Polyethylene as fuel for a new rocket engine

Self-eating rocket engine Credit: University of Glasgow

A ‘self-eating’ rocket engine which could place small satellites in orbit more easily and more affordably is under development at universities in Scotland and Ukraine.

In a paper published in the Journal of Spacecraft and Rockets, engineers from the University of Glasgow and Oles Honchar Dnipro National University in Ukraine discuss how they have built, fired, and for the first time throttled up and down an ‘autophage’ engine which could change how small satellites are sent into space.

Today, most rockets use tanks to store their propellant as they climb, and the weight of the tanks is usually many times greater than the weight of the useful payload. This reduces the efficiency of the launch vehicle and also contributes to the problem of space debris.

However, a launch vehicle powered by an autophage engine would consume its own structure during ascent, so more cargo capacity could be freed-up and less debris would enter orbit.

The autophage engine consumes a propellant rod which has solid fuel on the outside and oxidizer on the inside. The solid fuel is a strong plastic, such as polyethylene, so the rod is effectively a pipe full of powdered oxidizer. By driving the rod into a hot engine, the fuel and oxidizer can be vaporized into gases that flow into the combustion chamber. This produces thrust, as well as the heat required to vaporize the next section of propellant.

Simply by varying the speed at which the rod is driven into the engine, the researchers have shown that the engine can be throttled – a rare capability in a solid motor. Currently, the team has sustained rocket operations for 60 seconds at a time in their lab tests.

Dr. Patrick Harkness, a senior lecturer at the University of Glasgow’s School of Engineering, leads Glasgow’s contribution to the work.

Read more:  Engineers aim for the stars with new rocket engine

thumbnail courtesy of phys.org