ISRO's RLV-TD
INTRODUCTION:
Sriharikota Range, popularly known as SHAR is situated on an island off Sullurupeta - a small town in Nellore district, of the state Andhra Pradesh. This launch centre located at Sriharikota island, was named as Satish Dhawan Space Centre, SHAR (SDSC, SHAR) in September 2002, in memory of Prof Satish Dhawan, who was Chairman of ISRO from 1972 to 1984. The activities at SDSC, SHAR are grouped under vehicle assembly and static test operations, range operations, liquid storage and service facilities and, solid propellant space booster plant. However, the most fascinating events that take place in this quaint location are the launches of giant rocket boosters. Unknown to many, ISRO is getting ready to launch a high tech Reusable rocket, a capability which has no players but has aspirants aplenty.
BACKGROUND:
The Space Capsule Recovery Experiment (SRE-1) is an experimental spacecraft launched by ISRO in 2007, it is designed to demonstrate the capability to recover an orbiting space capsule, and the technology of an orbiting platform for performing experiments in micro gravity conditions. It was also intended to test reusable Thermal Protection System, navigation, guidance and control, hypersonic aero-thermodynamics, management of communication blackout, deceleration and flotation system and recovery operations.
The SRE-1 comprised of an aero-thermo structure, mission management unit, altitude sensors, inertial measurement unit, S-band transponder with unique belt array antenna embedded to ATS, power and electronics packages to support deceleration and flotation system. It also housed two microgravity payloads. The parachute, pyro devices, avionics packages of triggering unit and sequencer, telemetry and tracking system and sensors for measurement of system performance parameters were placed inside the SRE-1 capsule which performed flawlessly. All the above technologies will be applied in the Reusable Launch Vehicle Technology Demonstrator (RLV-TD) experimental vehicle.
Reusable Launch Vehicle Technology Demonstrator (RLV-TD):
A winged Reusable Launch Vehicle Technology Demonstrator (RLV-TD) has been configured to act as a flying test bed to evaluate various technologies, viz., hypersonic flight, autonomous landing, powered cruise flight and hypersonic flight using air breathing propulsion towards realising a Two Stage to Orbit (TSTO) fully Reusable Launch Vehicle.
Major milestones reach for the RLV-TD include:
- Completion of major actions identified by the National Review Committee during the Integrated Technical Review (ITR) of hypersonic experimental flight (RLV-TD HEX-01).
- Mission analyses on the design of trajectory, autopilot and guidance have been completed.
- The Avionics Bay powering for the Avionics packages in the Technology Demonstrator Vehicle (TDV) was carried out through Checkout System and On-Board Checkout Computer (OBCC).
- The second phase of the full scale Flush Air Data System (FADS) model was successfully tested and validated at the Wind Tunnel Facility, IIT, Kanpur with modified algorithms and recalibrated sensors.
- Radar Altimeter along with antenna was also validated through a Balloon test at TATA Institute of Fundamental Research (TIFR), Hyderabad and the capability of the system has been demonstrated.
- Trial assembly of Thermal Protection System for qualifying the bonding procedure and trial assembly of Booster with Interstage and TDV have been completed.
- The realisation of the flight hardware and its assembly and integration is in progress. The launch of RLV-TD HEX-01 mission is planned in 2014.
FIRST DEMONSTRATION FLIGHT:
The first test flight of the RLV-TD called as RLV-TD HEX-01 (Hypersonic Flight Experiment) is expected to occur in the month of March 2015. RLV-TD alone without the Solid Booster weighs about 3 tonnes, with a diameter of about 0.56 m and a length of about 10 m. The RLV-TD will be mounted on top of a S-9 Solid Rocket Booster (SRB) which weighs about 9 tonnes.
The main objectives of this test flight are:
1 - Validating the aerodynamic design characteristics during Hypersonic flight.
2 - Characterize induced loads during the Hypersonic re-entry into the atmosphere.
3 - Recovery of the HEX vehicle from the sea.
4 - Assess the performance of the carbon fibre used in construction of the nose of the vehicle.
5 - Demonstrating First Stage separation sequencing.
RLV-TD HEX-01 is the first out of four in the series of test flights. HEX-01 stands for Hypersonic Flight Experiment.The other four tests are:
1 - LEX (Landing Experiment)
2 - REX (Return Flight Experiment)
3 - SPEX (Scramjet Propulsion Experiment)
The conventional satellite launch vehicles PSLV and GSLV are not cost effective. Hence, currently efforts are being made to develop Reusable Launch Vehicle (RLV). The proposed vehicle is a two stage to orbit configuration with a semi-cryogenic winged booster and a cryogenic ballistic orbiter in which the first stage will fly back to the landing site near the launch pad like a conventional aircraft. It will serve as a flying test bed to evaluate various technologies such as hypersonic flight, autonomous landing, powered cruise flight and hypersonic flight using air breathing propulsion.
The S-9 Solid Rocket Booster (SRB) undergoing tests at Liquid Propulsion Systems Center
The RLV-TD will possess wings and tail fins, and will be launched atop a 9 ton solid booster called S-9, similar to the ones on the PSLV. RLV-TD is reported to be 9m long, with its wing span also measuring 9m. The RLV-TD plus the S9 Solid Rocket Booster stack will together weigh 12-ton. Following liftoff, the S-9 booster will climb to 100-km and accelerate several times the speed of sound with the RLV-TD. RLV-TD will then separate and glide down using its fin and wing controls and will land in the Bay of Bengal, close to the shore. The water landing is planned because India doesn't have a long enough runway which is more than 5 Km in length.
The next experiment would be to land the vehicle on a 2km runway after releasing it from an aircraft from a height of about 5km. The third step would be to take it to a higher altitude and try the ground landing.
SCRAMJET FLIGHT TEST:
Indian Space Research Organisation has developed a hydrogen based scramjet engine. All the ground based tests have been completed using the moderate size hypersonic wind tunnel and the conventional shock tunnel available within ISRO. The flight tests using the sounding rockets will commence shortly.
HYPERSONIC TECHNOLOGY DEMONSTRATOR VEHICLE (HSTDV):
This program is to demonstrate a scramjet engine integrated vehicle performance in autonomous mode. In addition to proving the design and performance of the scramjet engine the HSTDV will also be able to prove the associated technologies including aerodynamic design, aero-thermal design, materials and hot structures at hypersonic flight Mach numbers. The HSTDV mission involves launching the hypersonic air-breathing vehicle called Cruise Vehicle (CV) to a Mach number of 6.5 at an altitude of 30-35 km using a rocket launch vehicle. A single scramjet engine burning kerosene fuel powers the cruise vehicle for a sustained operation of 20 second duration.
