Author Topic: Indian rocket question  (Read 5737 times)

Online Stan Black

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Indian rocket question
« on: 01/10/2013 09:57 PM »
Could they use the GSLV liquid strap-ons to enhance the PSLV?

Offline sanman

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Re: Indian rocket question
« Reply #1 on: 01/10/2013 10:58 PM »
Could they use the GSLV liquid strap-ons to enhance the PSLV?

I dunno, but perhaps it might not be worth the effort, since the PSLV is an older-generation design from the 1980s, and it's meant for a lower payload segment.

http://en.wikipedia.org/wiki/Polar_Satellite_Launch_Vehicle#Variants

The PSLV-XL has the largest strap-on boosters out of all the PSLV variants, at 12 tons each, compared to the 40-ton ones on GSLV.


Offline antriksh

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Re: Indian rocket question
« Reply #2 on: 01/11/2013 04:10 AM »
Could they use the GSLV liquid strap-ons to enhance the PSLV?

If I am not wrong the total thrust of the PSLV 6 S9/S12 strap-ons is roughly the same as that of GSLV strapons. The only difference is the burn duration that is much more for the GSLV strap-ons.
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline markododa

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Re: Indian rocket question
« Reply #3 on: 08/13/2014 01:24 PM »
Maybe its necrobumping, this thread is old but since there is no PSLV Q&A thread i will ask here.
It seems that the core alone has for cylinders for injection vectoring, while the standard version has only 2 cylinders, am i missing something or 2 are enough?, also where are the roll control motors?

Offline edkyle99

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Re: Indian rocket question
« Reply #4 on: 08/13/2014 04:07 PM »
Maybe its necrobumping, this thread is old but since there is no PSLV Q&A thread i will ask here.
It seems that the core alone has for cylinders for injection vectoring, while the standard version has only 2 cylinders, am i missing something or 2 are enough?, also where are the roll control motors?
My understanding is that on all versions there are two strap-on modules that contain a top-mounted SITVC (Secondary Injection Thrust Vector Control) fluid tank for core pitch/yaw control and, below that, a small RCS tank and an RCS thruster that can gimbal to provide roll control.  On the Core Alone variant, two additional SITVC module tanks are added and, likely, more RCS propellant is also provided.  On versions with strap-on boosters, at least one pair of boosters has its own built-in SITVC tank for its own nozzle, to provide control during the first 45 to 70 seconds of flight.

 - Ed Kyle
« Last Edit: 08/13/2014 04:55 PM by edkyle99 »

Offline antriksh

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Re: Indian rocket question
« Reply #5 on: 08/14/2014 10:14 AM »
Maybe its necrobumping, this thread is old but since there is no PSLV Q&A thread i will ask here.
It seems that the core alone has for cylinders for injection vectoring, while the standard version has only 2 cylinders, am i missing something or 2 are enough?, also where are the roll control motors?
Nasadiya Sukta:
Srishti se pehle sat nahin thaa, asat bhi nahin | Antariksh bhi nahin, aakaash bhi nahin thaa | chhipaa thaa kyaa, kahaan, kisne dhakaa thaa | us pal to agam, atal jal bhi kahaan thaa ||

From: 1st verse of 129th Hymn of the 10th Book of Rig Veda

Offline markododa

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Re: Indian rocket question
« Reply #6 on: 08/14/2014 11:53 AM »
Maybe its necrobumping, this thread is old but since there is no PSLV Q&A thread i will ask here.
It seems that the core alone has for cylinders for injection vectoring, while the standard version has only 2 cylinders, am i missing something or 2 are enough?, also where are the roll control motors?

So the other two cylinders are solid motors or?

Offline pippin

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Re: Indian rocket question
« Reply #7 on: 08/14/2014 11:59 AM »
Strontium perchlorate? Holy moly, this makes hydrazine look like a pleasant fuel in comparison...

Offline edkyle99

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Re: Indian rocket question
« Reply #8 on: 08/14/2014 01:57 PM »
Maybe its necrobumping, this thread is old but since there is no PSLV Q&A thread i will ask here.
It seems that the core alone has for cylinders for injection vectoring, while the standard version has only 2 cylinders, am i missing something or 2 are enough?, also where are the roll control motors?

So the other two cylinders are solid motors or?
No.  The extra cylinders contain liquids, likely more of the injection fluid to make up for the missing strap on booster injection vectoring.

 - Ed Kyle

Offline markododa

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Re: Indian rocket question
« Reply #9 on: 08/14/2014 05:08 PM »
So the red barrels under the white ones are rcs systems for roll control, but what and where is the ACS?

