Author Topic: SSLV Discussion Thread  (Read 64445 times)

Offline Skyrocket

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Re: SSLV Discussion Thread
« Reply #20 on: 02/16/2018 12:45 pm »
Looks like we have the first info of the composition of this new launcher:

https://twitter.com/orfonline/status/964400636279205888

Can someone who is well versed with Indian missiles and rockets comment if existing solid rocket motors may have been used here?

The S85 looks like it is composed of various motor segments from the S139 which forms the first stage of PSLV and GSLV MK-2. The S-7 is the third stage of PSLV. S-4 seems to be a new motor. The optional fourth stage is the PS4 from PSLV.

It looks like a very cost effective launch vehicle. I would put the cost at less then $5 million per launch. 

No, the S85 has a different diameter than the the S139. The optional fourth stage is likely not the PS-4 from PSLV, which would be somewhat oversized.

Offline K210

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Re: SSLV Discussion Thread
« Reply #21 on: 02/16/2018 12:53 pm »
Looks like we have the first info of the composition of this new launcher:

https://twitter.com/orfonline/status/964400636279205888

Can someone who is well versed with Indian missiles and rockets comment if existing solid rocket motors may have been used here?

The S85 looks like it is composed of various motor segments from the S139 which forms the first stage of PSLV and GSLV MK-2. The S-7 is the third stage of PSLV. S-4 seems to be a new motor. The optional fourth stage is the PS4 from PSLV.

It looks like a very cost effective launch vehicle. I would put the cost at less then $5 million per launch. 

No, the S85 has a different diameter than the the S139. The optional fourth stage is likely not the PS-4 from PSLV, which would be somewhat oversized.

The PS4 has a diameter of 1.34m making it a perfect fit. Apart from PS4 isro has no other hypergolic upper stages. The only other possibility is they develop a new upper stage but that would still have to be based on PS4 technology unless they decide to use cryo which would not make a lot of sense in a small launcher.

As for the S-85 it could very well be a brand new motor. However how they will develop and test it in just 1 year i dont know.
« Last Edit: 02/16/2018 12:56 pm by K210 »

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Re: SSLV Discussion Thread
« Reply #22 on: 02/16/2018 01:34 pm »
Looks like we have the first info of the composition of this new launcher:

https://twitter.com/orfonline/status/964400636279205888

Can someone who is well versed with Indian missiles and rockets comment if existing solid rocket motors may have been used here?

The S85 looks like it is composed of various motor segments from the S139 which forms the first stage of PSLV and GSLV MK-2. The S-7 is the third stage of PSLV. S-4 seems to be a new motor. The optional fourth stage is the PS4 from PSLV.

It looks like a very cost effective launch vehicle. I would put the cost at less then $5 million per launch.

That would be a world record even given the cost in India - but I have great doubts due to the big segmented
first stage. This one is bigger than similar rockets in the US, Europe and Japan and their costs are in the $35 - 50 million range, and they use single body rocket motors.

They will be pretty good if they can fly it at less than $20 million price (though ISRO won't be out of customers even at higher costs).
Astronomy & spaceflight geek penguin. In a relationship w/ Space Shuttle Discovery. Current Priority: Chasing the Chinese Spaceflight Wonder Egg & A Certain Chinese Mars Rover

Offline K210

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Re: SSLV Discussion Thread
« Reply #23 on: 02/16/2018 03:23 pm »
Looks like we have the first info of the composition of this new launcher:

https://twitter.com/orfonline/status/964400636279205888

Can someone who is well versed with Indian missiles and rockets comment if existing solid rocket motors may have been used here?

The S85 looks like it is composed of various motor segments from the S139 which forms the first stage of PSLV and GSLV MK-2. The S-7 is the third stage of PSLV. S-4 seems to be a new motor. The optional fourth stage is the PS4 from PSLV.

It looks like a very cost effective launch vehicle. I would put the cost at less then $5 million per launch.

