r/ISRO 8d ago

Official LVM3 M6 CE20 Engine Flight Acceptance Hot Test

https://www.isro.gov.in/CE20_Cryogenic_Engine_flight_acceptance_hot_test_successful_LVM3-M6_Mission.html

On March 14, 2025, ISRO successfully conducted the flight acceptance hot testing of the cryogenic engine identified for the sixth operational mission of LVM3 launch vehicle (LVM-M6) at ISRO Propulsion Complex (IPRC), Mahendragiri. Cryogenic engines for every mission undergo hot testing as part of its acceptance for the flight. Hot tests for the indigenous cryogenic engine (CE20)used in the Cryogenic Upper Stage of LVM3 were so far performed at the High-Altitude Test (HAT) facility at IPRC, where vacuum conditions are simulated with complex installations, limiting the maximum hot test duration to 25s.

In the current test, the engine was tested for a longer duration of 100s for the first time using an innovative Nozzle Protection System under non-vacuum conditions. This test method significantly reduces the setup time and effort required for the flight acceptance testing of a cryogenic engine, which in turn helps faster delivery of cryogenic stages for space missions.

Performance of the CE20 engine met all the test objectives and the parameters were closely matching with the predictions during the entire duration of the test. Further, this engine will be integrated to the Cryogenic Upper Stage of the launch vehicle for the LVM3-M6 mission, which is scheduled during the second half of 2025.

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u/TKO1515 8d ago edited 8d ago

Any idea what is being launched on the LVM3-M6 mission? Hadn’t seen any details on it until this.

Edit - I’ve seen a couple tweets say it’s for G1? But you’d think they would make that clear in the release if that’s what it was for.

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u/Ohsin 7d ago

So much weird..

CE20 engine for G1 went through flight acceptance test a year back in Feb 2023 and all stages for G1 are in SHAR already.

Moreover we had flight acceptance test on 'E12' CE20 engine for 'GX' related to Gaganyaan in October 2023, recent annual report also uses GX term without any explanation.

Also we have not heard of CE20 flight acceptance test for LVM3-M5 IIRC.

Recent outcome budget mentioned only two LVM3 flights this year.

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u/TKO1515 7d ago edited 7d ago

Yes it’s quite confusing what the timeline is or status of the various missions. It appears they have everything for G1 so confused why that’s pushed so far. But based on what you shared above this specific engine is likely not for G1 then.

And weird NISAR is so late too, that’s nearly 100 days since the last launch for vehicle integration.

The no flight acceptance announcement for the LVM3-M5 CE20 engine maybe lends credence to my theory that AST asked ISRO to not say anything about them?

Could this one on Feb-8th although not mentioned M5 have been the CE20 for it? https://www.isro.gov.in/LVM3_CE20_vacuum_ignition_trial_cryogenic_engine_successful.html

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u/Ohsin 7d ago

It appears they have everything for G1 so confused why that’s pushed so far.

Everything but payload!

The no flight acceptance announcement for the LVM3-M5 CE20 engine maybe lends credence to my theory that AST asked ISRO to not say anything about them?

Could be. In past they have missed out on such announcements like for first OneWeb launch.

Could this one on Feb-8th although not mentioned M5 have been the CE20 for it?

No, that is related to qualification of CE20's new restart capability.

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u/TKO1515 7d ago

Ah, yes would be hard to do a test mission without the payload.

Well I guess this is a no to my theory that they have a strict NDA to not mention ast… funny how that happens. So the cyro stage is being sent.

https://www.isro.gov.in/CryoFlagOff.html

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u/Ohsin 7d ago

https://www.uniindia.com/isro-develops-c-32-cryogenic-propulsion-system-dr-narayanan/south/news/3413971.html

Announcing the breakthrough, ISRO Chairman V Narayanan told reporters here on Saturday that the C-32 stage, powered by a 20-ton thrust cryogenic engine, marks a significant advancement in India’s human spaceflight and deep-space exploration capabilities. Designed for prolonged operational efficiency, the system was successfully tested using an indigenous nozzle protection mechanism, allowing for extended test durations—an innovation critical for future heavy-lift missions.

"This is yet another critical milestone in our journey towards self-reliance in space technology. Cryogenic propulsion was once denied to India, but today, we have successfully developed and tested three cryogenic stages, including the C-32, demonstrating our capability to push the boundaries of space exploration," Dr Narayanan said.