Indian Space Program: News & Discussion - Sept 2016

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Re: Indian Space Programme Discussion - Sept 2016

Postby pankajs » 14 May 2018 08:16

http://www.thehindu.com/sci-tech/scienc ... 874464.ece
ISRO making green propellant
Scientists at the Indian Space Research Organisation (ISRO) have reported progress in the development of an environment-friendly propellant to power satellites and spacecraft.

The effort is to replace the conventional hydrazine rocket fuel, a highly toxic and carcinogenic chemical, with a greener propellant for future missions. Initial tests by a research team at the Liquid Propulsion Systems Centre (LPSC) here have shown promising results in the formulation and associated tests of a propellant blend based on hydroxylammonium nitrate (HAN).

<snip>

The in-house formulation consists of HAN, ammonium nitrate, methanol and water. While methanol was added to reduce combustion instability, the choice of AN was dictated by its capacity to control the burn rate and lower the freezing point of the propellant.

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Re: Indian Space Programme Discussion - Sept 2016

Postby SSridhar » 20 May 2018 15:29

L&T Defence to manufacture ISRO rocket engines in Coimbatore - The Hindu

L&T Defence will soon start manufacturing rocket engines in Coimbatore to power launch vehicles for the Indian Space Research Organisation (ISRO), Jayant Patil, member, L&T Board, said here on Saturday.

Speaking at a function the company had organised to deliver the 1,000th Integrated Propulsion Airframe System Hardware of Akash missile, he said it had just completed the ground breaking ceremony for a 5th plant in Coimbatore.

The plant that would be operational by the end of the current financial year would manufacture the rocket engines to cater to the increasing demand from the ISRO which plans a series of launches in the near future, said Mr. Patil, who is also the whole-time director, L&T Defence.

It had a similar manufacturing unit in Vadodara and the Coimbatore factory would be in addition to that as the ISRO demand has doubled from the 10 to 12 sets a year until recently. The company chose Coimbatore because there was a good ecosystem of suppliers of components, he noted.

The company’s association with the ISRO was not something new. It was at least four decades old as it had been working since the time of SLV rockets.

Likewise, L&T Defence units in Coimbatore were also supplying the airframe for the BrahMos missiles and would supply more components.

The company had also been associated with the Defence Research and Development Organisation in its missile development programmes and Akash surface to air missile was a major project for the company, Mr. Patil said and added that it also manufactured Akash sub systems like parts of radars and launchers.

A release from L&T Defence said that integrated airframe and system hardware was a critical system of the Akash missile comprising sustainer and booster motors and 112 sub assemblies, powering the missile with multi-directional and multi-target area defence.

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Re: Indian Space Programme Discussion - Sept 2016

Postby jaysimha » 06 Jun 2018 17:02

http://pib.nic.in/PressReleaseIframePage.aspx?PRID=1534505

Cabinet approves Polar Satellite Launch Vehicle Mark-III Continuation Programme – Phase 6

Thirty Operational Flights of PSLV
Posted On: 06 JUN 2018 3:25PM by PIB Delhi
The Union Cabinet chaired by Prime Minister Shri Narendra Modi has approved the Polar Satellite Launch Vehicle (PSLV) Continuation Programme (Phase 6) and funding of thirty PSLV operational flights under the Programme.

The Programme will also meet the launch requirement of satellites for Earth observation, Navigation and Space Sciences. This will also ensure the continuity of production in Indian industry.

The total fund requirement is Rs. 6131.00 Crores and includes the cost of thirty PSLV vehicles, essential facility augmentation, Programme Management and Launch Campaign.

Major Impact:

The operationalisation of PSLV has made the country self-reliant in the launching capability of satellites for earth observation, disaster management, navigation and space sciences. The PSLV Continuation programme will sustain this capability and self-reliance in the launching of similar satellites for national requirements.

The PSLV Continuation Programme – Phase 6 will meet the demand for the launch of satellites at a frequency up to eight launches per year, with maximal participation by the Indian industry. All the operational flights would be completed during the period 2019-2024.

