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Scotty!
Here's some GPS-based test data I
acquired a few years ago on Oscar Grassle's 235 with a stock 320, N80G,
with a two-blade, fixed-pitch ELIPPSE prop and one PLASMA I ignition at 10,000'
d-alt, leaned for max power/rpm.
174k/200 mph, 2680 rpm, 89hp/54%
182k/210 mph, 2800 rpm, 100 hp/60%
191k/220 mph, 2920 rpm, 113 hp/68%
200k/230 mph, 3040 rpm, 130hp/78%
202k/233 mph, 3090 rpm, 137 hp/83%
The average effective prop pitch,
based on TAS mph X 1056 / rpm, was 79.4" The hp numbers should be pretty close
even though I didn't take into account the increased intake density due to
dynamic pressure. Doing this with the last numbers at 202k, which would have had
the greatest effect, only changed it to 138hp/86%. The hp was also based on
a linear hp vs rpm estimate. 'Course, all of this is predicated on his
O-320 putting out 160 hp at rated map and rpm. I have reasonable doubt about
that; I would put it more at about 150 hp based on some other test data. The rpm
was corrected for known tachometer error. D-alt had stagnation temperature rise
accounted for in the OAT.
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