Propelling Dreams: Enhancing the LVM3 Rocket for India’s Gaganyaan Mission

Credits : Qualification tests conducted on 3 stages of the LVM3 rocket – ISRO

Introduction

As the Gaganyaan project progresses, building on insights from our previous blog post “Gaganyaan Mission: India’s Ambitious Space Exploration,” the Launch Vehicle Mark-3 (LVM3) stands at the forefront of this endeavor. Developed by the Indian Space Research Organization (ISRO), the LVM3 is a medium-lift launch vehicle currently being adapted for human spaceflight, a pivotal step towards India’s first crewed mission. Originally envisioned with human spaceflight capabilities, the LVM3 is engineered to limit maximum acceleration to 4 Gs during ascent, ensuring crew comfort. Additionally, its 5-meter diameter payload fairing can accommodate substantial modules, such as space station segments, demonstrating its versatility and readiness for complex missions^[1].

To meet the stringent requirements for human spaceflight, several enhancements are being made to improve the reliability of critical subsystems. These improvements include developing better margins, incorporating redundancy, and strengthening components^[2].

Let us delve into various improvements and qualification tests conducted at three different stages of the LVM3 rocket:

1. Solid Boosters – HS200
2. Liquid Stage (L110) – High Thrust Vikas Engines (HTVE)
3. Cryogenic Stage – C25 Engine Stage

HS200 booster qualification

The human-rated variant of the S200 solid strap-on booster, or ‘HS200’, was developed for the Gaganyaan programme in collaboration with Larsen & Toubro. The first static fire test of HS200 was conducted on 13 May 2022 at Satish Dhawan Space Centre (SDSC) for a duration of 135 seconds, carrying 203 tons of solid propellant. During the test, about 700 parameters were monitored and the performance of all the systems were normal^[3].

In alignment with the overarching objectives of the Gaganyaan mission, the HS200 booster underwent meticulous design enhancements aimed at bolstering the safety and reliability across its various systems,

• Enhanced Safety Features: Stronger ignition and insulation systems implemented. Additional safety features incorporated for motor case joints
• Improved Digital Control Electronics: Utilization of advanced digital control electronics for enhanced performance
• Robust Control System: Integration of one of the strongest electro-mechanical actuators available. Incorporation of multiple redundancies and safety measures for reliability
• Performance Enhancements: Reduction in chamber pressure for improved performance. Increased robustness and proof-leakability.

Human-Rated L110-G Vikas Engine

The successful completion of the final long-duration hot test of the human-rated L110-G Vikas Engine on April 6, 2023, at the ISRO Propulsion Complex (IPRC) in Mahendragiri marks a significant milestone in ISRO’s Gaganyaan program. The L110-G Vikas Engine powers the air-lit liquid core stage of the human-rated launch vehicle (LVM3-G) and is configured in a clustered arrangement, employing two engines.

Qualification Test Improvement Highlights^[4]:

• Enhanced Structural Margins: The Vikas engine uses storable propellants in a pump-fed gas generator cycle. Human rated Vikas engine has higher structural margins for sub-systems, improved assembly process and additional measurements for health monitoring.
• Health Monitoring Enhancements: Additional measurements for health monitoring facilitate real-time assessment and ensure optimal engine performance.
• Rigorous Testing Regimen: Human rated Vikas Engine development hot tests were conducted in a step-by-step manner at Principal Test Stand, ISRO Propulsion Complex. Nine engines had undergone 14 hot tests with a cumulative duration of 1215 s, including four long duration tests of 240 s each. Drawn from the extensive legacy and experience of liquid rocket engine development, the test campaign envelopes extreme operating duration, off-nominal mixture ratios and thrust level conditions as compared to flight operating conditions.
• Hardware : Four sets of hardware used for this test programme were fabricated at various Indian industries. Electro-mechanical Gimbal actuators and Command System module for engine pilot pressure control, with multiple redundancies were also qualified in the test.

Advancing CE20 Cryogenic Engine

Developed by the Liquid Propulsion Systems Center (LPSC), a distinguished arm of ISRO, the CE-20 stands as a testament to India’s burgeoning prowess in space technology. Designed to propel the upper stage of the LVM3, this innovative cryogenic engine represents a significant milestone in India’s space exploration endeavors. Notably, it marks the country’s first cryogenic engine featuring a gas-generator cycle, setting a new standard for efficiency and performance.

Qualification Test Improvement Highlights^[5]:

• Ground Qualification Tests: Completion of final round of ground qualification tests at ISRO Propulsion Complex, Mahendragiri, including a series of vacuum ignition tests, simulating flight conditions.
• Comprehensive Testing Regimen: Life demonstration, endurance, and performance assessments conducted under nominal and off-nominal operating conditions, ensuring engine reliability and safety for Gaganyaan missions.
• Rigorous Hot Firing Tests: Four engines subjected to 39 hot firing tests, totaling 8810 seconds, surpassing the minimum human rating qualification standard requirement of 6350 seconds.
• Acceptance Tests for Flight Engine: Successful completion of acceptance tests for the flight engine designated for the first unmanned Gaganyaan mission. The engine boasts a thrust capability of 19 to 22 tonnes and a specific impulse of 442.5 seconds, powering the upper stage of the human-rated LVM3 vehicle.

Conclusion

In conclusion, the advancements made to the LVM3 rocket and its subsystems within ISRO’s Gaganyaan project mark significant milestones in India’s journey towards its first crewed space mission. Moreover, in our next blog post, we will delve into the intricate Crew Escape system and Orbital Module systems to explore the comprehensive series of tests it has undergone till date. Stay tuned as we continue to unravel the complexities of India’s ambitious foray into human spaceflight.

References

1. The Next-Generation Launcher: GSLV-Mk III by S. Ramakrishnan, From Fishing Hamlet to Red Planet: India’s Space Journey, HarperCollins Publishers India, 15 December 2015.
2. Shri S. Somanath, Chairman, ISRO (11 August 2021), PRL Ka Amrut Vyakhyaan-02, ‘Reaching the sky: Indian Launch Vehicles’, Event occurs at 53:10–53:40 – via YouTube.
3. ISRO successfully tests large human rated solid rocket booster for the Gaganyaan programme
4. Vikas engine qualification test
5. Successful completion of Human rating of CE20 Cryogenic engine for the Gaganyaan Programme