Cubes,
You have motivated me to fly a flight test that I've been putting off for two years. I read your post yesterday and went out to fly the level performance, climb performance, and glide performance tests. These are the same tests that I've been teaching in my Flight Test Engineering course, but we've mostly been using Piper Warriors and Cessna 210s so that the students can ride along.
I ran through airspeeds from 60 knots to 150 knots in 10-knot increments. For the climbs, I started below 2500 ft MSL and climbed through 4000 ft MSL at 2500 RPM and 25" manifold pressure. I then reduced the throttle and descended at idle throttle at the same prop setting. The data comes from a flight data recorded mounted to the right wing tie down. It measures/estimates airspeed, attitude, angular rates, acceleration, and position at ~200 Hz.
Here's the Climb Polar:
The blue circles show the points on the polar, computed from an average of the stabilized section of the climb. Note that this plot shows the target airspeed rather than the measured airspeed - I'm still working out a calibration issue on that measurement. I was mostly between +/- 2 knots of the target airspeed during the maneuvers. The green line is a third-order regression that, ideally, represents the actual shape of the climb polar.
My maximum measured climb rate was about 1150 FPM at 80 knots IAS. The black starts at 0 airspeed and 0 climb rate and intersects the green line at what *should* be Vx, which here is looks like 75 KIAS.
Here's the Glide Polar:
It's not a great representation of glide, since the prop setting makes the propeller spin fast and create quite a bit of drag at idle. Even so, the slowest sink rate I measured was about 750 FPM at 80 KIAS. The intersection with the black line should show best glide speed, and that looks like it might be between 80 to 90 knots.
I still haven't processed the level flight data, but I tested the entire speed range from firewalled throttle to minimum controllable airspeed in increments of 1" of manifold pressure. After I convert the power setting to horsepower, I'm hoping it will give a nice power required vs airspeed curve that will give the minimum power and maximum range airspeeds.
