A propellant tank is a container which is part of a vehicle, where propellant is stored prior to use. Propellant tanks vary in construction, and may be a fuel tank in the case of many aircraft.
In rocket vehicles, propellant tanks are fairly sophisticated since weight is on a premium.
Rocket propellant tanks
Rocket propellant tanks are pressure vessels where liquid fuels are stored prior to use. They have to store the propellant, while minimizing slosh and particularly when the tank is nearly empty, minimizing vortexing.
Rocket propellant tanks are often constructed of materials such as aluminium alloys, steels or carbon fibre wound tanks.
These kinds of tanks are usually constructed using monocoque construction techniques. Balloon tanks are the most extreme of these, they are held rigid only by internal pressurisation, but are extremely lightweight.