India Space Indian Space Program

[Gessler]

Successful hot Test of Gaganyaan Service Module Propulsion System – System Demonstration Model (SDM)​

On August 28, 2021, ISRO successfully conducted the first hot test of the System Demonstration Model (SDM) of the Gaganyaan Service Module Propulsion System for a duration of 450 s at the test facility of ISRO Propulsion Complex (IPRC), Mahendragiri, Tamil Nadu. The system performance met the test objectives and there was a close match with the pre-test predictions. Further, a series of hot tests are planned to simulate various mission conditions as well as off-nominal conditions.

The Service Module is part of the Gaganyaan Orbital module and is located below the crew module and remains connected to it until re-entry. The Service Module (SM) Propulsion System consists of a unified bipropellant system consisting of 5 nos. of 440 N thrust engines and 16 nos. of 100 N Reaction Control system (RCS) thrusters with MON-3 and MMH as Oxidizer and Fuel respectively. The System Demonstration Model (SDM), consisting of 5 nos. of 440 N engines and 8 nos. of 100 N thrusters, was realized to qualify the propulsion system performance in ground. A new test facility is established at IPRC, Mahendragiri for testing the SDM.

The System Demonstration Model (SDM) in Clean Room​

 

[Nilgiri]

 

[Nilgiri]

ISRO’s new series of heavy-lift rockets to carry between 5-16 tonnes to GTO

To attain total self-reliance in the launch of heavy satellites (weighing above 4 tonnes) and to meet future demands, the Indian Space Research Organization is working on a fleet of five new rockets. According to a senior official, the five Heavy-lift Launch Vehicles (HLV) are in their project...

www.wionews.com

To attain total self-reliance in the launch of heavy satellites (weighing above 4 tonnes) and to meet future demands, the Indian Space Research Organization is working on a fleet of five new rockets. According to a senior official, the five Heavy-lift Launch Vehicles (HLV) are in their project report stage.

In terms of design and appearance, this new fleet of rockets would be quite similar to the existing SSLV, PSLV and GSLV and GSLV Mk3 rockets, but they would be powered by even more capable, powerful and technologically advanced engines. Presently, India pays and utilises the services of Ariane-5, a foreign rocket, to launch satellites that weigh over 4 tonnes.




Speaking at a virtual event organised by ISRO and CII, N Sudheer Kumar, Director, Capacity Building Programme Office, ISRO, revealed that variants of this new fleet of heavy-lift rockets would be able to place a payload weighing anywhere between 4.9 tonnes and over 16 tonnes in the tonne synchronous Transfer Orbit (GTO). This is an enormous improvement over the current maximum lift capability of 4 tons that the GSLV Mk3 rocket has performed to GTO.

GTO is an intermediary orbit (180km at its closest point to the Earth and 36,000km at its farthest point from the Earth) into which heavy satellites are launched by rockets. After being placed in GTO, the satellites use their onboard propulsion to reach a circular orbit 36,000 km above the earth (it is at the same distance from the earth at any given point of time). Being in the 36,000km circular orbit (also known as Geostationary or GSO orbit) allows for communication and monitoring of a large portion of the Earth. three satellites in GSO orbit are capable of covering nearly the entire globe.




According to Kumar, the work to upgrade the lift capability of GSLV Mk3 to 7.5 tonnes to GTO, is on the verge of being concluded. This major upgrade to India’s rocket is being made possible owing to the development of two kinds of rocket engines: a semi-cryogenic engine that burns a special variant of kerosene (dubbed ISROsene) and liquid oxygen; and a cryogenic engine that burns a mixture of liquid hydrogen and liquid oxygen. The said semi-cryogenic engine stage is dubbed as the SC120, and the upgraded cryogenic engine stage is dubbed as the C32. As per ISRO’s naming convention for rocket stages, the letter (s) refers to the type of engine fuel-Solid (S), Liquid (L), Semi-cryogenic (SC) and Cryogenic (C) and the accompanying number refers to the mass (in tonnes) of propellant carried. Simply put, a rocket is a combination of multiple engines (stages) that are vertically stacked.

