I recently installed quick release prop adapters on two of my Multirotors.

they both used T-Motor motors with flat hub props that have three bolts allowing the prop to be bolted down to the bell.

The adapters have two parts, one the bolts to the bell, and the other bolts to the prop. The adapters are in two types, CW, and CCW.

the markings are clear and that way, you won't accidentally thread on a prop of the wrong rotation.   

However, there is confusion on this labeling that is potentially dangerous!

The following applies to the adapters I used, and I have no experience with other types

For motors with CW rotation, the adapter to use should be the one marked CCW, and respectively the adapter marked CW go on the motors with the CCW rotation.  

This is the opposite to what I assumed and  I have seen no instruction sheets or explanation anywhere.  This applies to the ones sold by Rctimer and probably other popular sources, however I can only speak as to the way the ones I bought work.

The problem is, if you install the CCW adapter on a motor with CW rotation, it will be self loosening, not self tightening, and you don't want your prop flying off in flight.   If they are installed wrong, and they are snugged up very tight, then chances are, the prop won't fly off, but over time, it is bound to happen because the prop will have loosing forces on it.

To be sure,  when they are installed.  spin the prop just a little bit snug   then rotate the bell in the direction that it is supposed to turn, place an obstacle in the path of the prop (finger) and as the leading edge of the prop meets the resistance of your finger, then the prop will break free and allow the bell to continue rotation until the threads run out and the props falls off. This would mean your props are self loosening.  When correctly installed, what should happen is when the prop meets resistance of your finger, the it should stop you from being able to spin the bell, and your prop will become snugged up to the point of locking it.

My adapters are now  installed with CW on CCW rotation motors and CCW on CW rotation motors and this works fine.  

I can spin a prop on to each mount, and not even snug it up, and go fly!

when I am back, the prop is good and tight because when installed correctly they are self tightening.

I had a crash and a couple of near crashes finding this out, I am very glad that the incidents happened in un-populated areas.  I think that manufacturers who are producing these should supply the user with information to prevent the likelihood that they will be installed wrong.

Loss of a prop while in flight is a certain crash and could be very dangerous if it is a heavy copter with CF props

Richard

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Replies

  • I have made contact with T-Motor and they are aware of the error.

    Hopefully the documentation will be corrected soon.

    scan.pdf

    https://storage.ning.com/topology/rest/1.0/file/get/3702326645?profile=original
  • Happened to me a few minutes ago, bench testing a U-11 and a 29" three bladed prop ($420 each!)

    I was not thinking and blindly followed instructions - as the OP stated the documentation is completely incorrect.

    The motor was running at 50% throttle on a bench test rig. When I increased throttle to 60% the prop hit the ceiling and hung there for a moment digging a neat 29" hole. The prop is scuffed and scratched, but not damaged.

    That was almost a bad day.

    Tri-Prop fail 6.JPG

    Tri-Prop fail 7.JPG

    Tri-Prop fail 9.JPG

  • Thank you fpr the post. I had this same issue with the same adapters 3 weeks ago on my 680 pro. Now that I have them on right I really like these things. I'm putting some on my iris.
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