Earliy German Gas Turbine Engines

[Dragonsinger]

Hi Guys
Are there any details on the life expectancy of the German Gas Turbines? The BMW for example. And what about the ground equipment used to start them?

[FLYBOYJ]

From what I've seen you were looking from 12 to 50 hours on the Junkers Jumo 004B-1. They were started by a small engine in the nose bullet of the engine - here a photo of the one...

[Dragonsinger]

Hi Flyboyj
Yeah a lot of the smaller stuff is started this way today, but larger engines tend to need either a small turbine to force them to rotate, like a windmilling prop, or a compressor to do the same job. But I have never read of anything about these engines start ups and if you plan a diorama you tend to need items other than the plane. I was also aware that the lifespan of these engines was very limited hence the need for mounting in a nacel, Unbolt it and bolt on a new one then do the rebuild in the maintenance area.
Plus from the early fifties any repair work on a gas turbine was done in a clean environment subject to rules similar to an operating theatre. With these aircraft operating from grass fields or poorly maintained runways the problems of FOD (Forigen Object Damage) was very high but in the situation that they were flying in it was almost impossible to keep the runway clean.
There is also the probability that the maintenance crews were either unaware of the problem or did not believe it was as critical as it is.
Many thanks for the photo and the info
Dragonsinger

[FLYBOYJ]

Originally Posted by Dragonsinger

Hi Flyboyj
Yeah a lot of the smaller stuff is started this way today, but larger engines tend to need either a small turbine to force them to rotate, like a windmilling prop, or a compressor to do the same job. But I have never read of anything about these engines start ups and if you plan a diorama you tend to need items other than the plane. I was also aware that the lifespan of these engines was very limited hence the need for mounting in a nacel, Unbolt it and bolt on a new one then do the rebuild in the maintenance area.
Plus from the early fifties any repair work on a gas turbine was done in a clean environment subject to rules similar to an operating theatre. With these aircraft operating from grass fields or poorly maintained runways the problems of FOD (Forigen Object Damage) was very high but in the situation that they were flying in it was almost impossible to keep the runway clean.
There is also the probability that the maintenance crews were either unaware of the problem or did not believe it was as critical as it is.
Many thanks for the photo and the info
Dragonsinger

Actually FOD issues were considered in those days but by the time the end product got to the operator the mission requirement dictated how strict FOD requirements were going to be carried out. I would guess Me 262 operations had other things on their mind because of their grave situation. From what I understand it wasn't until the late 50s where FOD prevention was started to be taken very serious, especially when the cost of turbine engines jumped as they got more complicated.

[Dragonsinger]

I fully agree with you abut the difficulties faced by the German ground crews and it is interesting to know that FOD etc, was known about and recognised but I disagree about the complexity of the engines. The only real advances have simplified the engines rather than complicated them. For example the move to annular combustion chambers instead of multiple smaller ones has reduced the number of components. Re-heat is still simply a ring of nozzles to spray extra fuel into the exhaust stream and the engineering on an axial flow compressor is simply extended to produce more components as opposed to the radial one which is more painstaking to balance.
The true changes in complexity have come in the ancillaries (jet pipe flaps etc) and the metallurgy (if we have not actually moved on to ceramic technology) used in the internal components and the use of computers in engine control.
Aircraft are now so complex that the cost is approaching the point where they will not be easily committed to combat against similar aircraft of an enemy. In WWII the aim was to take the pilot out because he was the weak link in that it took longer to train him than it did to build several fighters. Now this is reversed and you have a situation where a 2inch rocket is probably the best anti aircraft weapon as it is aimed, not guided and the aircraft have tremendous difficulty seeing it coming and can not use electronic or other means to deflect it. I may be wrong but I believe that gunfire was the method used to down the only stealth bomber lost in action.
We are in a situation where the Lightning shown below or a Me163 could take out the most advanced fighter available today.

I find that worrying.
Dragonsinger

[FLYBOYJ]

Originally Posted by Dragonsinger

I fully agree with you abut the difficulties faced by the German ground crews and it is interesting to know that FOD etc, was known about and recognised but I disagree about the complexity of the engines. The only real advances have simplified the engines rather than complicated them.

That's very wrong. Have you ever seen the inside of an F101 or J79? The fuel control of a T-56 is probably more complicated than a whole Jumo that powered the -262! I've worked extensively around modern (T-56, RB-211, JT8 and Arriel 2B) and early (J-33 J-47 and M701) engines and could tell you they have gotten way more complex with time. Manufacturing inprovements have done away with many multipe parts but overall something like a J-47 is a tinker toy when compared to say an F100

[Dragonsinger]

I did say the engines, not the ancilaries, and to quote you post "The fuel control of a T-56 is probably more complicated than a whole Jumo that powered the -262!" so we are in agreement.
Though possibly not about the abilities against modern fighter aircraft but I am thinking of the direct attack as an intercept. NOT a dog fight.
Besides, It's no fun to agree all the time
Lets keep the fun flowing
Regards
Dragonsinger

[FLYBOYJ]

Originally Posted by Dragonsinger

I did say the engines, not the ancilaries, and to quote you post "The fuel control of a T-56 is probably more complicated than a whole Jumo that powered the -262!" so we are in agreement.

No we're not - I was using the fuel control as an example. The machining, heat treating, inspection and internal maintenance is still a lot more complicated today. Configuration construction was improved, sure - but in essence those improvements only opened up room for growth - look at an internal schematic of say a Goblin engine and compare the fuel or oil system with a modern turbine engine.

