On 8/27/2023 4:18 AM, Phillip Matheson via KRnet wrote:
FYI I removed my 60 x 70 today and put a 68 x 59 ( too low of a pitch) but
gave it a single flight
Static, brakes wouldn’t hold but around 2400
Climb 2500 70kts over 1000 rpm
WOT over 2750 only 100kts
Phil.
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Phil,
Have you verified your tachometer and ASI? Generally speaking a longer
prop is more efficient. Your numbers for ground run and climb with the
new prop seem to be in the ball park but your cruise number looks to be
in serious error. In theory that prop should result in 150+ mph at 100%
efficiency. (pitch in inches X 2800 rpm X 60 minutes / 12 in. per foot
/ 5280 feet per mile = 156 mph ) . We can't expect 100% efficiency but
often the numbers compute that way.
Any chance you can get the original prop re-pitched? With a good set of
wheel covers and a properly sized prop you should get a cruise at 2500
rpm in the 150 to 160 mph range. Keep working at it. You'll get there.
Larry Flesner
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