All rockets used some form of solid or powdered propellant up until the 20th century, when liquid-propellant rockets offered more efficient and controllable alternatives. Solid rockets are still used ...

Gelled propellants are produced from liquid propellants with the addition of gelling agents. They are solid at rest, for example in a tank, and become flowable under the influence of shear stress, as ...

A hybrid-propellant rocket is a rocket with a rocket motor that uses rocket propellants in two different phases: one solid and the other either gas or liquid. The hybrid rocket concept can be traced ...