The Programme will also meet the launch requirement of satellites for Earth observation, Navigation and Space Sciences. This will also ensure the continuity of production in Indian industry.

PSLV Continuation Programme was initially sanctioned in 2008, and four phases have been completed and the fifth phase is expected to be completed by Q2 of 2019-20. The Phase 6 approval will cater to the launch of satellite missions during the period Q3 of 2019-20 to Q1 of 2023-24.


Background:

PSLV has emerged as a versatile launch vehicle to carry out Sun-Synchronous Polar Orbit (SSPO), Geo-synchronous Transfer Orbit (GTO) and low inclination Low Earth Orbit (LEO) missions. With the recent successful launch of PSLV-C41 on 12th April, 2018, PSLV has completed three developmental and forty three operational flights and the last forty one flights have been successful. PSLV has established itself as a workhorse vehicle for national satellites with a production capacity that would enable responding fast to commercial launch opportunities also.


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http://pib.nic.in/PressReleaseIframePage.aspx?PRID=1534499

Cabinet approves Continuation Programme for Geosynchronous Satellite Launch Vehicle Mark-III
Posted On: 06 JUN 2018 3:21PM by PIB Delhi
The Union Cabinet chaired by Prime Minister Shri Narendra Modi has approved funding for the for Geosynchronous Satellite Launch Vehicle Mark-III (GSLV Mk-III) continuation programme (Phase-I) consisting of ten (10) GSLV (Mk-III) flights, at a total estimated cost of Rs. 4338.20 crores. This includes Rs. 4338.20 Crores and includes the cost of ten GSLV Mk-III vehicles, essential facility augmentation, Programme Management and Launch Campaign.

The GSLV Mk-III continuation Programme – Phase 1 is the first phase of operational flights that will enable the launch of 4 tonne class of communication satellites to meet the country’s satellite communication requirements.

The operationalisation of GSLV Mk-III will make the country self-reliant in the launching capability of 4 tonne class of communication satellites, and sustain & strengthen the space infrastructure and reduce the dependence on procured launches from foreign countries.

The operationalisation of GSLV Mk-III will make the country self-reliant in the launching capability of 4 tonne class of communication satellites and sustain & strengthen the space infrastructure and reduce the dependence on procured launches from foreign countries.

The GSLV Mk-III Continuation Programme – Phase 1 will meet the launch requirement of communication satellites to meet the national demand for High Throughput Satellites for rural broadband connectivity, increase and sustain the availability of transponders for DTH, VSAT and Television broadcasters.

GSLV Mk-III Continuation Programme – Phase 1 will be the first phase of operational flights of the GSLV Mk-III launch vehicle and the approval will cater to the launch of satellite missions during the period 2019-2024.

Background:

The Geosynchronous Satellite Launch Vehicle Mark-III (GSLV Mk-III) has been developed towards achieving indigenous launch capability to launch 4 tonne class of satellites into Geosynchronous Transfer Orbit (GTO). It has completed one experimental flight (LVM3-X) in 2014 and one developmental flight (GSLV MkIII-D1) in 2017. The second developmental flight will be completed by Q2 of 2018-19 this year. The Continuation Programme – Phase 1 will enable independent access to space for 4 tonne class of communication satellites, and establish GSLV Mk-III as a cost-effective workhorse vehicle to launch 4 tonne class of communication satellites in order to meet the national requirements as well as to boost its commercial potential in the international market for launch services.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Vips » 06 Jun 2018 22:56

Cabinet approves Rs 10,900 crore for 30 PSLV, 10 GSLV Mk III launches.

In a big boost to India’s space programme, the Cabinet has given the financial approval of Rs 10,900 crore for the launch of 30 PSLV and 10 GSLV Mk III rockets in the next four years.

“With the Cabinet approval of Rs 4,338 crore for 10 launches of 10 GSLV Mk III (Isro’s fat boy) in the next four years, we will be able to launch heavier satellites weighing around 4 tonne. This will be a big leap forward as we don’t have to depend on foreign spaceports for launching heavier satellites,” minister of state in PMO Jitendra Singh said.

