Help, I think I have built a monster...

I tried to create a really powerful quad with HK components and an APM 2.5. It looks like I have created an unflyable monster:

The first flight attempts were a disaster. Upon just touching the throttle it jumped in the air and flipped on its back faster than I could react. It wasn't damaged, so I tried again as slow as possible correcting pitch/roll tendencies before take off. But as soon as it is in the air it's uncontrollable because it's reacting very very fast. It just takes 1/8 throttle to take off. After 3 take off flips it was damaged and I had to stop.

I have calibrated the ESCs and everything is basically working as it should (rotation direction, roll/pitch/yaw etc.). What I noticed was, that one prop was accelerating slower to the idle rotation speed after arming than the others.

Here is my setup:

My guess is, that the stock PID values are wrong for such a setup. I could also increase the distance between the motors by using the booms from the Hexa HAL Frame.

Any guess what could be wrong, or what a conservative PID setup would look like?

Thanks,

Erik

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Replies

  • I had this exact problem with my Turnigy HAL Hexacopter. Everything seemed fine but as soon as I took off it would flip fast and hard! After 3 days of going through everything and finally setting up a rig to stop the crashes it hit me. I had plugged in the servo wires from the escs to the board in a counter clockwise orientation instead of clockwise. So simple!!! Such mysterious symptoms. 

  • Set your rate-p for both down to 0.0650.  Try again.  If it takes off but feels to sloppy slowly raise up until it feels solid.

  • Very good!

    HERE is how to obtain and analyze the logs. There is a very good video down the page.

    -=Doug

  • Congratulations on getting to this point, now the real work/fun begins.

    1) Make/rig some form of tether mechanism to allow about 16 inches/ 35 cm of vertical space. I used two lengths of cord, one on each opposite leg, tied to a heavy item. The idea is to prevent an out-of-control event but allow some vertical lift for low hovering.

    2) Confirm your configurations:

      a)Frame type loaded into APM via MP

      b)Radio calibrations

      c)Motor wiring/positions via a CLI command test found HERE.

    3) Find and post your tlog here. It will tell us your parameters and give us a picture of the flight event.

    4) Confirm your radio is in ACRO (airplane) mode, not HELI.(What radio TX are you using?)

    I do not think your arm length, motor selection, props, etc are the problem.

    This type condition usually results in a configuration issue of another kind.

    Do not mess with your PIDs, yet.

    Let us know...

    -=Doug

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