The first technology demonstrator (TD) launch of the Indian Space Research Organisation’s Reusable Launch Vehicle (RLV), or the spaceplane in popular parlance, will take place on May 23 at 9.30 a.m. from the Satish Dhawan Space Centre (SDSC), Sriharikota, according to ISRO officials.
Visually, the RLV-TD is a rocket-aircraft combination measuring about 17 m, whose first stage is a solid propellant booster rocket and the second stage is a 6.5 m long aircraft-like winged structure sitting atop the rocket.
However, the popular perception of the technology as a marriage between rocket and aircraft is a misnomer.
In RLV-TD that is awaiting launch at SHAR, the first stage, weighing about 9 tonnes, is merely the Satellite Launch Vehicle (SLV-3) flown in the 1980s.
The vehicle will take off like a rocket and the RLV will be taken to a height of 70 km and where the booster will release the vehicle to carry out its manoeuvres.
A conventional launch vehicle (LV), says Dr. Sivan, spends the lowest time of its flight in the atmosphere, whereas the RLV system spends all the time in the atmosphere. Also, while an LV experiences limited flight regime of say Mach 0 to Mach 2 or so, the RLV experiences a much wider range of flight regimes.
Hence the technology of an RLV is much more complex basically arising from the design of the control and guidance systems, he pointed out.
In HEX1, the winged RLV is otherwise a dummy with no powered flight of its own. At the end of the HEX1 mission, the aircraft will land in sea. However, the ultimate objective of the RLV programme of ISRO is to enable the vehicle traverse a very wide range of flight regimes from Mach 0 to Mach 25 based on air-breathing propulsion for achieving two-stage-to-orbit (TSTO) launch capability.
The integrated test system (booster plus the RLV-TD) is already at the SDSC (SDSC), Sriharikota. Prior to being moved to Sriharikota, the RLV subsystem underwent acoustic tests at the National Aerospace Laboratories of the CSIR (CSIR-NAL) and the booster went as a separate subsystem directly from VSSC. At SDSC the two were mated together.
Dr. A.S. Kiran Kumar, ISRO Chairman, called the first test launch HEX1 “a very preliminary step” and stressed that “we have to go a long way” before it could be called a re-usable launch system. “But these are very essential steps we have to take,” he said.
Scientists at ISRO believe that they could reduce the cost of launching things into space by as much as 10 times if reusable technology succeeds, bringing it down to USD 2,000 per kg.
The making of the Indian space shuttle or RLV-TD has taken 5 years and the government has invested Rs 95 crore in the project. This flight will test the capability of the vehicle to survive a re-entry at speeds higher than that of sound so it is called a hyper sonic experiment. The 6.5-m-long ‘aeroplane’-like spacecraft will weigh 1.75 tons and will be hoisted into the atmosphere on a special rocket booster.