Self tightening props?

ronhiner · Jan 4, 2014

I'm one of the influx of newbies here. Sorry if this has been asked and answered before...

I had just replaced a prop and got ready for a new flight. I powered up my P2V and let it spin for a couple moments before I took off. I went up to 20 feet and hung there for a minute or two. Then 40 feet, then 60 feet. And then... one of the prop blades took off spinning upwards. And my brand new P2V tumbled out of the sky. Fortunately, we have fresh 9" blanket of soft snow of the ground to absorb the impact. Two props broke, and the camera got knocked loose from the mount. So it looks like nothing serious.

But... do you guys tighten the props down before flight with the wrench? I wouldn't think that would be necessary. Perhaps it is.

Oh, and anybody know where to get P2V prop guards? The only ones I can find are 1/2" too small. These props are pretty fragile.

Pull_Up · Jan 4, 2014

Wow! No I don't tighten them at all, just flick of the wrist until they hit the bottom of the thread and turn the motor about a quarter turn. If the props are installed correctly on the correct motors then it's pretty impossible for them to spin off. The torque of the motor turning the correct way drives the prop down on to the thread. Unless there was some catastrophic failure of threads or of the prop hub itself those things can't come off in normal flight.

I'd be suspecting an incorrect prop went on an incorrect motor. If you're sure you got silver to silver and black to black dot then maybe one of the props had the wrong coloured hub applied at the factory? If you try to tighten the props by spinning the wrong way they just spin around and around, never hitting the bottom of the shaft and giving the motor that slight turn.

Nvr2fst · Jan 4, 2014

I have pondered how a self tightening prop could come off when I first got mine. Beyond what Pull_Up stated, a motor locking up or stopping really fast may do this. Has it happened ? I am not aware of any.

Is it possible you got some debri of some sort in the motor ? Why did you replace the prop ? Could some dirt, small twig or rock have gotten in the motor when you crashed/damaged the first prop. It could have knocked around a bit before it jammed on the windings and the top of the motor. Does the motor spin totally free ? If it was from debris in the motor you may want to make sure they are all cleaned out. Turn upside down and blow compressed air in the motors. Compare to the others. Do you see any damage to the windings in the motor ?