It is 1800 for a 2 blade prop, and 1200 and 2400 for a 3 blade prop,
if my memory serves me.
I worked the math once. Light goes off 60 times per second, which is
3600 times a minute. And you have to account for the number of blades.
Just pull up with a street light to your back and try it. The prop
will stop. Should be at one of the numbers above.

It is not every multiple of 60.


"G.R. Patterson III" wrote in message ...
Drew Dalgleish wrote:

Do the math to figure out what speed will stop the prop and see if
your tach agrees

Any multiple of 60.

George Patterson
Great discoveries are not announced with "Eureka!". What's usually said is
"Hummmmm... That's interesting...."