Engineers at NextAero have been experimenting with rocket engine throttling methodologies. Throttling changes the thrust output of the rocket engine as a function of time.

“Rocket engine throttling is an important capability for our customer projects”, said Dr. Graham Bell, CEO of NextAero. “It allows them to either gently approach an operating condition, or sweep operating conditions in a rapid amount of time”.

The demonstrated rocket engine has a throttle profile during startup, a change in throttle position during the run, and a throttle down process. The propellants are LOX/ethanol with the throttling producing approximately 60kg of thrust and a change of approximately 20kg. The engine runs for approximately 12 seconds.

Dr. Bhavraj Thethy, senior propulsion engineer at NextAero said “The challenge with throttling is making sure many parameters stay within specified bounds during operation”. “Throttling is also useful for a wide range of propulsion use cases, such as launch vehicles, in-space propulsion for example satellites, and planetary or lunar landers”.

Presently the throttling is performed in a open-loop control system. Closed-loop control is being investigated.