In a major success, the Indian Space Research Organisation (ISRO) on Sunday successfully conducted its third and final landing in the Reusable Launch Vehicle (RLV) Landing Experiment (LEX). The RLV LEX-03 winged vehicle, named "Pushpak' executed a precise horizontal landing, showcasing advanced autonomous capabilities under challenging conditions. As the objectives of RLV LEX are accomplished, ISRO is to embark on RLV-ORV, the orbital reusable vehicle.
Meachanism of precise and soft landing
After the success of earlier missions namely, ALV LEX-01 and LEX-02, Pushpak has re-demonstrated the autonomous landing capability of the RLV under more challenging release conditions and more severe wind conditions. According to press release issued by the ISRO, Pushpak was released from an Indian Air Force Chinook Helicopter at an altitude of 4.5 km. From a release point 4.5 km away from the runway, Pushpak autonomously executed cross-range correction manoeuvres from the release point which was 4.5 KMs from the runway.
It approached the runway and performed a precise horizontal landing at the centreline. Because of Pushpak's low lift-to-drag ratio aerodynamic configuration, the landing velocity exceeded 320 kmph. This is much higher as compared to 260 kmph for a commercial aircraft and 280 kmph for a typical fighter aircraft. Following its touchdown, the velocity was reduced to nearly 100 kmph using its brake parachute. After the parachute brakes functioned, the landing gear brakes were employed for deceleration. During the ground roll phase, Pushpak utilised its rudder and nose wheel steering system to self-maintain a stable and precise ground roll along the runway.
Features of Pushpak
This mission did the simulation of the approach and landing interface and high-speed landing conditions for space-returning vehicles. The mission reaffirmed ISRO's expertise in acquiring the most critical technologies needed for the development of a Reusable Launch Vehicle (RLV). The landing mission also validated the advanced guidance algorithm catering to longitudinal and lateral plane error corrections, which is essential for the future Orbital Re-entry Mission. It is worth mentioning that RLV-LEX uses multisensor fusion including sensors like the Inertial sensor, Radar altimeter, Flush air data system, Pseudolite system and NavIC. Significantly, ISRO also demonstrated its capability of design to reuse flight systems for multiple missions by reusing the winged body and flight systems without any modification, from the LEX-02 mission.
The mission, led by VSSC, was a collaborative effort involving multiple ISRO centres SAC, ISTRAC, SDSC-SHAR, with significant support from the Indian Air Force (IAF), Aeronautical Development Establishment (ADE), Aerial Delivery Research and Development Establishment (ADRDE), Regional Centre for Military Airworthiness (RCMA) under Centre for Military Airworthiness and Certification (CEMILAC), National Aerospace Laboratories (NAL), Indian Institute of Technology, Kanpur, Indian aerospace industrial partners, Indian Oil Corporation of India and Airport Authority of India (AAI).
