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As mentioned surely the plane has had it engines changed out several times. But the engines which started in one F-15 way back (well F-15A's built back in mid 70's are becoming rare, though most are still relatively old) might still be in another now. They've been overhauled and rebuilt replacing wearing or fatigue life parts, but P&W hasn't built several complete fleets worth of completely new F100 engines for F-15's i in the last 30 years. You might say the engines are kind of like your grandpa's old hammer where your dad replaced the handle and you repaced the headWith regards to a modern airforce, I don't think an F-15 sitting on the apron at Holloman AFB in 2010 has the same engines it rolled out of Long Beach with in 1974. I don't know that for certain but it doesn't sound feasible so the statement 'engines have to last because that's how long the plane lasts' feels limited in accuracy to me.
When in a light plane I have always noticed that the engine seems to begin to sound "funny" as soon as I am over a large body of water.
When in a light plane I have always noticed that the engine seems to begin to sound "funny" as soon as I am over a large body of water.
Joe - you'd have to look at what type of failure the engine had to determine if the whole thing was tossed. Compressor and turbine bearing failure was common as well as burner cans coming apart. Let's not forget compressor and turbine blades coming apart as well. If the failure involved penetration of the engine case by failing parts that have flung off the compressor or turbine disk, or if the engine caught fire and burned for a while, I don't see much being salvaged. When early centrifugal flow turbines failed and started throwing parts, there usually wasn't much left. As we know axial flow engines fared much better again providing there wasn't any prolonged fire or engine case penetration, and even then, one half the case can be replaced.But TBO's for fighter engines, which is really what we're talking about, the Me262 engines wouldn't necessarily be completely sh*tcanned either I wouldn't guess, have multiplied if anything more than the lives of the a/c themselves, especially if you compare on an apples to apples basis their lives in peacetime service. Though, the fact that a WWII combat a/c would likely be destroyed in a weeks or months in a combat zone, or else become obsolete not long after that, or simply wear out itself (for example Soviet fighters with wooden and fabric parts) was a factor in considering equipment life, obviously. Perhaps it should have been in more cases (as in criticism of US Browning .50 of being a long lived machine gun heavy for its performance compared to shorter lived Soviet 12.7mm a/c mgs). But late war German jet and some piston, engines had short enough TBO-lives to cause servicibility/availability problems with the planes they were fitted in.
Joe
I was thinking more of scheduled overhaul/rebuilds of mature engine designs with predictable life, where most are overhauled without failing first. For early jets with less predictable life and no previous experience, you're probably right, many probably failed in operation in ways that completely ruined the engine (not to mention causing destruction of the whole airplane sometimes, usually so in case of single engine jets).Joe - you'd have to look at what type of failure the engine had to determine if the whole thing was tossed. Compressor and turbine bearing failure was common as well as burner cans coming apart. Let's not forget compressor and turbine blades coming apart as well. If the failure involved penetration of the engine case by failing parts that have flung off the compressor or turbine disk, or if the engine caught fire and burned for a while, I don't see much being salvaged.
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?
Well Wikipedia seems a good place to start - if a bit obvious !
Jet engine - Wikipedia, the free encyclopedia
At the time in question the different compressors had different advantages and dis-advantages. BOTH offered about the same effective pressure ratio although the axial would eventually (early 50s) easily far surpass the capabilities of the axial in that regard.
Axial was much shorter, lighter and simpler. It was also much fatter which meant more frontal area and drag.
There is a reason a two seat Venom can be side by side.
In 1943-45 you pay your money and take your choice.
Thanks bud. Appreciate it. Another page in the education of timshatz!
Acceleration dependent on available Thrust less drag.
Climb also based on thrust available as well as the lift of the airplane and the angle of the climb.
rate of climb = (T-D)*V/W for unaccelerated flight
for high angle of climb (a) and unaccelerated flight you have to account for change in Induced Drag and that must be accounted for in the above equation (L= W*cos a and as induced drag changes with changes to CL then Di (1) = Di (0) cos>>2 a..
where Di(1) is induced drag at a climb angle, Di(o) is induced drag at level flight and cos>>a is cos squared of a.
So the Vampire (and Me 262) climb rates are more about the Velocity enting the climb) rather than acceleration, as well as lift loading of the aircraft based on the wing.
Anybody ever see a U-2 climb..? not much acceleration but gawd what a climbe rate for a relatively low T/W ratio (not much induced drag on that beast but a very low lift loading)
Colin, you choose. I only have a limited view of each aircraft and any comparision is perfectly fine by me. And plus, wounldn't seeing who would win in a dogfight be one deciding factor in the better fighter?
A. Can you define some of the terms please such as T=thrust , D=drag=induced drag+parasite/profile/skin friction/wave drag ,V=velocity , W=weight so on
B. So in the end which was a faster climber - the Me262 or the Vampire ? (or the Meteor come to that)
I suspect the Vampire but I do not know. What I was trying to communicate is the acceleration per se doesn't have as much effect on climb rate from level steady flight as the Lift Loading, Velocity and Angle of climb
I got the impression that the point was that WWII jets couldn't just pull the nose up into a climb and accelerate away from a pursuing recip. The ability to accelerate anywhere is a critical function, it's just that 1st-gen jets were pretty poor at it, even in level flight.That is interesting :-
So in other words the ability to accelerate is not an over-riding critical function when considering the ability to climb - It would also help to explain why some planes with tremendous acceleration such as the P47 were fairly lousy climbers
I got the impression that the point was that WWII jets couldn't just pull the nose up into a climb and accelerate away from a pursuing recip. The ability to accelerate anywhere is a critical function, it's just that 1st-gen jets were pretty poor at it, even in level flight.
I'm not sure why you think the P-47 had tremendous acceleration
I got the impression that the point was that WWII jets couldn't just pull the nose up into a climb and accelerate away from a pursuing recip. The ability to accelerate anywhere is a critical function, it's just that 1st-gen jets were pretty poor at it, even in level flight.
I
Early jets were pretty much commited once they were landing or taking off, which lines up wiith your point pretty much I think.