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Isro eyes kerosene to boost GSLV Mk III’s lifting power to 6 tonnes

Nilgiri

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https://timesofindia.indiatimes.com...r-to-6-trillion/articleshowprint/67716433.cms

NEW DELHI: Indian Space Research Organisation (Isro) is working on upgrading its heavylifter GSLV Mk III where the upper stage of the rocket will have highly refined form of kerosene as fuel in order to increase its payload capability.

Talking to TOI, Isro chairman K Sivan said, “To increase the payload capability of GSLV Mk III+ from 4 tonnes to 6 tonnes, we are in the process of making some improvements in rocket stages. First, we are working on enhancing the cryogenic stage fuel loading from 25 tonnes to 30 tonnes. Second, we are also working on changing the core stage L110 — which has 110 tonnes of unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide (N2O4). We want to replace L110 stage with semicryogenic engine that will carry liquefied oxygen and highly refined kerosene called kerolox (aka RP-1) instead of liquefied hydrogen.”

Sivan said, “The first test of the advanced version of Mk III will take place in December 2020. With upgrade in Mk III, we will also have to upgrade the launchpad facility at Sriharikota. We have therefore issued a tender notice recently inviting quotations for infrastructure upgrades at the second launchpad.”

However, the chairman clarified the rocket with the semicryogenic stage won't be used for the Gaganyaan mission. The current GSLV Mk III with L110 stage will only be used for the manned mission with some modifications.

The advantage of using kerolox is that it is 10 times dense — meaning the same volume of kerolox will generate more thrust than the same volume of hydrolox*. It is also cheaper, more stable at room temperature and less hazardous than hydrolox. Elon Musk-promoted Space X currently uses kerolox in its Falcon 9 rocket for launching heavy payloads.

“With increase in payload capacity, the advanced GSLV MK III will help Isro cut expenses and save time,” Sivan said. Currently, India uses the services of Arianespace to launch its heavy satellites weighing over 4 tonnes. Last year on December 4, Isro had used the services of Arianespace for launching its heaviest satellite Gsat-11 weighing over 5.7 tonnes from French Guiana.

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

*Nilgiri note: Isp is superior for H2/LOX and offsets the density disadvantage at higher altitudes (where Isp becomes the key factor). A good basic read on the issue: http://blog.retlaw.net/blog/2014/11/3/why-use-kerosene-in-a-rocket

@Dante80 @GeraltofRivia ....Making more use of the GSLV platform over time (like has been brought up in comparisons with other launchers). Specific impulse of RP-1/LOX is around 350 seconds..whereas for UDMH/N2O4..its 293 seconds.

This will bring payload from 4 tonnes to 6 tonnes (to GTO).

@VCheng @Joe Shearer @Vibrio @Skull and Bones @randomradio @Water Car Engineer @jbgt90 @scorpionx
 
*Nilgiri note: Isp is superior for H2/LOX and offsets the density disadvantage at higher altitudes (where Isp becomes the key factor). A good basic read on the issue: http://blog.retlaw.net/blog/2014/11/3/why-use-kerosene-in-a-rocket

@Dante80 @GeraltofRivia ....Making more use of the GSLV platform over time (like has been brought up in comparisons with other launchers). Specific impulse of RP-1/LOX is around 350 seconds..whereas for UDMH/N2O4..its 293 seconds.

This will bring payload from 4 tonnes to 6 tonnes (to GTO).

For reference, linking two good database pages for the LV.
http://spaceflight101.com/spacerockets/gslv-mk-iii/
http://www.spacelaunchreport.com/gslvmk3.html

Now, for the article itself.
Yes, a change like this has a lot of merit. You could say that the L110 stage is the main culprit for GSLV not being able to throw more than 4t to GTO-1800. I mean, the thing has the same GLOW as CZ-5 (for example), but only 40% the performance at this reference orbit.

It is understandable. The Vikas engine relies on very early Ariane pedigree, and while the standard hypergolic solution has some merits (in handling and ease of air ignition for example), said merits are squandered by the bad efficiency of the stage (that has to act as a sustainer too).

Replacing L110 with a kerolox stage would do wonders for the LV. Here is some speculation on how it will be done.

