ORIGINAL: scooterinvegas
I lighty touch the back side of the prop and count the how many times the prop taps my finger in 6 sec. I then times this number by 5. Easy.
(Because this is in the ''beginners'' forum, I have to say this is a joke. Do NOT touch the prop with your finger when the engine is running!) [:@]
But if you are going to touch the prop when it is running, do it from behind!