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Old Oct 16, 2012, 02:08 AM
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Polynésie française, Îles du Vent, Papeete
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Quote:
Originally Posted by quadslo View Post
Today I tried Dennys adapters and Graupner 14x8 props. And I have problem.
I went flying, started slowly until s800 was hovering and than added little bit of throttle. I heard strange sound from one of the props and s800 almost crashed.

So I landed and I saw that one motor starts to vibrate heavy when throttle over half. I tried other prop and it was the same. It even vibrated the same at full throttle with a prop off! And I noticed the same behaviour on one other motor.

Anyone had the same problems? What could I do?
I balanced all the props. I thought it was a faulty prop.

video of the problem:
http://youtu.be/dKziC9w9hBw
i have the same problem with 14x8 if the ground is not horizontal at take of .
i think when a motor want to compensate to much on the ground , vibrations start. But i never had problem in flight even in hard flying.
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Old Oct 16, 2012, 02:15 AM
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i use THIS stuff over the soldered pads of my F450 & discovery builds, maybe a dab on potential problem areas in the esc might help.

once dry it can easily be peeled off in one piece if required, so much less problematic than conformal coatings.

i wouldn't however suggest coating the whole esc though.
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Old Oct 16, 2012, 03:11 AM
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I do believe that I now know the sequence of events that lead to the FOD. When I was developing my F1 carbon inspection machine I used the TM 4008 motor which is a high pole count motor like the stock S800 ones. I went through a period of FOD as a result of incompatable ESC's (supplied by TM) High pole count motors need very high timing or they loose sync when the throttle is advanced very fast. So my machine was fine until it hit turbulence and then it would flip. The problem was compounded when I used larger props.

What I think happens is this.
A motor looses sync. and effectively stalls then the adjacent motors immediately speed up and then they also stall due to the fast response needed. This power surge then causes the opposite motors to speed up as the model starts to sense that it is dropping. I did cure this problem with ESC's from Suppomotor (50 Amp.) which have a high advance setting for high pole count motors. I did also run my S800 on these as well when the standard ESC's needed replacing. Everything was fine until 5.12 and then the problem came back again.

As there seems to be no further problems since using my prop. adapters and 5.14 I think that may be due to the slightly less load from the smaller prop's (Safety Factor) I would like to think that the lower vibration levels also help but my gut feeling is that the problem was always with the motor ESC combination. And the MC frequency used to control the motors.
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Old Oct 16, 2012, 03:48 AM
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Polynésie française, Îles du Vent, Papeete
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hi denny what do you think about that
motor problem (0 min 21 sec)

have have the same thing during some takeoff on a non horizontal ground and my props ( graupner 14x8 ) are well balanced .
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Old Oct 16, 2012, 03:52 AM
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That sounds like an esc to motor timing loss. Is there anyway to advance the timing on your esc's?
I find it extremely strange that DJI used high pole motors and did not use appropriate esc settings.
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Old Oct 16, 2012, 04:06 AM
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But the most common FOD happens hovering with a pretty stable bird , no wind etc. where it´s suppose not to push to hard the firmware, even little vibration not to much amps not hi temps
Anyway it´s suppose to be a "professional" oriented not too cheap machine and by the moment is just an unreliable expensive toy unusable at any set for safety reasons
I claim from DJI an urgent extended test program until they resolve the problem prior to a severe accident occurs due to their passivity .
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Old Oct 16, 2012, 04:09 AM
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Quote:
Originally Posted by flytahiti View Post
hi denny what do you think about that http://youtu.be/dKziC9w9hBw
have have the same thing during some takeoff on a non horizontal ground and my props ( graupner 14x8 ) are well balanced .
probably bended axis
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Old Oct 16, 2012, 06:05 AM
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Quote:
Originally Posted by flytahiti View Post
hi denny what do you think about that http://youtu.be/dKziC9w9hBw
have have the same thing during some takeoff on a non horizontal ground and my props ( graupner 14x8 ) are well balanced .
You can see the motor vibrating like hell, causing that noise. You should use different props..
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Old Oct 16, 2012, 06:28 AM
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Australia, NSW, Stanhope Gardens
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Originally Posted by Mac176 View Post
Hello All,
Does anyone know what the specs are for the temps on the S800 motors and ESCs?
Mac
Possibly the overheat was caused by the craft trying to yaw based on either compas or sensor. With it being effectively tied down where it couldn't move it makes sense that it may run some motors faster then others in an attempt to yaw and when it dosent move as expected it'll keep increasing the throttle.

