The air intake on the front of the nacelle needs to point directly into the incoming airflow whereas SKYLON’s wings and body need to fly with an angle of incidence to create lift, so the intake points down by 7 degrees to account for this. The rocket thrust chambers in the back of nacelle need to point through the centre of mass of the vehicle so are angled down; again by 7 degrees but it is a coincidence the angle is the same.

Read more on the SABRE Engine.

The take off runway needs to be 5.6 kilometres long to accommodate the very high take off speed (close to Mach 0.5) and have enough length to abort the takeoff and come to a stop. The first 4 km will have to stronger than normal runways due to the high take off speed which lead to high tyre pressures which in turn means high loads on the runway surface. The remaining 1.6 km can be lighter construction as this is a stopway in the event of an aborted takeoff.

Landing can be on almost any runway - possibly even a grass strip. The landing speed is low (70 m/sec) and the tyre pressures are reduced after takes off to save weight. SKYLON is designed to land in a 30 knot crosswind.

In air-breathing mode the maximum speed is Mach 5.4 at 26 km (1615 m/sec) once in orbit SKYLON is travelling at orbital speed over 7.7 km/sec.

The black appearance is due to the reinforced glass ceramic material that protects SKYLON from the re-entry heating when it returns to the Earth’s atmosphere.

No. The SABRE engine is a combined cycle engine which air-breathes like a jet engine but with a pre-cooler heat exchanger in front of the turbine compressor. There is a secondary bypass ramjet in the nacelle, but this is subsonic combustion and so not a Scramjet.

The last full development cost estimate was done in 2004, and it came to $12 billion for the SKYLON C1 configuration.This is comparable to the cost of developing the A380 or Ariane 5.

On entry into service the price of a launch expected to be around $30 million to $40 million, but as the number of SKYLONs and the number of flights increases the price should fall to around $10 million.

If a very major application like solar power satellites increases the number of launches further the price could fall to around $2 million. All these prices are fully commercial, giving a profit after all costs (including the vehicle development costs) are accounted for.

Yes, with a special module in the payload bay. The most recent studies on the SKYLON Personnel/Logistics Module (SPLM) show this can carry as many as 24 passengers (and a captain).

The commercial problem is that neither the sub-orbital nor the small satellite market is big enough to recover the development costs.

But there are also technical reasons. The SABRE engine makes single stage to orbit possible so there is no engineering point in a suborbital vehicle. A bigger vehicle also has less technical risk as the scale effect increases the payload fraction whist scaling the SABRE engine down introduces additional technical challenges.

Yes – Very! For many reasons

1) Each launch is much cleaner than current launch systems. The major exhaust products in air-breathing mode are water and nitrogen. There are some nitrous oxides produced but with the likely flight rates this will have an insignificant effect on the environment. In rocket mode the major exhaust product is only water. Also as SKYLON is reusable there is much less energy and materials used per launch.

2) The engine thrust for the class of vehicle is lower because SKYLON is lighter and the lift comes from the wings so the noise beneath the flight path is lower – but still noisier than a modern civil airliner.

3) Because of SKYLON’s reusability the amount of orbital debris created by space activity would reduce significantly.

4) SKYLON’s hydrogen technologies could be applied to civil aviation like LAPCAT or even hydrogen powered subsonic airliners. This would make civil aviation much more environmental friendly if the hydrogen is produced without creating carbon dioxide.

5) Once in operation SKYLON could make space based energy options, like Solar Power Satellites, He3 mining (or production), or nuclear waste disposal, commercially viable. Any of these would result in a significant improvement in the environmental impact of mankind’s energy generation.