In a message dated 12/20/2004 5:53:18 P.M. Central Standard Time,
REHBINC@aol.com writes:
For the second run at 10k, was the rpm held to 2500 rpm as
before?
YES.
If so, then why does the fuel flow increase from 8.9 gph to 9.8 gph with
a temperature increase of 3 C for the first run at 12k?
I wasn't there. I didn't write the original numbers. I may have
made the telephone mistake and inadvertently transmogrified info thereby
supporting antidisestablishmentarianism.
.
With constant MAP and RPM, a 3 C increase in OAT should amount
to roughly 1% decrease in mass air flow. It seems as though the fuel flow
should decrease by the same amount to maintain the same enrichment. Shaft
power should decrease by slightly less than this due to the reduction in
throttling losses at WOT.
Am I missing something here?
Yes.
As for a 3% increase in power resulting in a 9% increase in TAS at a
given altitude, a change from 61% to 64% is a 5% change, not 3%. Even so, 5%
added power resulting in a 9% increase in speed defies basic fluid dynamics.
At normal aircraft Reynolds numbers, speed will change roughly with the
cube root of power until you enter the transonic region. In other words an 8
fold increase in power will result in about twice as much
speed.
So? We are not normal.
I think it is the data that is fibbing.
OK, Do it yourself. As I said to Chris, ".. I'll have to do
myself."
At least someone reads these things.
Scott Krueger
AKA Grayhawk
N92EX IO320 Aurora, IL
(KARR)