Not undermining your empiric tests, but couldn't you just have calculated the result directly?
Mini weighs 250g so it needs to displace at least 250g of water.
250g of water = 250cm³ = 15.23cubic inches
Can't include Mini's volume into the mix since it's not watertight by any means, although I guess the plastic has some floatation but then again the floats add grams...

If I may, I would suggest a hollow thin plastic floats instead of the styrofoam to minimize weight.
I would also try to place the floats on the side of the craft to minimize wind surfaces.
I'd think a thin lexan bulges on both sides would be the best option, which would turn the hull more saucerlike and with cutouts on the corners to allow free thrust. Wouldn't even be that difficult to hot mold said floats...hmmmm

Miixxa Posted at 1-18 16:18
Not undermining your empiric tests, but couldn't you just have calculated the result directly?
Mini weighs 250g so it needs to displace at least 250g of water.
250g of water = 250cm³ = 15.23cubic inches

I did calculate the results first and did get 15 cubic inches of zero weight flotation. That did not include the weight of the extra hardware (pontoons and bracket, so I wanted a real-world test to back up the data. There is another of my topics stating the early assessment but it was on another forum. I did find that the density of the floats supplied is higher than a typical block of simple hard foam. I suspect that was to make it stronger.

I would like to put the floats on the side but I think that would block the airflow from the props. Once again, the goal was not to land but to simply keep it from sinking completely.

I would have gone with a GetterBack setup but a lot of the water around here is less than 6 feet deep and that model needs more depth to activate.

Interesting idea about the saucer shape.

This is all just part of the hobby for a retired engineer ;-)

Ready to use
https://ru.aliexpress.com/item/33006624788.html

LRaven Posted at 1-19 02:48
Ready to use
https://ru.aliexpress.com/item/33006624788.html

OMG, not happening on a Mini. Talk about huge wind resistance!

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.

But with the pontoons, it won't be submerged at the floatation devices.  It will be wet and "ruined" but will be retrievable for repair/replacement.  No coverage if he can't get it back.

It would be interesting to experiment and gather data for using some "sculpted" pontoons that would improve the aerodynamics.  Simply making the leading and trailing ends of them pointed seems like it would likely improve (decrease)l the drag numbers a certain small amount.  

..........

Might consider something much simpler (if available in your area):

https://www.amazon.ca/Waterbuoy-Rapid-Activation-Floating-Chain/dp/B002SG9L7W

corresponding YouTube video:



There are a number of these types of devices available - not sure if this is the best mini 250g drone option available or not. If anyone finds a particularly good one, please share!

Another drone-specifc option:

https://www.amazon.ca/GetterBack ... overy/dp/B01891TFXO

correspoding YouTube video:

AG0N-Gary Posted at 1-23 12:02
It would be interesting to experiment and gather data for using some "sculpted" pontoons that would improve the aerodynamics.  Simply making the leading and trailing ends of them pointed seems like it would likely improve (decrease)l the drag numbers a certain small amount.

It wouldn't make any difference to the weight penalty and additional surface area.

If the people that suggest these contraptions ever published actual performance  data, they would be a lot less attractive.
For some reason it's very difficult to get any of them to give this information.

Labroides Posted at 1-23 15:03
It wouldn't make any difference to the weight penalty and additional surface area.

If the people that suggest these contraptions ever published actual performance  data, they would be a lot less attractive.

i know it has been a long time in coming with my impromptu evaluation so I apologize for that.

I did find that the simple 15 cu in float did result in a range reduction of about 20%. Now, that is with virtually no wind. I am pretty sure it is greater in high wind.
3 months late...again sorry ;-)

GaryDoug Posted at 4-7 20:54
i know it has been a long time in coming with my impromptu evaluation so I apologize for that.

I did find that the simple 15 cu in float did result in a range reduction of about 20%. Now, that is with virtually no wind. I am pretty sure it is greater in high wind.

Thanks for that.
It's very hard to get any feedback on that sort of thing.
That sounds about right for the way you've done it.
I'd love to find some numbers for those pontoons that get promoted but no-one seems to stick with.

Labroides Posted at 4-7 21:12
Thanks for that.
It's very hard to get any feedback on that sort of thing.
That sounds about right for the way you've done it.

I really appreciate your post. I am a retired test engineer, so I do like to "test" things ;-)

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/

Total garbage, unreliable junk!

DAVIDTNZ Posted at 6-14 07:07
Total garbage, unreliable junk!

Can you give us some more details of your experiences? I notice that they are sold out for a while.

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.

not if you have the dji care refresh. You must return the drone in order to get a replacement, so getting it back in any state is better than nothing.

Anyone tried the ''getherback'' gizmo?

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 remain pretty dang scared of my next door river. Crashing over land is ok, water ......... too risky for all factors mentioned above.

Great idea!

