Bix3 crash in auto mode (log included)

Hello all,

In the last couple of months I have utterly destroyed two Bixlers. Needless to say I need some advice.

The last crash went like this. The auto mode was set up to fly a trip around the ball park at an altitue of 60 meters (approx. 200ft). When I put the plane in auto mode on the ground the prop went spinning and she took of in a head wind. Then the plane climbed to an altitude of maybe 5 meters (approx. 16 ft) and headed for waypoint 1. The altitude remaind way too low and the turns where way to wide. About 300 meters (approx. 1000ft) wide! Given the low altitude and the wide wide turns the plane eventually found a tree and exploded into pieces. Luckily I was able to recover most of the expensive parts.

My setup:

  • Bix3 kit with Small Parts CNC motor mount
  • 2200kv outrunner motor
  • 6x4 CCW prop (mounted with the text to the front)
  • 2200 mAh LiPo as power source in the nose
  • 2200 mAh LiPo payload to counter balance the tail weight in the nose
  • The plane was balanced at the proper point
  • The servos where centered so that the ailerons, flaps and rubber where level
  • The plane was set to be in auto mode the whole time, from start to crash, any change in mode was from the Ardupilot

My two main questions are:

  • Why did the plane not climb to the required 60 meter (approx. 200 ft) ?
  • Why did the plane take very wide turns and went off track so far?

I really hope you people can help me because I have destroyed two Bixlers and would rather not have this happen a third time in a row.

Thanks in advance.

2016-04-03 15-01-38 80.bin

2016-04-03 15-01-38 80.bin.log

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  • Moderator

    I have to ask, have you done test flights in FBW-A and Loiter? At what angle does the plane climb in FBW-A with at 80% throttle and holding full up pitch? Are all your control surfaces moving the right amount? What amount of elevator up/down is recommended?

    Have you also done an autotune?
    In your log the pitch lags behind and below the desired pitch, towards the end requesting 15-17° and getting 4-6°.

  • Hi,

    Thank you for your help. I have bought a new Bix3 and will try this.

    Jakub Mędrzycki said:

  • One additional remark: the Arduplane seemed to respond sluggish to keeop the plane level. When I had the plane in my hand before flight I noticed the sluggish movement of the servos like the Ardupilot was giving just a little bit of input.

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