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JHines · September 29th, 2003, 20:41

[ QUOTE ]
[partial quote] All fuel delivery gizmos, be they updraft carburetors in a Cessna 172, fuel injectors in a Navajo, or fuel control units in a Rolls Royce RB211 high-bypass fanjet engine, deliver fuel by mass, not by volume, in order to achieve a given combustion ration, i.e., ratio of air to fuel by mass, not volume.

[/ QUOTE ]

I agree. But turbine equipment, in particular, operates in a closed loop. That is, it feeds the combustor just enough BTU's (or put another way, fuel mass) to maintain the set N1 (or T4 or whatever).

So back to my question above, given two hypothetical identical flight profiles on the same aircraft, each starting with 100% full by volume tanks (or "slam full" tanks, as we say in the South), but at different temperatures (ambient & fuel), do you or don't you see a difference in range, because at colder temps the same "full by volume" tanks have more fuel mass in them?

Or doesn't it matter because turbine pilots order fuel by weight instead of just having the tanks topped??

September 29th, 2003, 20:41	#23
JHines Junior Member Join Date: May 2003 Location: SC Posts: 292	Re: Here\'s the answer to the question you are really asking: [ QUOTE ] [partial quote] All fuel delivery gizmos, be they updraft carburetors in a Cessna 172, fuel injectors in a Navajo, or fuel control units in a Rolls Royce RB211 high-bypass fanjet engine, deliver fuel by mass, not by volume, in order to achieve a given combustion ration, i.e., ratio of air to fuel by mass, not volume. [/ QUOTE ] I agree. But turbine equipment, in particular, operates in a closed loop. That is, it feeds the combustor just enough BTU's (or put another way, fuel mass) to maintain the set N1 (or T4 or whatever). So back to my question above, given two hypothetical identical flight profiles on the same aircraft, each starting with 100% full by volume tanks (or "slam full" tanks, as we say in the South), but at different temperatures (ambient & fuel), do you or don't you see a difference in range, because at colder temps the same "full by volume" tanks have more fuel mass in them? Or doesn't it matter because turbine pilots order fuel by weight instead of just having the tanks topped??