Why are there no small turboprops?

"Mike Rapoport" wrote in message link.net...

Diesels are more
promising.

And can run on the same gas.

"Robert M. Gary" wrote in message
om...
"Mike Rapoport" wrote in message
link.net...

Diesels are more
promising.

And can run on the same gas.

Only some can run on jet fuel. Jet fuel has almost no lubrication
qualities, while diesel does. Jet fuel will eat up some things, like fuel
pumps.
--
Jim in NC


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"David CL Francis" wrote in message
...
[...]
Can you explain why the efficiency of turbines is much higher at
altitude? What sort of efficiency are you talking about?

Mainly the same reason turbocharged reciprocating engines operate more
efficiently at altitude. You're carrying around a compressor that just
isn't all that useful down low. Once you get higher, where there's less
drag, you get more "bang for the buck" out of the engine. Of course, as
Mike Rapaport pointed out, there's also the issue of efficiency with respect
to the size of the engine (independent of operating altitude).

The bottom line with respect to that point is that, for the purposes a
typical 100-300hp engine would be used, reciprocating engines are more
practical.

Pete

Barney Rubble wrote:

Slightly off-topic, why has no-on mentioned diesel engines (that run on
Jet-A1)? This has got to be the way to go, better economy, better operation
at altitude, simpler mechanicals (less to break) and FADEC/ECU controlled?

Actually, because of the higher compression ratios, the mechanicals are not simpler.

For the majority of GA this has got to be the long-term answer, even in the
US.

I agree. They are more expensive than gas-burners, but it will be nice when it
becomes possible to replace my O-320 with a diesel in the 180hp range (IMO).

George Patterson
I childproofed my house, but they *still* get in.

Morgans wrote:

Only some can run on jet fuel. Jet fuel has almost no lubrication
qualities, while diesel does. Jet fuel will eat up some things, like fuel
pumps.

Any diesel designed for aircraft will be designed to run on jet fuel. Doesn't make
any sense to do it any other way.

George Patterson
I childproofed my house, but they *still* get in.

"David CL Francis"

Did you know you can buy true turbo jets for model aircraft? They cost
about $3000 and give about 20 lb thrust, They are around 4" in diameter.
--
David CL Francis

And wear out in a few hundred hours, at best, and consume vast quantities of
fuel.
--
Jim in NC


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Did you know you can buy true turbo jets for model aircraft? They cost
about $3000 and give about 20 lb thrust, They are around 4" in diameter.

I was out for a bike ride and passed by a model radio controlled
airport. A guy was taxiing out and I was thiking, "Oh that is
a ducted fan (or whatever the heck they call it)." I then said to
a guy, "Man that sounds like a turbine." He told me it was.
I went home looked it up online. This is what I came up with.

http://jetcatusa.sitewavesonline.net/p200.html
http://www.jethangar.com/


This guy had an F-14 and some other fighter plane. They had
operable brakes too. Cool but at that price, I could have
paid for my PPL and my IA too....well almost.


Gerald

"G.R. Patterson III" wrote

Any diesel designed for aircraft will be designed to run on jet fuel.
Doesn't make
any sense to do it any other way.

George Patterson

Right. I was commenting on the fact that not all diesels will run on jet
fuel, not airplane diesels. Did I mis-read? Won't be the last time.
--
Jim in NC


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"Thomas J. Paladino Jr." wrote in message The Maule is almost more
on par with a Cessna Caravan, not a 182 or 172.

The Maule M-7 series is about the size of a C-172. It is a 4 seater. The
Caravan can have up to 14 + 2 seats.

Either way, I'll rephrase the question a bit; why are there not more small
turboprops available for GA, and why are they not standard accross more
models?

In general, turboprop engines don't match fuel consumption with piston
engines until over the 300 horsepower range. The metals required for a
durable, efficient turbine engine are expensive. If a manufacturer produced
a turbine such as you describe, airframe manufacturers would be clamoring
over each other to install them on their airframes. You don't see it
happening because such an engine doesn't exist (yet).

D.

there is a company making small turbo props, I cant remember the name of them,
but they have a 200 HP one

"Thomas J. Paladino Jr." wrote:

I have always wondered why there are no small GA turboprops. It seems like
most of the major problems & maintenance issues associated with GA aircraft
are related to the piston motor, and as far as I can tell, turboprops are
much more reliable, fuel efficient, smoother running and easier to maintain.

So it begs the question, why are there no small turboprops in the 100-300hp
range for use on GA aircraft? I would think that turbine engines of this
size would be relatively easy to produce, and would be ideal for GA
applications. The smoother operation and lower vibration levels would also
ease wear and tear on the entire airframe and avionics components. So what's
the deal? Does turbine technology not translate downwards very well? Would
it be cost prohibitive? Am I entirely missing something?