I clipped a multi rotor gate last week and cartwheel landed. The wing was slightly damaged and the fuse joint had some sponge. Seemed to fly fine, though. :-) Soooo, I took her out again and about 30 seconds into my first flight I did a high speed snap roll from about 150 feet up. I was probably doing about 80mph when I started the snap and mid roll the wing flexed where the previous damage was and the fuse started to torsion under the new angle of pressure.
The plane was too far away and going to fast to see the finer details of the failure but it looked liked the fuse crunched and forced the wing into a negative G which snapped it in half instantly. My poor 2lb plane never stood a chance.
One half of the wing ripped off and fluttered down while the rest of the plane entered a death spiral. I had about 10% control at this point and tried to slow down the rate of spiral and descent but I don't know that I helped any. The plane pile drove so hard into the grass that the entire motor, 10x10 prop, and a good inch of the fuse was completely underground.
As I walked over to the mangled remains I was worried about battery damage. The Tacon 10 motor I'm using has the fun inward protruding motor shaft and I didn't have my trusty Dollar Tree pool noodle in place for protection. There was no sign of fire until I moved the plane.
Pulling the fuse shifted the motor shaft that had embedded into the 2nd cell of my, at this point, still fully charged 4s 2200. Once the shift happened huge amounts of white smoke started pouring out.
I quickly pulled all the electronics I could away from the battery. One by one each cell went up, letting out more and more smoke. This was my first 'in person' lipo fire, so I was impressed to be honest. I wasn't too worried about fire since the grass was so green. There is a nice little burn patch that remains, but no real risk of fire was ever present.
It took about 15 minutes for the battery to finish hissing and smoking. Even after that, though, it was still too hot to touch. All my electronics survived. Crazily enough, The motor has no damage. It was buried so far into the ground that all the surrounding dirt kept it protected.
I haven't run it up yet so that will be the real test, but the bearings still feel nice. I guess since the shaft was connected to a super heated chemical fire there might be some internal damage I'm not aware of yet, but we'll see :-)
12.28.2016 nnSpitfir 800 Series
10.29.2016 nnP-39 v2
06.13.2016 nnChipmunk v2
10.04.2015 Manic Micro nnTiger Moth
07.22.2015 Sonic Series nnP-39
01.02.2015 nnMiG 3 800 Series
11.22.2014 nnChipmunk 800 Series
09.22.2014 nnMiG 3
08.27.2014 nnMoth Minor
08.18.2014 nnBucker Bu 180