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S900 weak top plate wobbling
3563 29 2014-11-30
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dragant
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Serbia
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Is this normal that top plate is so soft and wobbling  with slight press on booms???



2014-11-30
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mostey
lvl.2
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United States
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More support of this issue
http://vimeo.com/111001369
2014-11-30
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dragant
lvl.2
Serbia
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I think that much more support we should get from the company who own this forum and produce S900 ;)
2014-11-30
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junglerto
lvl.1

Finland
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dragant Posted at 2014-12-1 03:33
I think that much more support we should get from the company who own this forum and produce S900 ;)

right on! DJI seems to not answer to any problems.
2014-12-1
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ducpeter
First Officer
Flight distance : 62175 ft
Germany
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sometimes yes and no
2014-12-1
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mostey
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We have to stir the pot sometimes. Squeakiest wheel gets oiled first
2014-12-1
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DJI-nick
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China
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The stress situation is different when it flies, did you meet any problem when you were flying it and you feel that must have some connection with this?
2014-12-4
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dragant
lvl.2
Serbia
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Yes! I can't get rid of vibrations in my videos
2014-12-5
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Jsbryant
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Im having major issues with low frequency wobble and bouncing. You can see the main frame and arms vibrating and bouncing. Its better with gains at 100 but anything over that and its unusable at this stage. The shaking transfers down through the landing gear and gimbal. Before you ask, yes! all props and motors are balanced, Isolation dampeners are aligned. Im at the point of having to buy a new S900 frame and send this one back to DJI as both myself and I would say soon the dealer will be at his wits end with it. There is some thing fundamentally flawed with my frame and from what I can gather a few others also.

DJI???
2014-12-15
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Blade_Strike
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You try blade tightness, too tight = bad, too loose = bad? Hint is you cant run gains that everyone else does.. Something is not right. Please explain how you balanced your blades and motors..?
2014-12-16
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Tahoe_Ed
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Blade and Nick are correct.  Static movement does not translate into flight movement.  The gains issue is problematic as the majority of users are not having issues with them.  I fly a S900, Blade flies an S900 so we are not talking about a theoretical knowledge but from what we own and fly.  We are here to help if you can help refine the problem.
2014-12-16
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Jsbryant
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Blade_Strike Posted at 2014-12-17 00:06
You try blade tightness, too tight = bad, too loose = bad? Hint is you cant run gains that everyone  ...

The blades have been weighed on a good set of micro scales. Motors have been balanced using Vibrometre and applying tape to a points around the motor casing to ware the motor vibration is minimal. I have done all this over and over with building a couple of S800 and now the S900 Im confident I have the props and motors balanced. This is NOT the issue but thanks for asking.
2014-12-16
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Jsbryant
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Tahoe_Ed Posted at 2014-12-17 01:22
Blade and Nick are correct.  Static movement does not translate into flight movement.  The gains iss ...

Im actuall sending the unit back to DJI Im going into the dealer this morning and will be packing the item back into the box for shipping. This is NOT! an isolated issue.
2014-12-16
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Blade_Strike
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Jsbryant Posted at 2014-12-17 02:36
The blades have been weighed on a good set of micro scales. Motors have been balanced using Vibrom ...

You missed it completely.. We are asking for how tight the blades are? This is the root cause to a lot of people vibrations.
2014-12-16
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Jsbryant
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Jsbryant Posted at 2014-12-17 02:36
The blades have been weighed on a good set of micro scales. Motors have been balanced using Vibrom ...

When it starts to bounce and shake the IMU starts to compensate for the lateral movement. If the gains are higher than 110 the issue is increased with the IMU being more reactive. It looks ridiculous! in the air.
2014-12-16
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Jsbryant
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Blade_Strike Posted at 2014-12-17 02:55
You missed it completely.. We are asking for how tight the blades are? This is the root cause to a ...

The blades have been installed to the correct DJI spec with tauck rench. 0.4NM
2014-12-16
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Blade_Strike
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How was this done? Did you clean the screws and blade grips? If not, you can not get the correct torque.

I would also suggest to start playing with the torque.. I have found it's more like .3-.35nm to get the correct tightness. What you want is the blade tight enough to not fall under it's own weight when held vertical.
2014-12-16
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Jsbryant
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Blade_Strike Posted at 2014-12-17 03:14
How was this done? Did you clean the screws and blade grips?

All white marking paint was removed then reapplied once re installation of props was complete but I did not clean the actual threads on the bolts as I didnt think that was necessary and I cant see that being the cause. and blade grips were clean. The props are working as they should and there is very! little high frequency vibration in the main frame when hovering. The vibration is a low frequency wobble or shaking/bouncing. This is not! a prop issue but I understan if you have not witnessed this behavour why you would assume it was.
2014-12-16
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Tahoe_Ed
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All I can say is not all users are seeing this issue.  You are correct to send your units back to DJI for repair/replacement.  
2014-12-16
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Jsbryant
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Tahoe_Ed Posted at 2014-12-17 03:33
All I can say is not all users are seeing this issue.  You are correct to send your units back to DJ ...

