Jets use something like 100% "excess air" in their combustion process,
unlike piston engines. Much of this air is used for internal engine cooling
and some is used as "bleed air" for cabin pressurization, de-icing, etc.

Rod
"vincent p. norris" wrote in message
...
As far as the amount of air being passed through an engine, for a
reciprocating engine, the amount is much smaller than a jet engine.
Gallons
per second for a piston engine, and hundreds of gallons for a jet engine?
Something like that.

Let me see..... The fuel-air mixture for a piston engine is about 14
pounds of air per pound of avgas, is it not? Would it be about the
same for jet fuel?

How "big" a pound of air is depends on pressure and temperature
(Boyles' and Charles' Laws, if I recall correctly), but I can't even
guess how big a box it would take to hold a pound of air at STP.
Perhaps someone else can. I guess any good chemist could do it.

vince norris