----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- My STC engine is redlined on the tach at 2575RPM
using the McCauley 7150 prop. In use it usually will not go over 2550RPM at full
throttle level flight. High cruise at 2450RPM in still air gives an indicated
airspeed between 115 and 120. I never believed the airspeed was correct, changed
to a test indicator which basically indicated the same speed, changed out the
pitot tube and speed remained the same. A close check in still air with the
Garmen 295 indicated 113-114 ground speed, the indicator showing 115-117. So in
the end the plane was actually flying faster than I thought. I would note
that the original manual in 1946 indicated that new Ercoupes had a cruise speed
of 110MPH to 120MPH. I never believed that, and thought 105 to 110 was more
correct. My plane has a fairly new paint and I keep it waxed which help it gain
a mile or two. Take off with this Coupe is basically normal, with 550 per minute
climb from density attitude 2000ft under max load.
I have a friend that has a Coupe with the 85HP
engine and he has the 49 pitch prop, which climbs about the same as my plane
with a similar load, but I seem to have a higher cruise speed. I can slow my
plane down to 2200RPM and keep 100-105 cruise using a flat four gallons an
hour. High cruise is 4.7 to 5 gallons an hour. Fred C
Fowler
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