Make App - Optical Tachometer (Helicopter)

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Hi all, Got a Desire HD and a radio control helicopter (Trex 500).

Would like to be able to look at the heli in flight with the camera (in video mode is ok) and see what speed the rotors are spinning at.

All that's required is a method of adjusting the camera shutter speed while pointing at the heli until the blades look stationary. (Maybe use the volume rocker for adjustment)

Also a little routine to put the revolution figures on screen.

The heli blades should spin at about 2700rpm but for a wider variety of helis, would like to read a range from about 1900 to 3200 rpm.

A shutter harmonic frequency could be used as I dont think the shutter can operate at these speeds.

There are units available that use this method... But the mobile phone with camera already has the hardware needed. Just need a little bit of programming, I'm guessing.

If anyone can help i'm sure there would be a lot of interest from various fields....

Feedback on the idea welcome.....

aero star

PS. Thinking of existing measuring apps available, any reason why shutter speed can't be added to give object speed calculation and result etc etc

PPS Recording the heli in flight and then applying the Tachometer software would be ok.... might be easier to adjust the shutter speed for the video recording... ???