70mm EDF Failure

[telnar1236]

A couple weeks ago, my modular trainer jet crashed due to a power system failure. I initially was thinking it was the ESC since I was using an old and somewhat unreliable one, but turned out to be something I have never seen before. The metal support for the motor stator and bearings fatigued through, and broke off, making the motor non-functional and, unfortunately, destroying the ESC. The EDF was a bit out of balance from being crashed a few times in my modular F-104 when I was developing it and I guess the vibrations were high enough and the metal cheap and brittle enough that a crack formed. I still think this is the best 70mm 4s EDF out there, but only if it remains in balance. If there is any significant unbalance, watch out! Like I said, I have never seen this happen before with an EDF unit, and I have flown units that were far worse balanced than this one, but I think I'll be respecting the importance of balancing far more.

The two shiny bits I circled used to be a solid piece.

 

[bisco]

bummer, good luck with the next one!

 

[telnar1236]

bummer, good luck with the next one!

It's such a weird and cool failure, I'm not even upset about it, I just have to laugh

 

[bisco]

i know, never seen that before

 

[leaded50]

thats a QX motor, not expencive ones.

 

[telnar1236]

thats a QX motor, not expencive ones.

Definitely a cheaper EDF, but it gets a ton of thrust and pretty good efficiency. Prior to snapping, which was due to unbalance caused by a crash, I was getting four-and-a-half-minute flight times and 1600g of thrust one a 4s 4000 mAh battery which I have not seen any other EDF replicate. But looking at where it broke, it does look like a case of bad design. There's a cut-out with very sharp corners that as far as I can tell serves no purpose apart from maybe saving 3g of weight or something but definitely results in a much weaker internal structure

 

[LitterBug]

A little glue, and it will be back in the air!! 😁

 

[Mr NCT]

A little glue, and it will be back in the air!! 😁

That should be an automated post!!!

 

[telnar1236]

A little glue, and it will be back in the air!! 😁

Maybe a bit of glue and a welder. The plane it was in is already back up and flying, but that motor is toast. When I was going through and repairing the plane, I discovered that the motor breaking like that killed not just the ESC, but every bit of electronics in the whole airframe except for the receiver and one servo