So, just flying around a field today, applied some throttle to crest some trees, both rear props sheared off all 3 blades, mid-air.

I am running Matek F405-AIO, speedix 35A BLHeli_32 escs, have caps on all escs, to reduce noise. Crash yesterday knocked a cap off and it got all twitchy because of the electrical noise. Fixed it (or so I thought) last night, but quad flies with a slightly high pitched whine now.

I haven't changed and PIDs recently, but did up the sample rate from 8 to 16Khz, switched to PT1 (checked motors, not hot) and always had notch 1 turned off.

Any ideas? Has this happened to you?

What motors? Which props? What battery? (4S, 5S, etc)

A picture of the props after they had disintegrated would tell us much more than the video.

Sorry, more detail

4s, hypetrain motors, DalProp 6045s.

Here's a pic.



I'm wondering if the props on the rear (which were older) had already been stressed in a crash yesterday. Or also from how I tighten the bolts, maybe I gripped the props a bit and stressed them too. Just seems amazing that they both sheared at the same time.

I shouldn't laugh, but what a mess!

I don't think that 2450kv on 4S would be enough to blow up the props like that, so I doubt if it was because the speed was more than the props can stand.

It is quite cold though and that's going to make the plastic much more brittle. If you had already stressed the props in a previous crash, they would be more likely to break in the cold. Once one blade comes off, the completely unbalanced prop would probably be quite likely to throw the remaining blades.

I don't think it's down to you over-tightening the prop nuts either. That normally causes the hub itself to fracture and the hubs still look fine in your photo.

Thanks for the reply. Reassuring. Please do laugh, it's a right bloody mess. Landed in a huge clay hoofprint.

I think some previous stress and the cold (it was only about 5ºC this morning, plus a cold wind) plus the unbalancing effect you describe explains it well.

New props time.

(26-Jan-2018, 04:09 PM)gmk Wrote: Thanks for the reply. Reassuring. Please do laugh, it's a right bloody mess. Landed in a huge clay hoofprint.

I think some previous stress and the cold (it was only about 5ºC this morning, plus a cold wind) plus the unbalancing effect you describe explains it well.

New props time.

At least it didn't land in a cow pat!

Mud is one thing....

I have some of those DalProps. Depending on the material you bought, they can fracture at the hub on crashes very easily. I can't remember which material bends and which one fractures. I have never had one break in mid-air though.

props snap mid air more often to ABS back in the days, but the latest DAL props shouldn't do that. another guess is the low temperature? props can become brittle when it's freezing... but still it shouldn't break mid air... not all 3 blades at the same time anyway...

I had the same thing happen last weekend, prop nut still secure and all. But kingkong props. Cold outside though.

This happened to me again, twice towards the end of last week. It's an issue with DAL 6045 props I think, on high KV motors, flattening out and stressing. I switched to HQ 6x3x3s and they fly waaay better and no issues yet, even after about 10 (gently) crashes.

Another prop you can try for 6" props is Master Airscrew. I have both the 2 blade and 3 blade 6045's and have been pretty happy with them. Seem to be very high quality from a long time R/C prop manufacturer that not everyone knows about.

https://www.masterairscrew.com/collectio...opellers/6