News Release

Poeton coating helps Skylon move closer to take off

23rd October 2003

 
POETON COATING HELPS SKYLON MOVE CLOSER TO TAKE OFF

Poeton Industries has contributed its expertise in surface coating technology to the development of a unique heat exchanger that is expected to play a vital part in making the Skylon spaceplane a viable commercial proposition.

Skylon is a single stage to orbit (SSTO) winged spaceplane being developed by rocket engineers from the abandoned 20 year-old HOTOL project.

The plane, which is designed to give low-cost access to space, has a 275 tonnes gross take-off weight but needs to carry 220 tonnes of propellant. Which is why engineers are currently investigating technologies that will help to increase its 12 tonne payload and make it a more viable commercial proposition.

For example, Skylon's Sabre engine, which delivers air breathing thrust at take off and reverts to a high specific impulse rocket engine in space, employs its rocket combustion chamber, nozzle and pumps in both propulsion modes, in order to avoid the weight penalty of a separate air-breathing engine.

This innovation required the design of unique, high-power heat exchangers that also posed a challenging manufacturing problem for the specialist companies involved, including Poeton.

The pre-cooler is a counter-flow design that consists of many thousands of small-bore, thin-walled tubes. Its manufacture required 2,000 km of tube and 1.2 million drilled holes. Much of the development work has focused on header machining and heat exchanger brazing - which is where Poeton became involved.

The company's Apticote 400 coating process is applied to areas where the tubes - each 1mm diameter with a wall thickness of just 25 microns - are brazed to the main feed tube.

Explaining the process, Poeton's technical manager Roger Walker says that following extremely complicated masking the coating is applied selectively to an area of the tube inside and out before brazing. The assembly is then placed in a vacuum furnace at 900oC, at which point the Apticote 400 melts, forming a fillet that creates a perfect seal.

Commenting for Reaction Engines Ltd, manufacturer of the Sabre engine, spokesman Richard Varvill says: "Despite this manufacturing technology being beyond state-of-the-art, Poeton's development work has helped to prove the brazing cycle."

The companies involved in the development programme hope that advanced manufacturing technologies such as these will enable Skylon to be operated commercially and allow operators to offer cheap and reliable transport into space.

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File: Skylon
dennis@cka.co.uk