showed good reliability given the circumstances.timshatz said:That posting is representative of many articles/postings stating that the 003 engines were lousy wtih respect to reliability while the 004s were much better, they still lasted a very short time. Again, the point is about reliablity. And engine that lasts 20-25 hours is not reliable. Engines of today routinely get 10,000 hours of flight time. That is a reliable engine. 20-25 hours is not reliable.
Your first comment doesn't look right to me, I can't put my finger on it...And todays engines have to last for ages, because that's how long the plane lasts.
Now how long will an Me262 in spring of 1945 last on average?
In the Luftwaffe's case, I think this has more to do with unfortunate coincidence than intelligent design... So it makes a lot of sense to have an engine lifetime in the vicinity of the total aircraft's lifetime...
something I only recently found out. The Vampire used the same plywood laminar construction as had been developed for the Mosquito, though more metal was used in the Vampire. This mixed wood/metal construction was continued in both the Venom and Sea Venom types, which were not retired until 1967 in the RAN.
The Sea Venom had an initial climb rate of 5900 feet per minute. Does that not suggest superior accelaration, I assume that climb rate and accelaration are related in terms of their power demands?
the Jumo 004 A had a significantly longer lifetime than the B, that is fact. The B was a trade-off solution between material availability and service life.that is also fact.In the Luftwaffe's case, I think this has more to do with unfortunate coincidence than intelligent design
And I never said so. I said with a plane lasting years it makes sense to have an engine lasting a few years (didn't say it has to be 1:1). With a plane whose lifecycle is measured in weeks it doesn't make sense to have its engine lasting for years. Disprove me.With regards a modern airforce, I don't think an F-15 sitting on the apron at Holloman AFB has the same engines it rolled out of Long Beach with in 1974.
With a plane whose lifecycle is measured in weeks it doesn't make sense to have its engine lasting for years. Disprove me.
The point here is despite an airframe with a lifecycle lasting weeks, no one in 1945, allied or axis was building a turbine engine lasting years, even if they wanted to.
I'm with you on the engine life Flyboy. Any bird with a lifecycle on the engines of 20-25 hours is going to make me VERY nervous. Jeez, if that's the average, what's the deal with the substandard engines that snuck by QC.
Matter of fact, I don't think I've ever met a pilot who wasn't at least "very sensitive" to whatever his engine was doing. And that's on a 2000 TBO Lycoming.
Some people are mixing expectet engine life time with reliability.
It is right that an unreliable engine has an shorter average lifetime than an reliable. But to assume a short life engine is unreliable is simply wrong.
If we assume a gaussian normal distribution with the peak at 20 hours engine life, the variance (width of the bell) is the factor to determine reliability. This could be small or wide. The average life time will be the same. So if only very few engines last significant longer than 20 hours, there will be very few engines which will last significant shorter. Thats a reliable engine. For an unreliable one its the other way around. But we dont know the variance and so we cant judge reliability. Engine life time alone is meaningless.
In fact, one of the problems which reduced the life time on the jumo 004 was the blade lengthening because of low heat resistant materials. But this lenghtening is a very steady process, which is controllable.
Of course this is not the only problem of the Jumo 004. And so its difficult to say it was reliable or not.
regards
thrawn
Some people are mixing expectet engine life time with reliability.
It is right that an unreliable engine has an shorter average lifetime than an reliable. But to assume a short life engine is unreliable is simply wrong.
If we assume a gaussian normal distribution with the peak at 20 hours engine life, the variance (width of the bell) is the factor to determine reliability. This could be small or wide. The average life time will be the same. So if only very few engines last significant longer than 20 hours, there will be very few engines which will last significant shorter. Thats a reliable engine. For an unreliable one its the other way around. But we dont know the variance and so we cant judge reliability. Engine life time alone is meaningless.
In fact, one of the problems which reduced the life time on the jumo 004 was the blade lengthening because of low heat resistant materials. But this lenghtening is a very steady process, which is controllable.
Of course this is not the only problem of the Jumo 004. And so its difficult to say it was reliable or not.
regards
thrawn
Wrong.
And on what you wrote about jets. You see, by now everyone with decent interest in jet engines knows well enough about the relative advantages of centrifugal or axial compressors. And it is ****ing common knowledge that none is definetly superior to the other or else they were not both used until this day. But no, always someone has to make it look as if his country's engine concept choice was inherently superior.
All true...
Great posts Cromwell, especially about the differences about the two engines. I was not aware of the differences in that light. Very interesting. As I am a relative novice on Jet Engines (I know how they work in principle but that doesn't mean squat in the real world), where do Turbofans fit in. Any link I can go to for a comparison to co-axle or are they the same?
On another note, somebody on the board used to use a Sterling and had a low opinion of it. Said something like it was useless for everything but opening beer bottles or some such. I can't remember. It might've been Airframes or one of those guys who were in the British Army in the 70s.