“This GSLV Mk II programme has materialised and evolved in the last three to four years under the Modi government. It is in keeping with the Make of India programme and is totally an indigenous programme," Singh said, adding, "With this programme, Isro will be able to launch not only mini satellites of foreign countries but also foreign satellites of over 4 tonne weight.”

The Cabinet has also given approval for 30 PSLV launches with the financial sanction of Rs 6,573 crore, he said.

“Besides the satellite launches, India should look forward to the upcoming Chandrayaan-2 launch in October as it will be a significant achievement in space programme for the country,” the minister said.

Talking to TOI after the Cabinet approval, Isro chairman K Sivan said, “It is the happiest moment for all of us in Isro. The Cabinet approvals for the PSLV and GSLV rocket launches will give a big boost to Indian space programmes. The satellite launches will not only be significant for our space agency but also benefit the common man. Under the Modi government, Isro has taken giant leaps in space programmes.”

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Re: Indian Space Programme Discussion - Sept 2016

Postby Indranil » 06 Jun 2018 23:33

It goes to show the low cost of the Indian launches. PSLV: 30 million per launch and 67 million per GSLV MkIII launch.

But where is the budget for GSLV Mk2?

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Re: Indian Space Programme Discussion - Sept 2016

Postby srin » 07 Jun 2018 00:37

^^^ Further computing ...
cost per kg for PSLV: $7900 (LEO), $25000 (GEO)
cost per kg for GSLV mk3: $6700 (LEO), $16750 (GEO)

Now, this is a bit simplistic because it doesn't account for PSLV XL vs core-only configurations.

SpaceX falcon 9 for LEO costs less than half of this, but it is more complication (expendable vs reusable). I need to research this a bit more.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Indranil » 07 Jun 2018 03:45

Clarifications:
1. I am not sure of all the expenses involved. The chairman said at the beginning of this year that a PSLV launch costs $15 million.
2. The cost of the launches are slated to come down significantly as the volume. For example, godrej only recently reached 60% capacity. The break-even point is at 80%.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Karthik S » 07 Jun 2018 14:26

Dr. Harsh Vardhan

Verified account

@drharshvardhan
Follow Follow @drharshvardhan
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In a step to self-reliance, #ISRO clocks onboard satellites successfully synchronized to #NPL’s primary atomic clocks within 3 nanoseconds-a milestone for high-precision satellite-based communication. #SaafNiyatSahiVikas #vigyansevikas. @IndiaDST, @CSIR_IND, @PMOIndia, @PIB_India


Good news!

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Re: Indian Space Programme Discussion - Sept 2016

Postby kit » 07 Jun 2018 17:14

Karthik S wrote:
Dr. Harsh Vardhan

Verified account

@drharshvardhan
Follow Follow @drharshvardhan
More
In a step to self-reliance, #ISRO clocks onboard satellites successfully synchronized to #NPL’s primary atomic clocks within 3 nanoseconds-a milestone for high-precision satellite-based communication. #SaafNiyatSahiVikas #vigyansevikas. @IndiaDST, @CSIR_IND, @PMOIndia, @PIB_India


Good news!


proves time and again India can develop whatever tech it wants to

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Re: Indian Space Programme Discussion - Sept 2016

Postby Vips » 08 Jun 2018 00:23

Isro gets nod for semi-cryogenic engine, will boost GSLV’s lift capability by 1 tonne.

The Space Commission has given approval to Indian Space Research Organisation (Isro) to develop a semi-croygenic engine, which will increase the lifting capability of its GSLV Mk III rocket by one tonne.

alking to TOI about the new project, Isro chairman K Sivan said, “After a presentation before the Space Commission, Isro has got the approval for developing the semi-cryogenic rocket stage. The deadline to develop this stage is 29 months. Once the stage is ready, the carrying capability of GSLV Mk III will increase from the existing four tonnes to five tonnes.”

