billdunn wrote:

This may be a stupid question but bear with me.
Has consideration been given to using titanium for major components of a

rotary engine ? Would it

save that much weight ?
Williams and other companies including the feds are investing alot of

money in developing a small

turbine for general aviation. Willaims I have heard is having trouble

with the metallurgy required

for a small diameter turbine. If they get it worked out , they will have

a turbine but there are

still problems, fuel consumption, High altituden operation, IFR flight

regimes (not necessarily

bad ), more redundant systems etc. Making the rotary case and rotor out

of titanium might be a

relatively "low tech" solution to a high tech problem.

I have read any number of articles making the case that the best engine

in the 10,000 to 20,000'

flight enviornment is turbo charged or supercharged device.

Thanks for your patience,,,any comments

bd

It is not the fed's money. Unfortunately it is yours and mine.
I don't expect William's will give it back to us when it becomes
obvious that they have failed. What is it now two or three years
beyond schedule?

I think a titanium rotor was tried but I think the heat transfer
characteristics were unfavorable.

Actually I think the turbo charged IC engine is pretty good
all the way up to 57,000 feet. Our man Jeff Spitzer, chief engineer
on the Predator, at General Atomics and resident rotor head got
the turbo charged Rotax 914 powered Predator up to 57,000 feet.

Back in WW II a lot of turbo charged airplanes flew up to 45,000 feet.
It was years before a jet fighter could climb to the operating
altitude of a turbo charged piston engine B36. The big improvement in
jets was when they developed intake ducts to act as ram jets
...sort of super charging the turbine engine.

Paul Lamar

I cannot let that one stand Paul.  The ducts do not operate as ramjets in
any
way shape or fashion. The inlets for supersonic flight are quite critcal
but the bet they can do is supply most of the total pressure to the
compressor first stage. 

Is that total static and dynamic pressure? Or just total static pressure?

Total static pressure which is more (I would guess) than say the P80 
would get at the compressor face at that time. That was the point 
I was trying to make. You must admit there have been some big
improvements in inlets over the years to handle the shock waves.

I am aware of the improvements in hot section
temperature and compressor efficiency.

Sorry I used the term "intake ducts to act as ram jets
...sort of super charging the inlet."  PL

The big improvement was in increasing the
efficiency and pressure ratio of the compressor, and increasing the
allowed turbine inlet temp with better materials and cooling.
Vance J. (Jet engineer at GE before becoming rocket "scientist" at
Rocketdyne)

 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2002 All world wide rights reserved.