The realisation of an Indian Reusable Launch Vehicle is a step closer to becoming a reality as the Reusable Launch Vehicle Autonomous Landing Mission (RLV LEX) has been successfully accomplished by the Indian Space Research Organisation (ISRO). At the Aeronautical Test Range in Chitradurga, Karnataka, the trial involved a winged body lifted to an altitude of 4.5 km by an Indian Air Force Chinook helicopter, subsequently freed to execute an independent landing on a runway.
This is the first time that a winged body has been released mid-air by a helicopter and carried out an autonomous landing. The RLV LEX 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.
Under conditions similar to those of a space re-entry vehicle landing, the autonomous landing was executed, achieving landing parameters such as precise body rates, the sink rate of landing gears, and ground relative velocity. To accomplish the Reusable Launch Vehicle Autonomous Landing Mission (RLV LEX), several cutting-edge technologies were necessary, including accurate navigation hardware and software, a Pseudolite system, a Ka-band Radar Altimeter, a NavIC receiver, an indigenous landing gear, Aerofoil honeycomb fins, and a brake parachute system.
ISRO designed localised navigation systems using pseudolite systems, instrumentation, and sensor systems. The Ka-band Radar Altimeter provided precise altitude information with the aid of a Digital Elevation Model (DEM) of the landing site.
