They do that for smaller engines. Absolutely. They call it a bladder tank. Here is an article about it: https://www.space-propulsion.com/spacecraft-propulsion/h

They do that for smaller engines. Absolutely. They call it a bladder tank. Here is an article about it: https://www.space-propulsion.com/spacecraft-propulsion/hydrazine-tanks/hydrazine-tank-overview.html https://www.space-propulsion.com/spacecraft-propulsion/hydra... > I sort of imagine a board with a spring on the top end of the canister You are better off doing it with gas pressure instead of a spring, but yeah absolutely. Very good thinking.