Sydney - Scientists in Australia launched a supersonic scramjet engine into space for the second time in a week on Thursday, as they work towards building a device which could revolutionise air travel.
University of Queensland scientists launched a scramjet which reached an altitude of more than 325km and travelled at a speed of about 7 500km per hour.
The launch, carried out with researchers from the Japanese Aerospace Exploration Agency (JAXA), followed the first blast off at the outback Woomera rocket range last Saturday.
"The rocket launch looked as expected, we had another clean liftoff," designer Michael Smart said.
Scramjet engines are hi-tech devices which fly above the earth's atmosphere at several times the speed of sound.
It is hoped they could ultimately see commercial flight times slashed and be used to cut the cost of launching satellites.
The tests are designed to compare the differences between various different engine shapes. A British-designed bullet-shaped engine was tested on Saturday while Smart said Thursday's experiment involved an engine shaped like a "series of wedges".
Scramjets do not have to carry their own oxygen supplies for combustion and have the advantage of a lack of moving parts.
But Smart said the launch of the engines is a problem yet to be overcome as they only start working at about five times the speed of sound.
Scientists are aiming to refine the engines to devise one which would be good enough to be incorporated into a vehicle.
The scramjet engines being tested weigh about 100kg and measure 1,5m long, 0,50m high and 0,20m wide. - Sapa-AFP