Space: The Development of Single-Stage Space Flight

Dr Robert Charles Parkinson MBE has worked for the Rocket Propulsion Establishment, Perme, British Aerospace, Matra Marconi and Astrium. He has had papers published in Spaceflight and JBIS. He also worked on Project Daedalus. He is a member of the International Academy of Astronautics and was awarded the MBE in the 2002 New Years Honours List.

Dr Parkinson is also President of the British Interplanetary Society and an advocate for the enthusiastic development of astronautics technology and capabilities. Here he comments on the latest development in space technology – single stage space flight:

Before the first Sputnik orbited the Earth, the pioneers of the British Interplanetary Society (BIS) thought that we would fly into Space with reusable rockets. They could not imagine that the complex and expensive machines needed to launch payloads would be casually discarded after each launch and dropped into the Atlantic. They also thought that once we solved the difficult technical problems, spaceflight would become a matter of routine. We would build stations in Space, colonize the Moon, and send humans to Mars.

What actually happened was that the ICBM boys made throw-away rockets light enough to get us into Space. But it remained expensive. The only real commercial market was communications satellites – another BIS idea through one-time Chairman Arthur C Clarke – and that was because everybody used the phone (and later bought Sky TV). Most things people dreamed about remained too expensive and out of reach.

The Space Shuttle made an attempt at being reusable, but to do it with pure rocket technology involved developing two vehicles, one sitting on top of the other. The development costs for that were too high for even the US Congress to fund, so a compromise was adopted that still threw half of the vehicle away on each flight. In the 1980s NASA started looking at using air breathing engines to get into orbit, but to fly all the way to orbital speeds would use extreme technology.

About the same time, in another BIS meeting, a small group started wondering how little you would have to do to make a vehicle work that would take off like an airliner, fly into orbit and return on a regular, perhaps even daily, schedule. The answer was to use air breathing to perhaps Mach 5 or 6, and then use rocket propulsion for the rest of the way. But the engine would have to be very light and efficient.

At that time Alan Bond came up with a design for such an engine. The secret was to use cold liquid hydrogen to cool hot intake air down to about -180 C, and then use conventional gas turbine technology to pump the air to pressures normally found in a rocket engine. Later, above Mach 5, liquid oxygen would replace the air to make it into a pure rocket.

The key component in this engine was an ultra-light, highly efficient heat exchanger that would cool air by a thousand degrees in a matter of centimetres, and would not instantly clog with ice as water vapour in the air condensed. When government funding stopped in the late ‘80s, Alan Bond founded his own company – Reaction Engines Limited (REL) – and looked for private backers. It now looks as if he has succeeded. The first prototype heat exchangers have been built and are being tested at his site near Abingdon.

Along with the engine, REL have a vehicle concept – Skylon – which was recently the subject of an extensive review by experts from the UK and Europe, and which passed with flying colours. Skylon would take-off like an airliner, accelerate to Mach 5.5 in airbreathing mode, and then continue to orbit on its rocket engines. More importantly it would then return to base, without throwing away anything other than fuel, to be used again and again. It offers the possibility of low cost, regular access to Space as envisioned in the 1950s, making possible all the other things that we thought that we would do when we got there.

Bob Parkinson

President; British Interplanetary Society