The Indian Space Research Organisation (ISRO) on Wednesday successfully flight-tested its new-generation, high-performance sounding rocket at the spaceport in Sriharikota, near here.

The Advanced Technology Vehicle (ATV- D01), weighing three tonnes at lift-off, is the heaviest sounding rocket developed by the ISRO. It carries a passive scramjet (supersonic combustion ramjet) engine combustor module as a test-bed for a demonstration of the air-breathing propulsion technology. An ISRO release said the rocket successfully flew at a velocity of more than Mach 6 (six times the speed of sound) for seven seconds. These conditions were required for a stable ignition of active scramjet engine combustor module planned in the next ATV flight.

“The successful flight-testing is a step ahead towards the advanced technology initiative from the ISRO in the area of air-breathing propulsion,” the release said.

The air-breathing rocket systems used the atmospheric oxygen from their surroundings and burned it with the on-board fuel to produce the forward thrust. This was in contrast to the conventional chemical rocket systems, which carried both oxygen and fuel on board, a rocket technologist said.

The air-breathing rockets, therefore, are much lighter and more efficient than the conventional rockets, leading to reduction in the cost of space transportation. That is, the cost incurred to put a satellite in orbit will be much lower.

The development of scramjet engine was complex and it involved a number of technological challenges. They included mixing of very high speed air (velocity around 1.5 km a second) with fuel, achieving stable ignition and holding the flame in addition to ensure efficient combustion within the length of the combustor, the rocket technologist said.