Doppler measurement

[antslake]

I downloaded waveosscope but I am not sure if I am doing all right
I got 2 readings, 84kmh and 137kmh
Both much less than I expected, but this is my first speed plane.

I am adding the video, maybe someone else can do it, and tell me if I am doing anything wrong.

It's a projeti running a mega 16/15/3 (I think, can't see label) just bought the plane, and a 5.5x4.3 graupner prop.

I would love to get over 100mph with this plane.

http://www.rcgroups.com/forums/showthread.php?t=572565#post6099545

[antslake]

Oh it was about 60? F that morning.

[BMatthews]

Based on a more or less normal 80% efficiency factor of the prop you'd have to spin that puppy at a little over 30,000 rpm to get 100 mph out of it.

Or dive it from a great height...

Doppler requires a consistent sound to do the measurements with and a consistent approach to within a close proximity to the microphone. A far and then a near pass would mess things up. You want to make the model pass withing a close distance each time. Something like perhaps 10 to 20 feet. Also I'm not sure an electric motor makes the sort of sound that such a program would requre. For example the sharp sound of an engine exhaust is far easier to doppler than a purr of a motor or the ZZZZZZ of a prop.

[antslake]

I got the information for doig it from this thread

http://www.rcgroups.com/forums/showthread.php?t=571167&highlight=doppler

I am going to post my question there, maybe they can help.