Mavic gimbal issue; you all need to read!

[kenwae]

Although I have not had this problem, yet; it's nice to know what could happen and how to fix it; I will say that I tried an auto landing, and was not impressed with how hard it came down. Not smashing hard, but a lot harder than I would have done it manually.

 

[TheLightSpeed!]

If you see how much flow you can pull through the slot in the dome with your mouth it's so big you can't pull a suction on it. (No jokes please).

So after I wrote this, I went to Apache Junction and flew on a 88 degree day with the Dome on. All of a sudden my video got super choppy, and I couldn't help but wonder if it was heat?

But who knows. I agree do as you wish

 

[Masonjar]

Thank you!!!! I had to pull the front corners up and out to get it back under the clamp, but it did the trick. I have no idea why it happened but I'm so thankful for this thread.

 

[Masonjar]

If you see how much flow you can pull through the slot in the dome with your mouth it's so big you can't pull a suction on it. (No jokes please).

So after I wrote this, I went to Apache Junction and flew on a 88 degree day with the Dome on. All of a sudden my video got super choppy, and I couldn't help but wonder if it was heat?

But who knows. I agree do as you wish

I read that if you leave the dome on you are stopping air flow to the fan.

 

[AlanTheBeast]

I read that if you leave the dome on you are stopping air flow to the fan.

Not stopping, but certainly restricting as the slot and the holes near the tabs are a small area compared to the air intake.

One could drill holes in the sides of the dome to increase airflow. Say, 3 holes of 5 mm on each side - that would be getting close to the area of the inlet.

 

[TheLightSpeed!]

I would say in most situations the slot in the dome is sufficient. In Arizona it's probably not

 

[Kevo Droning]

So, I got my Mavic weeks ago.... flew it with no issues... the other day landing on a pathway it slid to the left and clipped a curb... the Mavic dropped the last about 10" inches somewhat hard.

At first glance the prop didn't even have a scuff really, and it took right back off.

But immediately, I noticed Jello-ing in the video... BAD!

So I freaked and started an RMA.

Then my girlfriend and I were looking at it and realized the gimbal base had slid over the corner of the Mavic? I pushed a little and "pop" it popped right back into place! All good? Again, flew it and still the video is jello-ing?

No damage, zero, and I have this issue....

I even tried to change props... nada.

Then looking at it again with my GF, she points out that the gimbal is sitting against this metal tab... and the back of the gimbal is firmly against the Mavic and the front if springy.

So I pulled the base of the gimbal back out like I found it, and realized the gimbal was supposed to be on top of this limiting tab... slid it back on top of the tab, slid the corner of the gimbal back under and viola, it's perfect!

Lesson - the "auto landing" kind of sucks. A little wind and it can move. Be way clear of anything two feet around just in case.

Also, the gimbal is different... and can slide below the tab that is designed to limit this exact behavior.

I hope this helps someone else. I keep seeing all these "jello" complaints, and I'm 99% sure it's usually caused by the gimbal having direct contact with the bird, or a major vibration in the blades etc.




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Same thing happened to me with the tab. One of my little front end bunges had popped out... reset it and pushed he gimble under this tab on the rear. works great!

 

[AlanTheBeast]

I've said it before and I'll repeat again and forever.

Heat kills electronics regardless of the ambient temperature.​

In nose down (forward flight) there is less airflow on the bottom heatsink. Getting more air to it via the bottom vent is essential. Restricting that flow with the dome on is not helping at all. At least modify the dome to permit more airflow.

 

[jonny2pints]

Although I totally agree with you about overheating electronics causing problems.
Why do you insist on recommending fellow pilots drill holes in their new toys?
The area of the square vent has no relevance to the cooling fan blade area, (fan swept area) which is considerably smaller.
The vent holes in the Mavic bubble where not guessed by the guy that designed it.
He would have a pretty bad day if they all got returned because of overheating issues!
Ducting of equal area to the fan is preferable on the intake side of systems for greatest efficiency. However if the intake side has a smaller area the intake air speed increases so long as the fan receives enough energy to sustain the same RPM.
In conclusion, it's my understanding that if the area of the intake holes is less than that of the fan swept area all that happens is the same volume of cooling air enters, but at a higher velocity.
So can we please stop drilling unnecessary holes in Mavic's?

 

[AlanTheBeast]

Drilling holes in Mavic's is wonderfully liberating.

But here I'm talking about the silly dome - not the drone.

You'r observation regarding how much the fan can actually breathe is nice, but ignores that the holes at the little slot in the dome and near the tabs is likely smaller than that. So don't drill 6 holes. Drill 4 if you feel that way.

Also note that Drone Valley did a test of this and noted that the drone was hotter when operated with the dome on. Yes, it was not a perfectly conducted test but it was good enough to show the drone was hotter with the dome on.

 

[dwallersv]

Also note that Drone Valley did a test of this and noted that the drone was hotter when operated with the dome on. Yes, it was not a perfectly conducted test but it was good enough to show the drone was hotter with the dome on.

The Drone Valley guy is a valuable contributor to the community, and does some nice reviews and some other technical videos.

