What The??

[robbo1]

This is an image of my cnc alloy 442 prop. Does anyone have any ideas or insight into the cause of this? Did it hit something or was it just failure from fatigue? Spinning the prop is 1600kv motor on 6s.

[martin]

Its a job to say if the blade hit something & failed as there is no other signs of damage on the rest of the prop, what i can tell you is that aluminium props are not very strong compared with bronze or SS props. Especially on high power systems, seen this happen many times with aluminium props with blades tearing off.

[fweasel]

Looks like straight up metallurgical failure, no signs of an impact.

[NativePaul]

I would guess fatigue, as there is no noticable damage other than the missing bit, not always but often there is damage to both blades with prop strikes.

What make is it? Aluminium alloys vary in strength a lot. the 7075 Tenshock use and the proprietary alloy blend TP use are a LOT stronger than the typical 6061 many others use, and having worked several for friends I would say they are of similar strength the the stock BeCu used on Octura and ABC.

[robbo1]

Three out of three, with the same diagnosis confirms for me it was a failure. You hear of alloy props failing but this has been a first for any prop for me (usually run octura).

Prop has no brand markings on it, so unsure of make. Bought from Rc Boat Bitz many years ago with a handful of runs on it.

[ray schrauwen]

I wonder if they are cut from billet or cast and then cut?

[bogieboy]

i would think they would be easier to just cut from a billet, but i may be wrong... the CNC props i have had did not look like cast aluminum, i have a cast aluminum prop for my DV60, was cheap and fast shipping (aka 2 day shipping and $14...LOL and it looks nothing like the CNC prop material even after sharpening, balancing, etc...

[Gary]

LOL My props look like that all the time !!!

[Dr. Jet]

Look closely at the granular-appearing surface of the broken bit and the shape of the fracture, it looks like classic metal fatigue. I'll run those CNC aluminum props all day on 2S. On 6S, you are better off with BeCu or SS (Tenshock or TP may work, but caveat emptor).