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ISRO has proudly achieved a third consecutive experiment success in RLV LEX-03 following the success of RLV LEX-01 and RLV LEX-02 missions.
What is RLV?
RLV is a Reusable Launch Vehicle developed by ISRO with the goal of developing a cost-effective and sustainable space transportation system. It is designed to be used multiple times, similar to an aircraft, which can significantly reduce the cost of access to space.
Three consecutive experiments were conducted to demonstrate and reaffirm ISRO’s expertise in acquiring the most critical technologies required for the development of a Reusable Launch Vehicle (RLV).
The objectives of the landing experiment (LEX)
Post the success of RLV LEX-01 and RLV LEX-02 missions, the third and the final test mission RLV LEX-03 was conducted at the Aeronautical Test Range (ATR) in Chitradurga, Karnataka on June 23rd 2024. Two key objectives were:
1. Technology Demonstration: To demonstrate critical technologies required for the development of a fully operational reusable launch vehicle, including autonomous navigation, guidance, and control during the descent and landing phases.
2. Cost Reduction: To significantly reduce the cost of space missions by reusing the launch vehicle, making space access more economical, sustainable and frequent.
Key components of the landing experiment
1. RLV-TD (Technology Demonstrator): A scaled-down version of the final reusable launch vehicle, designed to test various technologies in real-flight conditions. In this case the technology demonstrator was the winged vehicle, named ‘Pushpak’
2. Autonomous Landing System: Includes advanced navigation, guidance, and control systems to ensure the RLV can autonomously land safely on a runway after completing its mission.
The Reusable Launch Vehicle – Landing Experiment (RLV LEX-03)
The LEX is a specific test conducted to validate the autonomous landing capabilities of the RLV. RLV LEX-03 re-demonstrated the autonomous landing capability of the RLV under more challenging release conditions (cross range of 500 m against 150 m for LEX-02) and more severe wind conditions.
Here are the main aspects of the experiment:
1. Flight Path: RLV-TD ‘Pushpak’ was released from a release point of 4.5 KM away from the runway by an Indian Air Force Chinook helicopter. It then autonomously navigated its way to a designated landing site.
2. Navigation and Control: The experiment focuses on the RLV’s ability to maintain precise control and stability during descent, manage aerodynamic forces, and make necessary adjustments to follow the correct trajectory. Pushpak autonomously executed cross-range correction manoeuvres, approached the runway and performed a precise horizontal landing at the runway centreline.
3. Landing Precision: The RLV must perform a controlled approach and touchdown on a runway, demonstrating its capability to land like an aircraft. This involves the use of landing gear and other mechanisms to ensure a safe landing. Due to this vehicle’s low lift-to-drag ratio aerodynamic configuration, the landing velocity exceeded 320 kmph, compared to 260 kmph for a commercial aircraft and 280 kmph for a typical fighter aircraft.
After touchdown, the vehicle velocity was reduced to nearly 100 kmph using its brake parachute, after which the landing gear brakes were employed for deceleration and stop on the runway. During this ground roll phase, Pushpak utilised its rudder and nose wheel steering system to autonomously maintain a stable and precise ground roll along the runway.
Key Achievements
1. Successful Test Flights: ISRO has conducted several successful test flights and experiments under the RLV program, demonstrating key technologies such as autonomous navigation and precise landing control.
Through this mission, the advanced guidance algorithm catering to longitudinal and lateral plane error corrections, which is essential for the future Orbital Re-entry Mission has been validated.
2. Technology Validation: The LEX has validated critical technologies needed for the development of a full-scale reusable launch vehicle, bringing ISRO closer to achieving its goal of cost-effective space access.
The RLV-LEX uses multisensor fusion including sensors like Inertial sensor, Radar altimeter, Flush air data system, Pseudolite system and NavIC. Notably, the RLV-LEX-03 mission reused the winged body and flight systems as such without any modification, from the LEX-02 mission, demonstrating the robustness of ISRO’s capability of design to reuse flight systems for multiple missions.
Agencies Involved in RLV LEX-03
The mission, led by Vikram Sarabhai Space Centre (VSSC), was a collaborative effort involving multiple ISRO centres – Space Applications Centre (SAC), ISRO Telemetry, Tracking and Command Network (ISTRAC), Satish Dhawan Space Centre Sriharikota Range (SDSC-SHAR) and ISRO Inertial Systems Unit (IISU), 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.
Shri. J Muthupandian is the Mission Director and Shri. B Karthik is the Vehicle Director for this successful mission.
Future Prospects
1. Development of RLV: Following the successful demonstration of landing technologies, ISRO plans to develop a full-scale RLV capable of carrying payloads to orbit and returning safely for reuse.
2. Integration with ISRO’s Fleet: The RLV is expected to become a key component of ISRO’s launch vehicle fleet, complementing existing rockets like the PSLV and GSLV by providing a more economical option for frequent launches.
3. Global Competitiveness: By developing a reusable launch vehicle, ISRO aims to enhance its competitiveness in the global commercial space market, potentially attracting international customers and offering cost-effective and reliable launch services
Conclusion
The Reusable Launch Vehicle (RLV) Landing Experiment (LEX) represents a significant step forward in ISRO’s pursuit of developing reusable space transportation technology. The successful demonstration of autonomous landing capabilities is a critical milestone, paving the way for future advancements in reusable launch vehicles. This technology promises to revolutionize space access, making it more affordable and sustainable, and positioning India as a leader in innovative space solutions.
