Hi
This may sound crazy. How about a quadcopter designed for underwater use. Brushless motors operate perfectly well submerged and the rest can be waterproofed quite easily. Idea being that one would use small props, basically the quad would operate in a different medium but essentially it should still stabilise as it does in air. I thought about escs (which don't like water) getting hot but they could be exposed, covered with tectyl or some other waterproofing spray.
As a fail-safe, waterquad would be slightly buoyant so in case of power loss, it would merely float to the surface. One would then have keep throttle on all the time to stay submerged and power up to sink as opposed to normal operation. I know that 2.4ghz does not work underwater but the older 35mhz systems do. For fpv, 1.3ghz could be used ?? Also I wonder which flight controller would work best, kk2 maybe for cost-effectiveness.
Has this been attempted before and if so, any success? Couldn't seem to find anything on this concept. I'm itching to start building but somebody please stop me if I'm wasting my time.
Replies
A quad is designed for the air. Why try to make one that will do both and just make 1 for underwater? I mean you would probably burn your motors/ESC just running them with that much resistance in water (like running a larger prop then your setup was designed for, only worse)
Interestingly enough as you only need the odd low speed burst under water the motors seem to handle it fine.
A good bit of water cooling obviously helps. I would still suggest getting the lowest RPM motors you can though that will still give you flight...
Just a guess but I think a regular quad copter motor set up would burn out under water as the motors would encounter such drag they would but out the esc's. Could be wrong but that's my guess. There are several RC submarines that could get a camera mounted on there and a few adjustments might be far easier than trying to use a pixhawk.
I made a water proof quad and the biggest problem I had was the camera case would fog up. VERY disappointing to spend such a long time setting it up only to have the underwater shots useless. It did not happen in my pool that was near 70 degrees but in water more like 64 it fogged up bad. It might have also been an issue because the camera was a Mobiius and the back gets really hot thus the coldest part in the case was on the other end near the lens. Murphy's law don't ya know.
The temp difference isn't as important as the amount of moisture in the air in the enclosure. A few things you can do about this are:-
1,Put the craft (or camera housing) in the fridge and get is super cold before sealing it up. This will force the moisture in the air in the craft to drop out it's moisture. if there is no visible moisture in it when you seal it up at these temps then unless sit leaks there shouldn't be anything visible at temps above the sealing temp.
2, Do the above and stick a few bags of silica (stuff you get in packaging that says "don't eat" inside.
3, Flush out and fill the craft with something like nitrogen. I purchased the 3 BP085 module for use with my pi ROV and it has a pressure sensor on it so filling the craft with nitrogen and sealing it with a slight positive pressure is handy as it stops any damaging condensation and the pressure sensor tells me my hull is in tacked before diving.
of course there are other methods (double glazing , heaters etc etc)
This was something I saw recently. http://www.aquacopters.com/ I'm planning to do a fiberglass water resisitant drone instead of a water proof drone, but I think it works. Tell me how it goes!
interestingly that site doesn't actually mention the copters going in water....
An ROV is on the wishlist for BoxBotix (along with a BBBoat and BBDroid so it's a long list). I am not an ROV expert so do not know how hard it will be. Have some friends who do this stuff. Will let you know if anything comes of it.
I was picturing a quad like structure with four motors on the back in a vertical "+" config. Then *in theory* you just rotate the current APMCopter code 90 degrees in pitch. Probably so many things wrong with that assumption, but that's why we have open source.
Do you mean a standard type quad setup with the X and then rotating the pitch of the props or rotating the motor prop assembly ?
rotate the entire frame (+ or X ; not sure which works best; if any) 90 deg in pitch. then rotate the code frame of reference to match. bill p helped me do something similar with VTOL code on the UAV dev board a long time ago. let us use it in a tail sitter VTOL where the code was just tricked into thinking it was hovering a 3D plane in hover mode. it's all a gross simplification, but i stopped doing calculus as soon as school was over. so I tend to stick with Barbarian Hacking.
anyway, you just use differential thrust from the four motors to move around. but you do not have depth control without at least a bit of fwd or reverse motion. e.g. top motor in fwd and bottom motor in reverse gets you nose down. i am sure the ROV experts will say there are many things wrong with the idea. then we go from there.
BTW, I do not think we would use the same kinds of motors/props as a quad. We are trying to get BoxBotix to the point where you just use the same BrainBox and different modules to convert between robots. As noted in previous posts I think motors/props similar to what they use on OpenROV could work.
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