"Soon the stage will be inducted into the rocket, then we will not depend on foreign sources for the launch of heavy communication satellites (weighing over 4 or 5 tonnes)," Kumar said. Regarding ISRO’s ongoing projects, he outlined that work was underway on the full-scale model of the Reusable Launch Vehicle Technology Demonstrator (RLV-TD), besides work to scale up the proto-model of the air-breathing engine. For ISRO, these are crucial technologies to master to develop a fully reusable space vehicle dubbed the "TSTO," or Two Stage to Orbit.

The Director of ISRO’s CBPO also shared the configuration of the fleet of five heavy-lift rockets that were in their project report stage. The configurations refer to new and more powerful rocket stages-SC400 semi-cryogenic stage, the C27 cryogenic stage, and S250 solid rocket booster. Simply put, depending on the type of mission, payload to be lifted and rocket required, different variants of engines would be stacked vertically to run a relay race to space. Each stage would detach from the rocket after propelling the rocket to a certain altitude and speed, then the next engine would take over. This process goes on until the satellite (payload) reaches its final orbital destination.

In terms of materials, ISRO is said to be working on developing carbon-carbon composites, ceramic matrix composite for reusable vehicles, metal-foams for crash landing interplanetary probes, besides crucial components such as solar panels, fibre optics Atomic clocks, deployable antennas, lithium-ion batteries, Application-Specific Integrated Circuits (ASICs) and Micro Electro Mechanical System (MEMS) Devices.

 

[Lonewolf]

ISRO’s new series of heavy-lift rockets to carry between 5-16 tonnes to GTO

To attain total self-reliance in the launch of heavy satellites (weighing above 4 tonnes) and to meet future demands, the Indian Space Research Organization is working on a fleet of five new rockets. According to a senior official, the five Heavy-lift Launch Vehicles (HLV) are in their project...

www.wionews.com

To attain total self-reliance in the launch of heavy satellites (weighing above 4 tonnes) and to meet future demands, the Indian Space Research Organization is working on a fleet of five new rockets. According to a senior official, the five Heavy-lift Launch Vehicles (HLV) are in their project report stage.

In terms of design and appearance, this new fleet of rockets would be quite similar to the existing SSLV, PSLV and GSLV and GSLV Mk3 rockets, but they would be powered by even more capable, powerful and technologically advanced engines. Presently, India pays and utilises the services of Ariane-5, a foreign rocket, to launch satellites that weigh over 4 tonnes.




Speaking at a virtual event organised by ISRO and CII, N Sudheer Kumar, Director, Capacity Building Programme Office, ISRO, revealed that variants of this new fleet of heavy-lift rockets would be able to place a payload weighing anywhere between 4.9 tonnes and over 16 tonnes in the tonne synchronous Transfer Orbit (GTO). This is an enormous improvement over the current maximum lift capability of 4 tons that the GSLV Mk3 rocket has performed to GTO.

GTO is an intermediary orbit (180km at its closest point to the Earth and 36,000km at its farthest point from the Earth) into which heavy satellites are launched by rockets. After being placed in GTO, the satellites use their onboard propulsion to reach a circular orbit 36,000 km above the earth (it is at the same distance from the earth at any given point of time). Being in the 36,000km circular orbit (also known as Geostationary or GSO orbit) allows for communication and monitoring of a large portion of the Earth. three satellites in GSO orbit are capable of covering nearly the entire globe.




According to Kumar, the work to upgrade the lift capability of GSLV Mk3 to 7.5 tonnes to GTO, is on the verge of being concluded. This major upgrade to India’s rocket is being made possible owing to the development of two kinds of rocket engines: a semi-cryogenic engine that burns a special variant of kerosene (dubbed ISROsene) and liquid oxygen; and a cryogenic engine that burns a mixture of liquid hydrogen and liquid oxygen. The said semi-cryogenic engine stage is dubbed as the SC120, and the upgraded cryogenic engine stage is dubbed as the C32. As per ISRO’s naming convention for rocket stages, the letter (s) refers to the type of engine fuel-Solid (S), Liquid (L), Semi-cryogenic (SC) and Cryogenic (C) and the accompanying number refers to the mass (in tonnes) of propellant carried. Simply put, a rocket is a combination of multiple engines (stages) that are vertically stacked.

"Soon the stage will be inducted into the rocket, then we will not depend on foreign sources for the launch of heavy communication satellites (weighing over 4 or 5 tonnes)," Kumar said. Regarding ISRO’s ongoing projects, he outlined that work was underway on the full-scale model of the Reusable Launch Vehicle Technology Demonstrator (RLV-TD), besides work to scale up the proto-model of the air-breathing engine. For ISRO, these are crucial technologies to master to develop a fully reusable space vehicle dubbed the "TSTO," or Two Stage to Orbit.

