Should I replace my props?

[naturekid]

Hi,
I had an accounter with a wall... Should I replace my props? Seems to be okay, but did not try to fly up and high....

 

[SkyeHigh]

Time to change them - there may be hairline cracks that could fail in flight. Not worth risking your aircraft for the cost of a set of props.

 

[GadgetGuy]

Hi,
I had an accounter with a wall... Should I replace my props? Seems to be okay, but did not try to fly up and high....

View attachment 157651View attachment 157652

The first one has chips, and all are scuffed. Best to replace with new and save for emergencies only, or just bin them.

 

[msinger]

One bonus with the Minis is the props are screwed on, so they are much more secure than models that have removable props. If you remove the props, carefully inspect them, and find no damage around the areas where the screws are installed, then you'd probably be fine to continue using them. It's a possible risk you'd be taking though, so you need to determine whether or not it's worth it to keep using them.

 

[old man mavic]

yes change the whole set ,they cost a lot less than a new drone,and purely from a safety factor ,you are increasing the drones ability to stay airborne,

 

[chiangmaicharlies]

But they hardly look damaged to me. I've flown lots of flights with ones looking worse than this. Never had a problem.

 

[msinger]

But they hardly look damaged to me

Yep! But, the real question -- is there any damage that would prevent the props from separating from the drone mid flight? That's what the OP should be looking for since the damage in the above photos is not showing anything that should negatively affect the drone's ability to fly.

 

[Dbez1]

I recently brushed a tree branch and the drone kept going although I brought it home immediately. From the top, two of my props just looked a little scuffed but when I turned the drone over, there were significant cracks that weren’t visible from the top. Moral of the story is “If in doubt, throw them out”. Also, when doing a pre flight inspection, check both sides of the props. I wish I had taken photos to show you.

 

[old man mavic]

this whole subject of possible prop damage is really a no brainer
even if you flew 100 missions and never ever hit anything ,those props will have been subject to all the stresses placed on them during those flights
once you make contact with any stationary object ,and even insects, and flying debris such as leaves ,then there is going to be extra stresses placed on those props during such events,
and over time ,those stresses can and will have a bearing on the props condition
all any of us can do is to regularly inspect the props on our drones both visually, and tactilely
to check their condition ,at that point we can then make an informed discission ,on their structural condition
dont play devils advocate ,just change them out ,if they have made contact with anything
and one final thing even if you have put new props on your drone ,unfortunately that fact alone does not guarantee that they wont fail ,but at least you have done your best to mitigate such an issue occurring the next time you take off

 

[SmilingOgre]

I would. When they get looking like that, I can sense the difference when I put on a new set. Drone just flies better. Four new props costs less than a fill up of gas.

 

[Yorkshire_Pud]

Just in case you are wondering why people are mentioning the small chip out of the blade in the first photo, such chips can cause localised stress concentration at the point (sharp corner) of the chip. This is why engineers design rounded corners in certain items. Those concentrations can start a crack that grows across the blade.
Secondly, the mavic mini uses staggering motor rpm's, I am fairly sure I have seen 14,000rpm reported in the DATs from my mavic mini and possibly 16,000rpm. I suspect the Mini 2 will have similar rpms.
From an engineering point of view, circular motion is an acceleration and its size is proportional to the radius of the path and the square of the rpm.
If you go to the bottom of the webpage
Centripetal and Centrifugal Acceleration Force
you will find an accelerataion calculator based on rpm & radius.
At a guess your chip is about 0.055m from the motor centre, I won't spoil the fun for you but try typing in some rpm and a radii of .055m and see what values you get for the accelerations at that radius. Look at the "g" value (last box), that's the number of times that the acceleration is greater than gravity.
As far as the acceleration is concerned the mass is irrelevant, but mass comes into consideration when you start considering other effects e.g. balance and stresses.

With regards to replacing blades, if you need to replace one blade on a motor replace both blades on that motor, they are most likely matched for balance pairs.

 

[bmcelya]

I change props after any prop strike, all 4 on that side. If I haven’t hit anything, I change them all at 50 hours. Too long? I keep two full sets in the the case should I need them while away from home. Propellers seem like the weakest link to me. I also carry a small tube of blue loctite, in case of loose screws anywhere on the aircraft. Double zip locked. An accidental loctite leak into a motor could be a problem. Well, that’s what I do unless someone tells me better.

 

[msinger]

I change them all at 50 hours. Too long?

Even 2 flights could be too long if you're flying with damaged props. Inspecting the props pre flight is always better than going off a random number.

 

[bmcelya]

Even 2 flights could be too long if you're flying with damaged props. Inspecting the props pre flight is always better than going off a random number.

Agree mostly. I wouldn’t take off with a questionable prop. Pre-flight inspection of props et al is mandatory for me. Post flight as well. I was just curious how long folks go on mini2 props that haven’t hit anything. Never had one break, but I don’t suppose they last forever. Could be that a prop that has never had impact could last the life of the UAV. I replace them with new at 50hrs. If I hit something hard enough or see damage, I change them right away. It’s a judgement call, which could change with time, experience, and what I learn here. If I find that pilots are getting 200hrs, I’ll factor that in. Thanks for you thoughts on this msinger.