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Mini pontoons weight and volume
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GaryDoug
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Being paranoid about losing the Mini while flying over water, I decided to buy a pontoon kit (about $12 from China) to use while practicing over a salt water area. It was not to be used to actually land on the water. Mainly I wanted to see how this set would affect preformance. And I wanted to measure the actual amount of floatation that would be required to keep it from sinking. I am aware that the DJI repair insurance only covers drones that can be returned for repair, not ones lost at the bottom of a bay ;-)

To me, it seemed to perform mostly as normal with the folowing exceptions. First, it took about twice the battery power to move around, so count on only about half the battery life, maybe 15 minutes unless it is just hovering in calm winds. Second, I did notice many more ESC error messages, but they only happened when the drone was hovering at low altitude with it's side to a wind of about 10 mph. I assume the large area of the pontoons from the side was responsible for that.

It appears that the amount of floatation to keep it from sinking is about 13 cubic inches of Styrofoam.







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GaryDoug
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Another thing I noticed is that the Mini seems to be able to hover much lower to the ground with these attached without going into landing mode. I wonder if the sensors are being partly blocked or offset in some way.
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Akirasho
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Looks a way to deliver hotdogs for Doordash…..

So many things will have to go right in a situation going wrong for that to work IMHO.
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Charles Adams
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The mount looks 3d printed.  If so, any idea on where the model came from and if it's available?
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GaryDoug
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I would not recommend them in anything but the lightest winds. And I really wouldn't trust them to allow the drone to land on the water reliably, unless you just want to feed the alligators ;-)

The goal here was to determine in actual use how much flotation would be needed to keep it from sinking. Perhaps a 13 cu. in. flat piece of Styrofoam on the top would be adequate.
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GaryDoug
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Charles Adams Posted at 1-16 15:09
The mount looks 3d printed.  If so, any idea on where the model came from and if it's available?

I have no idea about a 3D model but some optional landing gear is avaiable for about $3.

The float set is very commonly available on eBay and from other sources in China.
Example: https://www.aliexpress.com/item/ ... vD_BwE&gclsrc=aw.ds
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Charles Adams
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GaryDoug Posted at 1-16 15:15
I would not recommend them in anything but the lightest winds. And I really wouldn't trust them to allow the drone to land on the water reliably, unless you just want to feed the alligators ;-)

The goal here was to determine in actual use how much flotation would be needed to keep it from sinking. Perhaps a 13 cu. in. flat piece of Styrofoam on the top would be adequate.

OK, though I admit that I am very interested in this setup.  Flying from my boat is my primary use case, and there is appeal in developing a reliable "flotation" system.  I'm not particularly interested in launching from or landing on water, but I AM interested in keeping the drone afloat if it ditches.  I've been fortunate (careful flying????) to have never lost a drone in the lake.
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GaryDoug
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Charles Adams Posted at 1-16 15:20
OK, though I admit that I am very interested in this setup.  Flying from my boat is my primary use case, and there is appeal in developing a reliable "flotation" system.  I'm not particularly interested in launching from or landing on water, but I AM interested in keeping the drone afloat if it ditches.  I've been fortunate (careful flying????) to have never lost a drone in the lake.

This is an early attempt to emulate the pontoons in effect. I haven't used it much but it does fly in still air ok. I know what you mean about using it on a boat. Most users say it's not really needed.
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120ccpm
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Since water has a density of 1g/cc, the equation to calculate how big of a floater you need to prevent the MM from sinking is pretty simple:
Volume of Floater + Volume of MM (expressed in cc) > Weight of Floater + Weight of MM (expressed in grams)
If you ignore the volume of the MM, 270cc of styrofoam (density 0.05g/cc) should be enough to keep the MM afloat (270 > 14 + 249). But if you take the volume of the MM into consideration, and you estimate it to - say - 100cc, then you would only need 170cc of styrofoam (170 +100 > 9 + 249) to keep it afloat. It would be almost fully submerged of course, but it would stay afloat.
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AG0N-Gary
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It may keep it from sinking, but it can still land upside down and be contaminated by the (salt) water.
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Labroides
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Being paranoid about losing the Mini while flying over water, I decided to buy a pontoon kit (about $12 from China) to use while practicing over a salt water area.
You should be more paranoid about how this contraption has handicapped your drone and how that is more likely to cause it's loss than make your flying safer.
The Mini is a weak, slow drone on its own without being lumbered with this.
I don't see any mention of how much it has reduced its speed.
Or how increasing the windage so much will cause it to be more easily blown away.

