Cryogenic Engine CE20 & LVM3 Stages

Cryogenic Engine CE20 & LVM3 Stages

  • Context:

  • ISRO successfully demonstrated the Boot-Strap Mode start of the CE20 cryogenic engine on November 7, 2025.

  • The test was conducted under vacuum conditions at the High-Altitude Test (HAT) facility at the ISRO Propulsion Complex in Mahendragiri for a duration of 10 seconds.

  • This achievement demonstrates the capability to start the engine without an auxiliary start-up system (stored gas bottles), which is essential for enabling multiple in-flight restarts for future multi-orbit missions.

  • CE20 Cryogenic Engine:

  • It is India's largest cryogenic engine

  • It is designed and developed by the Liquid Propulsion Systems Centre (LPSC) to power the C25 upper stage of the LVM3 rocket.

  • Capabilities of CE20:

  • It is a gas-generator cycle cryogenic engine.

  • It is qualified for operation at thrust levels ranging from 19 to 22 tonnes.

  • The engine has also been qualified for the Gaganyaan missions.

  • Bootstrap Mode:

  • Traditionally, the engine requires a stored gas start-up system to initiate the turbopumps.

  • The new Bootstrap mode uses a multi-element igniter to facilitate starting under tank head conditions without external assistance.

  • This prevents a reduction in payload capability caused by carrying extra gas bottles.

  • About Cryogenic Propulsion:

  • A system that uses propellants stored at low temperatures (below 123K)

  • It uses a combination of Liquid Oxygen (oxidizer) and Liquid Hydrogen (fuel)

  • It offers a high Specific Impulse which is significantly higher than solid or liquid propellants.

  • This makes it ideal for the terminal stages of launch vehicles.

  • About LVM3 (Launch Vehicle Mark-3) Stages:

  • LVM3 is a three-stage heavy-lift launch vehicle with a lift-off mass of 640 tonnes.

  • It is capable of placing 4,000 kg satellites into Geosynchronous Transfer Orbit (GTO) and 8,000 kg into Low Earth Orbit (LEO).

  • Stage 1 uses Solid Rocket Boosters.

  • Meaning fuel is a solid propellant (HTPB).

  • As huge thrust is required for liftoff solid fuel is used.

  • The solid fuel provides the huge thrust required for lift-off

  • Stage 2 uses a Liquid engine.

  • Here the rocket is powered by two Vikas engines (liquid propulsion).

  • Fuel is liquid. (UDMH(fuel) + N2O4(oxidiser to burn the fuel))

  • Stage 3 is Cryogenic Upper Stage(C25)

  • It is powered by the indigenous CE-20 engine.

  • Fuel here is LOX and LH2.

  • This stage injects the spacecraft into the desired orbit.