That would be a world record even given the cost in India - but I have great doubts due to the big segmented
first stage. This one is bigger than similar rockets in the US, Europe and Japan and their costs are in the $35 - 50 million range, and they use single body rocket motors.

They will be pretty good if they can fly it at less than $20 million price (though ISRO won't be out of customers even at higher costs).

It costs about $22 million for a PSLV-XL so this new SSLV will probably be in the 5-10 million range. If this does become operational then the PSLV-CA will probably be retired.

Offline TrevorMonty

Re: SSLV Discussion Thread
« Reply #24 on: 02/16/2018 08:14 pm »
Needs to be in $5-10m range as it will be competing directly with LauncherOne and Electron for smaller payloads.


Offline Skyrocket

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Re: SSLV Discussion Thread
« Reply #25 on: 02/17/2018 01:03 pm »
with 500 kg payload to LEO and 116 t lift off mass, SSLV has a pretty poor payload ratio compared to other solid fuel rockets.

For comparison:
Vega has a launch mass of 137 t and can orbit 1430 kg to LEO.
Taurus/Minotaur-C has a launch mass of 73 t and can orbit 1320 kg to LEO.

Offline hop

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Re: SSLV Discussion Thread
« Reply #26 on: 02/18/2018 02:49 am »
The PS4 has a diameter of 1.34m making it a perfect fit. Apart from PS4 isro has no other hypergolic upper stages.
"bi-propellant RCS / Velocity trimming" sounds like something that could be derived from a spacecraft propulsion system. Think a bi-prop version of the HAPS stage Orbital offers for Pegasus, based on the LAM from ISRO satellite buses. (edit: This is purely speculation on my part, based on the description and the fact that a small liquid trim stage is often desirable on all-solid vehicles)
« Last Edit: 02/18/2018 02:50 am by hop »

Offline Steven Pietrobon

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Re: SSLV Discussion Thread
« Reply #27 on: 02/18/2018 03:17 am »
with 500 kg payload to LEO and 116 t lift off mass, SSLV has a pretty poor payload ratio compared to other solid fuel rockets.

That might be because for polar orbits, SSLV has to do a dog-leg to avoid Sri Lanka.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline vineethgk

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Re: SSLV Discussion Thread
« Reply #28 on: 02/18/2018 07:19 am »
with 500 kg payload to LEO and 116 t lift off mass, SSLV has a pretty poor payload ratio compared to other solid fuel rockets.

That might be because for polar orbits, SSLV has to do a dog-leg to avoid Sri Lanka.
The reported performance and mass of SSLV looks more comparable to Epsilon, but falls short of that as well by a bit. I would guess the dog-leg is perhaps the primary culprit in that. By comparison, PSLV reportedly has payload shortfall of over 500kg owing to this.

Offline vineethgk

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Re: SSLV Discussion Thread
« Reply #29 on: 02/18/2018 03:18 pm »
It is my impression that ISRO's rocket designs have been compromises of sorts based on certain resource and technology constraints they operated under. For instance, GSLV was envisaged as a short-cut to a 2-tonne GTO launcher largely based on available PSLV technologies - especially that awkward design feature of liquid strapons that burn longer than the solid core. That the GSLV took too long to become really operational due to various reasons is another story. GSLV-III too seems to have similar constraints owing to its relatively weak core stage.

In case of SSLV, they may have made compromises to make the LV operational in the shortest possible time by making maximum use of existing infrastructure, even if it meant an inefficient design in terms of payload-mass fraction. They do not have much time to invest in new facilities if they intend to have it ready for flight testing by end of next year (which I doubt they would, 2020 or even 2021 looks a more probable date to me). While the S85 and S4 stages appear all new, the S7 second stage is likely sourced from PS3 of PSLV. The velocity trim stage (fourth stage) *could* be based on a single engined PS4 (a lighter PAM-G), or perhaps it is an all-new light upper stage.

