CE-7.5

The CUS15 upper stage of GSLV-F09 powered by the CE-7.5 engine at Stage Preparation Facility
Country of origin	India
First flight	15 April 2010 (failure) 5 January 2014 (success)
Designer	ISRO LPSC
Manufacturer	ISRO HAL
Application	Upper-stage booster
Status	In use
Liquid-fuel engine
Propellant	LOX /LH2[1]
Cycle	Fuel-rich staged combustion
Configuration
Chamber	1
Performance
Thrust, vacuum	73.5 kN (16,500 lbf)[2]
Chamberpressure	5.8 MPa (58 bar) / 7.5 MPa (75 bar)
Specific impulse, vacuum	454 seconds (4.45 km/s)
Dimensions
Length	2.14 m (7.0 ft)
Diameter	1.56 m (5.1 ft)
Dry mass	435 kg
Used in
Upper stage ofGSLV

TheCE-7.5 is acryogenic rocket engine developed byISRO to power the upper stage of itsGSLV Mk-2 launch vehicle. The engine was developed as a part of the Cryogenic Upper Stage Project (CUSP). It replaced theKVD-1 (RD-56) Russian cryogenic engine that powered the upper stage of GSLV Mk-1.^[3]

CE-7.5 is a regeneratively-cooled,variable-thrust, fuel-richstaged combustion cyclerocket engine.^[4][5]

The specifications and key characteristics of the engine are:

• Operating Cycle –Staged combustion^[6]
• Propellant Combination –LOX /LH2^[7]
• Maximum thrust (Vacuum) – 73.55 kN^[8]
• Operating Thrust Range (as demonstrated during GSLV Mk2 D5 flight) – 73.55 kN to 82 kN^[2][9]
• Engine Specific Impulse - 454 ± 3 seconds (4.452 ± 0.029 km/s)^[4][6]
• Engine Burn Duration (Nom) – 720 seconds^[8]
• Propellant Mass – 12,800 kg^[8]
• Two independent regulators: thrust control and mixture ratio control^[7]
• Steering during thrust: provided by two gimballed steering engines^[7]

ISRO formally started the Cryogenic Upper Stage Project in 1994.^[10] The engine successfully completed the Flight Acceptance Hot Test in 2008,^[6] and was integrated with propellant tanks, third-stage structures and associated feed lines for the first launch. The first flight attempt took place in April 2010 during the GSLV Mk.II D3/GSAT-3 mission. The engine ignited, but the ignition did not sustain as the Fuel Booster Turbo Pump (FBTP) shut down after reaching a speed of about 34,500 rpm 480 milliseconds after ignition, due to the FBTP being starved of Liquid Hydrogen (LH2).^[2] On 27 March 2013 the engine was successfully tested under vacuum conditions. The engine performed as expected and was qualified to power the third stage of the GSLV Mk-2 rocket. On 5 January 2014 the cryogenic engine performed successfully and launched theGSAT-14 satellite in the GSLV-D5/GSAT-14 mission.^[11][12]

To aid in the development ofNGLV, technologies for multiple restart and development of a spark torch igniter was conducted on the Vernier engine of the GSLV CUS in March 2025.^[13]

CE-7.5 is being used in the third stage of ISRO's GSLV Mk.II rocket.^[14]

• CE-20
• SE-2000
• LVM3
• NGLV

• Rocket engines of India
• Rocket engines using hydrogen propellant
• Rocket engines using the staged combustion cycle

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