The Director of ISRO’s CBPO also shared the configuration of the fleet of five heavy-lift rockets that were in their project report stage. The configurations refer to new and more powerful rocket stages-SC400 semi-cryogenic stage, the C27 cryogenic stage, and S250 solid rocket booster. Simply put, depending on the type of mission, payload to be lifted and rocket required, different variants of engines would be stacked vertically to run a relay race to space. Each stage would detach from the rocket after propelling the rocket to a certain altitude and speed, then the next engine would take over. This process goes on until the satellite (payload) reaches its final orbital destination.

In terms of materials, ISRO is said to be working on developing carbon-carbon composites, ceramic matrix composite for reusable vehicles, metal-foams for crash landing interplanetary probes, besides crucial components such as solar panels, fibre optics Atomic clocks, deployable antennas, lithium-ion batteries, Application-Specific Integrated Circuits (ASICs) and Micro Electro Mechanical System (MEMS) Devices.

I think those payload are with recovery of booster and main motor ,as the size and thrust is sufficient for 30 ton or above max to gto

 

[Nilgiri]

I think those payload are with recovery of booster and main motor ,as the size and thrust is sufficient for 30 ton or above max to gto

Well working outwards from CE-20 (once its proven+reliable), you are correct about its final potential given its quite the monster for final stage (200kN +/- 20kN).

i.e one could technically have variants with immense lower stages to get to the envelope you speak of.

Some websites even have a x2 CE-20 upperstage (for "SHLV"):

realtime.at - Domain gecatcht

This could either increase the total potential to GTO by another factor of 2 or reduce lower stage need by similar factor (right down to SSTO with only CE-20 etc.).

We will have to see how the variants (committed to) firm up with time.

It is a key advantage that ISRO has done by going this size with CE-20 though (with long term scalability envelope in mind)....other space agencies you will notice have their upper stage for heavies about half of it and reach the same profile of GTO here (by bulking up the lower stages)....i.e ~ 10 - 15 ton GTO payload.

But there is also advantage to keeping things more conventional in lower stages and letting CE-20 (given its Isp) do more legwork in launch profile so to speak....i.e it helps to drive lower cost requirement in lower stages per launch.

It all depends on requirements of what is needed at GTO (and at LEO) for India going forward and how the economies of scale here end up like.

@Gautam @Gessler @Milspec @Anmdt @Yasar @Kartal1 @T-123456 @Cabatli_53 @MisterLike et al.

 

[Gautam]

Well working outwards from CE-20 (once its proven+reliable), you are correct about its final potential given its quite the monster for final stage (200kN +/- 20kN).

i.e one could technically have variants with immense lower stages to get to the envelope you speak of.

Some websites even have a x2 CE-20 upperstage (for "SHLV"):

realtime.at - Domain gecatcht

This could either increase the total potential to GTO by another factor of 2 or reduce lower stage need by similar factor (right down to SSTO with only CE-20 etc.).

We will have to see how the variants (committed to) firm up with time.

It is a key advantage that ISRO has done by going this size with CE-20 though (with long term scalability envelope in mind)....other space agencies you will notice have their upper stage for heavies about half of it and reach the same profile of GTO here (by bulking up the lower stages)....i.e ~ 10 - 15 ton GTO payload.

But there is also advantage to keeping things more conventional in lower stages and letting CE-20 (given its Isp) do more legwork in launch profile so to speak....i.e it helps to drive lower cost requirement in lower stages per launch.

It all depends on requirements of what is needed at GTO (and at LEO) for India going forward and how the economies of scale here end up like.

@Gautam @Gessler @Milspec @Anmdt @Yasar @Kartal1 @T-123456 @Cabatli_53 @MisterLike et al.

It is all very confusing at the moment. The photo posted shows the older configuration. This is the newer ones:

I have heard of 4 different cryo upper stages being made so far.

C32 : Under prototype testing phase. For augmenting the GSLV Mk-3
C34: As shown above
C27: In the older configuration as shown in the article.
C90: For a SHLV

They were all to be powered by the CE-20 engine. Now there are 2 new Methalox engine being built, they are not as powerful as the CE-20 but are going to be clustered. The Methalox will likely replace the CE-20.