Matthew Dobrski Posted at 1-18 12:32
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 ...
https://vimeo.com/181290003

I just realized that I never posted anything about a flight I did back in February over water while using the single block of Styrofoam atop the Mini. Just over  a mile in total distance and about 1550 feet range. No payload mode was triggered. I believe this was the last time I used any flotation on any drone.
https://app.airdata.com/share/pGadDb

djiuser_AfSBjawoJYlj Posted at 12-5 12:37
I remain pretty dang scared of my next door river. Crashing over land is ok, water ......... too risky for all factors mentioned above.

Your fear is irrational.
The drone is no more likely to crash over water than it is on land.
But handicapping a lightweight drone with that sort of contraption ... that's making things quite risky.

But go ahead and try it if you want.
Many nervous flyers are attracted to these things, but we don't see reports from anyone that continues using them.

Labroides Posted at 12-5 15:23
Your fear is irrational.
The drone is no more likely to crash over water than it is on land.
But handicapping a lightweight drone with that sort of contraption ... that's making things quite risky.

"Your fear is irrational."

Maybe, but I had that fear, at least at first. Think of it as using training wheels. Right now I wish some in my country had a little more fear ;-)

I just took another look at that flight data. I see that the Mini had no problems going 16+ mph into a slight headwind and 17+ mph downwind. I think that is the max speed shown in the user manual for P mode. So how did that top-hat float reduce the performance? Obviously it did not go slower. So...I am forced to think that more power was somehow applied to make the 17 mph. I say this because the study I did showed a reduced range by 20%....so it was a greater battery drain. Hmmm.....

GaryDoug Posted at 12-5 20:20
I just took another look at that flight data. I see that the Mini had no problems going 16+ mph into a slight headwind and 17+ mph downwind. I think that is the max speed shown in the user manual for P mode. So how did that top-hat float reduce the performance? Obviously it did not go slower. So...I am forced to think that more power was somehow applied to make the 17 mph. I say this because the study I did showed a reduced range by 20%....so it was a greater battery drain. Hmmm.....

So how did that top-hat float reduce the performance? Obviously it did not go slower. So...I am forced to think that more power was somehow applied to make the 17 mph. I say this because the study I did showed a reduced range by 20%....so it was a greater battery drain. Hmmm.....

I don't like to guess but here's a guess to explain this anyway ...

DJI slipped a little surprise in with a recent firmware update that allows the DJI Fly drones to access up to Sport Mode speed when needed to better handle strong winds.
With the added air resistance, the drone isn't going as fast as the flight controller thinks it should for a given tilt angle, so the flight controller increases the tilt angle to get more speed, just as it would for a headwind.
If the flight data shows tilt angles >20° in normal mode that would confirm it.

Labroides Posted at 12-5 21:19
So how did that top-hat float reduce the performance? Obviously it did not go slower. So...I am forced to think that more power was somehow applied to make the 17 mph. I say this because the study I did showed a reduced range by 20%....so it was a greater battery drain. Hmmm.....

I don't like to guess but here's a guess to explain this anyway ...

I really like that guess. And I somewhat agree that there is more going on here than meets the eye. But...this flight was back in Feb 2020.

I have always wondered if maybe the specs are a bit flexible depending on conditions. In other words, make it go as fast as the specs say even if you have not selected Sport mode.

And what does Position or Sport mode mean anyway? Is it a setting that restricts the control of the speed...or is it a setting that just limits the max speed?

Labroides Posted at 12-5 21:19
So how did that top-hat float reduce the performance? Obviously it did not go slower. So...I am forced to think that more power was somehow applied to make the 17 mph. I say this because the study I did showed a reduced range by 20%....so it was a greater battery drain. Hmmm.....

I don't like to guess but here's a guess to explain this anyway ...

"If the flight data shows tilt angles >20° in normal mode that would confirm it."


Wow, I am not sure where to find that, wasn't aware that was in the log files. But apparently I do still have the dat file and the txt file from that day. Might be a bit late for me to get going on that now (too sleepy) but thanks for the info.

GaryDoug Posted at 12-5 21:29
I really like that guess. And I somewhat agree that there is more going on here than meets the eye. But...this flight was back in Feb 2020.

I have always wondered if maybe the specs are a bit flexible depending on conditions. In other words, make it go as fast as the specs say even if you have not selected Sport mode.

what does Position or Sport mode mean anyway? Is it a setting that restricts the control of the speed...or is it a setting that just limits the max speed?
In Normal Mode the max tilt angle is restricted to 20°
In Sport Mode, it can go to 30°
More tilt = more speed, but requires more power to compensate for the lost downward thrust.

GaryDoug Posted at 12-5 21:49
"If the flight data shows tilt angles >20° in normal mode that would confirm it."

It's all in there if you dig deep enough.

http://www.mediafire.com/file/tr ... -01_FLY079.DAT/file

Labroides Posted at 12-5 21:51
It's all in there if you dig deep enough.

OK so I decided to forgo sleep and check anyway. It looks like the max value for pitch was -24.8 at about the same time it was going 17 mph.