Just a thought....
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Old Oct 16, 2012, 07:44 AM
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Originally Posted by flytahiti View Post
hi denny what do you think about that http://youtu.be/dKziC9w9hBw
have have the same thing during some takeoff on a non horizontal ground and my props ( graupner 14x8 ) are well balanced .
That is not a phase loss, I think it is a damaged motor shaft or bearing. It does however show quite well the effect of a torsional oscillation in the arm.
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Old Oct 16, 2012, 09:07 AM
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I know the Flip of Death issue has been beaten to death on this forum and elsewhere, everything seems to be pointing to some issue with the ESC or it's signal path to the WKM.
I actually believe DJI when they say from the first post in this thread,

"Your confidence in our products is paramount" and
"rest assured we will always do everything in our power to insure your safety and satisfaction."
It looks like according Chillis picture they have made changes to the arms and it looks like they have insulated the wires. Does this mean V1 isn't safe?. Several people have volunteered to ground there systems until the FOD is fixed. Surely that points to a lack of confidence, can we please get some direction on what we should do with the S800, is it safe?, should V1 owners be worried? Or is this still undetermined what the problem is and V1 is fine.
. If they are going to do everything in there power to ensure our safety and satisfaction, informing us if it's safe should be the first thing.
(I hate bitching about this, I just want to feel secure my system is safe to use)
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Old Oct 16, 2012, 09:30 AM
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My S800 is going on an Outdoor Shoot over Water in T minus 8 Days...hope it does not embarrass me... "it wont hit anyone where its going, just open water"

I have 3 Helis, this S800, and a 1000 Octo for this production...so if this thing gives us issues we cant figure out on set, it will remain in the case it was sold in!

On another Note that video showing the pulsing, I say go back to the original DJI Props and do that same test, if it does the same thing then you can rule out the props.

Statement of the Day:

I think DJI should have Field Tested this machine a bit longer and harder in the hands of REAL people, not Professionals who stand to gain monetary compensation, but guys across the World in different "Uncontrolled" Environments...Before Releasing it to the General Public!

This is a Standard Practice with many products and I have personally been a Beta Tester for quite a few big name companies over the years in this Hobby.
It is the Typical Corporate Practice to make deadlines of release dates and only test in the hands of a few select. This practice is all to common and it should not be tolerated ANYMORE! If DJI has the resources to Innovate UAV's of this caliber, they certainly should be able to get to the bottom of this FOD phenomena and Innovate a Real Solution to this Major Defect!

Will they is anyone's guess, personally I feel a bit burned and if it wasn't for Robert at UAV Products helping me with parts and speed controllers and intel I would have sold this thing off in a second! I don't have time or money for setbacks in this business. When I get a Job, I need to know that I have a reliable, Trustworthy, Safe, and Capable Machine to work with. If I have to worry and think "I hope it don't flip and hurt someone" then I DONT WANT IT! Period! It only takes one time to Ruin Your Safety Record and your Name is Crap! Not to mention the Legal Ramifications, Just Because you have Insurance Does not Mean you are Protected if you are Flying a Known Problematic Craft.

Remember the TOYOTA Recall with the Faulty Throttle? It finely took a Whole Family to Get KILLED before Toyota would admit Fault and Fix the Throttle's

Is it going to take someone to get Smacked in the Head before DJI make's a change? What if someone does FOD into the "Talent" with this known Issue? Do you think your Insurance will back you in Court? I dont...not with so many people around the world having issue.

Sorry for the Long Winded Post, but really had to tell it like it is...

The sad part of this whole deal is DJI does have a Killer Marketing Staff, and in Theory a Very Nice all inclusive Packaged Product that appeals to many, myself included, only to bite us in the pocket book, and then be blamed for doing something wrong...

Flame Suit ON!
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Old Oct 16, 2012, 09:41 AM
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Old Oct 16, 2012, 10:34 AM
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France, Pyrénées Orientales
Joined Feb 2009
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Oufffffffffffffff

Hi,

Flight test with blades XOAR 15" with Denny adaptators

Suddenly the S800 do not answer more radio control

I switch immediately mode: Manual Man !!!

Fortunately he was 1 meter ground

I do not know yet if this is a radio problem or Wookong ...

S800 PROBLEM (1 min 8 sec)
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Old Oct 16, 2012, 10:39 AM
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Austria, Wien, Vienna
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Quote:
Originally Posted by jdm66 View Post
Hi,

Flight test with blades XOAR 15" with Denny adaptators

Suddenly the S800 do not answer more radio control

I switch immediately mode: Manual Man !!!

Fortunately he was 1 meter ground

I do not know yet if this is a radio problem or Wookong ...

http://www.youtube.com/watch?v=z5cI8...ature=youtu.be
oh man whatever is was its a nightmare to have to come close and take of the lipo from a machine in the air ! Happy to see that nothing worse happened !

Boris
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