I have seen 4 different semi-cryo 1st stage so far:

SC120: Under prototype testing. For the GSLV Mk-3 augmentation. One SCE-200 engine.
SC160: Don't know what for. Probably one SCE-200 engine.
SC200: For HLV. 5 SCE-200 engines clustered.
SC400: For HLV & SHLV. 5 SCE-200 engines clustered together.

 

[Gautam]

Some updates on other missions:

Aditya L1 solar observatory will be launched in Q3 of 2022 by a PSLV.

XPOSAT observatory will also be launched in Q3 of 2022. the launch vehicle will be the new SSLV ! SSLV hasn't had its 1st developmental flight yet. The D1 mission is scheduled for next month. D2 will be a commercial mission for launching 4 American satellites in early 2022. So the 3rd flight will be the XPOSAT.

Some microgravity experiments by colleges/universities.

 

[Nilgiri]

They were all to be powered by the CE-20 engine. Now there are 2 new Methalox engine being built, they are not as powerful as the CE-20 but are going to be clustered. The Methalox will likely replace the CE-20.

Hmmm...maybe thats what that german website is talking about with the 2xCE-20 for the SHLV....i.e this methalox engine x2 instead.

Hopefully ISRO gives clear picture soon what the routes are firmly.

Even though methalox (semi cryo methane + LOX) has slightly worse Isp than full-cryo (LH2/LOX)...it is better (iirc) than kerolox (RP-1 and LOX) and might afford better economy and reliability overall in fabrication and use than full cryo.

So let us see.

 

[Nilgiri]

https://twitter.com/i/web/status/1438438369558597637

 

[Gautam]

Hmmm...maybe thats what that german website is talking about with the 2xCE-20 for the SHLV....i.e this methalox engine x2 instead.

Which German website ? Gunter's Space Page ?

Even though methalox (semi cryo methane + LOX) has slightly worse Isp than full-cryo (LH2/LOX)...it is better (iirc) than kerolox (RP-1 and LOX) and might afford better economy and reliability overall in fabrication and use than full cryo.

Sadly we will be replacing the Hydrolox upper stage with the Methalox. The Kerolox lower stage is going nowhere.

From a pure Isp stand point this change makes little sense. Maybe it is something else. Cost, complexity, materials handling & storage etc.

 

[Nilgiri]

Sadly we will be replacing the Hydrolox upper stage with the Methalox. The Kerolox lower stage is going nowhere.

From a pure Isp stand point this change makes little sense. Maybe it is something else. Cost, complexity, materials handling & storage etc.

Not sad at all....if there is brutal cold resource analysis that outputs this route as more optimal, its the way to go.

Isp is just one factor.....i.e do we put a ferrari engine in every car?

Methalox is halfway there between kerolox and hydrolox in Isp, yet carries lot of the advantages of kerolox (i.e semi cryo).

If it literally (production wise with same amount of resources in manpower, money, RnD etc) in say a 10 year span puts a much larger amount of payload into space than hydrolox, it has to be done.

It is part of reason SpaceX (with Raptor engine) is going methalox too.....there is something in its balance w.r.t economy of scale that hits sweetspot that kero and hydro do not.

In jet engines we make similar compromises all the time....i.e take on board a number of factors (raw output and cost related) rather than just one that gets a more known raw hallmark in performance/efficiency.

Do you have references regarding this decision w.r.t methalox for ISRO ULV-HLV?

CE-20 will have role to play seeing out GSLV mk 3 and maybe some of the early ULV I suppose. Let us see.

 

[Gautam]

Do you have references regarding this decision w.r.t methalox for ISRO ULV-HLV?

Here is what we know of the Methalox so far :

Dr. Somnath, the current director of VSSC, stated in 2016 that ISRO was developing a pathfinder project for Methalox propulsion. The engine was supposed to be small and produce around 3 tons (~30 kN) of thrust. They were just trying to develop operational experience of Methalox engines. At that time there was no intention of switching the upper stage Hydrolox engines with Methalox.

Around 2018-19 news about another Methalox engine started doing rounds. This one was supposed to have 10 tons of thrust. Here is a slide about the 10 ton (98 kN) Methalox engine. Sorry but this is the best quality photo I could find. I am sure there is a better quality version somewhere. I can't seem to find it.

