Jean Claude,
I thought that the equivalent area is derived from the drag force equation:
D = 1/2 * rho * Cd * A * v^2 by expressing A.
It seems you are saying the the equivalent area is A*Cd. If that's the case, you would need to multiply my results by the drag coefficient of a flat plate.
Yes, if you have a rotor model which calculates disk AoA as a function of (among others) air speed. I can fly a quick ASI calibration at 200 km/h to give you accurate airspeed. However, It will be between 190 and 210 km/h. There seems to be not too much variation in the drag area, so maybe an error of +/- 0.06 m^2. That's pretty good.
That is correct. However, I have reached 225 km/h on several occasions. The ASI calibration may, hover, be not very good at speeds that high. Remember, that we set Vne at 195 km/h. It only needs to be accurate up to Vne.
Greetings, -- Chris.
I thought that the equivalent area is derived from the drag force equation:
D = 1/2 * rho * Cd * A * v^2 by expressing A.
It seems you are saying the the equivalent area is A*Cd. If that's the case, you would need to multiply my results by the drag coefficient of a flat plate.
Main uncertainty is the airspeed.
Yes, if you have a rotor model which calculates disk AoA as a function of (among others) air speed. I can fly a quick ASI calibration at 200 km/h to give you accurate airspeed. However, It will be between 190 and 210 km/h. There seems to be not too much variation in the drag area, so maybe an error of +/- 0.06 m^2. That's pretty good.
In my post # 26, I mentioned that my calculation is for a 8.6 x 0.2 m rotor, without being contradicted.
That is correct. However, I have reached 225 km/h on several occasions. The ASI calibration may, hover, be not very good at speeds that high. Remember, that we set Vne at 195 km/h. It only needs to be accurate up to Vne.
Greetings, -- Chris.