It's always amusing how the nervous new flyers attracted by such things always assume they will always be able to easily retrieve their dunked drone because it has floats.
Are you planning to have a boat handy or only fly within 10 feet of the shore?

I wonder if the sensors are being partly blocked or offset in some way.
It would be easy to tell by looking at recorded flight data but if it is, that introduces some additional potentially serious problems.

I fly safely over water most of the time and there's no way I'd strap on junk like this and expect to fly safely

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120ccpm
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AG0N-Gary Posted at 1-16 17:25
It may keep it from sinking, but it can still land upside down and be contaminated by the (salt) water.

The OP said he simply wants to be able to retrieve the drone, not to keep it above water. He even posted a photo where the styrofoam is on top of the AC, which means the AC would end up completely submerged.
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Geebax
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120ccpm Posted at 1-16 17:52
The OP said he simply wants to be able to retrieve the drone, not to keep it above water. He even posted a photo where the styrofoam is on top of the AC, which means the AC would end up completely submerged.

If it goes into salt water and is submerged, getting it back is relatively pointless as the electronics will be stuffed anyway.
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Geebax Posted at 1-16 18:22
If it goes into salt water and is submerged, getting it back is relatively pointless as the electronics will be stuffed anyway.

DJI Care Refresh does not cover lost aircrafts, this is why the OP wants to be able to retrieve it.
Water damage is covered, as long as you can retrieve the AC.
See https://www.dji.com/service/djicare-refresh/info
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GaryDoug
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120ccpm Posted at 1-16 18:40
DJI Care Refresh does not cover lost aircrafts, this is why the OP wants to be able to retrieve it.
Water damage is covered, as long as you can retrieve the AC.
See https://www.dji.com/service/djicare-refresh/info

Thanks. It would seem that you are the only member here who reads the whole post. Most just jump in and criticize before they know anything. You are probably wasting your time explaining it to them.
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GaryDoug
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120ccpm Posted at 1-16 16:42
Since water has a density of 1g/cc, the equation to calculate how big of a floater you need to prevent the MM from sinking is pretty simple:
Volume of Floater + Volume of MM (expressed in cc) > Weight of Floater + Weight of MM (expressed in grams)
If you ignore the volume of the MM, 270cc of styrofoam (density 0.05g/cc) should be enough to keep the MM afloat (270 > 14 + 249). But if you take the volume of the MM into consideration, and you estimate it to - say - 100cc, then you would only need 170cc of styrofoam (170 +100 > 9 + 249) to keep it afloat. It would be almost fully submerged of course, but it would stay afloat.

Yep, 270cc (16 cubic inches) is very close to my original estimate of 15 cubic inches. The floats seem to provide about 13 cubic inches when half submerged, and that works obviously.

And to answer another poster, I DO plan to have a boat handy as I live on the waterfront.

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GaryDoug
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I would be perfectly happy using the GetterBack kit but as far as I can read, it may not deploy in water less than 6 feet deep and that would not work around much of my area.
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Lucas775
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Since it is 250g or over do you have to register it?
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Labroides
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GaryDoug Posted at 1-16 18:55
Thanks. It would seem that you are the only member here who reads the whole post. Most just jump in and criticize before they know anything. You are probably wasting your time explaining it to them.

Thanks. It would seem that you are the only member here who reads the whole post. Most just jump in and criticize before they know anything. You are probably wasting your time explaining it to them.


