self-igniting propellant

Starting in 1935, Prof. O. Lutz of the German Aeronautical Institute experimented with over 1000 self-igniting propellants.

Liquid-propellant rockets can be throttled (thrust varied) in realtime, and have control of mixture ratio (ratio at which oxidizer and fuel are mixed); they can also be shut down, and, with a suitable ignition system or self-igniting propellant, restarted.