Explaining the project, Sivan said, “A GSLV Mk III rocket comprises two strap-on boosters (to provide thrust during a launch), middle stage that carries liquid fuel nitrogen tetroxide and unsymmetrical dimethylhydrazine, and the second stage, which consists of a cryogenic engine. Once the semicryogenic stage is developed, we will simply replace the middle liquid fuel stage with it. The new stage is likely to be an exact fit and the rocket will look like the earlier one from outside"

He said, “The first launch of Isro’s heaviest rocket GSLV Mk III DI last year carried 3.1 tonne weight. The second launch of Mk III D2, scheduled in July this year and which will carry Gsat-29 satellite, will have the load capability of 3.7 tonnes. We can easily raise the weight up to 4 tonne. With the semicryogenic stage, the same rocket will be able to carry the load up to five tonne. With the increased capability, we don’t have to depend on foreign spaceports to launch our satellites weighing over 5 tonnes.”

Sivan said, “Isro’s satellites will now track the production of 25 crops from earlier eight crops. The satellite forecast about the crop acreage and production helps farmers and the government plan better management of the yield.”

Isro has over a dozen remote-sensing satellites like Cartosat, Resourcesat and Risat-1 for agriculture forecast and other social welfare applications. However, the demand for such applications in recent times has increased and therefore the space agency is planning to launch six more satellites dedicated to land and water, cartography, oceanography and environment.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Amber G. » 08 Jun 2018 01:25

^^^(-1) BTW if you want to check your clock (or your computer/iPhone's) against NPL standard, maintained by CSIR --

You can check it here <NPL's clock>

(few dozen milliseconds delay due to the signal reaches you over internet but accurate within .1 second or so).

You can set "time.nplindia.org" in your date/time setting of your computer/tablet and your device will automatically sink to that standard time automatically periodically. (Most computers use MS or apple time server but one can change it in one's setting)

***

Also the article (or a few I checked) does not give technical details (eg witch type of atomic clocks) - wonder if the detail is covered by popular media.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Katare » 08 Jun 2018 06:58

srin wrote:^^^ Further computing ...
cost per kg for PSLV: $7900 (LEO), $25000 (GEO)
cost per kg for GSLV mk3: $6700 (LEO), $16750 (GEO)

Now, this is a bit simplistic because it doesn't account for PSLV XL vs core-only configurations.

SpaceX falcon 9 for LEO costs less than half of this, but it is more complication (expendable vs reusable). I need to research this a bit more.


This should include cost of satellites also.

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Re: Indian Space Programme Discussion - Sept 2016

Postby abhik » 08 Jun 2018 11:25

The Space Commission has given approval to Indian Space Research Organisation (Isro) to develop a semi-croygenic engine, which will increase the lifting capability of its GSLV Mk III rocket by one tonne.

I was under the impression that the development was well under way, with testing to start soon :cry: is it still in PPT stage?

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Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 08 Jun 2018 14:10

It must be for the launcher. The engine is or has undergone tests in Ukraine and full testing will be done in Mahendragiri. Probably this is for the experimental flights etc

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Re: Indian Space Programme Discussion - Sept 2016

Postby JTull » 08 Jun 2018 14:27

Amber G. wrote:^^^(-1) BTW if you want to check your clock (or your computer/iPhone's) against NPL standard, maintained by CSIR --

You can check it here <NPL's clock>

(few dozen milliseconds delay due to the signal reaches you over internet but accurate within .1 second or so).

You can set "time.nplindia.org" in your date/time setting of your computer/tablet and your device will automatically sink to that standard time automatically periodically. (Most computers use MS or apple time server but one can change it in one's setting)

***

Also the article (or a few I checked) does not give technical details (eg witch type of atomic clocks) - wonder if the detail is covered by popular media.


Thanks.

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Re: Indian Space Programme Discussion - Sept 2016

Postby SSridhar » 08 Jun 2018 14:40

abhik wrote:
The Space Commission has given approval to Indian Space Research Organisation (Isro) to develop a semi-croygenic engine, which will increase the lifting capability of its GSLV Mk III rocket by one tonne.

