Indian defence scientists are aiming to build a plane designed to cruise at speeds three times faster than existing fighter aircraft while consuming less fuel.

The Hyderabad-based Defence Research and Development Laboratory (DRDL) is building an 8metre technology demonstrator, which will be powered by a supersonic combustion ramjet (Scramjet) engine that takes oxygen from the atmosphere and burns liquid hydrogen.

"The ground tests of the engine would begin in 2005 and we aim to fly the unmanned aircraft in 2007," DRDL Director Prahlada told PTI in Bangalore.

The aircraft would be built in India's aviation capital, Bangalore, and Hyderabad. It would be a high speed transport aircraft with an engine that does not have a compressor or a turbine.

"The scramjet engine takes in oxygen from the atmosphere, liquefies it and uses it for the cryogenic engine, improving the efficiency of the plane by several factors because the weight of the fuel, particularly for long distances, constitutes around 70 per cent of the total weight of the aircraft," officials said.

The technology demonstrator would be a precursor to President A P J Abdul Kalam's dream project and DRDO's Aerobic Vehicle for Hypersonic Aerospace Transportation (AVATAR).

India has achieved considerable progress in the air breathing engine technology (ramjet) at sub-sonic speed in its surface-to-air Akash missile programme, but is yet to master the technology at supersonic speed of up to Mach 7 (speed of sound is referred to as Mach). "We are improving on our expertise in air breathing engine technology and it would be used in an unmanned aircraft," Prahlada said.

Incidentally, the country is in race with the US, Japan, Russia and China to build a hypersonic plane which is expected to revolutionise low cost space travel. The Indian Space Research Organisation has begun conceptual studies to build and launch a reusable launch vehicle using air-breathing technology by 2015, he said.

DRDL is jointly working with academic institutions, including the IITs and the Indian Institute of Science, besides collaborating with the Mishra Dathu Nigam (Midani) to develop high temperature Nickel-Cobalt alloys and carbon composite materials, which could withstand heat during high-speed flight of the hyper plane.