Originally Posted by Dragonsinger

Though possibly not about the abilities against modern fighter aircraft but I am thinking of the direct attack as an intercept. NOT a dog fight.

I don't quite understand what you're trying to say???

Originally Posted by Dragonsinger

Besides, It's no fun to agree all the time
Lets keep the fun flowing
Regards
Dragonsinger

That's fine - just pointing out what I know first hand having worked on both modern equipment and jet warbirds.

[Dragonsinger]

Well I Have to go offline untill tomorrow after this post but to try to explain. The basis for the gas turbine is still identical to the original and the same as for a piston engine but put into a linear configuration. Of course the machining and heat treatment etc is a lot more sophisticated today. As I said, we may even be into ceramic technology for various components and synthetic lubricants can now achieve miracles of lubrication and cooling. However the bigest advances are in avionics and the control achievable on the thrust being developed. Not the basic principals. If you look in another field vehicle engines, as are gas turbine engines, are now considerably more advanced but this tends towards control of the fuel and the burn process. But in the case of vehicle engines the technology is so precise that manufacturers can now produce an engine which will function up to the point of catastrophic failure and practically to the minute on the life expectancy of that engine. the last bit is only to illustrate that I accept the improvements in the ENGINEERING which have taken place. Aero engines are far more closely monitored and far better serviced. Like cars they now achieve their biggest advances in the fuel delivery and monitoring systems and a failing engine can be compensated to a large degree by costant monitoring and adjustment to the cooling, fuel delivery and lubricating systems and today these have got so complex you need a computer to control them and this is fully acceptable in todays world.
To illustrate my point, if you take all the avionics systems away from any of the engines you named and supplied it with fuel it would still run, It would develope nowhere near its full capacity, but it would still run. This is what I mean when I say that the advances and complexities are to the anciliaries and not the basic engine.
Last sensible engine I worked on was a Spey in 1974 so I am out of date without a doubt and would need several months of catch up schooling to be regarded as competent because doing it from memory is not good enough in the aircraft industry.
Since this was started as a querey about starting WWII German gas turbines we are off thread a bit at this point. Do you want to move this to a different thread?
Regards
Dragonsinger

[FLYBOYJ]

Originally Posted by Dragonsinger

Well I Have to go offline untill tomorrow after this post but to try to explain. The basis for the gas turbine is still identical to the original and the same as for a piston engine but put into a linear configuration. Of course the machining and heat treatment etc is a lot more sophisticated today. As I said, we may even be into ceramic technology for various components and synthetic lubricants can now achieve miracles of lubrication and cooling. However the bigest advances are in avionics and the control achievable on the thrust being developed. Not the basic principals. If you look in another field vehicle engines, as are gas turbine engines, are now considerably more advanced but this tends towards control of the fuel and the burn process. But in the case of vehicle engines the technology is so precise that manufacturers can now produce an engine which will function up to the point of catastrophic failure and practically to the minute on the life expectancy of that engine. the last bit is only to illustrate that I accept the improvements in the ENGINEERING which have taken place. Aero engines are far more closely monitored and far better serviced. Like cars they now achieve their biggest advances in the fuel delivery and monitoring systems and a failing engine can be compensated to a large degree by costant monitoring and adjustment to the cooling, fuel delivery and lubricating systems and today these have got so complex you need a computer to control them and this is fully acceptable in todays world.
To illustrate my point, if you take all the avionics systems away from any of the engines you named and supplied it with fuel it would still run, It would develope nowhere near its full capacity, but it would still run. This is what I mean when I say that the advances and complexities are to the anciliaries and not the basic engine.

And again, my point - the engines today are more complicated by some of the examples you have shown, even though the basic operational concept is still the same. Agree the ancillaries or accessories as we call them have greatly contributed to the performance and reliability, overall the processes in building production turbine engines are extremely complex when compared to the fist generation engines that powered Meteors, F-80s or even Me.262s.

Originally Posted by Dragonsinger

Last sensible engine I worked on was a Spey in 1974 so I am out of date without a doubt and would need several months of catch up schooling to be regarded as competent because doing it from memory is not good enough in the aircraft industry.

Spey was/ is a great engine - I assume it was in RN Phantoms. I do work on L-29 and L-39s - their engines are late 1950s and early 1960s technology and their simplicity is astounding. Take the M701 - an engine that has its roots traceable to the Nene - Just about in destructable and when the hot sections come due you throw them away - but then again they were designed that way for East Bloc and 3rd world operations.

Originally Posted by Dragonsinger

Since this was started as a querey about starting WWII German gas turbines we are off thread a bit at this point. Do you want to move this to a different thread?

No problem - the beauty of this forum is we'll allow the threads to goo off topic a bit - it seems that they always come around again.

[Dragonsinger]

Hi Again
I Understand and accept your view and it seems that you have come to an understanding of mine, even if you don't fully accept it. Thats great because as you say, this forum is meant to expand our horizons (that sounds like pretentious carp ((and I just wrote it ----HELP ME ---- HELP ME)) so we should be somewhere near getting along with each other. Looks like the main difference is that I'm regarding the engine as a set of linked units and you are regarding it as indivisible. Given that, your view is correct.

Yeah it was RN Phantoms, and Buccaneers, and Vixens, Blah blah Blah, Even A Swordfish.
Please remember that an aircraft fitter in the RN is a combined job doing airframe, engine, and even ground equipment but most people find that they are better at different aspects and tend to be given mainly that type of work
but not exclusively.

So once more thanks for the stimulating discussion and your info on the German gas turbines. All of this has been filed and I hope our readers have been educated and entertained.
Regards
Dragonsinger