However, this one was a complete waste. There were so many problems with his testing protocol and process as to render the results utterly meaningless. The very first that cam to mind is the starting conditions of the two scenarios.

I'd completely ignore DV's test of this, and if he's reading, I respectfully suggest he remove this video, do some research into how to correctly do a temperature test like this, and redo to whole thing.

 

[AlanTheBeast]

Do your own test perfectly and report back.

 

[jpelton722]

Thanks for this thread, this just happened to me and praise the LORD this fixed it!

 

[TheLightSpeed!]

Drilling holes in Mavic's is wonderfully liberating.

But here I'm talking about the silly dome - not the drone.

You'r observation regarding how much the fan can actually breathe is nice, but ignores that the holes at the little slot in the dome and near the tabs is likely smaller than that. So don't drill 6 holes. Drill 4 if you feel that way.

Also note that Drone Valley did a test of this and noted that the drone was hotter when operated with the dome on. Yes, it was not a perfectly conducted test but it was good enough to show the drone was hotter with the dome on.

Drone Valleys test was a joke. He flew with the Dome off, tested, then put on the dome, flew again and tested. Of course it was warmer. He's an idiot. IMO

To do it right you have to have a controlled ambient temp. And test it at rest and after flight under both scenarios.

 

[AlanTheBeast]

Drone Valleys test was a joke. He flew with the Dome off, tested, then put on the dome, flew again and tested. Of course it was warmer. He's an idiot. IMO

To do it right you have to have a controlled ambient temp. And test it at rest and after flight under both scenarios.

NS. Still waiting for someone here to "do it right".

 

[quick_dry]

In conclusion, it's my understanding that if the area of the intake holes is less than that of the fan swept area all that happens is the same volume of cooling air enters, but at a higher velocity.
So can we please stop drilling unnecessary holes in Mavic's?

Not quite how it works, but I also doubt that DJI design it optimising the aerodynamics all that much - the Mavic could have way better aero and still maintain the portability., but maybe not the 'look' or the cost of tooling.
The fan doesn't necessarily have the same mass flow when the holes get smaller, as they can be more restrictive - the flow will speed up, but unless the hole was oversized for that flow anyway, there is more energy loss in getting it through the smaller hole and less goes through.

But this all could be meaningless argument, who knows if the added restriction makes a real difference - nobody knows the specs of that fan so you can't say for certain the holes needed to feed it.

I don't see how holes in the side of the gimbal globe are going to harm anything, they might not have any meaningful impact but it's only a clip on clear plastic dome, not the drone itself.

Nobody has tested, nobody knows for sure, but erring on the side of caution would be that if you're flying in really hot conditions, the holes in a clip on cover hurt it less than the potential results from overheating. (It isn't a particularly powerful fan, so I don't think the gimbal cover would choke it... but... without testing I wouldn't hang my hat on that)

 

[TTFullTimer]

Would it have helped if you had the gimbal protector cover on Mavic fulltime while flying/landing?


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Do not fly with the dome in place. It will restrict cooling air flow. Mine gets hot enough as it is. Flying in high desert conditions. I rested mine between four minute flights as I was concerned about how hot it was. As far as the discussions of flow velocity, when you have a fan pulling in air once the pressure differential reaches atmospheric you will get no more flow the flow will "choke"

 

[vk2fro]

TheLightSpeed! you just saved me a lot of research. I hit a tree with my mavic (only one damaged prop) and fell about 6 feet into grass. The gimbal popped out from under that L shaped tab. Being a cautious fellow I slept on it, sobered up (hint folks, dont fly after a few ales; especially in postage stamp sized parks!) and did an inspection of the craft and wondered "wow that gimbal sure is loose." Next flight I'll need to do a gimbal cal before flight - the gimbal/camera assembly is fine (it was still filming after the bird came down), so I'm assuming it just got jarred out of place. Had I not done a thorough postflight inspection, I may not have noticed, and ended up with a blind bird.

 

[Mavman]

I'll take some photos... if you look at the gimbal of the Mavic you'll see what I mean.

It sits on the four plastic shocks, but has a tab that limits its travel down.


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I let my girlfriend fly it one time, she was too eager, got distracted by an instagram message and clipped a tree. Had the bubble on which got cracked, and I had the same jello effect. Also figured out it had come loose from the tab, put it back and everything is fine. If it was t for the dome, would have probably broke the gimbal.

Also for the dome haters, in addition to the one slit, there are also inlets around where the bottom part clips in.

 

[vk2fro]

I let my girlfriend fly it one time, she was too eager, got distracted by an instagram message and clipped a tree. Had the bubble on which got cracked, and I had the same jello effect. Also figured out it had come loose from the tab, put it back and everything is fine. If it was t for the dome, would have probably broke the gimbal.

Also for the dome haters, in addition to the one slit, there are also inlets around where the bottom part clips in.

I've modified my dome, and used a dremel sanding drum on it; opening up the sides, so air can easily get into it. It wouldn't have saved me the other night though, as I didn't have it on. (probably a blessing in disguise, as the camera would have whacked it). My gimbal calibration went through fine. And I have progressed - I no longer use "Auto" take off - I arm the motors on the ground, and take off manually now