ISRO's REUSABLE LAUNCH VEHICLE MISSION | RLV-TD LEX | AUTONOMOUS LANDING MISSION

RLV LEX

"ISRO Successfully conducted Reusable Launch Vehicle Autonomous Landing Mission (RLV LEX). The Test was conducted at the Aeronautical Test Range (ATR), Chitradurg, Karnataka in the early hours of April 2, 2023" ISRO's Official website. 

The RLV LEX MISSION stands for Reusable Launch Vehicle Mission for Autonomous Landing and Powered cruise, which is the second test among the five to be conducted under the mission. The 1st test, the RLV-TD was successfully carried out on May 23, 2016.

This test was specific on objectives like autonomous navigation and guidance-and-control, aero-thermodynamic characteristics, thermal protection system evaluation.

The RLV took off at 7:10 am IST by a Chinook Helicopter of the Indian Airforce as an underslung load and flew to height of 4.5 KM (above MSL). When the predetermined pillbox parameters were attained, based on the RLV's Mission Management Computer cpmmand, the RLV was released in the mid air, at a down range of 4.6 km. Release conditions included 10 parameters covering position, velocity, altitude and body rates etc. The release of RLV was autonomous. 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 that, ISRO successfully achieved the autonomous landing of a space vehicle.

Some actual images released by ISRO.

In a first in the world, a winged body has been carried to an altitude of 4.5 km by a helicopter and released for carrying out an autonomous landing on a runway. 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. LEX utilized several indigenous systems. Localized Navigation systems based on pseudolite systems, instrumentation, and sensor systems, etc. were developed by ISRO. 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 turns other operational launch vehicles of ISRO more cost-effective.