It was in May last year when chairman of Indian Space Research Organisation (ISRO), K Sivan, had unveiled that the Indian space agency is planning to develop world class propulsion technology to ensure cost effective re-usable, recoverable, re-startable and reliable space launches.
Now in a latest, ISRO chairman has again unwrapped more on thi ambitious plan of ISRO and it is now looking to perfect its reusable launch vehicle (RLV) technology not only for first-stage recovery, which Elon Musk-promoted SpaceX has already achieved, but also developing technology which would allow ISRO to recover second stages of a rocket, reports Times Of India.
For uninitiated, A multistage rocket, or step rocket uses two or more rocket stages, each of which contains its own engines and propellant. In serial or tandem staging schemes, the first stage is at the bottom and is usually the largest, the second stage and subsequent upper stages are above it, usually decreasing in size. In parallel staging schemes solid or liquid rocket boosters are used to assist with launch.
Private space agency, SpaceX, has a long term goal to reuse both first & second stages of their orbital launch vehicle and the company has achieved a successful landing and recovery of a first stage in December 2015. However, recovering the second stage is much more difficult and no space agency including SpaceX has achieved this so far. It is due to the heat shield, landing engines and other equipment required to achieve it.
To accomplish this difficult task, ISRO is going to conduct an advanced version of the reusable launch technology (RLV) test in June-July.
According to ISRO chairman, the space agency is working on a reusable launch technology in order to recover the first and second stages of a rocket to reuse them in order to cut cost and carry heavier payloads. The first rocket stage will be recovered on a vertical landing spot on the sea like SpaceX has been doing it with its Falcon family of rockets.
The RLV-Technology Demo was successfully completed its first test flight on 23 May 2016, which lasted for 770 seconds and reached a maximum altitude of 65 kilometres (40 mi). It was designed to evaluate various technologies, and development of the final version is expected to take 10 to 15 years. The fully developed RLV is expected to take off vertically like a rocket, deploy a satellite in orbit, return to Earth, and land on a runway.
For the second stage, ISRO is developing a winged body like a space shuttle. This shuttle will be attached as a second stage in a rocket. It will carry the top portion of the rocket comprising a satellite or spacecraft to space. Once it injects the satellite in its orbit, the shuttle will glide back to the earth and land on an airstrip like an aircraft.
Reusable Launch Vehicle – Technology Demonstrator (RLV-TD) is one of the most technologically challenging endeavors of ISRO towards developing essential technologies for a fully reusable launch vehicle to enable low cost access to space. The configuration of RLV-TD is similar to that of an aircraft and combines the complexity of both launch vehicles and aircraft. The winged RLV-TD has been configured to act as a flying test bed to evaluate various technologies, namely, hypersonic flight, autonomous landing and powered cruise flight. In future, this vehicle will be scaled up to become the first stage of India’s reusable two stage orbital launch vehicle.
RLV-TD consists of a fuselage (body), a nose cap, double delta wings and twin vertical tails. It also features symmetrically placed active control surfaces called Elevons and Rudder. This technology demonstrator was boosted to Mach no: 5 by a conventional solid booster (HS9) designed for low burn rate. The selection of materials like special alloys, composites and insulation materials for developing an RLV-TD and the crafting of its parts is very complex and demands highly skilled manpower. Many high technology machinery and test equipment were utilised for building this vehicle.
A team of 750 engineers at Vikram Sarabhai Space Centre, National Aeronautical Laboratory, IITs and Indian Institute of Science worked on the design and development of RLV-TD and the associated rocket. RLV-TD underwent 120 hours of wind tunnel, 5,000 hours of computational fluid dynamics and 1,100 runs of flight simulation tests. RLV-TD has mass of 1.75 tonnes, wingspan of 3.6 meters and overall length of 6.5 meters (excluding the rocket).