So we have 2 Methalox engines ? A 3 ton & a 10 ton thrust class. In 2019 there was news reports that the 10 ton engine was a derivative of a Hydrolox engine & the 3 ton engine has a electric pump motor.

One of the two projects is trying to convert the existing cryogenic engine, which uses liquid hydrogen for fuel, into a LOx-Methane engine. The other is a smaller engine of 3 tonnes thrust, which will feature an electric motor.

Source: https://www.thehindubusinessline.co...ane-powered-rocket-engine/article29483292.ece

The Hydrolox engine that the 10 ton Methalox engine is based on is probably the CE-7.5 engine. But the new Methalox will be more powerful than its Hydrolox predecessor. The CE-7.5 can deliver a max thrust of 73.5 kN as opposed to 98 kN of the Methalox. The 3 ton engine is completely new and it can be used on satellites/landers as thrusters replacing the hypergolic LAM.

In August of 2020, we get news that there is yet another Metholox engine under development. Dr. Somnath in a presentation says that LPSC is getting ready to test the 10 ton Methalox engine. This is also where Dr. Somnath mentions plans to replace the CE-7.5 & even the CE-20 engines with the upcoming Methalox engine. The Methalox engines might be clustered replace the cryogenic engines. The 10 ton Methalox is shown in the poster below.

https://twitter.com/i/web/status/1294174427001901056

ISRO can replace the CE-7.5 with one Methalox engine. They will need to cluster 3 of the Methalox to replace the CE-20 though. The CE-20 falls in the 200 - 220 kN (20.4 - 22.4 ton) thrust category.

The poster above says they are studying 3 operating cycles :
1. Fuel Rich Staged Combustion Cycle : The CE-7.5 is a FRSCC engine. It's Methalox derivative inherits that operating cycle.
2. Expander cycle : For the 3 ton Methalox engine. A simple operating cycle to replace an equally simple hypergolic cycle.
3. Gas Generator cycle : This is the new engine I was talking about. The CE-20 is a GG cycle engine, ISRO is trying to make a Methalox derivative of that too ?

A Methalox derivative of CE-20 will probably produce more thrust than the original. The CE-20 is currently one of the most powerful cryogenic upper stage engine in the world. A more powerful version of that engine can clustered & used on the HLV/SHLV.

Also notice the Isp, just 360+ sec. That's probably vacuum Isp not sea level. The CE-7.5 engine had vaccum Isp of 454 seconds. A 94 sec drop in Isp or 0.92 km/sec drop in velocity. Quite a significant drop. Whatever has been gained in thrust levels is being bled away by Isp.

Still they should be able to do most, if not all, earth bound satellite launches using the Methalox engine. But I think they will have to retain the hydrolox engines for interplanetary missions. Given the CE-7.5 has been problematic in service & this is the smallest hydrolox we have, ISRO will probably retire that. The CE-20 however is going nowhere, at least until we develop a FRSCC cycle hydrolox engine of that thrust class. I doubt ISRO would do that though. The Isp gain for switching from a GG cycle to a FRSCC cycle would be 10-15 seconds. Which is good but probably not enough to justify the investment.

The development of a 200-250 kN FRSCC cycle hyrolox engine would cost around $1-1.5 billion and take about 5-6 years. $1.5 billion for an Isp gain of 15 seconds ? No thank you. ISRO will just keep making larger & larger upper stage tanks to carry more fuel. So the upper stage engine will need to be certified for higher burn times. That's not the most efficient way but it is a lot cheaper.

ISRO is already doing that. The CE-20 engine burns for around 600 seconds. That has been upgraded to 800 seconds. I already mentioned there are at least 4 different cryo stages being made/proposed. The C32, C34, C27 & the C90 carrying 32, 34, 27 & 90 tons of propellant respectively. The currently used stage in GSLV is the C25.

Anyway that's enough rambling from me.

In December of 2020, ISRO chairman mentions testing a Methalox engine. Presumably 10 ton engine as the 3 tons engine has already been tested.

"One month back, we tested the LOX/Methane engine and the results were good," Sivan said.

Source: https://economictimes.indiatimes.co...for-rockets/articleshow/80045012.cms?from=mdr

The LPSC website says that Cold Flow tests of the Methalox engine was successully carried out in October 2020. The tests probably ran from October to November.