I was under the impression that the development was well under way, with testing to start soon :cry: is it still in PPT stage?

No, not at all. It is for developing the stage and associated test rigs etc. "Isro has got the approval for developing the semi-cryogenic rocket stage."

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Re: Indian Space Programme Discussion - Sept 2016

Postby Katare » 09 Jun 2018 10:55

Why test it in Ukraine? Are we missin testing infra or some tech tie up with Ukrainians?

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Re: Indian Space Programme Discussion - Sept 2016

Postby thammu » 09 Jun 2018 12:31

Katare wrote:Why test it in Ukraine? Are we missin testing infra or some tech tie up with Ukrainians?


The technology has been bought from Ukraine - refer wikileaks

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Re: Indian Space Programme Discussion - Sept 2016

Postby Trikaal » 09 Jun 2018 12:42

thammu wrote:
Katare wrote:Why test it in Ukraine? Are we missin testing infra or some tech tie up with Ukrainians?


The technology has been bought from Ukraine - refer wikileaks

You mean this?
https://wikileaks.org/plusd/cables/07KYIV2245_a.html

It says ISRO bought engine blueprints from Ukraine because Ukraine did not have the capability to actually build the engine.

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Re: Indian Space Programme Discussion - Sept 2016

Postby prasannasimha » 09 Jun 2018 15:28

The blueprints were originally Ukranian but we built the engine ourselves with many modifications and the Ukranians themselves were unable to build the engine. the cold flow test etc were done here in India . I think to speed up testing for such a large engine till our testingfacility for such a large engine was constructed we tested some componentes in Ukraine. At least that is what some reports say.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Trikaal » 09 Jun 2018 19:35

Nothing wrong with buying blueprints. It was actually very smart. Why rebuild the wheel? What is important is that we acquired the technology and became self sufficient. This is TOT in its truest sense, not CKDs and SKDs.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Katare » 10 Jun 2018 01:18

Even NASA and Boeing bought Russian defunct engine designs and data to support their own product developments. It clearly says the contract allows for building one engine which could only be used for studing design features. We would have our own design in parallel is my guess.

Why would Ukrain maintain test facilities for such large rockets which they don’t make or fan’t make or need? Do you have a link that refers to testing in Ukraine?

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Re: Indian Space Programme Discussion - Sept 2016

Postby chola » 10 Jun 2018 01:54

Trikaal wrote:Nothing wrong with buying blueprints. It was actually very smart. Why rebuild the wheel? What is important is that we acquired the technology and became self sufficient. This is TOT in its truest sense, not CKDs and SKDs.


Very smart indeed. We could scavenge Ukraine for a lot more in aerospace. ISRO as a whole has done EXCEPTIONALLY well with home grown solutions so there is no fear that we end up dependent on firangis in this space (no pun intended.)

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Re: Indian Space Programme Discussion - Sept 2016

Postby kit » 10 Jun 2018 05:06

chola wrote:
Trikaal wrote:Nothing wrong with buying blueprints. It was actually very smart. Why rebuild the wheel? What is important is that we acquired the technology and became self sufficient. This is TOT in its truest sense, not CKDs and SKDs.


Very smart indeed. We could scavenge Ukraine for a lot more in aerospace. ISRO as a whole has done EXCEPTIONALLY well with home grown solutions so there is no fear that we end up dependent on firangis in this space (no pun intended.)


Ukraine does have a big base for aerospace .. esp engines for tanks and that revered tech of aerospace / marine turbines and jet engines .. theres just a lot of talent there that can cross pollinate indian tech sector... a big opportunity for indian private companies

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Re: Indian Space Programme Discussion - Sept 2016

Postby ashish raval » 10 Jun 2018 05:24

chola wrote:
Trikaal wrote:Nothing wrong with buying blueprints. It was actually very smart. Why rebuild the wheel? What is important is that we acquired the technology and became self sufficient. This is TOT in its truest sense, not CKDs and SKDs.


