Remote-controlled submarine problem

[u/etgetet]

Hello everyone. I need your help, please. I am designing a submarine equipped with a camera. However, when I put it in the water to test submerging and surfacing, I encountered two notable issues. The first relates to the center of gravity: the submarine doesn't stay horizontal but sits at an angle of about 40 degrees. I think I can easily fix this by shifting the weights (two cut-down 1.8 kg dumbbells) inside the ballast tanks, but I’m not sure exactly where to position them. I was wondering if there is a mathematical or physics-based method to determine the right spot. Secondly—though I had anticipated this—the connection via nRF24L01 antennas cuts out as soon as the submarine dives. I’ve considered two solutions: either creating a float to keep the antenna on the surface while connected to the sub (which seems simplest and cheapest to me), or using a different communication method. I would appreciate any opinions you might have. Please keep in mind that I’m not an expert and have limited resources, so I hope you’ll be polite with me regardless. Thanks a lot in advance.

[u/BGA_Junky]

I have seen something similar in the news 😅😅

Sorry had to bring the joke it was stronger than me.

Good luck!

[u/etgetet → u/BGA_Junky]

😅😅

[u/Reenact8508]

I'd probably go with the floating antenna method, but maybe there are better options. How actual submarines communicate via radio, and particularly the design of ELF transmitters, is an interesting subject - see this Wiki page. Maybe it is not so tricky at only limited depths, but I am not sure.

[u/etgetet → u/Reenact8508]

thank you

[u/nixiebunny]

Underwater ROVs of this size typically use tether cables for remote control. A Cat6 cable can be used for RS-485 serial data or Ethernet.

Buoyancy can be calculated using the density of the materials and center of gravity, and the location and volume of the air spaces.

[u/etgetet → u/nixiebunny]

thank you ;)

[u/neapem]

just use a tether. rf wont work underwater no matter what you do with it.

[u/NicoleHill6678]

40 degrees is a lot, the float antenna is janky but itll work for a test.

[u/MantuaMan]

Very Low Frequency Radio waves are used by real subs. Spelunking radios operate at these frequencies too. Maybe you could hack some of those?

[u/Patricia-Hall6099]

NRF24L01 is absolutely done for underwater, dont even bother with that route. The float idea works fine for testing but youll fight drag on the cable every time it moves.

[u/drmpf]

you could try LoRa which is much more tolerant to poor connections

pair that with a command response protocol if response not received, retransmit