Source: https://www.lpsc.gov.in/timeline.html

Since then there has been no further updates. COVID was probably screwed this too. Unlike the SCE-200 there is no problems with testing. The test stand at Mahendragiri can easily test all of these Methalox engines.

OTOH, Skyroot Aerospace managed to test their 100% 3D printed regeneratively cooled LNG-LOX cryogenic engine called "Dhawan-1" in September 2020.

We don't have the thrust figures yet but this can probably generate no more than 30 kN. So not as powerful as ISRO's engine but still a pretty good effort.

 

[Gessler]

OTOH, Skyroot Aerospace managed to test their 100% 3D printed regeneratively cooled LNG-LOX cryogenic engine called "Dhawan-1" in September 2020.
View attachment 31316
We don't have the thrust figures yet but this can probably generate no more than 30 kN. So not as powerful as ISRO's engine but still a pretty good effort.

Did they actually test it? IIRC, they just unveiled it - all the testing so far concerned only the solid motors & the only liquid one to be tested was the orbit-adjustment motors.

 

[Gautam]

Did they actually test it? IIRC, they just unveiled it - all the testing so far concerned only the solid motors & the only liquid one to be tested was the orbit-adjustment motors.

They said so on their twitter page. Strange their twitter page is down. Can you access it ?

 

[Gessler]

They said so on their twitter page. Strange their twitter page is down. Can you access it ?

No, can't even find it. Strange.

 

[Nilgiri]

The 3 ton engine is completely new and it can be used on satellites/landers as thrusters replacing the hypergolic LAM.

This indeed is a major advantage to methalox, it can be scaled and applied quite readily...and you get many dividends from one "chunk" of research.

It (methane) can also be produced on other planetary systems more readily (than say hydrogen and definitely more than kerosene which is a complex fossil fuel)...of course far in the future kind of thing, but still worth to chart the underlying basis early now.

3. Gas Generator cycle : This is the new engine I was talking about. The CE-20 is a GG cycle engine, ISRO is trying to make a Methalox derivative of that too ?

Stands to reason as very likely. Consider much is being done for kerolox for the lower stage which is already semi-cryo. A lot of double dipping can be done for methane+LOX from that off the bat compared to full cryo hydrolox.

Liquid hydrogen is never friendly material at the best of times....doing away with it all together and only having to worry about LOX side of things eases up on lot of RnD on (I would think) a whole array of things regarding turbopump reliability and all the plumbing for starters.

Also notice the Isp, just 360+ sec. That's probably vacuum Isp not sea level. The CE-7.5 engine had vaccum Isp of 454 seconds. A 94 sec drop in Isp or 0.92 km/sec drop in velocity. Quite a significant drop. Whatever has been gained in thrust levels is being bled away by Isp.

Perfectly fine provided/given:

a) That Isp will improve with more RnD application (using SpaceX raptor as reference I believe the objective lies somewhere in the low 400s currently, though it is a staged combustion cycle, not GG)

b) You are assuming same volume and mass of fuel for velocity drop. But one can simply provision the (methalox) stage with appropriately more fuel (and thus mass) to get same delta V.

(b) may seem like a backward step (i.e making the whole rocket somewhat bulkier given a heavier upper stage will also cascade downwards with payload requirements held constant)...but again you have to remember the larger total costs involved.

i.e There is a reason why full cryo (hydrolox) is rarely used as a bulk core lower stage even though it has the best Isp (and could theoretically produce the lightest rocket per payload). It simply costs too much (especially at those thrust needs scaling wise) and hence why kerolox (RP-1 + LOX) is the "go to" gold standard there.

It is again that whole "LH2 is never friendly material at best of times" imposing (fairly heavily) on the actual rocket engine design, fabrication and system scaling costs while maintaining the required reliability.

Hence why hydrolox is relegated to upper stage (if that) generally where you have no more air resistance to punch through as much and you can actually harness its fuel efficiency premium well.

So simply put if in X period of time with Y amount of resources inputted....you get slightly less efficient rockets (individually) but they end up costing less (esp far less) than that efficiency loss (to make up for it), its a good thing to go for....as you simply will be able to launch (given the costs impact on production chain) an X-ton payload 10 times a year instead of say 6 times...even though the latter technically uses the more efficient/elegant upper stage.

i.e cost paradigms like scaling up lower stage (and del cost increase there) to accomodate slightly heavier upper stage of methalox (del cost decrease there) ....compared to the del costs of expensive "premium Isp " upper stage (high cost) and less need (cost saving) in lower stage.

