The Indian Space Research Organisation is one big step closer in its quest for a Reusable Launch Vehicle (RLV). The success of the Landing Experiment (LEX) or Pushpak as it has been named after the mythological flying craft, executed a precise horizontal landing, its third, at the Aeronautical Test Range in Chitradurga, Karnataka. LEX was dropped from an Indian Air Force (IAF) Chinook heavy-lift helicopter from an altitude of 4.5 km from the runway.
The mission was programmed to simulate the approach and landing interface of the experimental aircraft. In this last experiment, LEX was released at a cross range of 500 meters instead of the 150 meters of the last such experiment carried out in March. The profile of the recovery successfully mimicked the high-speed landing conditions of a spacecraft.
Pushpak landed at a speed of 320 kmph, a speed faster than that of a landing fighter aircraft (roughly 280 kmph) or an airliner (approximately 260 kmph). The experimental aircraft was slowed down using a brake parachute to nearly 100kmph. The inbuilt brakes of the aircraft then brought it to a halt.
Through this mission the advanced algorithm essential to land the spacecraft, especially in the longitudinal and lateral plane for course correction, have been validated. The LEX uses multi-sensory fusion which includes an inertial sensor, radar altimeter, flush air data system and NAVIC among others. The mission also borrows from the previous two missions as it used the winged body and flight systems from the LEX-02 and LEX-01 missions. The airframe structure and landing gear were strengthened to tolerate higher loads while landing, this was a learning from the first LEX mission.
Vikram Sarabhai Space Centre (VSSC) Liquid Propulsion System Centre (LPSC) and the ISRO Inertial Systems Unit (IISU), National Aerospace Laboratories (NAL), Centre for Military Airworthiness and Certification (CEMILAC), Indian Institute of Technology (IIT) Kanpur, Aerial Delivery Research and Development Establishment as well as various ISRO were involved in this successful validation exercise.
