Received the spare parts a few days ago (2009-08-17). Total cost was €106, including shipping. The battery holder was out of stock, so I bended a thin (1.5mm) aluminium sheet into the right shape. It’s far from perfect, but it should do the job. However, some new problems popped up: The heli won’t spool up on its own.

I see the engine/ESC try for a second or 2, then giving up. Presumably, some safety in the ESC kicks in. If I bring back the throttle to 0 and start over, the engine retries. During these few seconds, I can see the engine move back and forth a bit. It doesn’t rotate much, a few revolutions at most.

However, if I spin the rotor manually (30rmp or so, just a gentle push) and throttle up the engine while it’s spinning, everything seems fine. The engine spools it up without any noticeable problems. I don’t see any vibration in the engine nor in the rotor… Clearly it’s those initial rpm’s that cause the problem.

Obviously either the engine or ESC is wasted, but I’m still figuring out which one. Some additional things I noticed/tested:

  • The ESC seemed to have lost (some of) its settings: The first time I got the rotor spooled up, the rpm dropped significantly when I fed in some negative pitch. After I re-set the ESC to be in governor mode, the rpm remained constant.
  • The 3 phases of the engine seems to be equal when measured resistively: 46,1mV/.9A; 46,4mV/.9A; 44,8mV/.9A

[flv:/wp-content/uploads/2009/08/motor-esc-problem.mp4 480 352]

One Comment

  1. flyer says:


    Do you hear the motor ‘grinding’ when applying throttle?
    I replaced the standard esc on mine (after I managed to get it to burn out) with one that has a super-soft startup mode. It won’t spool up when not applying power fast enough. Haven’t had that problem with the original one though …

    Nice to see/hear other ppl flying and maintaining a MT.
    If you’re interested in sharing some ideas, drop me an email.