1. A year back or so, I came upon this entry on RSW. I did not know that Yuzhmash was contracted for this one, although it is pretty apparent why. Now it is pretty evident that they were working on SCE-200. I think that it is pretty certain that the engine will be used on the new stage.

2. So, the two Vikas on L-110 will be replaced by a single SCE-200. With a pretty spiffy ORSC component and a lot more efficiency (around 335 Isp at vac), this engine is going places. Literally..XD

3. Have in mind the following. SCE-200 is probably not air-ignitable. I base this assertion on the fact that the engine itself is very, very similar to the RD-810 that is designed for the Mayak and the new Zenit. I'll come back to this later.

4. If you pay attention on the article above, it says that the launchpad facility at Sriharikota will have to be upgraded. At first glance, this is pretty much expected, but the article also talks about the fact that the C-25 upper stage is also getting a 16% propellant increase too (accompanied I presume with a stage stretch too).

Now, let's do some synthesis. We know that the SCE-200 is not air ignitable, that C-25 is getting a stretch, that SCE-200 has a lot more than double the thrust of the Vikas 2 (of which a pair is used in L110) and that Sriharikota 2 is getting an upgrade.

So, I opened up SilverBirds and started playing around. C:

What I got out of it is that the new stage will hold around 200t~210t of propellant, and if it works as advertised then the new GSLV will be 7-8m taller (for a total height of more than 50m, assuming that the new stage uses the same 4m diameter Al structure).

What I also got out is that in that case Mr Sivan is not really telling us the whole story, since the projected GTO-1800 performance for the LV will be much more than 6t. What I got was close to 7.3t from a GLOW of ~730t (which is the same weight as Ariane 5, for reference).

Pretty good stuff!
 
For reference, linking two good database pages for the LV.
http://spaceflight101.com/spacerockets/gslv-mk-iii/
http://www.spacelaunchreport.com/gslvmk3.html

Now, for the article itself.
Yes, a change like this has a lot of merit. You could say that the L110 stage is the main culprit for GSLV not being able to throw more than 4t to GTO-1800. I mean, the thing has the same GLOW as CZ-5 (for example), but only 40% the performance at this reference orbit.

It is understandable. The Vikas engine relies on very early Ariane pedigree, and while the standard hypergolic solution has some merits (in handling and ease of air ignition for example), said merits are squandered by the bad efficiency of the stage (that has to act as a sustainer too).

Replacing L110 with a kerolox stage would do wonders for the LV. Here is some speculation on how it will be done.

1. A year back or so, I came upon this entry on RSW. I did not know that Yuzhmash was contracted for this one, although it is pretty apparent why. Now it is pretty evident that they were working on SCE-200. I think that it is pretty certain that the engine will be used on the new stage.

2. So, the two Vikas on L-110 will be replaced by a single SCE-200. With a pretty spiffy ORSC component and a lot more efficiency (around 335 Isp at vac), this engine is going places. Literally..XD

3. Have in mind the following. SCE-200 is probably not air-ignitable. I base this assertion on the fact that the engine itself is very, very similar to the RD-810 that is designed for the Mayak and the new Zenit. I'll come back to this later.

4. If you pay attention on the article above, it says that the launchpad facility at Sriharikota will have to be upgraded. At first glance, this is pretty much expected, but the article also talks about the fact that the C-25 upper stage is also getting a 16% propellant increase too (accompanied I presume with a stage stretch too).

Now, let's do some synthesis. We know that the SCE-200 is not air ignitable, that C-25 is getting a stretch, that SCE-200 has a lot more than double the thrust of the Vikas 2 (of which a pair is used in L110) and that Sriharikota 2 is getting an upgrade.

So, I opened up SilverBirds and started playing around. C:

What I got out of it is that the new stage will hold around 200t~210t of propellant, and if it works as advertised then the new GSLV will be 7-8m taller (for a total height of more than 50m, assuming that the new stage uses the same 4m diameter Al structure).

What I also got out is that in that case Mr Sivan is not really telling us the whole story, since the projected GTO-1800 performance for the LV will be much more than 6t. What I got was close to 7.3t from a GLOW of ~730t (which is the same weight as Ariane 5, for reference).

Pretty good stuff!

A real treat to read! Thanks!
 
This is in line with the goal of ISRO to double the capacity of all its launch vehicles.
 
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