With the assistance of the Liquid Propulsion Systems Centre, ISRO successfully tested a hybrid motor at the ISRO Propulsion Complex (IPRC), Mahendragiri. Liquid oxygen (LOX) served as the oxidizer and Hydroxyl-Terminated Polybutadiene (HTPB) served as the fuel for the motor. A hybrid motor employs solid fuel and liquid oxidizer, as opposed to solid-solid or liquid-liquid combinations.
In today’s test, a hybrid motor with a 30 kN flight equivalent showed ignition and sustained combustion for the planned 15 seconds. The motor function was adequate.
Throttling is made easier by the use of liquids, and the ability to adjust the flow rate of LOX makes restarting possible.
Both HTPB and LOX are environmentally friendly, however LOX is safer to handle. Due to the hybrid motor’s scalability and stackability, it may be possible to develop a new propulsion system for upcoming launch vehicles.