My quad (recently renamed to the "flying duckling") had a bit of a mishap today
the angle on that left motor and the shape of the prop isn't just an optical illusion unfortunately! Luckily I had already ordered some spares from jdrones, so I should be flying again tomorrow.
The crash happened when I was successfully flying in LOITER mode for the first time. The quad was holding nicely at about 20m, with just a little bit of wind drift, when one motor suddenly stopped. Unfortunately I didn't have my ground station running at the time, so I have no clue as to why it stopped. I certainly can confirm that a quad flies very badly on 3 motors - it tumbled to the ground and hit pretty hard. I think I was lucky it was on grass, and I only lost one arm and a prop.
It has been a week of unfortunately accidents for the CanberraUAV team. Last Sunday we were flying our UAV plane on autopilot for the first time, when we had a bad crash:
That bit of grey stuff on the right is the edge of the engine sticking out of the ground. It buried itself quite deep when it hit at nearly 30 m/s. Luckily we did have mavlink logging on for this one, and after looking at it for a bit we were able to determine that we'd screwed up the dip switch settings. We had the plane in elevon mode, which doesn't work well if you don't in fact have elevons!
We're trying again tomorrow with a cheaper foam plane, just to get some more experience with APM on a disposable plane. We'll move up to the more expensive planes again once we really know what we're doing.
Meanwhile, I'll put another arm on my copter, and make sure I turn on logging before my next flight, so I have some hope of working out why an engine stops (if it happens again). My best guess is that one of the connectors to an ESC may have become disconnected due to vibration, but thats just a guess. I'll also try running it on my bench for a while, in the hope that the problem may happen when its tied down.
Meanwhile, a new toy arrived from ebay. I bought a laser tachometer for the princely sum of $6.99 (plus $6.95 in postage). I used it to test the speed of the props on my quadcopter. Very handy! I just put little reflective stickers (which come with the tachometer) on the props and the tachometer quite happily locked onto them. You can see them in the above photo.