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[Help!] Not a noob, had a malfunction, need advise

Author: fhagan02@me.com 2015-7-11 12:20
4 2223
Like a motioned in the title I'm not a noob. Do everything by the books every flight. Never seen this with my two Phantom 2's or Phantom 3 Pro until tonight.

Normal take off, with 17 sats, all green, with 4 mph wind...and within about 350-450 feet my P3 starts "wondering about." Phantom just started spinning in semi-tight yawing circles with ZERO stick input. When I notice it's random movement on my iPad screen I made quick movements with the sticks (yawing) to see if the P3 was receiving my input. It was BUT it kept spinning maintaining current altitude for the most part. Immediately switched to Atti mode and regained control. Brought it in closer, flipped back to P-GPS and all was normal so I landed right away.

What the devil happened? I powered down, powered up, took off and tested again....twice. No issues.

• 174 flights with zero issues
• Latest firmware install since the day it was released
• Did a cold IMU calibration last night since I hadn't done one in about 3 weeks. Did it in the same spot as before. No issues. Mod reading was at 1500 when complete.
• Did a successful compass calibration right before the flight (Mod reading was at 1520-ish right before flight)
• No power lines around. (I've taken off and tested from this home point site 70-80 flights at least.)

I checked the fight within the Pilot App to confirm my stick movement and more importantly my LACK of stick movement while it did it's little walk about in the air. Pict attached with notes...

Any advise would be warmly welcomed.

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Tahoe_Ed
I sounds like you either a GPS or IMU issue.  The circling is typical of toilet bowl effect and the fact that your gimbal tilted points to the IMU and GPs as well.  I would continue to watch the mod values on the IMU when you fly.
2015-7-11 13:11
fhagan02@me.com
Tahoe_Ed Posted at 2015-7-11 13:11
I sounds like you either a GPS or IMU issue.  The circling is typical of toilet bowl effect and the  ...

Thanks much. I think I'll do a fresh, cold IMU cal. again tomorrow to be safe.
2015-7-11 13:18
mtnmaddman
Last edited by mtnmaddman In 2015-7-11 20:33 Editor
fhagan02@me.com Posted at 2015-7-11 13:18
Thanks much. I think I'll do a fresh, cold IMU cal. again tomorrow to be safe.

Do you do a compass calibration before every flight?  (Which I don't think is necessary)  Seems like a lot of problems occur,  right after that,  Most every time someone reports a problem like this they start by saying I just calibrated the Imu or compass or both.

I have read many different opinions and circumstances as to when it is necessary to recalibrate.  I think an occasional calibration is necessary, but if your system is not calling for either to be calibrated then I am not sure I would be doing it, if the bird is flying correctly.

Calibrating when not nec. may be applying some incorrect reading due to an RF or magnetic anomaly occurring at the time you calibrate.  Now in your circumstance, did you calibrate your remote also,  it sounds to me like your yaw stick needs to be calibrated.  

The bird resets when you turn it on and adapts to stick signals positions from your remote.  A recalibration of the bird and not the remote, may be a problem that would manifest in way that you saw your bird act.
2015-7-11 20:32
fhagan02@me.com
mtnmaddman Posted at 2015-7-11 20:32
Do you do a compass calibration before every flight?  (Which I don't think is necessary)  Seems lik ...

Thanks for the info
2015-7-11 22:43
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