Though I'm not sure how feasible this is in technical terms it is, a possibility that occured to my mind is whether they can attach two S9/S12 strapons to the LV as an option to achieve higher payloads. That would jack up the costs a bit, but a mass production of S12 strapons could perhaps lower its cost in the long-term.
« Last Edit: 02/18/2018 03:21 pm by vineethgk »

Offline Kosmos2001

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Re: SSLV Discussion Thread
« Reply #30 on: 02/20/2018 06:21 am »
For comparison:
Vega has a launch mass of 137 t and can orbit 1430 kg to LEO.
Taurus/Minotaur-C has a launch mass of 73 t and can orbit 1320 kg to LEO.

How is it possible considering Vega has a propellant/total mass ratio of 0.898 (vs 0.893 Taurus-XL), 340.5 MN·s of impulse (vs 189.6 MN·s Taurus-XL) and is launched from a ~5.23º inclination (vs ~34.71º Taurus-XL)?
« Last Edit: 02/20/2018 06:22 am by Kosmos2001 »

Offline sanman

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Re: SSLV Discussion Thread
« Reply #31 on: 03/30/2018 10:17 am »
Somebody posted this up on Reddit:

http://www.spaceworkscommercial.com/wp-content/uploads/2018/02/Nano-Microsatellite-Market-Forecast-8th-Edition-2018.pdf




Not sure what they're basing any ranking on. What's IOC mean - "entry into service date"?
« Last Edit: 03/30/2018 01:34 pm by sanman »

Offline vyoma

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Re: SSLV Discussion Thread
« Reply #32 on: 05/14/2018 09:17 pm »
https://m.timesofindia.com/india/isro-to-rope-in-industry-majors-for-mini-pslv-project/articleshow/64034805.cms

Quote
May 4, 2018, 23:06 IST TNN[ Surendra Singh ]

NEW DELHI: Indian Space Research Organisation (Isro) will rope in private companies or consortiums for its mini-PSLV project aimed at tapping the small satellite launch market. Isro chairman K Sivan told TOI that the first such rocket is likely to be tested by the middle of next year.

The project – first reported by TOI – involves assembling a small rocket in three days, at a lower cost. It takes 30 to 40 days to put together a normal PSLV, which is 44m tall and 2.8m in diameter. Dr Sivan said, "Isro will initially build one or two mini rockets. Thereafter, private companies will be given the contract to build them. Antrix (Isro’s commercial arm) is working on the business model.” The consortium of companies that will be given the task to build the mini rocket may include industry majors like Larsen & Toubro (L&T) and Godrej Aerospace.

Quote
A PSLV costs around Rs150 crore, while a mini-PSLV can be made with one-tenth the money. The rocket will weight one-third that of a normal PSLV which weights 300 tonnes. The mini version will have a payload capacity of less than 700 kg, compared to a normal PSLV’s capacity to carry more than 1,750kg to a sun-synchronous polar orbit of 600km altitude.

Offline worldtimedate

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Re: SSLV Discussion Thread
« Reply #33 on: 05/31/2018 07:51 am »
ISRO's big scheme to send small rockets into space

Quote
India's space agency aims to create a consortium of companies to build and market a small rocket to launch low-weight satellites at lesser cost and within shorter durations, as it seeks to tap into burgeoning global demand for such services.

Led by Antrix Corp - the commercial arm of the Indian Space Research Organisation - the consortium will include engineering major Larsen & Toubro, Godrej Aerospace and Hindustan Aeronautics Ltd. The combine will help Isro build a small rocket capable of carrying 500 kilogram satellites into the lower earth orbit.

Quote
"Our aim is that one or two rockets will be launched by Isro, the industry should then make the rockets and launch satellites," said K Sivan, chairman of Isro in an interview with ET. He said Isro has approached these companies and that "they are all interested".

"The price of a satellite launch on this small rocket is expected to be less than one-fifth of the current launch costs," Sivan added. The first development flight or launch of the rocket will be by 2019.

Quote
Typically, Isro takes around 45 days to assemble its workhorse the Polar Satellite Launch Vehicle (PSLV). The smaller rocket, to be powered by a solid booster, is expected to be ready for launch in three days.

