Rocket Main Tank

Rocket Fuel tanks

In modern launchers, two tanks are used, one for fuel and one for the oxidizer, but it has not always been the case. The Redstone rocket for example used a single tank with an internal separation, as we can see below.

Sloshing and other effects

Special care must be taken to avoid sloshing and vortexes in the tanks, that may lead to bubbles in propellant flow.

Wall thickness and material

Tank material mostly depend on money and on what's available on the market. For robust tanks, we will use 6061 Aluminium or steel.

The thickness of the tank walls obviously depend on the internal pressure, but also on the diameter of the tank. See [1]. Aluminium walls can be 2mm thick and 0.4m wide for a pressure up to 13 bar with no safety factor.

Accessories

Engine fuel supply pipe and valve, tank pressure sensor, fill and drain pipes and valves.

For a cryogenic fuel or a high vapour pressure fuel tank: pressure relief valve, venting valve.

Thermal insulation

Cryogenic fuel tanks may require to be insulated to limit vaporization or even boiling.

A list of thermal conductivities is available on Wikipedia.

Expanded polystyrene has a thermal conductivity of 0.03 W/m.K, PU foam has a 0.02, mineral insulation 0.04, neoprene 0.054, cotton 0.03. A more precise list of low conductivity materials is available here.