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ISRO Discussion Thread

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4 hours ago, Nivee~ said:

<All soldiers shouting at the sky with megaphones> HOOOOT!!!!!!!!!

 <Satellites deorbit from the soundwaves> :D

Stop that kid, he’s got a MANPAD!

Spoiler

62fb1447d201f534de4c9250dce5faeadb7112a0

 

4 hours ago, Nivee~ said:

But jokes aside, it could be a valid long range ICBM....

True. If they reduce interstage lengths and trim that skirt, it’s a credible silo-based weapon.

All too often the problem with ICBMs, though, is that they have a massive dead zone. I don’t see India committing to something that cannot be quickly downgraded for in-theatre use.

For example, one of the many interpretations of Russia’s Rubezh was that it was a Yars with the top-most stage thrown away to optimize its range for European targets.

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5 hours ago, DDE said:

Stop that kid, he’s got a MANPAD!

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62fb1447d201f534de4c9250dce5faeadb7112a0

 

True. If they reduce interstage lengths and trim that skirt, it’s a credible silo-based weapon.

All too often the problem with ICBMs, though, is that they have a massive dead zone. I don’t see India committing to something that cannot be quickly downgraded for in-theatre use.

For example, one of the many interpretations of Russia’s Rubezh was that it was a Yars with the top-most stage thrown away to optimize its range for European targets.

Considering that most of the potential targets for an Indian nuclear strike are fairly nearby to them, I really don't see much of a point for them to develop ICBMs

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4 hours ago, insert_name said:

Considering that most of the potential targets for an Indian nuclear strike are fairly nearby to them, I really don't see much of a point for them to develop ICBMs

“Superpower by 2020”, unreliable relations with the US in the long term, et cetera et cetera.

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On 1/20/2019 at 9:55 AM, DDE said:

It counts as a deferred Christmas.

Except for the R-9, which managed to use superchilled lOx to cut propellant loading time to 20 minutes.

How did they keep it ready? No idea, but the thing was deployed by the dozens, unlike the four+two R-7 launchers in total.

Solid fuels are no charmer either.

This capability is only really important if someone is hooting (I'm not fixing that!) your satellites down.

This is why the Zenit has the much touted all-automated 90-minute roll-out-to-launch capability.

Oddly enough, I had to defer Christmas as well.  Made it to my parents' on January 7th.

Early US ICBMs were LOX (I think Atlas was the last, and wiki claims it was in service through 1964.  Peak had 129 rockets deployed, but I have no idea how long it took to launch them).  I think the main fear was someone attacking your ICBMs with something fast enough (typically sub launch) to get to them before they launched.

Solid fuels certainly have the fear of unintended ignition and having to deal with that (presumably if the silo isn't open, it is too late to open it and let the missile out).  Explosion during flight is a more real failure mode, all too well known to shuttle astronauts. I still favor them over hypegolics.

- I also *really* overdo them in KSP.  If they cost anything like the in-game cost I'd be pushing them hard.  Alas, while SRBs are presumably fairly simple to make, making them *safely* is sufficiently expensive to limit them to small boosters surrounding many rockets types.

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14 hours ago, wumpus said:

Oddly enough, I had to defer Christmas as well.  Made it to my parents' on January 7th.

Nope, you just hit is square on the head... in a different Christian denomination.

14 hours ago, wumpus said:

I think the main fear was someone attacking your ICBMs with something fast enough (typically sub launch) to get to them before they launched.

That fear is still there even for solids. If it’s not propellant loading, then it’s delays in the nuclear command-and-control loop. IRBMs and nuke subs in territorial waters are terrifying precisely because nobody even gets the time to press the big red button - encouraging a preemptive opening strike on suspicion alone.

14 hours ago, wumpus said:

Alas, while SRBs are presumably fairly simple to make, making them *safely* is sufficiently expensive to limit them to small boosters surrounding many rockets types.

The “tech level” for large solids is apparently quite a bit higher than large liquids, since the entire body is a combustion chamber. I’ve read what OKB Fakel produced when asked if they could duplicate the Shuttle SRBs - something like a ten-year-long nationwide effort, with still inferior performance, and that’s on paper.

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6 hours ago, DDE said:

That fear is still there even for solids. If it’s not propellant loading, then it’s delays in the nuclear command-and-control loop. IRBMs and nuke subs in territorial waters are terrifying precisely because nobody even gets the time to press the big red button - encouraging a preemptive opening strike on suspicion alone.

