India on Sunday moved a step closer to having its own ‘space shuttle’ or reusable space vehicle with the successful completion of the Reusable Launch Vehicle Autonomous Landing Mission (RLV LEX) by ISRO. The test of the Reusable Launch Vehicle RLV LEX, an autonomous winged spaceplane, was conducted at the Aeronautical Test Range in Karnataka’s Chitradurga in the early hours on Sunday.
With LEX, the dream of an Indian Reusable Launch Vehicle arrives one step closer to reality, ISRO said in a statement.
The RLV LEX resembles the space shuttles operated by US space agency NASA for 3 decades before retiring them in 2011. It is a space aircraft with wings that can land like a regular aircraft after returning from space. RLV is essentially a space plane with a low lift-to-drag ratio requiring an approach at high glide angles that necessitated a landing at high velocities of 350 kmph.
The RLV was taken to an altitude of 4.5 km using a Chinook Helicopter of the Indian Air Force as an underslung load. The helicopter carrying the vehicle took off at 7.10 am. After the desired altitude was reached and all the predetermined parameters were attained based on the RLV’s Mission Management Computer command, the vehicle was released. Following that, the vehicle flew automatically and completed an autonomous landing on the ATR air strip at 7:40 am.
Release conditions of the RLV included 10 parameters covering position, velocity, altitude and body rates, etc, and its release was also autonomous. After the release, the RLV performed approach and landing maneuvers using the Integrated Navigation, Guidance & control system, and landed at the Aeronautical Test Range runway.
According to ISRO, the autonomous landing was carried out under the exact conditions of a Space Re-entry vehicle’s landing —high speed, unmanned, precise landing from the same return path— as if the vehicle arrives from space. Landing parameters such as Ground relative velocity, the sink rate of Landing Gears, and precise body rates, as might be experienced by an orbital re-entry space vehicle in its return path, were achieved.
The RLV LEX used several state-of-the-art technologies including accurate Navigation hardware and software, Pseudolite system, Ka-band Radar Altimeter, NavIC receiver, indigenous Landing Gear, Aerofoil honey-comb fins and brake parachute system.
It is also notable that it was first in the world that a winged body was carried to an altitude of 4.5 km by a helicopter and released for carrying out an autonomous landing on a runway.
Several indigenous systems have been used in the Reusable Launch Vehicle, including navigation systems based on pseudolite systems, instrumentation, and sensor systems. Digital Elevation Model (DEM) of the landing site with a Ka-band Radar Altimeter provided accurate altitude information.
Extensive wind tunnel tests and CFD simulations enabled aerodynamic characterization of RLV prior to the flight. Adaptation of contemporary technologies developed for RLV LEX will make operational launch vehicles of ISRO more cost-effective.
The RLV is ISRO’s attempt at developing essential technologies for a fully reusable launch vehicle to enable low-cost access to space. According to ISRO, the RLV’s configuration is the same as 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,” the space body says in its website.
RLV 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. In actual use, the RLV will be launched using rockets, and after completing space missions, it will make a re-entry and land like conventional aeroplanes.
At present Elon Musk’s SpaceX is the only company with operational reusable space vehicles. However, its Falcon 9 rockets land vertically.
