Why are there no small turboprops?

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?

Thomas J. Paladino Jr. wrote:

I have always wondered why there are no small GA turboprops.

GOOGLE is your friend.

http://www.mauleairinc.com/Our_Planes/Maule_M-7-420AC/

On Mon, 24 May 2004 05:16:31 +0000, Shiver Me Timbers wrote:

Thomas J. Paladino Jr. wrote:

I have always wondered why there are no small GA turboprops.

GOOGLE is your friend.

http://www.mauleairinc.com/Our_Planes/Maule_M-7-420AC/

I've always wondered the same. To take his question and run with it, why
are small turbo props not the defacto engine used throughout small GA
planes?

Seems to me that a variety of small jets and turbo props could be made,
which are just as safe and have slightly better performance envelopes than
currently exist while having less failures and vibration to boot.

Is simple economics the answer? $30k piston versus something like $80k
turbine, or something like that?

Hi Greg,

I've always wondered the same. To take his question and run with it, why
are small turbo props not the defacto engine used throughout small GA
planes?

As said before by Peter Duniho, they simply don't suit well. There scaling
down is making them inefficient, there fuel consumption - especially at
lower altitutes - is higher, so is the amount of fuel to be loaded for the
same distance.

If you take a look at the turboprop conversions 'done' to the P210, the
Bonanza and so on, you'll find that there range is reduced. Some
conversions cope with this by improving the load (more hp, proved to fly
with a few extra pounds). But all in all that makes these planes not more
efficient - especially the ones normally operated at lower altitudes - the
ones without pressurization.

Seems to me that a variety of small jets and turbo props could be made,
which are just as safe and have slightly better performance envelopes than
currently exist while having less failures and vibration to boot.

There _will_ be a lot of new small jets - but none of them in a 'normal'
price range of a spam can. The engines are much to costly for that. Lowest
priced jet - if completed - will be the D-Jet by Diamond Aircraft. Single
engine jet with a maximum FL of 250 (and I just can't see how they will
cope with making this engine efficient at that altitude...)

Is simple economics the answer? $30k piston versus something like $80k
turbine, or something like that?

Much more. Especially maintenance is cruel. Turbines do have less moving
parts, but the parts are of a much higher quality and the personnel is
trained as hell...

regards,
Peter

Greg Copeland wrote:

Is simple economics the answer? $30k piston versus something like $80k
turbine, or something like that?

It's certainly one answer. The price on that Maule is $450,000. With an IO-540, it's
$173,420.

I've read that there are technical problems building small turbines; ie. the smaller
the diameter of the turbine, the faster the blades must spin to produce power.

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

On Mon, 24 May 2004 at 13:48:53 in message
, G.R. Patterson III
wrote:
It's certainly one answer. The price on that Maule is $450,000. With an IO-540, it's
$173,420.

I've read that there are technical problems building small turbines; ie. the smaller
the diameter of the turbine, the faster the blades must spin to produce power.

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

"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 opined

Greg Copeland wrote:

Is simple economics the answer? $30k piston versus something like $80k
turbine, or something like that?

It's certainly one answer. The price on that Maule is $450,000. With an
IO-540, it's
$173,420.

I've read that there are technical problems building small turbines; ie. the
smaller the diameter of the turbine, the faster the blades must spin to
produce power.

The biggie is edge effects. There is a minimum clearance between the turbine
and the case, and that clearance is independent of the diameter of the
turbine. So small turbines have much higher tip losses.


-ash
Cthulhu for President!
Why vote for a lesser evil?

On Mon, 24 May 2004 13:48:53 GMT, "G.R. Patterson III"
wrote:



Greg Copeland wrote:

Is simple economics the answer? $30k piston versus something like $80k
turbine, or something like that?

It's certainly one answer. The price on that Maule is $450,000. With an IO-540, it's
$173,420.

I've read that there are technical problems building small turbines; ie. the smaller
the diameter of the turbine, the faster the blades must spin to produce power.

Look at the specs on those turbines used in model airplanes. The RPM
is almost unbelieveable.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

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