Vikas Engine

The Vikas Engine is a family of liquid-fuelled rocket engines developed by the Indian Space Research Organisation (ISRO) for use in various stages of India’s launch vehicles. It forms the technological backbone of India’s space propulsion systems, powering the Polar Satellite Launch Vehicle (PSLV), Geosynchronous Satellite Launch Vehicle (GSLV), and LVM3 (Launch Vehicle Mark-3). Renowned for its reliability, efficiency, and adaptability, the Vikas Engine has been a cornerstone of India’s space programme since the 1980s.

Historical Background and Development

The origin of the Vikas Engine dates to the late 1970s, when ISRO sought to develop indigenous liquid propulsion technology for its expanding launch vehicle programme. In its early years, India collaborated with the French space agency CNES (Centre National d’Études Spatiales), which provided technical expertise and licensing based on the Viking engine used in the Ariane launch vehicles.
The name “Vikas” is derived from the Sanskrit word for “development” or “progress,” symbolising India’s technological advancement and self-reliance in space technology. The Indian version of the engine was significantly modified to suit local materials, manufacturing capabilities, and mission requirements.
The first flight using a Vikas Engine took place in 1980 on the Rohini Satellite Launch Vehicle (RSLV) test series, and by the late 1980s, it was integrated into the operational PSLV and GSLV systems. Continuous evolution over the decades has made it one of the most dependable engines in ISRO’s inventory.

Technical Specifications

The Vikas Engine is a liquid bipropellant rocket engine, using a combination of Unsymmetrical Dimethylhydrazine (UDMH) as the fuel and Nitrogen Tetroxide (N₂O₄) as the oxidiser. Both are storable hypergolic propellants, meaning they ignite spontaneously upon contact, simplifying ignition systems and allowing long-duration storage.
Key specifications include:

• Type: Liquid bipropellant engine
• Propellants: UDMH (fuel) and N₂O₄ (oxidiser)
• Thrust: Approximately 725 kilonewtons (kN) at sea level
• Specific Impulse: Around 293 seconds in vacuum
• Burn Time: 150–170 seconds depending on configuration
• Engine Mass: Roughly 900 kilograms
• Chamber Pressure: About 58–60 bar
• Cooling: Regenerative cooling through the circulation of propellant around the combustion chamber walls
• Ignition: Hypergolic ignition (no external igniter required)

The engine’s design incorporates a gas generator cycle, where a small amount of propellant is burned to drive the turbine that powers the fuel and oxidiser pumps before entering the combustion chamber.

Variants and Applications

The Vikas Engine has been developed into multiple variants, tailored for different launch vehicles and mission profiles.
1. Vikas Engine for PSLV:

• Used in the second stage (PS2) of the Polar Satellite Launch Vehicle (PSLV).
• Provides the main propulsion during mid-flight, after the solid-fuelled first stage burns out.
• Ensures precise orbital insertion for Earth observation and scientific satellites.

2. Vikas Engine for GSLV:

• Powers the four strap-on boosters and the second stage of the Geosynchronous Satellite Launch Vehicle (GSLV).
• Each booster-mounted Vikas Engine operates in parallel, providing combined thrust for heavy payload launches.

3. Vikas Engine for LVM3 (GSLV Mk-III):

• Utilised in the core liquid stage (L110) of the LVM3, India’s most powerful launch vehicle.
• Two Vikas Engines operate together to lift heavy payloads to geostationary and interplanetary orbits.

Over the years, performance improvements have included better thrust control, refined injector designs, enhanced materials, and upgraded electronics for greater reliability.

Design and Working Principles

The Vikas Engine operates on a gas-generator cycle, ensuring a balance between simplicity, reliability, and efficiency.
Working Process:

1. The oxidiser (N₂O₄) and fuel (UDMH) are pumped from their respective tanks by turbopumps.
2. A small amount of the propellants is diverted into a gas generator, where they partially combust to drive the turbine.
3. The turbine powers both pumps, supplying propellant to the main combustion chamber.
4. Inside the chamber, the hypergolic fuel and oxidiser mix and spontaneously ignite, producing high-pressure exhaust gases.
5. The gases expand through the nozzle, generating thrust that propels the launch vehicle.

The regenerative cooling system circulates the fuel around the combustion chamber to absorb heat before injection, preventing thermal damage to the engine walls.

Manufacturing and Testing

The Vikas Engines are manufactured by Liquid Propulsion Systems Centre (LPSC) of ISRO, with major production support from the Hindustan Aeronautics Limited (HAL). Manufacturing involves high-precision engineering, particularly for components such as injector heads, turbopumps, and nozzles.
Each engine undergoes rigorous testing at facilities such as:

• ISRO Propulsion Complex (IPRC), Mahendragiri (Tamil Nadu)
• Liquid Propulsion Test Facility (LPTF), Mahendragiri
• Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram

Engines are subjected to multiple hot-fire tests simulating launch conditions before being cleared for flight, ensuring reliability and mission safety.

Upgrades and Evolution

The Vikas Engine has evolved through several iterative upgrades to enhance performance and adaptability:

• Vikas-2 and Vikas-2B: Improved injector efficiency and enhanced cooling design.
• Vikas-4 and Vikas-4B: Increased chamber pressure and thrust for GSLV and LVM3 applications.
• Advanced Variants: Integration of digital control systems and thrust-vectoring for improved guidance precision.

These upgrades have enabled ISRO to progressively increase payload capacity and improve mission flexibility across its launch vehicle fleet.

Role in Indian Space Missions

The Vikas Engine has been central to numerous landmark missions in India’s space history, including:

• PSLV-C37 (2017): World record launch of 104 satellites.
• Chandrayaan-1 (2008): India’s first lunar mission.
• Mangalyaan (Mars Orbiter Mission, 2013): The engine contributed to launch and orbit insertion phases.
• Chandrayaan-2 (2019) and Chandrayaan-3 (2023): Played a role in heavy-lift capabilities of GSLV Mk-III (LVM3).

Its proven reliability has established India as a key player in global satellite launch services.

Significance and Technological Impact

The Vikas Engine represents one of India’s most significant achievements in liquid propulsion technology. Its development established:

• Technological self-reliance in space propulsion systems.
• Operational reliability, with a near-perfect success rate in PSLV and GSLV missions.
• A scalable propulsion platform adaptable to future missions and vehicles.

It has also served as a technological foundation for ISRO’s ongoing semi-cryogenic engine (SCE-200) development, which aims to provide higher thrust for next-generation heavy-lift launchers.

Future Prospects

The Vikas Engine continues to play an integral role in India’s space missions, while newer systems gradually evolve alongside it. Future directions include:

• Integration with upgraded launch vehicles for deep-space and human spaceflight missions under the Gaganyaan programme.
• Use in modular launch systems supporting reusable and cost-effective space transport.
• Development of eco-friendly propellant alternatives and more efficient combustion technologies.