Or there are some who spend all their flying over the sea, have read dozens of these naive floatie stories,  understand very well what it's all about .. and do read the whole post before responding.

But it's usually a wasted effort.
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Charles Adams
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Labroides Posted at 1-16 17:42
Being paranoid about losing the Mini while flying over water, I decided to buy a pontoon kit (about $12 from China) to use while practicing over a salt water area.
You should be more paranoid about how this contraption has handicapped your drone and how that is more likely to cause it's loss than make your flying safer.
The Mini is a weak, slow drone on its own without being lumbered with this.

I have years of experience flying multiple drones, and agree that flying safely is the best strategy in any environment, especially over water.  In fact flying safely will prevent the vast majority of issues that people come here and report.  I am more interested in recovery, even if the equipment is unsalvageable.  I suspect that what you infer is true, enhancing the craft to keep it floating will probably contribute to an undesired outcome, a self fulfilling prophecy of a sort.
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GaryDoug
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Lucas775 Posted at 1-16 19:08
Since it is 250g or over do you have to register it?

I don't see why not.
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Geebax
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120ccpm Posted at 1-16 18:40
DJI Care Refresh does not cover lost aircrafts, this is why the OP wants to be able to retrieve it.
Water damage is covered, as long as you can retrieve the AC.
See https://www.dji.com/service/djicare-refresh/info

"Water damage is covered, as long as you can retrieve the AC."

And for those who did not purchase Care Refresh? There are moisture indicators built into the aircraft, and if activated, they nullify the warranty.
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120ccpm
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GaryDoug Posted at 1-16 18:59
Yep, 270cc (16 cubic inches) is very close to my original estimate of 15 cubic inches. The floats seem to provide about 13 cubic inches when half submerged, and that works obviously.

And to answer another poster, I DO plan to have a boat handy as I live on the waterfront.

270 is the absolute upper limit, that does not take into consideration the volume of the MM, which is not easy to estimate. The MM is about 13cm long, 6cm wide and 5cm tall, for a total of 390cc. Even assuming that only 1/4 of that is actual material, you have about 100cc of volume.
Long story short, I think 170cc might be enough to keep it afloat.

Having said that - and leaving the tone of some replies aside - I do agree that  a float on an aircraft the size and power of the MM does not look like a good idea: it might prevent the AC from sinking, but it might cause it to crash in the water in the first place!
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GaryDoug
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Empirical data usually prevails.
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GaryDoug Posted at 1-16 20:12
Empirical data usually prevails.

Your test gave you an approximate volume to keep the AC entirely out of the water. If you - like you do - just want to prevent it from sinking, then you should take into account its volume.
Think this way: if the MM were less dense than water (but still weight 250g), your test would give the same exact results (the pontoon will be half-submerged), yet the AC would actually float on its own.
If you are really thinking to go ahead with this idea, you should try to keep the float's dimensions to a minimum, in order to minimize its influence on the AC.
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GaryDoug
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The main problem with that approach is that you would have to submerge the Mini to determine it's density and true displacement. And I am not prepared to do that. Would anyone like to volunteer ;-)
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GaryDoug Posted at 1-16 20:43
The main problem with that approach is that you would have to submerge the Mini to determine it's density and true displacement. And I am not prepared to do that. Would anyone like to volunteer ;-)

You seem to be an excellent candidate to have a MM crashing in the water, and be able to retrieve it.

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GaryDoug
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You know, I was actually thinking the same thing ;-)
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DAFlys
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Lucas775 Posted at 1-16 19:08
Since it is 250g or over do you have to register it?

Yes,  would require registration,  they do it on take off weight.
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DJI Stephen
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Hello and good day GaryDoug. Thank you for reaching out and for sharing this information and accessory with us. Just a reminder that it is recommended to enable the Payload Mode fro enhanced safety. Please note that the Maximum Service Ceiling above Sea Level is 1500m and the maximum flight speed is limited when the Payload Mode is enabled. In addition DJI does not recommend using a 3rd party accessory when flying the DJI Mavic Mini for compatibility purposes. Thank you and have as safe flight always.
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GaryDoug Posted at 1-16 18:55
Thanks. It would seem that you are the only member here who reads the whole post. Most just jump in and criticize before they know anything. You are probably wasting your time explaining it to them.