I know this, I know its not a common issue but as you know it is becoming increasingly documented.
2014-12-16
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Tahoe_Ed
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Jsbryant Posted at 2014-12-17 04:21
I know this, I know its not a common issue but as you know it is becoming increasingly documented. ...

jsbryant, then you need to send it back for repair/replacement.  That is the best we can do for you.
2014-12-16
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Jsbryant
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Tahoe_Ed Posted at 2014-12-17 07:41
jsbryant, then you need to send it back for repair/replacement.  That is the best we can do for yo ...

2014-12-29
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fabien
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France
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Hi,

we fly S900 with a parachute unit fitted right on the top plate and experience absolutely no vibrations, and that one flies intensive..
It is only needed to epoxy glue the carbon tube between the landing gears units to stiffen the gimbal supports ( as they are connected to the carbon tubes going through the landing gears units) and also make sure that all screws are correctly tightened and thread locked.
Do not forget that the S900 is rated for maximum 8kg fully loaded which is less than 1,2 kg pulling each arm in hovering...
Also the propellers are not pushing down but only pulling up or pulling nothing in the worst case ( lol ) so you own't have any problems.
Most vibrations issues come from the landing gears when they are up, they have a big lever effect on the landing gears retracts unit and the best way to reduce this is simply to glue the carbon tube reinforcement between both units. Takes 10 mn of work
Best regards,
Fabien
2015-1-8
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signirr
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Italy
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fabien Posted at 2015-1-9 02:39
Hi,

we fly S900 with a parachute unit fitted right on the top plate and experience absolutely no vi ...

Fabien, this is not the solution.
2015-3-12
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gersphoto.orang
Second Officer
France
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DJI and my dealer told me the same thing to bring back my S900 and they will send it back to China. I had a better idea for them, send me back my 2000 euros and I will bring back my S900 to my dealer office.
2015-3-13
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fabien
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France
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signirr Posted at 2015-3-13 04:15
Fabien, this is not the solution.

HI,
the parachute unit is not relevant for sure, but the modification we make work with great success. It takes just a little time to make all these modifications and we have not a single customer whooshed any problems with their S900 since.

If DJI had to correct the problem, they would need to put stiffer central plates, so that the landing gears unit do not bend the plates, meaning they also get the gimbal damper supports moving, in flight. Or they would simply either glue the central tube between both retracts assembly or make a part that screws as it can reinforce the entire frame this way..

We assembled something like 14  or 15 units of S900 so far, all with these mods, and all customers are happy. We even have customers of other dealers coming to us for the modification so i can guarantee than either you make these mods, either you get stiffer central plates, but you need to reinforce the structure up or down to make clear videos...
I suggest that you take a S900 out of the box, put it upside down ( no need to install the arms) and pull / push the landing gears outside / inside and look at the movements on the gimbal support and look at the central carbon tube between both extract units slide both and back. Then glue that tube, just do that, and check the difference and you will notice that by the same way the entire assembly of center plats become also stiffer ;)
Maybe people like to spend hundreds of euros to get stiffer center plats, but that is NOT the real solution. It is indeed for the S1000 premium ( the S1000+ has been modified with stronger plates by DJI).
Best regards,
Fabien
2015-3-23
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fabien
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France
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I forget the link to the video to show how it is ( here it is a S900...) without gluing the tube...



Best regards,
Fabien
2015-3-23
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jdpitts
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United Kingdom
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fabien@e-copter Posted at 2015-3-24 07:31
I forget the link to the video to show how it is ( here it is a S900...) without gluing the tube...
...

you need this http://kopterworx.com/shop/dji-i ... ate-anty-jello.html
2015-4-12
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fabien
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France
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jdpitts@btinter Posted at 2015-4-12 20:00
you need this http://kopterworx.com/shop/dji-innovations/dji-professional-multirotor/s900-s1000-pa ...

Hi,

between 3 drops of bi component epoxy and 20 minutes to glue the boom, and an expensive anti jello plate that can in no way reinforce the area i reinforce there (there is only ONE screw on each retract unit + one screw per pillar, they can to reinforce this even with a 50Mm thickness carbon plate, these are just M2,5 screws holding them, my choice has been made very clearly and quick
The S900 should work as it's advertised out of the box, now if people prefer to throw away money in upgrades before even checking what is wrong and correct it with simple things that cost almost nothing, this is there choice ))
2015-5-25
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darreneger
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Australia
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We are also having the same issue with our S900. We have spent countless hours with our distributor trying to remove any potential source of vibration. Our gains are low and we have glued the landing gear tube. I have also made new brackets to locate the landing gear when in the raised position to ensure there isn't any lateral movement. We still can't get our S900 to fly without transmitting vibrations to the camera. We have come to the point that we are abandoning this platform as it is simply costing us too much time and money to fix when we should be working. Unfortunately, DJI seems to have forgotten its prosumer end of it's range and the whole S series needs to be updated especially in relation to a solid HD downlink.  Ideally, transferring the A2 and light bridge system from the I1 to the S series would be fantastic. Unfortunately, we are tired of waiting and have no roadmap from DJI. As a commercial operator, we cannot work with this company. A shame.
2015-5-27
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