Very smart indeed. We could scavenge Ukraine for a lot more in aerospace. ISRO as a whole has done EXCEPTIONALLY well with home grown solutions so there is no fear that we end up dependent on firangis in this space (no pun intended.)

Indeed. In have few friends who are super software engineers from their capital. They are quite keep in research but have lack of funds that west have. Give them funds and they can do things very quickly. In old days one of my professors worked with Ukrainian professors and their premier resesrch lab guys on Stirling engine development.
Have to be mindful about blunt attitude though.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Indranil » 15 Jun 2018 04:32

Does anybody know why S200 boosters on GSLV Mk3 have a burn time of 130 seconds, but separate after 150 seconds?

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Re: Indian Space Programme Discussion - Sept 2016

Postby JTull » 15 Jun 2018 14:03

Indranil wrote:Does anybody know why S200 boosters on GSLV Mk3 have a burn time of 130 seconds, but separate after 150 seconds?


I vaguely remember a discussion here - that was because they wanted to be sure of the aerodynamic stability of the new design (side-by-side) instead of stacked stages. Once the 2nd (core) stage was lit then 1st stage (boosters) would separate. In future they would shorten the gap.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Indranil » 15 Jun 2018 23:03

There was a detail wrong in my original question. The S200 separation occurs at 140 seconds and not 150 seconds as I had originally asked. But my question still stands.

JTull sahab, that cannot be the reason as the second stage lights up at around 114 seconds, 15 seconds before S200 burnout.

One reason could be that S200 actually burns for 140 seconds unlike what has been reported (even by ISRO!) Otherwise, carrying over 60 tons of dead weight makes no sense.

By the way, they did think of using S139 as strapons. Using the current L110 stage and the upper stage the payload is about 3 tons using 2 S139s and 5 tons using 4 S-139s. They don't want to use 4 S139s.

Their first goal is to stabilize the vehicle configuration for 4 tons to GTO using the S200+L110+C25 stage. Next, they will go for optimization and augmentation of C25 stage. By shedding inert weight of the stage and by increasing its fuel capacity they can reach up to 5 tons using the S200, and close to 4 tons using the S139. Replacing the L110 with the SC160 will give them additional 1 ton capability, i.e. 4 tons with S139 boosters and 5 tons using S200. With the optimized and augmented CUS, they can reach 5tons and 6 tons to GTO respectively.

It will be interesting to see if they keep the core stage diameter at 4 mtrs, or upgrade it to 5 mtrs when they move to the SC160 + augmented CUS stage.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Kakarat » 16 Jun 2018 00:09

Indranil wrote:There was a detail wrong in my original question. The S200 separation occurs at 140 seconds and not 150 seconds as I had originally asked. But my question still stands.

JTull sahab, that cannot be the reason as the second stage lights up at around 114 seconds, 15 seconds before S200 burnout.

One reason could be that S200 actually burns for 140 seconds unlike what has been reported (even by ISRO!) Otherwise, carrying over 60 tons of dead weight makes no sense.

By the way, they did think of using S139 as strapons. Using the current L110 stage and the upper stage the payload is about 3 tons using 2 S139s and 5 tons using 4 S-139s. They don't want to use 4 S139s.

Their first goal is to stabilize the vehicle configuration for 4 tons to GTO using the S200+L110+C25 stage. Next, they will go for optimization and augmentation of C25 stage. By shedding inert weight of the stage and by increasing its fuel capacity they can reach up to 5 tons using the S200, and close to 4 tons using the S139. Replacing the L110 with the SC160 will give them additional 1 ton capability, i.e. 4 tons with S139 boosters and 5 tons using S200. With the optimized and augmented CUS, they can reach 5tons and 6 tons to GTO respectively.

