‘Self-eating’ rocket could help UK take major share in space industry

New developments on a nearly century-old concept for a ‘self-powered’ rocket engine capable of flying beyond Earth’s atmosphere could help the UK take a bigger share of the industry spatial.

Engineers at the University of Glasgow have built and fired the first unsupported autophagic rocket engine that consumes parts of its own body as fuel. The autophagic engine design – whose name comes from the Latin word meaning “to eat oneself” – has several potential advantages over conventional rocket designs.

The engine operates by using waste heat from combustion to sequentially melt its own plastic fuselage as it fires. The molten plastic is fed into the engine’s combustion chamber as additional fuel to burn alongside its usual liquid propellants.

This means that an autophagic vehicle would require less propellant in the onboard tanks and the released mass could instead be allocated to the payload. Consumption of the fuselage could also help avoid worsening the problem of space debris, waste thrown into orbit around the Earth and which could hamper future missions.

Overall, greater efficiency could help autophagic rockets carry a larger payload into space compared to a conventional rocket of the same mass. They could, for example, take tiny “nanosatellites” directly into space without having to share space with more expensive conventionally fueled rockets.

The concept of a self-powered rocket engine was first proposed and patented in 1938. However, no autophagic engine design was fired in a controlled manner until a research partnership between the University of Glasgow and the Dnipro National University in Ukraine reaches this milestone in 2018.

Now Glasgow engineers have demonstrated that it is possible to use more energetic liquid propellants and that the plastic fuselage can withstand the forces needed to feed it into the engine without deforming. These are essential steps in developing a viable flight concept.

The team’s paper, titled “Investigation of the Operating Parameters and Performance of a Hybrid Autophagic Rocket Propulsion System,” was presented at the AIAA SciTech Forum on Wednesday, January 10 in Orlando, Florida.

In the paper, the team describes how they successfully tested their Ouroborous-3 autophagic engine, producing 100 newtons of thrust in a series of controlled experiments. The test fires were conducted at the MachLab facility at Machrihanish Air Base.

The Ouroborous-3 uses high-density polyethylene plastic tubes as its autophagic fuel source, burning it alongside the rocket’s main propellants, a mixture of gaseous oxygen and liquid propane.

Tests showed that the Ourobourous-3 is capable of stable combustion – a key requirement for any rocket engine – throughout the autophagic phase, with the plastic fuselage providing up to a fifth of the total propellant used.

Testing also showed that the rocket’s combustion could be successfully controlled, with the team demonstrating its ability to be throttled, restarted and pulsed in an on/off pattern. All of these capabilities could help future autophagic rockets control their ascent from the launch pad to orbit.

Professor Patrick Harkness, from the James Watt School of Engineering at the University of Glasgow, led the development of the Ourouboros-3 autophagic engine. He said: “These results represent a fundamental step on the path to developing a fully functional autophagic rocket engine. These future rockets could have a wide range of applications that would help advance the UK’s ambitions to develop as a key player in the space industry. .

“The structure of a conventional rocket represents between 5% and 12% of its total mass. Our tests show that Ouroborous-3 can burn a very similar amount of its own structural mass as propellant. If we could make at least one part of this mass available for payload, this would be an interesting prospect for future rocket designs.”

Postgraduate researcher Krzysztof Bzdyk, from the James Watt School of Engineering, is the corresponding author of the paper. He said: “Getting to this stage required overcoming many technical challenges, but we are delighted with the performance of Ourouboros-3 in the laboratory.

“From there, we will begin to look at how we can expand the propulsion systems of the autophages to support the additional thrust required for the design to operate like a rocket.”

The autophagic engine is one of 23 space technology projects recently selected to benefit from £4 million of funding from the UK Space Agency and STFC. The Glasgow team was awarded £290,000 to help establish further pilot testing of the prototype engine.

Dr Paul Bate, CEO of the UK Space Agency, said: “One of the key ways we are catalyzing investment in the UK’s growing space sector is by supporting innovations in emerging areas of space technology. The University of Glasgow’s impressive work towards an autophagic engine is an example that has great potential to meet the growing global appetite for developments in rocket propulsion efficiency and sustainability. »

Jack Tufft, a postgraduate researcher at the James Watt School of Engineering, is a co-author of the paper. He said: “We are really excited about the potential of the Ouroboros-3, and this additional funding will help us move forward in exploring further developments and improvements to our design. Our goal is to bring the autophagic engine closer to a test launch. , which will help us develop our design for future generations of autophagic rockets. »