Then the fact that hydrolox has no real scaleability to other kind of rocket thrusters (given the nastiness of LH2 and hand holding needed for it).

It is conceptually the same reason I mention earlier with the ferrari engine being good for a sports car but to actually get a population mobile, you need lot more cheaper options of transport (rather than just one kind of apex).

In any case you pretty much summarized this kind of stuff yourself right after (my bad as I was responding as I read):

Given the CE-7.5 has been problematic in service & this is the smallest hydrolox we have, ISRO will probably retire that. The CE-20 however is going nowhere, at least until we develop a FRSCC cycle hydrolox engine of that thrust class. I doubt ISRO would do that though. The Isp gain for switching from a GG cycle to a FRSCC cycle would be 10-15 seconds. Which is good but probably not enough to justify the investment.

As for skyroot et al:

We don't have the thrust figures yet but this can probably generate no more than 30 kN. So not as powerful as ISRO's engine but still a pretty good effort.

It indeed is a great effort as the key thing here is production turnaround. If engines can reliably be printed, that saves immense amount of manhours and associated costs.

What thrust you do manage to get is somewhat secondary to that as this is gamechanger for lot of light payload missions...that takes the burden off the resource-heavy rockets which can then focus on heavier set piece payloads.

==========================

@Sinan @Joe Shearer @Saithan @xenon5434 @UkroTurk 🚬 @VCheng et al may find this thread a good read.

 

[Gautam]

This indeed is a major advantage to methalox, it can be scaled and applied quite readily...and you get many dividends from one "chunk" of research.

It (methane) can also be produced on other planetary systems more readily (than say hydrogen and definitely more than kerosene which is a complex fossil fuel)...of course far in the future kind of thing, but still worth to chart the underlying basis early now.




Stands to reason as very likely. Consider much is being done for kerolox for the lower stage which is already semi-cryo. A lot of double dipping can be done for methane+LOX from that off the bat compared to full cryo hydrolox.

Liquid hydrogen is never friendly material at the best of times....doing away with it all together and only having to worry about LOX side of things eases up on lot of RnD on (I would think) a whole array of things regarding turbopump reliability and all the plumbing for starters.




Perfectly fine provided/given:

a) That Isp will improve with more RnD application (using SpaceX raptor as reference I believe the objective lies somewhere in the low 400s currently, though it is a staged combustion cycle, not GG)

b) You are assuming same volume and mass of fuel for velocity drop. But one can simply provision the (methalox) stage with appropriately more fuel (and thus mass) to get same delta V.

(b) may seem like a backward step (i.e making the whole rocket somewhat bulkier given a heavier upper stage will also cascade downwards with payload requirements held constant)...but again you have to remember the larger total costs involved.

i.e There is a reason why full cryo (hydrolox) is rarely used as a bulk core lower stage even though it has the best Isp (and could theoretically produce the lightest rocket per payload). It simply costs too much (especially at those thrust needs scaling wise) and hence why kerolox (RP-1 + LOX) is the "go to" gold standard there.

It is again that whole "LH2 is never friendly material at best of times" imposing (fairly heavily) on the actual rocket engine design, fabrication and system scaling costs while maintaining the required reliability.

Hence why hydrolox is relegated to upper stage (if that) generally where you have no more air resistance to punch through as much and you can actually harness its fuel efficiency premium well.

So simply put if in X period of time with Y amount of resources inputted....you get slightly less efficient rockets (individually) but they end up costing less (esp far less) than that efficiency loss (to make up for it), its a good thing to go for....as you simply will be able to launch (given the costs impact on production chain) an X-ton payload 10 times a year instead of say 6 times...even though the latter technically uses the more efficient/elegant upper stage.

i.e cost paradigms like scaling up lower stage (and del cost increase there) to accomodate slightly heavier upper stage of methalox (del cost decrease there) ....compared to the del costs of expensive "premium Isp " upper stage (high cost) and less need (cost saving) in lower stage.

Then the fact that hydrolox has no real scaleability to other kind of rocket thrusters (given the nastiness of LH2 and hand holding needed for it).

It is conceptually the same reason I mention earlier with the ferrari engine being good for a sports car but to actually get a population mobile, you need lot more cheaper options of transport (rather than just one kind of apex).

