Wrecked My Little Mini 2

JOHNVOSS · Mar 19, 2022

Where is it written that props are balanced pairs?

Yorkshire_Pud · Mar 19, 2022

It isn't written anywhere, it's deductive reasoning,
BUT both the Mavic Mini and the Mini 2 the manuals do say

"If a propeller is broken, remove the two propellers and screws on the corresponding motor and discard them. Use two propellers from the same package. DO NOT mix with propellers in other packages."

JOHNVOSS · Mar 19, 2022

I guess that's close enough. Thanks.

Yorkshire_Pud · Mar 19, 2022

Just out of curiousity and from the logs 10,000rpm is approximately hover speed for the motors on my mavic mini. The blade tip is around 59.5mm from the centre of the motor. Plug those numbers into a calculator and the acceleration at the blade tip is 6,654g. The acceleration is proprtional to the radius so at 30mm it is 3,355g.
I am pretty sure I have seen more than 14,000rpm on occasions in my logs.

Centrifugal Force Calculator

Use our centrifugal force calculator to determine the force acting on a rotating object.

www.omnicalculator.com

It makes me wonder what force is actually exerted on those tiny screws.
I wonder if @sar104 could come up with an approximation?

eEridani · Mar 19, 2022

Using that calculator (and making a few assumptions about mass distribution running out the prop), my Air2 prop at 4.6 grams is creating just under 50 pounds force per pin. Yikes!

br14nh · Mar 19, 2022

There is a post on the forums where a pilot had the motor/s jam up because the lug that holds the prop to the motor came off and jammed the motor. I believe this was after an earlier crash where the propellers did not appear damaged, so the pilot continued to use them.

If the drone has crashed in a way that has damaged one prop blade, it is also likely to have put stress on all the lugs of all the props. I would be changing the lot as a precaution.

SkittleBob · Mar 21, 2022

Sneak said:
...I hit a tree and it flipped a bunch of times and hit the ground... I just dced the controller and drove and got it out the field...
What should I do in the future if something like this happens again...

How far away were you flying?

It's much easier to avoid trees if you're flying within VLOS.

JOHNVOSS · Mar 21, 2022

SkittleBob said:
How far away were you flying?

It's much easier to avoid trees if you're flying within VLOS.

Paludo · Oct 8, 2022

As an old school helicopter guy (both full size and RC), I guess I have have the 'need' to balance and match all pairs. I have a top of the line set up, and have done it for Sky Hero 6, Mavic Air 1, Mavic 2 Zoom, Mavic Mini 2, and 10 RC helicopters. I will admit that the DJIs are very consistent, and required only a single pass with an emery board to match them, so from my experience, I'd say that they are good to go without concern, but chipping or cracks I replace without hesitation - just to be sure Murphy's Law doesn't get me.