Kitfox abrupt departure sensitivity to low speed stalls

[rv9ralph]

James,
I am not an aerodynamicist nor am I a test pilot. However, I think you are getting in the weeds trying to decipher this.

The testing of an aircraft starts using a stabilized and constant airspeed at least 15 knots/mph above the tested and demonstrated stall for that aircraft. Then the timed climb is conducted starting at a predetermined altitude maintaining a constant airspeed for one minute noting the altitude at the end of one minute. Repeat starting at the same altitude, with a decrease in airspeed by 5 knots and climb one minute then note the altitude. Repeat again, and again When this data is plotted, there will be an increase in the rate or angle of climb up to a point and then it will drop off. This is the data point that will give the appropriate Vx and Vy for that tested aircraft. With certified aircraft, it is considered to apply to the whole fleet of the same type of aircraft (hence the purpose of "type certified") with experimental aircraft, each one is considered unique and needs to be tested to demonstrate their performance.

This climb is not hanging on the prop, just above stall. The test is conducted using airspeeds (remember, you start 10 knots above stall), in increasing increments until the performance drops off. The position over ground is not considered in making these tests.

That is it for now.
Ralph