I have read your posts and totally understand your goal. I have watched several videos of people finding drones at the bottom of a river/pond etc. And if there was some sort of flotation, it could have been recovered and the care refresh used if they had that. I think it's a worthy idea if one is going to be flying over water quite a bit.
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GaryDoug
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For what it is worth, my Mini is now registered with the FAA. Easy and cheap enough to do that.
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That makes the MM too heavy for 'us' here in NL.
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Ive been also considering this device, and made me think of some sort of airbag that could deploy if AC gets in contact with water.
I agree with some that flying unsafely can lead to most problems, and adding so much air resistance may increase issues.
Thanks for the tests!
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GaryDoug
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InspektorGadjet Posted at 1-18 03:59
Ive been also considering this device, and made me think of some sort of airbag that could deploy if AC gets in contact with water.
I agree with some that flying unsafely can lead to most problems, and adding so much air resistance may increase issues.
Thanks for the tests!

There is a small buoy system that does about that. But it seems to need a required water depth of 6 feet or more to deploy. It seems to be pressure activated, not water activated. Search for GetterBack.
https://www.getterback.com/
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InspektorGadjet
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GaryDoug Posted at 1-18 08:38
There is a small buoy system that does about that. But it seems to need a required water depth of 6 feet or more to deploy. It seems to be pressure activated, not water activated. Search for GetterBack.
https://www.getterback.com/

Oh cool thanks for the info!
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Matthew Dobrski
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There's absolutely nothing wrong with experimenting and gathering knowledge and experience. Been there, did that. Soon you'll realize that such mod is crippling your MM to the point of being even more clumsy and useless. Moreover, you'll get enough confidence in piloting your drone over water without such ballast ...
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GaryDoug
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AGAIN....... I HAVE NO INTEREST IN LANDING ON THE WATER EVER.... NONE ;-) I am pretty sure I will have to repeat this message again and again.

This was purely an experiment to find the amount of flotation that would completely support the Mini, worst case. I did that by measuring the amount of water that was displaced when using these $12 floats and calculating the density of the floats themselves. It was strictly empirical data. As an extra, I did evaluate the performance loss just in case someone might find that interesting or useful.

For some followup today: I tested the performance again this time also comparing performance with the 1) both pontoons, 2) nothing, 3) 15 cu in of flotation attached to only the top, and 4) nothing. It is a moderately windy day gusting to about 15 mph. On only the first flight (pontoons) did I witness any anomalies, and that was only a wind speed warning message. No logged warning notifications occurred on any test. It does appear that the video shows some slight movement of foreground objects against far away objects in the background, typical of movement while hovering. The worst ones were as expected, with some payload attached.
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Labroides
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GaryDoug Posted at 1-18 13:08
AGAIN....... I HAVE NO INTEREST IN LANDING ON THE WATER EVER.... NONE ;-) I am pretty sure I will have to repeat this message again and again.

This was purely an experiment to find the amount of flotation that would completely support the Mini, worst case. I did that by measuring the amount of water that was displaced when using these $12 floats and calculating the density of the floats themselves. It was strictly empirical data. As an extra, I did evaluate the performance loss just in case someone might find that interesting or useful.

It was strictly empirical data. As an extra, I did evaluate the performance loss just in case someone might find that interesting or useful.
What would be interesting and useful is the comparison of speed in still air with and without, for P-GPS and Sport Modes.
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GaryDoug
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Labroides Posted at 1-18 15:01
It was strictly empirical data. As an extra, I did evaluate the performance loss just in case someone might find that interesting or useful.
What would be interesting and useful is the comparison of speed in still air with and without, for P-GPS and Sport Modes.

I will see if I can supply that ASAP. I do know that the full pontoon sets take about twice the battery power to fly around.
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