So I am thinking about maybe making a submarine (small) controlled by an arduino. I want to use ballast tanks to control depth, but am confused on how they work and was hoping someone could help. I know that to descend, they let out air and let in water, making them more dense. But to ascend, how do they let the water out and refill with air if they are in an air-less environment (underwater)?
But to ascend, how do they let the water out and refill with air if they are in an air-less environment (underwater)?
I think they carry compressed air. That means (in a real sub) you'd need a compressor on board to compress more air when you surface.
A common approach for hobbyists is for the submarine to have neutral buoyancy, so that motors can send it up and down with little effort.
They do not let air out.
In the real world the bubbles would be a giveaway.
Pumps are used to pump water , air or both.
I know that to descend, they let out air and let in water,
No You normally use the tanks to give the sub neutral buoyancy and then use the diving planes to change depth. In the case of a model/ 'bot use a small +ve buoyancy and the diving plans so that the sub will automatically surface if there is a problem.
Mark