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

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I don't see the fuel burn on the small turbines competing with the diesels,
but there are some attempts at getting close to the Lycosaur level.

Here is one - http://www.innodyn.com/

Don't know anything about them though.

As for light jets pushing down demand for twin piston and turbo props, you
are correct. You mentioned Diamond, and they are going straight after the
light twin and turbine single engine market with their single engine jet.
If you will accept a single engine, the economics seem to make sense to go
that route rather than with an equally expensive Piper or Beech plane.

It will be interesting to see what will happen. Some missions will likely
push folks to stick with the prop planes though.

R.,

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).


In the European market, Diamond offers both the single-engine DA40 and
the DA42 twin with Thielert Centurion engines. More than 100 of these
engines are flying. in the US, only the DA42 is offered. Also, Thielert
in Europe offers retrofit kits for Cessna 172s and Piper Warriors. Of
those, 30 or so are flying.

All other diesels I know of are not yet available in a certified kit,
although by now the sma retrofit to the 182 might be available.

--
Thomas Borchert (EDDH)

Thomas Borchert wrote in message ...
All other diesels I know of are not yet available in a certified kit,
although by now the sma retrofit to the 182 might be available.
There is at least one, I believe it is either a C172 or C182.
I can not tell the difference, all planes with the wings on top are
just cessnas to me.
Anyway, it is used as a jump plane operating from Seppe(EHSE) with a
SMA engine.
Call sign PH-PAC.

-Kees

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"

A gas turbine scales up easily and but is nearly impossible to scale
down. The auto manuacturers found that out in the 1940s - remember
the "car of the future" on the covers of Popular Science et al?
Turbines for cars are further away now than they were 55 years ago.
The turbine suffers from excessive fuel consumption at part throttle
(the piston engine is incredibly flexible that way)and in smaller HP
installations.

So much of the useful load of an aircraft is fuel, that fuel
efficiency is very important for overall mission performance.

The problem of an engine is to find the most efficient way to expand a
certain flow rate of compressed hot gas to atmospheric pressures. A
turbine can do this with large mass flow rates, but as the flow rates
become smaller, the turbine speeds (rpm) must increase enormously and
the centrifugal accelerations get out of hand. On the other hand, a
piston can process an expansion efficiently with small flow rates.

Think of it this way - a model airplane engine can be made to run with
1/20 of a cubic inch (.049 cu inch to even .010 cu inch), but piston
engine aircraft became impractical above a few thousand HP. That is
the range of practicality for a piston concept.

An engineering prof once said - if the gas turbine had been invented
first, the piston engine would have been looked on an ingeneous
solution to the turbine's material and speed and power range problems.

Diesels may eventually make it. They have a weight problem that may
be offset by a lower specific fuel consumption, but for a given
operating condition, spark ignition engines can nearly approach the
consumption of diesels by using turbo compounding and operation only
at full throttle.

In article ,
) wrote:

Think of it this way - a model airplane engine can be made to run with
1/20 of a cubic inch (.049 cu inch to even .010 cu inch), but piston
engine aircraft became impractical above a few thousand HP. That is
the range of practicality for a piston concept.

It is certainly possible to build much larger piston engines than that.
How about http://www.bath.ac.uk/~ccsshb/12cyl/

Howdy!

In article ,
Roy Smith wrote:
In article ,
) wrote:

Think of it this way - a model airplane engine can be made to run with
1/20 of a cubic inch (.049 cu inch to even .010 cu inch), but piston
engine aircraft became impractical above a few thousand HP. That is
the range of practicality for a piston concept.

It is certainly possible to build much larger piston engines than that.
How about http://www.bath.ac.uk/~ccsshb/12cyl/

But it is a *little bit* impractical as an *aircraft* engine...

yours,
Michael


--
Michael and MJ Houghton | Herveus d'Ormonde and Megan O'Donnelly
| White Wolf and the Phoenix
Bowie, MD, USA | Tablet and Inkle bands, and other stuff
| http://www.radix.net/~herveus/

Roy Smith wrote:

It is certainly possible to build much larger piston engines than that.
How about http://www.bath.ac.uk/~ccsshb/12cyl/

Ah! I've always wondered how that Antonov 225 Mrija was powered...

Stefan

In rec.aviation.owning wrote:
A gas turbine scales up easily and but is nearly impossible to scale
down. The auto manuacturers found that out in the 1940s - remember
the "car of the future" on the covers of Popular Science et al?
Turbines for cars are further away now than they were 55 years ago.
The turbine suffers from excessive fuel consumption at part throttle
(the piston engine is incredibly flexible that way)and in smaller HP
installations.

So much of the useful load of an aircraft is fuel, that fuel
efficiency is very important for overall mission performance.

The problem of an engine is to find the most efficient way to expand a
certain flow rate of compressed hot gas to atmospheric pressures. A
turbine can do this with large mass flow rates, but as the flow rates
become smaller, the turbine speeds (rpm) must increase enormously and
the centrifugal accelerations get out of hand. On the other hand, a
piston can process an expansion efficiently with small flow rates.

Think of it this way - a model airplane engine can be made to run with
1/20 of a cubic inch (.049 cu inch to even .010 cu inch), but piston
engine aircraft became impractical above a few thousand HP. That is
the range of practicality for a piston concept.

An engineering prof once said - if the gas turbine had been invented
first, the piston engine would have been looked on an ingeneous
solution to the turbine's material and speed and power range problems.

Diesels may eventually make it. They have a weight problem that may
be offset by a lower specific fuel consumption, but for a given
operating condition, spark ignition engines can nearly approach the
consumption of diesels by using turbo compounding and operation only
at full throttle.

While not quite a .049, here's a 3.7" in diameter, 2.6 lb turbine
that produces 16.5 lb of thrust.

http://jetcatusa.sitewavesonline.net/p70.html

Their biggest turbine is 5.12", 5 lb, and produces 45 lb of thrust.

Here's another outfit that sells a 3.5" diameter, 7.25" long, 1.9 lb
turbine with 11.4 lb of thrust.

http://www.swbturbines.com/model_turbines.htm

Now granted these are turbojets, not turboprops, but it appears to me
that making small turbines is possible...


--
Jim Pennino

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