It will be interesting to see if they keep the core stage diameter at 4 mtrs, or upgrade it to 5 mtrs when they move to the SC160 + augmented CUS stage.


https://ntrs.nasa.gov/archive/nasa/casi ... 019510.pdf
The design of separation-impulse devices is affected by residual thrust in the expended
stage. On stages with solid-propellant motors, an unexplained phenomenon sometimes
occurs: the solid propellant continues to burn after separation and causes a small
amount of positive thrust in the expended stage (ref. 11). This “chuffing” or
“chugging” can cause the expended stage to overtake and bump the continuing stage.
A similar problem has occurred on stages with liquid-propellant motors when there is a
reignition, or “burp,” after the nominal shutdown of the motor. These problems have
been overcome by igniting the motor of the continuing stage soon after separation, by
programming a long coast time between nominal burnout and separation to allow the
residual thrust to die out, or by moving the expended stage from the vicinity of the
continuing stage after separation by using one of the auxiliary devices discussed in
Section 2.1.3. The burp problem on liquid-propellant engines has also been relieved by
changing the fuel/oxidizer mixture ratio.


Though this is from NASA, ISRO could be doing it for similar reasons

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Re: Indian Space Programme Discussion - Sept 2016

Postby Indranil » 16 Jun 2018 00:26

It can be a reason. But ISRO takes care of this for S200 in a different way. The joint in the front is pyro separated moments before the joint at the back. This makes the residual energy of the spent stages take them away from the rest of the vehicle.

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Re: Indian Space Programme Discussion - Sept 2016

Postby arun » 16 Jun 2018 10:13

Agni V has taken another route to the problem of ensuring that the expended stage does not overtake and bump into the continuing stage. Retro-Rockets for stage separation.

T.S. Subramanian’s April 21, 2012 interview with Avinash Chander, then Chief Controller, Missiles and Strategic Systems, DRDO

We then went through a total philosophy change. Up to Agni-III, we ignite the upper stage first, then separate the lower stage so that there is no problem of separation.

We decided to leave behind that culture of space vehicles. We now put big retro motors, which create a thrust of four tonnes each – totally 16 tonnes of thrust – just to separate the stages so that no dead weight is passed on to the upper stage.


See Frontline:

‘Quality our concern'

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Re: Indian Space Programme Discussion - Sept 2016

Postby souravB » 16 Jun 2018 17:17

I don't know if this is the right thread to ask this or not, but I didn't found any other space based thread.
I wanted to ask any erudite people out there on India's capability of satellite based missile launch and flight path tracking.
I know we have come leaps and bound on satellite sensors but on this specific topic I came up empty on Google.
I know it's a very hush topic, but just wanted a general idea of where we are in this matter. you can just wink and I will take the hint. :rotfl:

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Re: Indian Space Programme Discussion - Sept 2016

Postby Vips » 17 Jun 2018 08:56

Isro spy case: The scientist who came in from the cold.

“We can direct compensation to be paid by persons involved in the investigation… We will require the state to recover the compensation from their properties…” Chief Justice Dipak Mishra added, “Let them sell their houses and pay. We are not concerned.” Going further, the Bench said, “We will clarify in our order that his reputation was dented… by this judgement, his reputation is reinstated.”


The Congress faction led by former defence minister AK Antony used the opportunity to bring down his archrival, then chief minister K Karunakaran, through allegations that his confidant, then Inspector General of Police Raman Srivastava, was also involved in the “spy case”

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Re: Indian Space Programme Discussion - Sept 2016

Postby Haridas » 17 Jun 2018 12:25

Indranil wrote:There was a detail wrong in my original question. The S200 separation occurs at 140 seconds and not 150 seconds as I had originally asked. But my question still stands.

JTull sahab, that cannot be the reason as the second stage lights up at around 114 seconds, 15 seconds before S200 burnout.

One reason could be that S200 actually burns for 140 seconds unlike what has been reported (even by ISRO!) Otherwise, carrying over 60 tons of dead weight makes no sense.

Stage thust of solid stage tapers rapidly after 130 sec, but still needs to drop significantly so that comparatively lesser thrust / impulse of retro rocket become useful (in addition to Aero load) .

