HELP. First flight, first crash, motor probs....

Hey guys-

I got my quad in the air for the first time today to do some tuning and hovering, setting of the throttle mid, etc. My setup is alot more powerful than I thought it would be! Anyway, I climbed and sort-of-hovered for a total of about 7 seconds. The it flipped over and crashed inverted after a 25 foot fall. I broke a prop and snapped a motor mount.

Just before the crash, I noticed that it was very jittery in the roll axis, rocking quickly back and forth about the axis. It crashed before I could land. In testing earlier, I noticed that one motor was starting slower and stopping faster than the other three.

I'm thinking that may have failed, or that my vibration is too high, or both. This is my first flight and first quad,so I'm a little lost on where to start and not yet proficient at reading the logs. I hope you can help me. Also, in post-crash checkout, I spun up each motor individually for about 5 seconds w/ props on. 2 of them worked great but almost immediately squealed and stopped spinning, and started to smoke. They are very hot to the touch. They barely hand-spin now. I'm assuming they are toast? What could cause that?


HK 550 frame

20a ESCs

Turnigy SK3-2826 1130kv motors

slow fly 11x4.7 props

Ardupilot ver 3.0.1

3S 3300mah 30c LiPo

Re: tlog file below- I'm not sure this is the correct one, the altitude should reflect about 20-30 feet max, and the only input I really used was throttle.

Damn I'm lost....

2013-08-22 21-47 6.log

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  • Just as an update so others can learn from my mistakes-

    Regarding the two engines that burnt out post-crash. The first burnt out engine had impacted the ground first, breaking the motor mount. Upon impact, the motor shaft had bent, inducing failure in my post-crash checkout. 

    The second burnt out engine was all my fault, a rookie mistake. I ran the otherwise good engine at full power for a total of about 17 seconds on the test bench. I wasn't paying attention and thought the throttle was much lower. Being my first day with motors running, I wasn't familiar enough with the system.

    Live and learn, I guess. The worst part in waiting 10-12 days for my replacement parts to come in from China. Ugh. Just in case, this time I ordered 4 extra motor mounts and 4 extra arms to add to the 8 extra props I already have.

    I'm using this unwanted downtime until my package arrives to experiment with the different types of anti-vibe APM mounts and double check the balance of the remaining motors and props.


  • Jim, first of all take a deep breath and consider that there are many of us out here who have been messing with these things for a couple of years or more and still regularly get lost. Number one critical skill with these beasts is patience. And yes it's eventually worth it!

    Your logging isn't set up to capture vibration which as you suspect may well be an issue here. Also a possible issue are the starting values for the basic stabilization PIDs. Read the Wiki pages regarding these things (the "Arducopter" tab at the top of this page, then "Arducoper Manual" then Table of Contents).

    Regarding the motors. Slow starting often just Mr. APM working to level the craft. Squealing and smoking however are definitely not good. My guess is that bent shafts from the crash have taken out the bearings. Those motors are toast, and I would be a little leery of their ESCs as well until they've been proven OK.

    When you get it back together dial the PIDs down and then find a spot with nice long grass or weeds and hover at no more than four or five feet for at least a couple of packs. Do not engage anything other than plain Stabilize mode and be ready to instantly chop the throttle if a crash is imminent.  If you do this you can likely "crash" repeatedly with no damage at all. This is how to get the aircraft and yourself tuned with minimum pain.

    Visit the post for more.
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