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Std rate turn while going straight?? (Read 4718 times)
Jun 1st, 2013 at 6:57am

jim_in_nh   Offline
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Just opened my new D1. Made sure it had plenty of charge, and updated the sw to latest rev (May 22, 2013).

Sitting on a level counter top, near a window, showing 5 bars on the GPS, the unit displayed a left yaw rate of 3/4 to 1x std rate turn. Roll attitude rocks back a fourth some (-8, +3). Pitch was fairly stable although wondered a little (+/- 2 deg). Ball in the center. Altitude from GPS was good.

Thought, well, maybe the state estimator needs some motion to sort out the yaw rate bias, so I pulled the car into the garage, set up the D1, got physically close to plumb and square, then tweaked the pitch and roll, which both needed only 1 degree. Ball was centered, roll indicated -4 (left bank) and wondered a bit, pitch was on the dot.

Drove around a bit. No improvement. While driving down a long, straight, smooth road with slight incline (negligible angular rates), pitch was about right but yaw rate was still ~left std rate. Roll showed left bank, but the crown in the road resulted in an actual slight right bank. Ball showed about 1/2 ball width to the right, which was correct. Overall, pitch was roughly correct, ball looked correct, but roll was off and wandered, although did respond to roll angle changes, and yaw rate consistently had a left std rate bias. Solid 4-5 bars on the GPS at all times. It's definitely not providing a reliable attitude indication at this point. It'll probably be Friday (6/7/13) before I can fly it (Cherokee 180), but I don't think I need to fly it to tell that something's not working properly.

I think I may have bad hardware, but looking for the thoughts of others...

Thanks!
Jim

Update:
I've attached some photos. Went out again. After about 0.4 miles, I stopped about to turn onto a road. While sitting still, the display indicated a 35 deg nose up, left bank, and 2x std rate turn. It settled back to the original odd behavior while driving down the road, about 5 min later.
I'm not worried about it when in skidding turns (in a car) vs. coordinated turns (in the plane), but I would think that sitting still and driving straight down a road, it ought to have predictable and normal behavior.

« Last Edit: Jun 1st, 2013 at 11:07am by jim_in_nh »  

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Reply #1 - Jun 4th, 2013 at 7:05pm

Dynon Avionics   Offline
Dynon Official
Dynon Technical Support

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Hi Jim,

So, the D1 has the ability to self-calibrate, but it will only do so when in actual flight (because it's looking for certain flight dynamics to know that it can make adjustments). Admittedly, it shouldn't be that far out in the first case. Take it flying if you'd like, but we suspect that something is going on with one of the sensors. Give our tech support a call at 425-402-0433 or email at support at dynonavionics.com

 

Please do not use Private Messaging on form to contact. For private support:
Email: support at dynonavionics dot com
Phone: 425-402-0433 (7am-5pm Pacific weekdays)
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Reply #2 - Jun 6th, 2013 at 1:27pm

jim_in_nh   Offline
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Hi.  I took the D1 flying yesterday afternoon, and it basically did the same things it has been doing on the ground.  The most common issue is a mix of yaw rate bias (usually left, but I saw a right yaw rate just over std rate at one point too...in S&L flight), and usually some degree of left bank roll error.  Pitch was usually ok, but at times would show about 5-7 degrees below the horizon.  At one point in the flight, I flew using just the D1, and was in a climbing right turn, when the D1 said S&L.  Rarely, but occationally, the correct attitude would show-up.

I've attached a lousy photo.  Kind of hard to see due to contrast issues, but out the window and the primary attitude indicator show a very slight right bank (1-2 deg?), but the D1 is showing a 5-6 deg Left bank.  Solid GPS the whole time.

I'll give tech support a call. 
Thanks,
Jim
 
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Reply #3 - Jun 6th, 2013 at 1:30pm

jim_in_nh   Offline
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Update:  I spoke with tech support.  Very helpful and informative.  He explained that this is probably a failure of one of the consumer grade sensors in its infancy.  He said the D1 was no doubt working fine when it left the factory because they are tested.

I really like the form and fit of the D1, and lots of nice features like running on internal power, nice size, very strong and solid GPS, display was fine even in bright sunlight, etc. 

For those of you with D1's, are you happy with them overall?  Are they spot-on accurate all the time?
 
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Reply #4 - Jun 6th, 2013 at 2:12pm

dabear   Offline
SkyView Flight Tester
Autopilot Tester
Warrenton, Virginia

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My D1 has been very stable even in acro.
 

Bear
CJ6A with M14PF
3 - 10" SV, 2 ADHRS, EMS, AP, AP/Knob Modules,
Intercom, Radio, Transponder, ADS-B, Dynon D1
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Reply #5 - Jun 6th, 2013 at 3:18pm

David Harvey   Offline
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I've flown about two hours and I also tested in the car before first flight. So far no problems but now I'm watching very carefully.
 
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