Hi Marc,
"
Obstacle clearance after a takeoff roll can't be used to derive climb RATE at a particular airspeed."

Evidence of why not is why I posted this question.

BTW, If you would, I would be very interested in knowing how you determined the distance from one altitude to another at a constant airspeed in order to determine the flight path angles at both Vy and Vx.
For example; Was wind considered? e.g. not knowing the wind exactly were 2 runs made in opposite directions as soon after the other as possible starting at the same altitude, then flying the same course and starting altitude at the other airspeed?