Props... How do they work?!

[SmackHappy]

Total noob questions here:

For my second build, I got el cheapo emax motors and props.
For the life of my I can figure out how the props will work!

The holes in the props are perfectly round.
So are the axels of the motors.
What prevents the props from slipping when the motor spins?!?

pics: http://imgur.com/a/HC1Uc

For example, I have the e300.
There the motors and props have notches so the motors and props ‘lock’ so they spin together.

Does that make sense?

Thanks!
Chris

 

[Aerialmediaone]

Most motors just use a round adapter like that. You won't be able to use your dji props, but they won't come loose in flight. I have used up to 20" props on electric airplanes with 2000+ watts and haven't had any issues at all. I do prefer tmotor style props for my more expensive multirotors though.


Sent from my iPhone using Tapatalk

 

[fengshuidrone]

Go get yourself some stainless nylon insert locking nuts (they're called ESNA nuts.) If your props need a washer between the prop and the nut, use stainless washers as well. Tighten them down until the prop is locked. Do not over tighten. You can tell when you've really gone overboard tightening when the plastic gets white stress marks in the hub.
Don't do that. I have seen people recommend blue locktight and the bullet shaped nuts that come with most motors. The nylon nuts are better. Locktight will dissolve plastic props at the worst place upon contact. Most people have no clue how to properly apply locktight and drench the threads and everything else with it. Speaking of Emax motors, try to avoid the ones that have a collet locking feature to attach the props to the tiny little thin diameter shaft (it's like 1.5 mm or something like that.) After I wrote all of that I saw that you are going to use CF props. You want to use the sleeve that allows no freeplay and makes the prop sit correctly on the shaft. Stick with ESNA nuts over the silver ones you are holding in the photos. Those have a nasty habit of coming loose. I am not positive but I believe that locktight will react with the resin in CF.

 

[SmackHappy]

So, it sounds like its only the tension between the nut, prop and top of the motor which prevents the prop from slipping when the motor is spinning, is that right?

I can’t imagine that working… but perhaps its just me and my closed mind…

 

[fengshuidrone]

I have three homemade quads. All three of them fly on this system with no prop related problems. You just need to tighten things properly. DJI includes that feature because of the general public first time behind a TX style audience they sell to. It looks to me more like a potential balance issue. Every motor out there (other than DJI and maybe a couple of others I don't know about) has the no flat style and there are millions of quads flying using this. Obviously it works. Get on the internet and search various sites for brushless outrunner motors. The vast majority of the cheap ones use the collet type prop mount. Better motors will come with an adapter that bolts to the top of the bell with the shaft on that like the ones you question. The best motors generally take a different kind of prop that bolts directly to the bell using a centering hole and two bolts.
ESNA nuts are incredibly good at not backing out. They are actually kind of difficult to even put on. Once it is tightened to were it should be it will stay that way.

 

[SleepyC]

So, it sounds like its only the tension between the nut, prop and top of the motor which prevents the prop from slipping when the motor is spinning, is that right?

I can’t imagine that working… but perhaps its just me and my closed mind…

It works, and has worked for years and years. Imagine a much more powerful motor for larger electric airplanes, it has only one bolt and a round hole. The "gripping" pressure of the bolt is plenty...

 

[Bartman]

So, it sounds like its only the tension between the nut, prop and top of the motor which prevents the prop from slipping when the motor is spinning, is that right?

that's all it is. carbon fiber props are very hard so getting the nut to grip the prop hub tightly can sometimes be a problem but there are ways to work out the most stubborn situations.
with wood props you make everything tight and then go fly a few times. usually after that you'll have to snug the prop nuts a little more and then they're good for a long time, or until you break the props, whichever comes first!

 

[SmackHappy]

Wonderful.
Thanks guys.