Jim

Long time ago in a land far away we used JP-1 (kerosene) in the J-33
engine. If we got caught out and there was no jet fuel at the base we
landed at we could fill up with gasoline to get to a jet fuel base or
get home. If we were using gasoline, we had to check TPT and not over
temp it. Bottom line was staying in engine specs we had less range
with gas than kerosene.

Big John

On Wed, 10 Mar 2004 21:41:16 -0500, "Jim Carriere"
wrote:

"Corky Scott" wrote in message
...
On Wed, 10 Mar 2004 15:42:28 GMT, "Robert Bates"
wrote:

OK, here's the part where I get flamed. On other newsgroups I have been
reading about guys burning biodiesel and atf in diesel engines so would a
turbine tolerate this?

My understanding is that, short term, a turbine engine will burn
anything that will flow and burn. Whether the turbine will tolerate
odd fuels that may burn at different temperatures than what the engine
was designed for over the long term is another question.

I completely agree that a turbine engine will work if it can burn fuel.

I disagree with your thinking about flame temperature affecting the engine.

[I hope none of this sounds condescending, that isn't what I intend. It's
just some basic applied engine theory, pretty straightforward stuff.]

For a given output, gas turbines will burn at about the same temperature
regardless of fuel types. This is mainly because the air:fuel ratio is very
lean (ballpark 50:1) compared to piston engines. The output at a given gas
temperature depends on the properties of the gas. Since only about 30% of
the air is used to support combustion, and of that most of it is nitrogen
anyway, this is why type of fuel doesn't have a great effect on a gas
turbine. Fuel flow is increased or decreased until a desired output is
achieved, and the gas temperature and engine rpm pretty much "find"
themselves.

Where fuel type does matter is in the fuel system and on turbine blade
materials. The fuel system is affected in different operating environments-
hot, cold, high and low altitude. Turbine blades materials and the lead in
avgas are a bad idea. Turbine blades are also more sensetive to dirty
exhaust (soot, etc) than, say, the exhaust valve in a piston engine.

On the other hand, back to what you said about if the fuel burns... As long
as the fuel can consistently get to the combustor (for liquid fuel,
vaporizing or gelling in the fuel lines are the main concerns) it will burn.
This is what is great about gas turbines- they run on cheap fuel. Octane
or cetane properties are irrelevant, because the combustion in a gas turbine
is constant like a blowtorch.

Back to the MiG 15 fuel, JP-4 is often described as a blend of gasoline and
kerosene.