But that's exactly why nearly all ICBMs are either solids or hypergolics.  You can't afford to add any fueling time to the loop.  Although now that I think about it, I'd be a lot happier if the Department of Defense had a ~30 minute chance to wrest the football from the president (not just the current or recent ones, but Reagan and his Alzheimer's was scary as well) between an order to arm the missiles and an order to fire them.

6 hours ago, DDE said:

The “tech level” for large solids is apparently quite a bit higher than large liquids, since the entire body is a combustion chamber. I’ve read what OKB Fakel produced when asked if they could duplicate the Shuttle SRBs - something like a ten-year-long nationwide effort, with still inferior performance, and that’s on paper.

I suspect the issue is how long a burn you need.  The Shuttle SRBs burned for 2 minutes, and used multiple segments stuck together (I'm pretty sure that's why the infamous O-rings were needed).  But back during the Apollo program, Aerojet was building the AJ-260 (for when you absolutely need 17,695.30 kN of thrust).  It appears that in the 1960s the US was developing the tech, although the last test blew the nozzle off the rocket (compared to F-1 development, that must have been nothing, although with significant more force uncontrolled because of that "nothing").

I think the issue is connecting segments of the SRBs together (I think the shuttle uses 4 segments and the SLS wants to add a fifth).  But there is also the issue that since the US has been building SRB-based ICBMs for decades, I also wouldn't be surprised if trying to quickly catch up is next to impossible.

Scott Manley made a video on the AJ-260: https://www.youtube.com/watch?v=UfMPgAQD420

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50 minutes ago, wumpus said:

I think the issue is connecting segments of the SRBs together (I think the shuttle uses 4 segments and the SLS wants to add a fifth).  But there is also the issue that since the US has been building SRB-based ICBMs for decades, I also wouldn't be surprised if trying to quickly catch up is next to impossible.

The AJ-260 was segmentless, cast directly on-site instead. No O-rings.

The Soviets delivered solid motors of similar size, if a decade or two later.

However, I think you’ve hit something on the head: the Soviets would have likely hit the usual rail mobility bottleneck with an SRB program.

Edited by DDE
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And that is precisely why Thiokol went for the segmented motors as early as Titan III: they had to ship the segments from Utah to either Canaveral or Vandenberg. Shuttle SRBs built on the knowledge base built up on those boosters.

 

I think the largest segmentlrss SRBs that are currently in service are either the first stage of Minuteman III or the AJ-60s used on Atlas V... And those are transported by truck and trailer when they have to be surface transported. I think they airlift Minuteman if they need to go to Vandenberg, but AJ-60 is trucked from Sacramento, CA to Canaveral.

Edited by MaverickSawyer
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I'm actually surprised that no-one here is talking about PSLV-DL...

Does anyone know what DL stands for?

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BTW, the launch is at 1:08  PM EST (18:08 GMT).

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New PSLV variant is launching in two hours from now its called PSLV DL

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Mostly fake news. What was Sputnik-2? I’m also sure several of the NOSS triplet busses were retrofitted with secondary experimental payloads, and that’s just a random example.

Edited by DDE

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Identical topics merged.

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Well about dang time! But their SCE-200 sorta looks like the RD-810 when you compare looks and specs..

And I found this! Looks like SSLV is INDEED based on a ballistic missile.... 

SSLV.jpg

Same core diameter, and I have a sneaky suspicion that the second and third stage are almost exactly the same as those on the Agni-V....

As long as they are used responsibly, it's okay..I guess..

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On 1/25/2019 at 10:50 AM, DDE said:

Mostly fake news. What was Sputnik-2? I’m also sure several of the NOSS triplet busses were retrofitted with secondary experimental payloads, and that’s just a random example.

Yes, but this the first time a fourth stage has been used. Isn't it amazing, this is totally awesome! Using the second or third stage for experiments? Pfff, lame. Using the fourth stage is revolutionary.

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On 2/3/2019 at 3:29 AM, NSEP said:

Yes, but this the first time a fourth stage has been used. Isn't it amazing, this is totally awesome! Using the second or third stage for experiments? Pfff, lame. Using the fourth stage is revolutionary.

How bout we use a 5th stage? 6th? Anyone?

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20 hours ago, Xd the great said:

How bout we use a 5th stage? 6th? Anyone?

I don't think there's any  rocket with that many staging events... :D

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6 hours ago, Nivee~ said:

I don't think there's any  rocket with that many staging events... :D

There is a five-stager.

https://en.wikipedia.org/wiki/Augmented_Satellite_Launch_Vehicle

Then there’s N-1 and Yenisei, if you include the lunar retromotor, N-1’s original Block D is a fifth stage, while Yenisei may take four stages just to get into LEO, and the lunar mission would be carried out using the fifth and sixth stages.

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