Congratulations to the countrymen on the historic success of ISRO
Reusable Launch Vehicle Autonomous Landing Mission (RLV LEX)
ISRO successfully conducted the Reusable Launch Vehicle Autonomous Landing Mission (RLV LEX). The test was conducted at the Aeronautical Test Range (ATR), Chitradurga, Karnataka in the early hours of April 2, 2023.
The RLV took off at 7:10 a.m. as an underslung load by a Chinook helicopter of the Indian Air Force and flew to an altitude of 4.5 km (above MSL). Once the predetermined pillbox parameters were achieved, the RLV was released in mid-air at a down range of 4.6 km, based on the mission management computer command of the RLV. The release condition consisted of 10 parameters covering position, velocity, altitude and body rate etc. The release of the RLV was autonomous. The rLV then performed approach and landing maneuvers using the integrated navigation, guidance and control system and completed an autonomous landing on the ATR airstrip at 7:40 AM IST. With this, ISRO successfully achieved the autonomous landing of the spacecraft.
The Space Re-entry Vehicle’s landing was a high-speed, unmanned, autonomous landing under the exact same landing conditions from the same return path as the vehicle arrived from space. Landing parameters such as ground relative velocity, sink rate of the landing gears, and precision body rate as might be experienced by an orbital re-entry spacecraft in its return path. RLV Lex demanded a number of state-of-the-art technologies including precision navigation hardware and software, pseudolight system, Ka-band radar altimeter, NAVIC receiver, indigenous landing gear, aerofoil honey-comb fins and brake parachute system.
For the first time in the world, a winged body has been carried by a helicopter to an altitude of 4.5 km and released to perform an autonomous landing on the runway. The rLV is essentially a space plane with a low lift to drag ratio requiring an approach at high glide angles, which requires landing at a high velocity of 350 kmph. Lex used several indigenous systems. Localized navigation systems based on pseudolight systems, instrumentation and sensor systems, etc. were developed by ISRO. A Digital Elevation Model (DEM) of the landing site along with a Ka-band radar altimeter provides accurate elevation information. Extensive wind tunnel testing and CFD simulation enabled the aerodynamic characterization of the RLV prior to flight. Adaptation of contemporary technologies developed for RLV LEX makes ISRO’s other operational launch vehicles more cost-effective
iSRO had demonstrated the re-entry of its winged vehicle RLV-TD in the HEX mission in May 2016. The re-entry of a hypersonic sub-orbital vehicle marked a major achievement in developing reusable launch vehicles. In Hex, the vehicle landed on an imaginary runway over the Bay of Bengal. Precise landing on the runway was one aspect that was not included in the Hex mission. The LEX mission achieved a final approach phase that coincided with a re-entry return flight path, demonstrating an autonomous, high-speed (350 km/h) landing. lEX began with an integrated navigation test in 2019 and was followed by a number of engineering model tests and captive phase tests in subsequent years.
Along with ISRO, IAF, CEMILAC, ADE and ADRDE contributed to this test. The IAF team joined hands with the project team and several sorties were conducted to complete the achievement of the release status. Dr. S. Unnikrishnan Nair, Director, VSSC, and Mr. Shyam Mohan N, Program Director, ATSP guided the teams. Doctor. Jayakumar M, Project Director, was the RLV Mission Director, and Shri Muthupandian J, Associate Project Director, was the Vehicle Director for the RLV mission. Shri Ramakrishna, Director, ISTRAC was present on the occasion. Chairman, ISRO/Secretary, A.V. Shri S Somnath witnessed the test and congratulated the team.
With Lex, the dream of an Indian reusable launch vehicle comes one step closer to reality