Bitcraze Forums

I've just finished assembling my CrazyFlie and am trying to fly it for the first time.

It seems to want to always flip or turn over immediately after takeoff. I've checked the motor rotations and propellor configurations and as far as i can tell they're correct. 1 & 3 rotate CCW and 2 & 4 rotate CW when view from above. I have 'A' blades on 2 & 4 and unmarked (and different) blades on 1 & 3. The blades are installed so that the leading edge of the blade is facing the direction of rotation.

One thing I've noticed is that the actual Yaw value being reported is constantly changing. It's never stable - even from first power up with the copter on the floor. The yaw is changing at about the rate of 1/10th per second. Pitch and roll seem stable. If I rotate the copter flat on the ground with the center of rotation being the battery I can see the yaw value change rapidly as a I rotate, then go back to changing again. The change seems to sometimes be positive or sometimes negative depending on the orientation of the copter.

The console says :

SYS: Build 31:ba1d111112ad (2013.4) CLEAN
SYS: I am 0x872338225552864966BFF48 and I have 128KB of flash!
IMU: MPU6050 I2C connection [OK].
IMU: HMC5883 I2C connection [OK].
IMU: MS5611 I2C connection [OK].
MPU6050: Self test [OK].
HMC5883L: Self test [OK].
MS5611: Self test [OK].

So there doesn't seem to be an immediately obvious hardware/firmware failure.

Any thoughts on what might be wrong ? Faulty hardware ? Anything I could attempt to repair?

Now that I am reading this, a while ago I posted something simliar (http://forum.bitcraze.se/viewtopic.php?f=11&t=506).

I also see the yaw value drifting slowly! If the USB cable is connected this is very visible, even fast. Without USB cable it happens but very slowly. I suppose the compass is affected by electromagnetism around...

The yaw drift is there because it is not fused/calibrated with another sensor like the roll and pitch are. The magnetometer can be used to do that but we haven't got any good result with it yet. The yaw drift is so low though that when you are manually piloting it you won't notice it.

As for the flipping takeoff it almost always have to do with either the motors turn in the wrong direction or a propeller is mounted wrong. Try to check that again, and if that doesn't fix it post some pictures so we can have a look at your setup.