In any case you pretty much summarized this kind of stuff yourself right after (my bad as I was responding as I read):



As for skyroot et al:

It indeed is a great effort as the key thing here is production turnaround. If engines can reliably be printed, that saves immense amount of manhours and associated costs.

What thrust you do manage to get is somewhat secondary to that as this is gamechanger for lot of light payload missions...that takes the burden off the resource-heavy rockets which can then focus on heavier set piece payloads.

==========================

@Sinan @Joe Shearer @Saithan @xenon5434 @UkroTurk 🚬 @VCheng et al may find this thread a good read.

@Nilgiri I am doing some compiling of ISRO's rocket engine components, turbopumps etc. on SF. This may interest you.

https://www.strategicfront.org/forums/threads/isros-engines-designs-components-prototypes.4385/

 

[Gessler]

shush

Thanks to GODOFPARADOXES on Twitter for finding info about the new developments.

I had previously written quite a bit about the requirement for a solid-fueled TEL-based Satellite Launch Vehicle* capability to quickly re-establish at least a limited satellite-based capability set in the event of existing long-term satellites being disabled/destroyed by hostile action in space. I had anticipated that this capability will be derived from the SSLV rocket being developed by ISRO - did not expect the defence agency DRDO (which builds missiles) to take this program forward.

Which is just as well, because from the looks of it, the VEDA seems to have a lot in common with the PDV Mk-2 ASAT missile in terms of form factor. This may allow for not only TEL-based all-terrain mobility, but perhaps also canisterization (with pre-determined satellite payloads)- likely to be a significant tactical advantage over similar concepts being explored by China like the Kuaizhou-11:

With modern Hall thrusters and their Xenon fuel, traditional liquid-fueled motors (which would have prevented such long-term storage options) are no longer necessary even for Orbital Maneuvering (up to a point anyway).

* https://defencehub.live/threads/the-future-of-indian-orbital-rockets.8512/

In all likelihood this missile/rocket (whatever you wanna call it...the lines probably haven't been that blurred since Titan-II!) would be owned & operated by the newly formed Defence Space Agency.

Defence Space Agency - Wikipedia

en.wikipedia.org

@Gautam @Nilgiri - would like your views. I may have gotten a bit carried away in the hurry.

Tagging you as well @Cabatli_53 and @Test7 as I believe you are interested in rocketry in general.

 

[Raptor]

shush

View attachment 32174

View attachment 32175

Thanks to GODOFPARADOXES on Twitter for finding info about the new developments.

I had previously written quite a bit about the requirement for a solid-fueled TEL-based Satellite Launch Vehicle* capability to quickly re-establish at least a limited satellite-based capability set in the event of existing long-term satellites being disabled/destroyed by hostile action in space. I had anticipated that this capability will be derived from the SSLV rocket being developed by ISRO - did not expect the defence agency DRDO (which builds missiles) to take this program forward.

Which is just as well, because from the looks of it, the VEDA seems to have a lot in common with the PDV Mk-2 ASAT missile in terms of form factor. This may allow for not only TEL-based all-terrain mobility, but perhaps also canisterization (with pre-determined satellite payloads)- likely to be a significant tactical advantage over similar concepts being explored by China like the Kuaizhou-11:

View attachment 32178

With modern Hall thrusters and their Xenon fuel, traditional liquid-fueled motors (which would have prevented such long-term storage options) are no longer necessary even for Orbital Maneuvering (up to a point anyway).

* https://defencehub.live/threads/the-future-of-indian-orbital-rockets.8512/

In all likelihood this missile/rocket (whatever you wanna call it...the lines probably haven't been that blurred since Titan-II!) would be owned & operated by the newly formed Defence Space Agency.

Defence Space Agency - Wikipedia

en.wikipedia.org

@Gautam @Nilgiri - would like your views. I may have gotten a bit carried away in the hurry.

Tagging you as well @Cabatli_53 and @Test7 as I believe you are interested in rocketry in general.

Why not use sslv in this regard or even Vikram 1?

 

[Gessler]

Why not use sslv in this regard or even Vikram 1?

It would depend on what DSA's doctrine & requirements are.

If they are serious about canisterization & long-term storage of prepared satellite payloads, SSLV would be too big.

That's why probably decided on a platform that uses K4 SLBM booster stage (which our ASAT missile also uses).