New Delhi:
The Indian Space Research Organisation’s (ISRO) Reusable Launch Vehicle (RLV), the first technology demonstrator (TD) is all set to be launched from the Satish Dhawan Space Centre (SDSC), Sriharikota on May 23 at 9:30 AM, ISRO officials have said. RLV-TD will make history because the first made-in-India and ISRO’s very own indigenous version of a 'space shuttle' will embark on its maiden launch.
Rocket-aircraft combination
A rocket-aircraft combination, the RLV-TD measures about 17 m. In the first stage, it is a solid propellant booster rocket, while in the second it is a 6.5 m long winged structure that looks like an aircraft and sits atop the rocket. In the first stage, the RLV-TD is the Satellite Launch Vehicle (SLV-3) flown in the 1980s. Like a rocket, it will first take off. The RLV will be released from the height of 70 km by the booster.
Hypersonic Experiment 1
The RLV was designed, assembled at the Vikram Sarabhai Space Centre (VSSC) in Thiruvanathapuram. It also underwent basic electrical, hydraulic and “sign check” tests. According to the director of VSSC, Dr K Sivan, objective of the experiment is to achieve hypersonic speeds. This will test the hypersonic aero-thermodynamic characterisation of the space shuttle’s re-entry, its control and guidance systems, autonomous mission management to land at a specific location at sea and testing of “hot structures” that make up the structure of the RLV. The experiment has been named Hypersonic Experiment 1 (HEX-1).
ISRO Chairman Dr AS Kiran Kumar has called the first test launch HEX1 “a very preliminary step”. He 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.
Technology
According to Dr Sivan, a conventional launch vehicle (LV) spends the lowest time of its flight in atmosphere, whereas the RLV remains all the time there. Talking about the flight regime, an aircraft has a limited one of say Mach 0 to Mach 2, the RLV on the other hand, experiences a much wider range. So, RLV’s technology is much more complex because of the design of the control and guidance systems, he said.
Flight regime
The winged RLV in HEX1 has no powered flight of its own and it’s otherwise a dummy. According to Dr Sivan, in this experiment, the RLV will experience a flight regime of Mach 5 and the booster alone will assist it. At the end of the HEX1 experiment, the aircraft will land in sea. The total flight duration of the space shuttle from launch till landing will be about 10 minutes. The objective of ISRO’s RLV programme is to allow the vehicle navigate a wide range of flight regimes from Mach 0 to Mach 25. This will be based on air-breathing propulsion for achieving two-stage-to-orbit (TSTO) launch capability.
Mating of booster and RLV-TD
The booster and the RLV-TD is at the SDSC, Sriharikota. The RLV subsystem underwent acoustic tests at the National Aerospace Laboratories of the CSIR (CSIR-NAL), then it was moved to Sriharikota, while the booster was sent directly from VSSC as a separate subsystem. The booster and the RLV-TD were mated together at SDSC.
Lower launch cost
When asked whether the Indian reusable launch system was aimed at bringing down the cost, the ISRO chairman said, “It will bring down the cost. Towards that, we will have to work and go through these initial steps.” If the launch of RLV-TD gets successful, it will save ISRO millions of capital invested in the following missions. The average cost of launching a space shuttle without a reusable spaceship is around 5000 USD per 1 kg. If this mission turns out to be a success, it will bring down the cost to around 2000 USD per kg., which is a reduction of more than half. The Indian government has spent a whopping 95 crores in the making of the RLV-TD.
Flying test bed
According to ISRO website, the present design is basically “a flying test bed to evaluate various technologies, namely hypersonic flight, autonomous landing, powered cruise flight and hypersonic flight using air-breathing propulsion using a scramjet engine.” After the HEX series of experiments, there will be the landing experiment (LEX), return flight experiment and scramjet propulsion experiment (SPEX).
