Diesel aircraft engines and are the light jets pushing out the twins?

In rec.aviation.owning R. David Steele /omega wrote:
What has happened to the development of the diesel aircraft
engines? As far as I have seen, only Diamond has a production
aircraft with diesel engines (they flew one across the Atlantic,
with 5.76 gph).

See http://www.avweb.com/ the column entitled Motor Head #2: Excerpts
from the Oshkosh Notebook.

And it looks like the small jets are pushing the turbo props and
the twin piston engines. Is it a matter of time before it will
be cheaper to just buy a small jet?

I'm not holding my breath on that one.

What puzzles me is why there doesn't appear to be anyone working on
turbines in the range of 160 to 250 HP for aircraft.

The upside to diesels is Jet-A is cheaper and more available just about
everywhere outside the US.

The downside is they tend to be heavier than the gas engines they would
replace, reducing the usefull load.

Turbines run on Jet-A and tend to be a lot lighter.

Put a 180 HP turbine in a 172 and you would have a real 4 place A/C,
though one with a long, funny looking nose to make the W/B work out.


--
Jim Pennino

Remove -spam-sux to reply.

wrote in message
...
And it looks like the small jets are pushing the turbo props and
the twin piston engines. Is it a matter of time before it will
be cheaper to just buy a small jet?

I'm not holding my breath on that one.

Me either. But if you believe the manufacturer's claims, it is just a
matter of time. Several of the "mini jet" designs under development are
cheaper than the existing turboprop models, single or twin, and cost about
the same as new piston twins.

Of course, you can't actually buy any of them right now, and it remains to
be seen what they will actually cost if and when they make it to market.

What puzzles me is why there doesn't appear to be anyone working on
turbines in the range of 160 to 250 HP for aircraft.

GA Flyer just included an "engines in development" article as part of their
Oshkosh coverage, and had a picture of exactly that, as well as a mention in
the article of the company producing the small turbines (I think they said
all for turboprop installations).

They are out there...you just need to look. Don't get distracted by the
lack of certificated engines, or lack of interest in certification. Not all
of the engine research and development going on is aimed at the certificated
market.

Pete

In article , wrote:
Put a 180 HP turbine in a 172 and you would have a real 4 place A/C,
though one with a long, funny looking nose to make the W/B work out.

The trouble is the missions a C172 flies (typically short distances, low
altitudes) makes a turbine incredibly fuel inefficient - all that useful
load would be taken up by the fully-filled additional tanks you'd need
to fly the same distance as the 180hp piston version. Just take a look
at the turbine Piper Meridian for some of the problems that has - if you
want to take 4 people in a Meridian, you have barely an hour of fuel
with basic IFR reserves. Top the tanks for decent range and it's a 2
person plane.

For normal light GA altitudes, a recip diesel is much better suited -
the extra weight is offset by not needing anywhere near as much fuel,
and it's efficient at the low altitudes we tend to fly at.

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"

wrote in message ...

And it looks like the small jets are pushing the turbo props and
the twin piston engines. Is it a matter of time before it will
be cheaper to just buy a small jet?

I'm not holding my breath on that one.

Well, they may not compete with 30-year-old twin cessnas selling for
200k, but a new Baron goes for around 1.2 million, so the comparison
is more relevant than you might think.

What puzzles me is why there doesn't appear to be anyone working on
turbines in the range of 160 to 250 HP for aircraft.
...
Put a 180 HP turbine in a 172 and you would have a real 4 place A/C,
though one with a long, funny looking nose to make the W/B work out.

The flight profile of a 172- low altitude and low speed- are the
opposite of what a turbine likes to operate in. What you'd have is a
horrendous gas-guzzler, unless you feel like climbing up into the
flight levels.

-cwk.

C Kingsbury wrote:

Well, they may not compete with 30-year-old twin cessnas selling for
200k, but a new Baron goes for around 1.2 million, so the comparison
is more relevant than you might think.

Diamond's goal is to sell its D-Jet for under 1 million. However,
operating costs will be a different story I guess.

Stefan

"Peter Duniho" wrote in message
...
wrote in message
...
And it looks like the small jets are pushing the turbo props and
the twin piston engines. Is it a matter of time before it will
be cheaper to just buy a small jet?

I'm not holding my breath on that one.

Me either. But if you believe the manufacturer's claims, it is just a
matter of time. Several of the "mini jet" designs under development are
cheaper than the existing turboprop models, single or twin, and cost about
the same as new piston twins.

Of course, you can't actually buy any of them right now, and it remains to
be seen what they will actually cost if and when they make it to market.

What puzzles me is why there doesn't appear to be anyone working on
turbines in the range of 160 to 250 HP for aircraft.

Small turbines are inherently inefficient so you are unlikely to see them in
this power range. The fuel consumption might be double that of a diesel.

Mike
MU-2



GA Flyer just included an "engines in development" article as part of
their
Oshkosh coverage, and had a picture of exactly that, as well as a mention
in
the article of the company producing the small turbines (I think they said
all for turboprop installations).

They are out there...you just need to look. Don't get distracted by the
lack of certificated engines, or lack of interest in certification. Not
all
of the engine research and development going on is aimed at the
certificated
market.

Pete

"Mike Rapoport" wrote in message
news
Small turbines are inherently inefficient so you are unlikely to see them
in this power range.

You're not listening. I already HAVE seen them in that power range. The
likelihood of having done so is irrelevant, since it's already happened.

The fuel consumption might be double that of a diesel.

It might be be, I don't know. Nevertheless, they do exist...

Pete

I meant that you are unlikely to see them on production aircraft. Sorry I
wasn't clearer.

Mike
MU-2


"Peter Duniho" wrote in message
...
"Mike Rapoport" wrote in message
news
Small turbines are inherently inefficient so you are unlikely to see them
in this power range.

You're not listening. I already HAVE seen them in that power range. The
likelihood of having done so is irrelevant, since it's already happened.

The fuel consumption might be double that of a diesel.

It might be be, I don't know. Nevertheless, they do exist...

Pete

"Mike Rapoport" wrote in message
nk.net...
I meant that you are unlikely to see them on production aircraft.

I'll buy that.

Though, I wouldn't go so far as to say it could never happen. Who knows?
Maybe there's an application where reduced weight or increased reliability
is more important, or perhaps the "fundamental" inefficiencies of small
turbines will turn out to not be so fundamental after all.

But you are right, for now the existing low-power turbines show no sign of
being targeted for certified, production aircraft.

Pete

"Peter Duniho" wrote in message
...
"Mike Rapoport" wrote in message
nk.net...
I meant that you are unlikely to see them on production aircraft.

I'll buy that.

Though, I wouldn't go so far as to say it could never happen. Who knows?
Maybe there's an application where reduced weight or increased reliability
is more important, or perhaps the "fundamental" inefficiencies of small
turbines will turn out to not be so fundamental after all.

But you are right, for now the existing low-power turbines show no sign of
being targeted for certified, production aircraft.

Pete


My understanding is that the reason that small turbines are less efficient
than large ones is because of efficiency losses at the tips of both the
compressor and turbine and the internal drag of the engine surfaces. Both
of these issues get more pronounced as things get smaller. Similiar to a
pipe with a cross sectional area of 1"sq flowing less than half as much
fluid as one with a cross section of 2" sq.

That is not to say that the engines will not get more efficient, it just
means that small turbines will be less efficient than large ones.

Mike
MU-2