Dan wrote:
RogerN wrote:
"cavelamb" wrote in message
m...
Stu,

Have you seen this one?

http://www.wimp.com/impossiblehelicopter/

There are optical tachs used on R/C heli's that you adjust the speed
of a shutter to make the blades appear still then read the rotor RPM.

RogerN


The military used to use strobe lights on real helicopters to "stop"
rotors. Another neat gag was a large F shaped devise that had a strip of
fabric across the opening. I think it was used to find out who was crazy
enough to approach the tips of spinning main rotors with it.

Dan, U.S. Air Force, retired


Gee, I did that a bunch of times.
That was how you measure the tracking on a UH-1.

Gotta admit, though, it would definitely get your attention!
For sure!