Offline Moon Rabbit

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Re: Indian rocket question
« Reply #10 on: 10/23/2017 12:52 PM »
bumping up this thread again (apologies)...but hoping someone will be able to help to answer a question about  the RCS (roll control system) for the PSLV first stage. The two figures attached below shows the thrusters on the RCS tank.

Am i right to say that the thruster will be able to only swing left-right?

Meaning the gimbal of the RCS thrusters is in just a single plane?
... a small RCS tank and an RCS thruster that can gimbal to provide roll control...

 - Ed Kyle
« Last Edit: 10/23/2017 02:57 PM by Moon Rabbit »
The Mercury Seven - Carpenter, Cooper, Glenn, Grissom, Schirra, Shepard, Slayton. “Somewhere, something incredible is waiting to be known.” - Carl Sagan

Offline Moon Rabbit

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Re: Indian rocket question
« Reply #11 on: 10/23/2017 02:33 PM »
Help needed again...for  answers to  questions pertaining to the  SITVC on the PSLV.

First question: Are the strontium  perchlorate kept  solely in the SITVC tanks (coloured yellow in figure 1) and there are no strontium perchlorate stored in the PSOM?

Second question: It is said that the SITVC on the PSOM are to augment roll control. The question is why are the RCS thrusters (my previous post) not sufficient that it need to be augmented.

The Mercury Seven - Carpenter, Cooper, Glenn, Grissom, Schirra, Shepard, Slayton. “Somewhere, something incredible is waiting to be known.” - Carl Sagan

Offline Moon Rabbit

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Re: Indian rocket question
« Reply #12 on: 10/23/2017 03:20 PM »
So the red barrels under the white ones are rcs systems for roll control, but what and where is the ACS?

The ACS would be the systems of thrusters that aids the PS1-PS2 stage separation - No. 28 Retro rockets, No.23 Ullage rockets and No 22 Retro rockets in the diagram below? Please do correct me if i am wrong.
« Last Edit: 10/23/2017 03:21 PM by Moon Rabbit »
The Mercury Seven - Carpenter, Cooper, Glenn, Grissom, Schirra, Shepard, Slayton. “Somewhere, something incredible is waiting to be known.” - Carl Sagan

Offline Steven Pietrobon

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Re: Indian rocket question
« Reply #13 on: 10/24/2017 05:29 AM »
bumping up this thread again (apologies)...but hoping someone will be able to help to answer a question about  the RCS (roll control system) for the PSLV first stage. The two figures attached below shows the thrusters on the RCS tank.

Am i right to say that the thruster will be able to only swing left-right?

Meaning the gimbal of the RCS thrusters is in just a single plane?

Yes, that's the way it looks. The two thrusters provide roll control. The SITVC injectors on the core nozzle provide yaw and pitch control. From https://www.isro.gov.in/launcher/pslv-c11

"SITVC for Pitch & Yaw, Reaction Control Thrusters for Roll, SITVC in two PSOMs for Roll Control."

Quote
Are the strontium perchlorate kept solely in the SITVC tanks (coloured yellow in figure 1) and there are no strontium perchlorate stored in the PSOM?

Yes. You can see in the cross section of the PS0M that no SITVC fluid is kept in the PS0M. For PSLV-CA two additional tanks are attached to the sides. This is presumably to provide additional strontium perchlorate to the core engine to make up for the loss of control from the PS0M during the initial phases of launch.

Quote
It is said that the SITVC on the PSOM are to augment roll control. The question is why are the RCS thrusters (my previous post) not sufficient that it need to be augmented.

The outward facing PS0Ms probably induce additional roll forces that can't be controlled by the RCS thrusters. By injecting strontium perchlorate, they can control this roll.

Quote
The ACS would be the systems of thrusters that aids the PS1-PS2 stage separation - No. 28 Retro rockets, No.23 Ullage rockets and No 22 Retro rockets in the diagram below?

Yes, except that No.22 Retro rockets are used for PS2-PS3 separation.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Moon Rabbit

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Re: Indian rocket question
« Reply #14 on: 10/24/2017 01:35 PM »
Thank you Steven.
I must say, the PSLV is now one of my favorite rocket.

Btw, found  this photo clearly showing the SITVC valves around the nozzle of the PS-1 core.
The Mercury Seven - Carpenter, Cooper, Glenn, Grissom, Schirra, Shepard, Slayton. “Somewhere, something incredible is waiting to be known.” - Carl Sagan

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