Originally Posted by IntegrityHndywrk
Hey razorblade. How about an update on that tachometer you got, now that you've had it for a little bit. I'm looking at other tachometers but they seem to have a 4 blade max limitation. How is yours working out? Do you only need to put a piece of tape on one blade to get a accurate reading? Also have you determined the proper point to take a head speed reading from? Would it be the blade's CG point? or the tips? It's looking like that is an exceptional tachometer for the price. Though i'm assuming it's because it's not a hobby related product. It is actually a tool for woodworkers, lathe operators, etc. But it appears to be working accurately for heli rotors?
Below is the tach I bought. It works out pretty good. I took the main blades off and tail blades off. Applied a .5 inch of piece of reflective tape (included) to the top of one blade grip. Then raised the throttle to max and measured the rpm by pointing the red laser emitting from the tachometer at the tape for about 4 seconds. I took several measurements. This is considered the no load reading. Well its actually not a "no load" reading since there is some minimal load exhibited by the main gear and tail belt mechanics. But it works well enough.
From what I have read, a more accurate reading can be taken by using an optical tachometer (more expensive) but than that involves having a buddy take the reading while you hover the heli at around 5 feet off the ground.