Jet Questions 51

1) Combustor cooling air and flame propogation
2) What starts the start cart?
3) Compressor blade and combustor materials.

[telquad]

Have been watching for a year or so. Your patient explanations are appreciated. You work with fascinating machines. The gas turbine defies intuition. Its working material - air - is a structural component of the engine itself, because of pressure and of speed. This isn't at all like the piston engines we are accustomed to. Thanks so much.

[Daluke]

Love the combustor operation videos. Almost always learn another thing or two!

[DScottDuncan]

Loved the 'destructive' (as opposed to non-destructive) testing of those compressor blades!  Thanks for that tidbit.  Interested in seeing the guy that bought the RR Avon for $1K get that going!  Isn't that a big & complicated choice for a first jet engine?  Can't beat the price; maybe I paid too much for my J44!

DD

[Rovertsmasher]

Have you ever mentioned what your favorite engine to work on is? or perhaps your favorite part of assembly/dis-assembly?  perhaps turbine disks or the compressor cases?

[fastmidis]

AgentJayZ, how do you deal with corrosion when refurbishing engine parts?How do you remove it?Do you use chemicals?Do all metals/alloys corrode?Are there diferent types of corrosion?Any hints & tips for diyers?Sorry if dealt in previous video and missed it!Greetings from Greece!

[buckhubach]

when the vise flattened out the curve of the turbine blade a bunch of the structural strength was lost, so its even stronger than that while its working normally

[Maccer]

Could you explain what happens when a turbojet or turbofan fitted to a millitary aircraft goes supersonic?  As I understand it, a supersonic intake would likely create all sorts of strange effects and shockwaves within the engine.  Is the airflow somehow slowed down to subsonic speeds before it enters the engine?

[docatomics]

~ thor added @ 17:00 
= needs operating temperature to reflect true " strengths " dimensions 

[Berilmen]

Thank you this video I like it but can i ask you engine.Where is the C.S.D and B.L.C? ...

[deSloleye]

I was wondering about the low-smoke modification for the J79. If I recall right, it's a different design of fuel nozzle AND a different design of combustor can. If that's so, do you get any ex-aviation units converted to natural gas burning LM1500s that have the low smoke cans and do they produce less smoke while burning gas instead of kerosene? I presume that the gas burns very cleanly regardless of what sort of can you use, but even gas stoves release particulate matter into your kitchen while burning very little gas, so a machine burning as much gas as an LM1500 might still smoke a little.

[YCbCr]

Docatomics' comment, which I couldn't reply to  ( needs operating temperature to reflect true " strengths " dimensions ) makes me ask if you would send a blade to carsandwater to be HHO torched (extremely high temp torch)?

[FrontSideBus]

Love those big hammers... For those fine adjustments :)

[txnx]

The outer shell of most of the sections appears to be made of sheet metal. Are these generally single sheets or sandwiched honeycomb? Are the engine's mounts usually located at the bearings, and how does the shell of the engine stay rigid enough to not interfere with the rotating parts? I'm guessing there's just enough clearance for some flex along the length of the turbine, but how rigid is it? A few thousandths per foot? Is the shaft and shell made to flex at the same rate during high-g maneuvers?

[hommie]

Another great addition to your video collection, don't think you have a bad video in your video collection. I have a question that has nothing to do with anything in this video though, several years ago S&S took delivery of a Orenda Iroquois engine and wondering if there has been any work done to it? I seen 2 showing the the beast and what showed then i have seen nothing since. Has any progress been made? I understand you are a busy shop and that engine is low on the priority list but aching to see that bad boy running. 

Thanks Jay I am a life time fan

[jakemj]

What seals all the movable stators between the compressor to the outside of the engine where the linkage is?

[BillyNoMates]

Is the start cart a centrifugal compressor type (like helicopter engines and the early Frank Whittle engines) ?
How oversize is the compressor to start larger engines ?

[deSloleye]

What gets me about the idling engine is that you have a compressor still using about 25-30000hp to turn and the turbine can take all of that out of the gas path and leave nothing that can be converted to thrust, but when it's running at 100% power it still only takes out that 30000hp to run the compressor and lets another 16000hp go past. Why is there such a difference in efficiency from the turbine at the different power levels? What changes, is it the turbine inlet temperature that carries that power past the turbine and lets something use it? It seems that the turbine is at 100% efficiency at idle such that the power produced by the compressor/combustor is the same as the power absorbed by the turbine and is the same as the power consumed by the compressor. At full power the turbine doesn't absorb all that power so there's some left over to do work with. What am I missing?

[TheLazyGuyWay]

I haven't seen that question, so sorry if you already answered that one in your videos:

What is the voltage of the igniter ?
Thanks

[AIMA]

Could the incoming air that keeps the flame centered also be the reason on your last video that the operator failed to do a running restart on the J79. He tried to catch it but in the end couldn't get it back to idle rpm. Is it possible he had enough RPM that he lost combustion in a few cans but had enough airflow to keep the others from restarting.. Or was it just combustion instability voodoo.

[saintsi]

Hi AgentJayZ. When you quote an engines power as i.e .30, 000 HP Is that the usable power or do we need to subtract 20, 000 HP that the engine use to run the compress? So a 30, 000 HP engine is really a 10, 0000 HP engine? Thank Si