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Getting to space has never been simple. A standing army of thousands is needed to launch the space shuttle, land it safely, and refurbish it so it is once again ready for flight.

And even the most basic space rockets require multiple stages, whose weight is mostly taken up by oxidisers needed to burn fuel. Rockets launch vertically to minimise the time they spend where Earth's gravity is strongest and shed stages to reduce their weight as they climb.

For decades, engineers have dreamed of a better way: a single-stage-to-orbit vehicle that would be lighter, cheaper, and easy to reuse. A fleet of these vehicles, supporters say, could be almost as easy to maintain as conventional jet planes, reducing the preparation time before each launch from months to days or even hours.

Since most of a rocket's weight is taken up by oxidiser, one logical approach is to save weight by developing an engine that can use oxygen from the atmosphere to burn fuel at least part of the way.

Are we getting any closer to this goal? Last week, the UK firm Reaction Engines announced they had received €1 million from the European Space Agency to develop three key parts for an air-breathing rocket engine. The firm hopes those components could one day help fulfill a decades-old plan to build a space plane called Skylon, which could take off and land on a runway like a conventional jet.

How do air-breathing engines work?

The basic air-breathing engine uses inlets at the front of the vehicle to suck in air. What happens after that depends on the design.

One common engine is the ramjet, which uses the geometry of the engine to slow air down. But ramjets are only useful at relatively low speeds. At hypersonic speeds - above 5 times the speed of sound, or Mach 5 - the slowed air is too hot to be useful for combustion.

A popular solution to this problem is the scramjet, which does not slow air down very much, but instead quickly mixes the fast-flowing air with fuel together to create thrust. But scramjets are only useful above Mach 5, meaning another system, perhaps a conventional rocket, is needed to propel the plane to hypersonic speeds.

4 comments

JLTan said... @ 1 March 2009 at 06:16

It will not work beyond a certain point, because air supply will thin out as one gets further and further beyond the atmosphere.

Arif Y said... @ 1 March 2009 at 06:37

Of course. Well, more technology is needed to fulfill it and becomes reality.

Arif Y said... @ 1 March 2009 at 06:48

Of course. Well, more technology is needed to fulfill it and becomes reality.

aRe_enD_bEE said... @ 29 May 2009 at 17:53

wow, what a nice space ship.....,

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