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Following this thread I
have read a lot about pilots flying behind a TSIO550 and burning 17.5
gph. My ES-P (7.5 CR) flys at FL250 set at 31.5" and 2500
rpm, burning 15.5-16.0 gph LoP and showing a TAS of 230+kt. I have a
LightSpeed dual EI system and turn an MT 4-blade prop.
Robert M.
Simon
ES-P N301ES
In a message dated 5/29/2007 11:10:10 A.M. Pacific Daylight Time,
walter@advancedpilot.com writes:
OK, Paul, let's review the
issue.
Compression ratio:
The higher CR WILL ALWAYS result in a lower EGT/TIT if all else is held
constant. Why? Boyle's Law. PV = nRT. As the volume
expands, the gas temperature goes down. More expansion; more temp loss =
lower EGT.
Walter:
There is no issue here to review, so please step away from the tutorial
podium. I fat fingered my previous email and met 17.5 rather
than 7.5 so I was intending to compare a rate to a rate. Your simplistic
physics above is all just dandy, but all else is never held
constant. The timing recommended by the engine builder for a 8.5 and
7.5 are different, the MP is different to recapture some of the detonation
margin and so on. All this has little to do with my original question
which was at the same rate of consumption of a precious resource, disposable
income, what sort of KIAS are LIV drivers achieving. You said in a
previous email that a typical cruise fuel flow LOP for the TSIO-550 is 17.5 gph
so fine, what indicated airspeeds are we seeing and if anyone now cares, if
there are differences what accounts for those differences. If higher CRs
are more fuel efficient as has been stated by many, well I would expect to see
LIVs equip with those engines cruising at 17.5gph attaining a higher indicated
airspeed. I chose KIAS because I thought it would simplify data
collection. Simple stuff, and since I did not spend my time building a
test stand, meaningful stuff at least for me.
paul
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