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



 
 
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  #1  
Old September 16th 04, 05:07 AM
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Default 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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  #2  
Old September 16th 04, 06:25 AM
Dude
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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.


  #3  
Old September 16th 04, 10:00 AM
Thomas Borchert
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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)

  #6  
Old September 16th 04, 03:46 PM
Stefan
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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

  #7  
Old September 16th 04, 03:55 PM
C J Campbell
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"R. David Steele" /OMEGA wrote in message
...
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).


The DA42 currently has a diesel engine, but Diamond is experimenting with a
Lycoming. Although they say that this would be for the European market only
and no decision has been made on a certification program, the fact is that
American pilots would probably be much more interested in this version. It
offers more power for about the same fuel burn and gas here is not much more
expensive than diesel.

I am very interested in one of these planes, especially the DA42 Observer
camera platform.

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?


Acquisition cost is one thing; operating cost is another. Turbines use much
more fuel and are far more difficult to insure. There will always be a place
for turboprops like the Caravan or Pilatus and for small piston twins.


  #8  
Old September 17th 04, 06:51 AM
Thomas Borchert
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C,

Although they say that this would be for the European market only


AFAIK, they say just the opposite (to me, at least): The Lyc version would be
for the US market. It's also a matter of using the DA42 in a training
environment, where pilots still need to be trained for three levers, not the
single one the Thielert has.

It
offers more power for about the same fuel burn and gas here is not much more
expensive than diesel.


Huh? Same fuel burn? Hardly.

--
Thomas Borchert (EDDH)

  #9  
Old September 17th 04, 02:24 PM
Kees Mies
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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
  #10  
Old September 17th 04, 08:13 PM
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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.
 




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