Aluminum Hybrid Rocket

A hybrid rocket is a type of rocket that uses a solid fuel but a liquid oxidiser. The throttle can thus be controlled by altering the rate at which the oxidiser is mixed with the fuel. This particular version uses Aluminium as the fuel, which is not the best fuel by many measures but it can be found in high quantities in the crust of many bodies.

The aluminum hybrid rocket is not very spectacular in terms of thrust and its specific impulse is dreadful, barely any better than a solid rocket BUT it can be refueled using the electrolysis option of the ISRU Refinery anywhere on the surface of the Mun, Ike or Tylo. It is thus useful for operating in those locations.