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Re: Indian Space Programme Discussion - Sept 2016

Postby Haridas » 17 Jun 2018 12:34

^^^ saw that Kakarat gave nasa reference on same line.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Hari Seldon » 17 Jun 2018 14:38

souravB wrote:you can just wink and I will take the hint. :rotfl:

wink wink.

But more seriously, mil applications for ISRO assets is a hush topic for good reason. Lotsa damage potential in commercial launch orders, inter-agency relationships etc. (not to mention tech sanctions) might apply if ISRO comes out of the closet, such as it were.

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Re: Indian Space Programme Discussion - Sept 2016

Postby souravB » 17 Jun 2018 16:31

Hari Seldon wrote:wink wink.

But more seriously, mil applications for ISRO assets is a hush topic for good reason. Lotsa damage potential in commercial launch orders, inter-agency relationships etc. (not to mention tech sanctions) might apply if ISRO comes out of the closet, such as it were.

thanks for replying.. yeah I know the implications for it.. oh and finally found one research paper written by some American expert in 2010..

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Re: Indian Space Programme Discussion - Sept 2016

Postby dinesha » 17 Jun 2018 18:33

souravB wrote:I don't know if this is the right thread to ask this or not, but I didn't found any other space based thread.
I wanted to ask any erudite people out there on India's capability of satellite based missile launch and flight path tracking.
I know we have come leaps and bound on satellite sensors but on this specific topic I came up empty on Google.
I know it's a very hush topic, but just wanted a general idea of where we are in this matter. you can just wink and I will take the hint. :rotfl:

You will get a fair idea from this Dec 2015 report by S. Chandrashekar
http://isssp.in/wp-content/uploads/2016 ... -India.pdf

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Re: Indian Space Programme Discussion - Sept 2016

Postby Haridas » 17 Jun 2018 22:20

dinesha wrote:
souravB wrote:I don't know if this is the right thread to ask this or not, but I didn't found any other space based thread.
I wanted to ask any erudite people out there on India's capability of satellite based missile launch and flight path tracking.
I know we have come leaps and bound on satellite sensors but on this specific topic I came up empty on Google.
I know it's a very hush topic, but just wanted a general idea of where we are in this matter. you can just wink and I will take the hint. :rotfl:

You will get a fair idea from this Dec 2015 report by S. Chandrashekar
http://isssp.in/wp-content/uploads/2016 ... -India.pdf

Have met him few times since 2002. Last visited NIAS Bangalore to meet his team of analysts. He got a copy of Rocket simulator that he said will be useful to understand true capabelity of paki, China and others, as part of his open source capabelity assessment.

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Re: Indian Space Programme Discussion - Sept 2016

Postby Indranil » 18 Jun 2018 10:00

Haridas wrote:Stage thust of solid stage tapers rapidly after 130 sec, but still needs to drop significantly so that comparatively lesser thrust / impulse of retro rocket become useful (in addition to Aero load) .

Haridasji,

I am aware of the thrust tail out on solid rockets. However, on GSLV Mk3, they cannot wait for the tail out to complete before separation because there can be severe asymmetry between the thrust of the two boosters in this region. The vehicle is designed to take a thrust imbalance of up to +- 10 kN ( they have only observed an imbalance of 3 kN so far in the two flights). Therefore, as soon as a drop in pressure below a minimum threshold is recorded in one of the two boosters, the separation of both the boosters is initiated. The separation is achieved using 6 rockets per booster. The three rockets at the top are fired momentarily before the three at the bottom. This ensures that after the separation, the residual thrust of the booster propels it away from the remaining rocket. You can see it action in the video released by ISRO (58 second onwards.

I had referred to this in a previous post.
Indranil wrote:It can be a reason. But ISRO takes care of this for S200 in a different way. The joint in the front is pyro separated moments before the joint at the back. This makes the residual energy of the spent stages take them away from the rest of the vehicle.

So my speculations have been right till now. The S200 "burnout" is actually around 143 seconds. And if I am not wrong the specific impulse of C25 stage was also slightly higher than what they had estimated.


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