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DJI › Return To Home Massive Descent Wobble
10-13-2013 08:24 PM  4 years agoPost 1
rocket_33

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Mount Pleasant, Michigan USA

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I have been working with my 550 using the DJI V1 NAZA unit with the latest firmware. Once I resolve my flyaway issues I have continued to work learning more about this.

I had several flights the other day and in watching the video, upon engaging the return to home feature, I notice that once the 550 has returned laterally and begins its descent, it has a tremendous wobble to it. It maintains this wobble throughout its decent. It stops when the 550 returns to a hover appx 20 meters (guessing) before its final descent.

The wobble seems pretty violent. I am uploading the video taken onboard for you guys to see what I mean.

Suggestions??

Watch at YouTube

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10-13-2013 11:52 PM  4 years agoPost 2
mike_mill

rrNovice

Latrobe,pa,usa

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I have the same problems with my 450 l have calibrated my radio two different ways one with the throttle trim all the way down which caused my quad to shake so bad It fell out of the air. With the trim centered it shakes but not as bad. I have never tried it all the way up.

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10-14-2013 02:10 AM  4 years agoPost 3
GM1

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Tallahassee, Florida US

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Well
Either add weight or go to smaller props.

On a dog sled team, if you're not the lead dog, the view never changes.

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10-14-2013 03:25 AM  4 years agoPost 4
rocket_33

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Mount Pleasant, Michigan USA

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Please explain more as to why so I get a better understanding. What is happening and how will that resolve it

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10-14-2013 04:13 AM  4 years agoPost 5
unclejane

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santa fe, NM, USA

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Yep, it's the 10" props. My F550 wobbles exactly like that with the stock DJI 10" props that come with the kit. Lowering the attitude gain a bunch will help with it a little bit.

The 8" props completely fix this instability though, so that'd be my suggestion.

No idea why this happens with those props, my guess is they're too heavy and the motors can't respond fast enough. Maybe that goofs up the controller...

LS

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10-14-2013 07:41 AM  4 years agoPost 6
rocket_33

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Mount Pleasant, Michigan USA

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Since I am running 10 inch props on 3S, if I went to the 8 inch props would I have to go to 4S or still run 3S? I can run 4S if needed, but would stay with 3S if I could

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10-14-2013 08:07 AM  4 years agoPost 7
mcfast

rrKey Veteran

Quebec Quebec Canada

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8 inch props on 3S

NAZA do not like to fly with a lite disk loading, makes them unstable, they fly better with a bit heavier disk loading, put smaller props or add some weight.

P.S. sorry for the spelling or the grammar I am dyslexic!

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10-14-2013 12:51 PM  4 years agoPost 8
unclejane

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santa fe, NM, USA

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Since I am running 10 inch props on 3S, if I went to the 8 inch props would I have to go to 4S or still run 3S? I can run 4S if needed, but would stay with 3S if I could
It'll work, but the performance will be a bit marginal. Especially towards the end of the pack, you'll be close to full throttle in the hover so control will degrade a little bit.

I've been using 3S with 8" props on mine and it's acceptable. But a set of 4S batts is coming in tomorrow and I can't wait lol.

I don't know if adding more weight as suggested by fast and GM will help, but it's worth a try I suppose. I have mine as light as possible with no landing gear or accessories except my FPV cam/xmitter and it's perfectly stable.

You might try manual mode also. I fly exclusively in manual mode now and that makes it like a FBL helicopter in terms of handling...

LS

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10-20-2013 02:58 AM  4 years agoPost 9
Dr.Tim

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Mojave Desert

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Try raising the Vertical Gain .. Also check your Roll and Pitch .. You will get this issue if the gains are to low.

From Simple minds come simple ideas! Approach Engineering

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10-20-2013 03:04 AM  4 years agoPost 10
rocket_33

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Mount Pleasant, Michigan USA

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Gains are already pretty high, I don't think raising them will help. I replaced the props with 8 inch and have a couple of 4S packs I am going to try tomorrow. Will let you know the results

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10-20-2013 11:10 PM  4 years agoPost 11
rocket_33

rrElite Veteran

Mount Pleasant, Michigan USA

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Did some limited testing today (one pack because it was too cold for me lol). It was quite windy today so similar to the other day.

The change was to go to 8 inch props rather than the 10, and 4S instead of 3S pack. The 4S pack was a little heavier due to the fact it had a bit higher capacity but I don't believe it affected the results significantly.

Proceeded to take it to altitude and initialize the RTH function. All seemed good and it returned and landed smoothly close to the liftoff position.

In reviewing the video, there was no evidence of the harsh wobble that was present before. There was some slight wobble, but not consistent and I believe it was corrections being made due to the high winds.

So my conclusion is with the wider RPM range available with the smaller props due to the lower efficiency in lift, I believe it had a better control of the decent and was able to do it at a slower rate which prevented it from entering its own downwash.

I did notice with the smaller props the climbout was a bit less aggressive at the same power settings than I observed with the 10 inch props.

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