ISRO's engines : Designs , Components & Prototypes.


Larsen & Toubro, JSW, Adani Group and Mahindra are among at least half a dozen home-grown companies or consortiums looking to partner the Indian Space Research Organisation (ISRO) on its heavy-lift launch vehicle mark-3 (LVM3), also known as Bahubali, said people aware of the matter.

These private entities are considering plans to submit expressions of interest (EoIs) for technology transfer from ISRO to manufacture and operate LVM3, the people told ET.

Those interested include an alliance between JSW and startup Ethereal Exploration Guild (EtherealX), a consortium led by Nagpur-based Solar Industries, Bharat Forge and Inox India, the people said.

For Inox India, a maker of cryogenic and propellant-handling equipment, a new aerospace certification would allow it to bid for in-flight equipment, including “propellant tanks, which are part of the rocket,” said chief executive Deepak Acharya on a recent earnings call. He termed the EoI for LVM3 manufacturing as a potential opportunity for Inox.

The selected company or consortium will have 42 months, or two realised launch vehicles, to complete the technology-transfer process. It will initially work with ISRO and IN-SPACe to absorb the technology before establishing the necessary infrastructure to independently manufacture LVM3 systems and subsystems.​
 
September 05, 2026

Indian Space Research Organisation (ISRO) demonstrated successful hot test of the Semi-Cryogenic Engine Power Head Test Article (PHTA) at full thrust level of 200Tonne at the ISRO Propulsion Research Complex (IPRC), Mahendragiri, Tamil Nadu on September 05, 2026. The Power Head Test Article (PHTA) encompasses all engine systems except thrust chamber. This is the 9th test in a series of hot tests using the PHTA. This is the first time that the PHTA is tested at 100% or full thrust level i.e. 200 tonnes. Previously, the tests were conducted at 47% (94 tonnes), 60% (120 tonnes) and 88% (175 tonnes) thrust levels successfully.

The test proceeded as predicted and all the engine parameters were as expected. The test duration was 35 seconds including operation of the engine powerhead at 200 tonne (100%) thrust level for a duration of 5 seconds. The switch over of propellant supply from a low pressure start tank to medium pressure run tank was also validated in order to enable long duration testing of PHTA in subsequent hot tests.

The Semi-Cryogenic Propulsion Stage (SC120), powered by the 2000 kN-class SE2000 engine, is being developed to replace the current L110 core stage of the LVM3 launch vehicle. The integration of the Semicryogenic stage along with the uprated cryogenic upper stage (C32) will enhance the LVM3 payload capability.​
 
Enhanced image of the LME-110:
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The nozzle extension on this engine (the black part) will likely use a Carbon-Carbon composite. The advantage of this type of nozzle is lower weight, easier re-furbishing for re-use etc.

This tech will probably be seen in all future ISRO engines. SCE-200 is a legacy Soviet/Russian design, so it retains the metallic nozzle. That might change in the future.

This tech was prototyped & tested with the L-2.5 engine used on the 4th stage of PSLV. That prototype C-C nozzle managed to reduce the weight by 67% compared to the older metallic nozzle. This alone had increased the PSLV's payload capacity by 15 kgs.

ISRO Develops Lightweight Carbon-Carbon Nozzle for Rocket Engines, Enhancing Payload Capacity


April 15, 2024
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ISRO has achieved a breakthrough in rocket engine technology with the development of a lightweight Carbon-Carbon (C-C) nozzle for rocket engines. This innovation accomplished by Vikram Sarabhai Space Centre (VSSC) promises to enhance the vital parameters of rocket engines, including thrust levels, specific impulse, and thrust-to-weight ratios, thereby boosting the payload capacity of launch vehicles.

VSSC, continuing its pioneering work in space research, has leveraged advanced materials like Carbon-Carbon (C-C) Composites to create a nozzle divergent that offers exceptional properties. By utilizing processes such as carbonization of green composites, Chemical Vapor Infiltration, and High-Temperature Treatment, it has produced a nozzle with low density, high specific strength, and excellent stiffness, capable of retaining mechanical properties even at elevated temperatures.

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A key feature of the C-C nozzle is its special anti-oxidation coating of Silicon Carbide, which extends its operational limits in oxidizing environments. This innovation not only reduces thermally induced stresses but also enhances corrosion resistance, allowing for extended operational temperature limits in hostile environments.

The potential impact of this development is significant, particularly for the Indian Space Research Organization (ISRO)'s workhorse launcher, the Polar Satellite Launch Vehicle (PSLV). The PS4, the fourth stage of the PSLV, currently employs twin engines with nozzles made from Columbium alloy. However, by replacing these metallic divergent nozzles with C-C counterparts, a mass reduction of approximately 67% can be achieved. This substitution is projected to increase the payload capability of the PSLV by 15 kg, a notable enhancement for space missions.

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The successful testing of the C-C nozzle divergent marked a major milestone for ISRO. On March 19, 2024, a 60-second hot test was conducted at the High-Altitude Test (HAT) facility in ISRO Propulsion Complex (IPRC), Mahendragiri, confirming the system's performance and hardware integrity. Subsequent tests, including a 200-second hot test on April 2, 2024, further validated the nozzle's capabilities, with temperatures reaching 1216K, matching predictions.

The collaborative effort involved the Liquid Propulsion Systems Centre (LPSC) at Valiamala which designed and configured the tested at IPRC, Mahendragiri which conducted the instrumentation and execution of the tests at their HAT facility.

Video:
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ISRO Develops Lightweight Carbon-Carbon Nozzle for Rocket Engines, Enhancing Payload Capacity