Sent: Sunday, May 04, 2008 8:50 AM
Subject: [FlyRotary] Re: Jet-A
Thanks for the vote of confidence(I think),
Mark.
I don't know, but I suspect there would be a
problem with Jet A in the typical rotary as well. Here is my very
initial take on what the major problem "Might" be trying to run on Jet
A.
The flash point of gasoline is nominally around
- 45F whereas the flashpoint of Jet A fuel ranges from 102 - 104F.
So more energy is required to ignite it even if the fuel mixture is in a
"combustible" state.
The Reid vapor point of JP fuels vary but
figures for Jet A as low as 0.1 psi can be found whereas it appears to
vary from 9 - 14.7 psi for automobile gasoline (these figures are
apparently mandate by various federal and state requirements) .
The vapor point basically relates to how easily the fuel will turn into a
vapor which is required for ignition. The higher the vapor point the
more easily converted to vapor - is my understanding.
To ignite and permit propagation of the flame
front each fuel type vapor content must fall between a minimum and upper limit
of concentration as a mixture. For example this mixture for gasoline is
between 1% (min) and 6% (maximum), but it varies for different fuels.
Naturally, our fuel system is designed to meet the mixture limits for
gasoline.
So My best guess is that give the higher flash
point required, given the much lower volatility (lower vapor pressure) and the
different mixture limits of Jet A is that neither a ordinary
piston engine nor the ordinary rotary would have much success in running on
Jet A..
However, I am not a fuel/combustion chemist nor
did I sleep at a Holiday Inn last night.
Ed
----- Original Message -----
Sent: Sunday, May 04, 2008 7:31
AM
Subject: [FlyRotary] Jet-A
OK, here's a question out of left field. A Lancair
recently went down in AZ right after being refueled. On the Lancair
list, the speculation is that it was fueled with Jet-A. I was curious,
if this happened to a rotary, would it run (continue to produce power) on
jet-a or would the engine quit? I speculate that due to the fuel pumps
continuously circulating the fuel to the fuel rails and back to the tank, it
probably wouldn't even start, but if it did, would it continue to run on the
mix of jet-a and mogas? I guess it depends on the ratio of mogas
to jet-a. Assuming that the fuel was almost 100% jet-A, would it still
run?
Ed, you've pretty much had everything happen to you that
can possibly happen in an airplane, what-you-say?
Mark
S.
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