REUSABLE LAUNCH VEHICLE TECHNOLOGY DEMONSTRATOR PROGRAM (RLV – TD)
What is this RLV-TD?
- Reusable Launch Vehicle-Technology Demonstration Program or RLV-TD is a series of technology demonstration missions that have been considered as a first step towards realizing a Two Stage To Orbit (TSTO) fully re-usable vehicle.
- A Winged Reusable Launch Vehicle technology Demonstrator (RLV-TD) has been configured to act as a flying test bed to evaluate various technologies, namely, hypersonic flight, autonomous landing, powered cruise flight and hypersonic flight using air-breathing propulsion
- RLV‐TD is a winged vehicle that will take off like a rocket and glide back to land like a plane.
- These technologies will be developed in phases through a series of experimental flights. The first in the series of experimental flights is the hypersonic flight experiment (HEX) followed by the landing experiment (LEX), return flight experiment (REX) and scramjet propulsion experiment (SPEX).
- The first stage will be powered by a semi cryogenic (liquid Oxygen and Kerosene ie., ISROSENE) winged booster capable of flying back and landing on a runway near the launch site like a conventional aircraft after burnout.
- The objective of the Semi Cryogenic Engine Development is to power the future heavy lift Unified Launch Vehicles (ULV) and Reusable Launch Vehicle (RLV) of India.
- This semi cryogenic engine, which uses a combination of cryogenic as well as earth storable propellants, developing a thrust of 2000 kN, is planned as the booster engine for the Common Liquid Core of ULV.
RLV‐TD is used to evaluate various characteristics like
- Hypersonic flight
- Autonomous landing
- Powered cruise flight
- Hypersonic flight using air-breathing propulsion.
ISRO has a proposed concept named Unified Launch Vehicle (ULV) sometimes referred as Unified
- The cost of access to space is the major deterrent in space exploration and space utilization. A reusable launch vehicle is the unanimous solution to achieve low cost, reliable and on‐demand space access. Today by using conventional rocket it costs about $5000 to put 1 Kg of payload in orbit. RLV can do the same for $500 for per Kg of payload. India currently spends about 300 crore rupees annually for satellite launches, where RLV in future will bring down this cost 10 times.
- Full fledged developed version of RLV can be used for manned missions in future.
What kind of tests will be carried out under RLV-TD….?
As part of this development sequence, ISRO has planned for four flight test sequence that will incrementally test the various flight characteristics as hypersonic re‐ entry, autonomous landing, powered cruise flight etc. The four flight test (4TD) sequence includes:
- Hypersonic Flight Experiment (HEX)
- Landing Experiment (LEX)
- Return Flight Experiment (REX)
- Scramjet Propulsion Experiment (SPEX)
HYPERSONIC FLIGHT EXPERIMENT (HEX)
- This is the first test of Reusable Launch Vehicle.
- During the mission, a booster rocket (Single strap‐on solid booster of the Polar Satellite Launch Vehicle (PSLV) with 9 tonne fuel) will take the 1.5 tonne RLV scale model to 70‐km altitude and release it.
- The booster rocket will fall back into the sea.
- The lofted RLV will re‐enter the atmosphere independently travelling at hypersonic speed and the descent speed would be controlled using the wings.
- The RLV has protective tiles to dissipate frictional heat during re‐entry.
- In the first trial‐flight, the RLV will not be recovered from sea because it will not be cost‐effective to do so. ISRO will instead use telemetry data on the re‐entry, deceleration and return.
Why this RLV – TD HEX1 landed on water and not in land….?
- This was primarily a hypersonic flight technology demonstration mission.
- So, the RLV – TD did not carry the capability to return to land for landing.
- Therefore after its primary mission glide through the atmosphere, it splashed down into the Bay of Bengal.
- Moreover to achieve the real time landing in ground we need to have a runway of about 5 Km, currently (longest runway now is about 2 Km) we don’t have such a long runway but in near future we can have such a long run way in Sriharikota.
LANDING EXPERIMENT (LEX)
- In the second phase RLV will be tested without its scramjet engine.
- After burnout, the booster will separate and fall away, and the RLV‐TD will go on to make an unpowered ascent.
- The RLV‐TD will then re‐enter the atmosphere at hypersonic speed and use aerodynamic breaking to decelerate.
- It will perform a range manoeuvres at 15‐km, a 2g turn towards its launch site.
- Once the RLV‐TD reaches 0.8 Mach, it will light up a turbofan engine to cruise back to its launch site at 0.6 Mach and make a horizontal landing on a runway.
RETURN FLIGHT EXPERIMENT (REX)
- In this phase, the RLV‐TD will be launched to orbit and then de‐orbited for a landing on a runway.
- This is achieved with the help of HEX and LEX.
SCRAMJET PROPULSION EXPERIMENT (SPEX)
- Eventually, the RLV will be powered by an air breathing scram jet which is being developed under a separate project called Air Breathing Propulsion Project (ABPP).