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Offline chota

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Re: SSLV Discussion Thread
« Reply #34 on: 07/04/2018 06:40 pm »
One more

Offline PonRam

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Re: SSLV Discussion Thread
« Reply #35 on: 08/03/2018 05:15 am »
S85 does seem a bit too big of a core to launch 500kgs to LEO. Simple delta-v calc would show a core 25ton block (S25) with S7 and S4 would be able to launch 500kgs to LEO considering delta-v losses of around 10% for drag and gravity which is the norm for a PSLV like vehicle. On top if you consider the dog-leg then they may need may be a S35 block. S85 seems an over-kill.

Offline K210

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Re: SSLV Discussion Thread
« Reply #36 on: 08/05/2018 01:27 am »
S85 does seem a bit too big of a core to launch 500kgs to LEO. Simple delta-v calc would show a core 25ton block (S25) with S7 and S4 would be able to launch 500kgs to LEO considering delta-v losses of around 10% for drag and gravity which is the norm for a PSLV like vehicle. On top if you consider the dog-leg then they may need may be a S35 block. S85 seems an over-kill.

I don't know the specifics but isro's solid motors do not use composite motor cases. This results in a worse thrust to weight ratio which results in the need for larger motors. Also the ISP for isro's solid motors are generally on the lower end which could also be a contributing factor towards the need for such a large first stage.

Offline calapine

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Re: SSLV Discussion Thread
« Reply #37 on: 08/05/2018 05:25 am »
Not sure what they're basing any ranking on. What's IOC mean - "entry into service date"?

Initial Operational Capability

Offline PonRam

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Re: SSLV Discussion Thread
« Reply #38 on: 08/06/2018 03:02 am »
S85 does seem a bit too big of a core to launch 500kgs to LEO. Simple delta-v calc would show a core 25ton block (S25) with S7 and S4 would be able to launch 500kgs to LEO considering delta-v losses of around 10% for drag and gravity which is the norm for a PSLV like vehicle. On top if you consider the dog-leg then they may need may be a S35 block. S85 seems an over-kill.

I don't know the specifics but isro's solid motors do not use composite motor cases. This results in a worse thrust to weight ratio which results in the need for larger motors. Also the ISP for isro's solid motors are generally on the lower end which could also be a contributing factor towards the need for such a large first stage.

My statement above is based on extrapolating from existing PSLV stages (thus taking into consideration the factors you have mentioned).

Offline worldtimedate

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Re: SSLV Discussion Thread
« Reply #39 on: 08/12/2018 09:00 pm »
ISRO wants to launch two demonstration flights of SSLV in May and October, 2019

Quote
The SSLV ( small satellite launch vehicle ) is being developed at a furious pace at ISRO's Vikram Sarabhai Space Centre. The SSLV will be an on-demand rocket for small satellites weighing about 500-700 kg. It will be autonomous and highly intelligent, versatile and capable of adapting to different launch situations and requirements.

Quote
Its first test launch is planned for mid-2019. Once proven, the SSLV's production would be offered to industry through Antrix Corporation, according to ISRO Chairman K. Sivan.

The SSLV is said to be Dr. Sivan's dream concept for a quick-response space vehicle, and the project was initiated when he was the Director of the VSSC until January this year.

Source : Small launcher will have a big impact

Quote
Among the key missions to look for in 2019 will be the Chandrayaan-2, Aditya-L1 (India's solar mission) and two demonstration flights of the SSLV (small satellite launch vehicle).

Quote
Aside of this, the agency also plans to have two demonstration flights of the SSLV in May and October after which it can go into production phase. "These launch vehicles will cost one tenth of a PSLV and compared to about 45 days needed to prepare a launch vehicle for launch, this will need only 72 hours. Also, it needs only three to four people as opposed to 300. But it can only launch payloads with a mass of 500-700 kg and we hope that the industry can soon start making these," Sivan said.

Source : Isro aims to launch 22 missions in 2019; 50 in 3 years

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