Here’s a comparison of various cryogenic engines:I would like to know why all major space powers shifted or trying to shift to expander cycle engine for their upper hydrolox stage. Except isro, even blue origins is also developing a hydrolox expander cycle engine
staged combustion cycle is not outdated tech. It is the most efficient thermodynamic cycle when compared to others cycles. The problem is that it is also more complex when compared to other cyclesHere’s a comparison of various cryogenic engines:
Cryogenic rocket engine - Wikipedia
en.wikipedia.org
Looks like CE7.5 type engines which replaced soviet union’s kvd1 have been retired everywhere. Looks like ‘staged combustion’ is an outdated technology other agencies don’t use anymore.
we are spending more than 1.5 lac crores and 2.5 lac crores on minority and SC/ST schemes, while ISRO and DRDO budgets are less than 15K crores eachInstead of wasting money on useless schemes for filthy people this is where government should spend.
Expander cycle is simple and cheap , but it is least efficient of all the cycles. What's the point of developing a new upper stage Cryo engine when we already have the most powerful oneI would like to know why all major space powers shifted or trying to shift to expander cycle engine for their upper hydrolox stage. Except isro, even blue origins is also developing a hydrolox expander cycle engine
Never ever use complex technology if simpler ones are available. This is perhaps why other agencies don’t use staged combustion cycle. Russia does not use KVD 1 (from which CE7.5 is derived) anymore. Plus CE7.5 is NOT the latest tech. That would be Full flow staged combustion that SpaceX’s Raptor deployed in 2019. CE7.5 is a fuel rich staged combustion and looks like no other agency uses this technology anymore. Perhaps the failure rate is high due to complexity and hence have not gone that route.staged combustion cycle is not outdated tech. It is the most efficient thermodynamic cycle when compared to others cycles. The problem is that it is also more complex when compared to other cycles
Who said to you that Oxidizer Rich Staged Combustion Cycle is safe.No, It's not safe. Infact Oxidizer Rich Staged Combustion is far more complex than a fuel rich cycle , because in Oxidizer Rich cycle, the Oxygen rich mixture corrodes the metal with which it interacts. It's very difficult to master , that's the reason why Americans had failed to master the Oxidizer Rich cycle untill they bought the NK-33 engines after the end of cold war. Only the Russians were masters in Oxidizer Rich cycles. Hence our SCE-200 engine is based on RD-810 design which inturn derived from RD-170Never ever use complex technology if simpler ones are available. This is perhaps why other agencies don’t use staged combustion cycle. Russia does not use KVD 1 (from which CE7.5 is derived) anymore. Plus CE7.5 is NOT the latest tech. That would be Full flow staged combustion that SpaceX’s Raptor deployed in 2019. CE7.5 is a fuel rich staged combustion and looks like no other agency uses this technology anymore. Perhaps the failure rate is high due to complexity and hence have not gone that route.
Oxidizer rich staged combustion is the most popular. The technology ISRO uses was developed in the 1970s and not used anymore and even to begin with only 3 or 4 engines used it compared to more than two dozen engines using oxidizer rich staged combustion cycle. Looks like ISRO may have gone for a complex technology because only Russia was ready to tech transfer cryogenic technology I.e. KVD1 fuel rich SC cycle. So ISRO may not have had any choice. But they could have tried to develop the safer oxidizer rich SC or full flow SC tech all these years. Why didn’t they?
Staged combustion cycle - Wikipedia
en.wikipedia.org
Here’s some literature on the various cycles:
Apparently the space shuttle used the staged combustion cycle.
Oh my my... Please check the specific impulse of staged combustion with gas generator & expander cycles.Here’s a comparison of various cryogenic engines:
Cryogenic rocket engine - Wikipedia
en.wikipedia.org
Looks like CE7.5 type engines which replaced soviet union’s kvd1 have been retired everywhere. Looks like ‘staged combustion’ is an outdated technology other agencies don’t use anymore.
Least efficient in terms of specific impulse is the gas generator cycle. Expander cycle is comparable to staged combustion cycle.Expander cycle is simple and cheap , but it is least efficient of all the cycles. What's the point of developing a new upper stage Cryo engine when we already have the most powerful one
What? Did you see the link I put in there? Most engines use Oxidizer rich combustion cycle. Even blue origin for passenger travel to space. They are not going to use unsafe tech for human flights? The tech that ISRO uses, no one uses the fuel rich cycle. Why is that?Who said to you that Oxidizer Rich Staged Combustion Cycle is safe.No, It's not safe. Infact Oxidizer Rich Staged Combustion is far more complex than a fuel rich cycle , because in Oxidizer Rich cycle, the Oxygen rich mixture corrodes the metal with which it interacts. It's very difficult to master , that's the reason why Americans had failed to master the Oxidizer Rich cycle untill they bought the NK-33 engines after the end of cold war. Only the Russians were masters in Oxidizer Rich cycles. Hence our SCE-200 engine is based on RD-810 design which inturn derived from RD-170
The cost is a little more than 300 crore, it will match up to the reused Falcon 9 with introduction of uprated cryogenic stage & SC120.SpaceX falcon9 versus ISRO GSLV Mk3..ISRO is way behind the Falcon9. Even the launch cost of a Falcon9 ($50 million) is less than the GSLV Mk3 ($63 million). How will ISRO compete at all? Impossible.
How does ISRO’s GSLV Mk-III fare against some of the world's most powerful rockets?
ISRO operates one of the most reliable and cost-effective launch platforms in the world.www.firstpost.com
We are talking within SC cycles - there are 3 types of SC cycles. See link I supplied. We will go by what is popular with space agencies. I am sure those guys know what is best. And clearly the CE7.5 technology is the least used or unpopular. And the full cycle SC appears to be the latest and most complex. Read the literature at a high level.Oh my my... Please check the specific impulse of staged combustion with gas generator & expander cycles.
Yeah that’s what the article says. Plus Falcon9 has been launched 52 times compared to two times for Mk3. You can kiss heavier launch market goodbye as SpaceX is going to corner 70-80% market share. Technology can also bring down costs. I think ISRO’s marketing of cheaper launch costs due to low manpower costs won’t last forever. Better figure out what needs to be done to compete against Falcon9, urgently.The cost is a little more than 300 crore, it will match up to the reused Falcon 9 with introduction of uprated cryogenic stage & SC120.
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I know there are three types.We are talking within SC cycles - there are 3 types of SC cycles. See link I supplied. We will go by what is popular with space agencies. I am sure those guys know what is best. And clearly the CE7.5 technology is the least used or unpopular. And the full cycle SC appears to be the latest and most complex. Read the literature at a high level.
Yeah that’s what I am saying - we are stuck with an unpopular Russian technology. So now what? Can we develop an oxidizer SC tech or the latest full cycle tech?I know there are three types.
The reason for ISRO choosing staged combustion cycle in the first place for the GSLV CUS instead of simpler GG cycle is because it was supposed to be replacement of the KVD 1 stage in form, fit and function.
FFSC is complex & is used in metholox engines. ORSC in kerolox engines as fuel have coking (soot deposition) issues.
Hydrogen do not have that problem. Hence FRSC for cryogenic engines.