Tired of bumping along to Oshkosh?

I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.


"Rich S." wrote in message
...
http://tinyurl.com/9t6e8

Rich S.

wrote:
I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.


So the aircraft I cited that DID use avgas in jet engines on every
flight don't count?

Dan, U.S. Air Force, retired

wrote:
I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.

Funny, most engines I'm aware of compress the air, or the air/fuel
mixture, but don't try to compress the fuel.


Matt

Where are you getting these "compression" figures?

" wrote in message
...
I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.


"Rich S." wrote in message
...
http://tinyurl.com/9t6e8

Rich S.

" wrote in message
...
I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.


"Rich S." wrote in message
...
http://tinyurl.com/9t6e8

Rich S.




Why are you referencing my post?

Rich S.

Most piston engines I'm familiar with compress the fuel/air mixture 8-10:1,
not 14:1. Since the fuel is delivered to a jet engine AFTER the compressor
stages (which compress the ambient air only) I'm having trouble wrapping my
head around the 70:1 compression ratio.

Jim



" wrote in message
...
I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.

wrote:

Unless something has changed, jets cant burn avgas-too hot,will burn up
turbine wheels etc.Pilot was probably bs-ing you

Nothing has changed, the reverse cycle just doesn't work. ie. you
typically can't burn JetA in an AvGas engine...

I had a key to the mogas pump, I believe he said it would burn that as
well. He opted to wait for the FBO to pump the JetA, had to page him and
wait 45 minutes or so...

I had fun bumping along to Oshkosh. When the bumps got too bad me and the
old gal changed altitude or didn't fly above the roads or over the big
metal-roofed barns which made such considerable thermals. 500' agl sure
was fun, though, chasing and racing 18-wheelers and an occasional hawk,
buzzard, or crow.

Last time bumping along it was nice to have that 10 closest airports feature
on the GPS for getting on the ground when the thunderstorms closed in.

Last time in Oshkosh it was those kids on green JD 4ormore-wheelers you had
to look out for. They would run you down.

RST Engineering wrote:

Most piston engines I'm familiar with compress the fuel/air mixture
8-10:1,
not 14:1. Since the fuel is delivered to a jet engine AFTER the
compressor stages (which compress the ambient air only) I'm having trouble
wrapping my head around the 70:1 compression ratio.

Jim


Jim
From what I recall (disclaimer my recall isn't the best!) his compress ratio
is probably ok but you are correct the only part that is being compressed
is the air, the fuel burn "powers" the turbine which is connected to the
compressor to produce more power. The excess heat is discharged out the
exhaust. In a Fan jet the compressor is made bigger to flow more air than
the "turbojet" can ignite and the excess is routed around the turbine so
you have more airflow with less waste heat out the exhaust.
Am I close?

John

Has anyone here been certified to actually work on a jet engine, how would
you keep from exceeding 620 degrees egt, the fuel control cant operate under
the avgas parameters in correcting the egt, the retired af person does not
appear to know anything about a jet engine. In a J-57 where you have 16
stages of compression prior to injecting the fuel in the combustion chamber
how would you bleed off enough air and still maintain power using avgas, the
combustion chambers and rest of the hot section can not take the extreme
heat of regular avgas, the flashpoint is too high compared to jp-4 or
similar fuel. How could the fuel control work properly when it is lubricated
by the jp-4. please tell me

"Bryan Martin" wrote in message
...
As I recall, the biggest problem with burning gasoline in a turbine is the
the TBO is shortened due to the lower lubricating qualities of gasoline
over
jet fuel. The fuel pumps and injectors wear out quicker.


in article , at
wrote on 8/5/05 11:14 PM:

I stand by my original post, in a jet engine you compress the fuel
approximately 70 to 1, gas is normally compressed 14 to 1. To use avgas
except in a emergency can burn up the combustion chambers and burn the
turbine wheels severely. You can not feed them on a regular basis.


"Rich S." wrote in message
...
http://tinyurl.com/9t6e8

Rich S.