Arihant-class SSBN - News & Discussions
- Thread starter Nick
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Also, another thing I'm noticing just now.
Compare the length of the missile compartment on the old S5 model...
...and the new one:
The new compartment goes much closer to the tail than before. This could mean that we've indeed gone in for an increase in the number of missile tubes.
16 now seems likely. Maybe even 20.
Compare the length of the missile compartment on the old S5 model...
...and the new one:
The new compartment goes much closer to the tail than before. This could mean that we've indeed gone in for an increase in the number of missile tubes.
16 now seems likely. Maybe even 20.
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My own calculation. Take it with a pinch of salt.
A composite filament wound rocket motor casing would take the missile's fuel mass fraction to 0.9 to 0.95. So essentially 90-95% of the rocket's mass will be the mass of the combustible fuel. The rest 5-10% is the weight of the payload, payload bus, electronics, inter-staging & stage separation equipment etc.
I assumed A-5's all-up-weight is 55 tons. Since the Indian defence industry has been making/using composites for some time I went with the 95% figure for my calculations. That gives me a fuel mass of 49.5 tons & 5.5 tons of non-fuel mass. ISRO's POEM satellite bus is about 920 kgs. I assume A-5's payload bus will have similar weight. We have no data on the weight of electronics & the staging equipment. I assume its around 500 kg, let's say 580 kgs.
So, 580 + 920 kg= 1.5 tons. Subtracting 1.5 tons from the non-fuel mass of 5.5 tons, we get around 4 tons of throw weight.
You see what I do in my free time.
My own calculation. Take it with a pinch of salt.
A composite filament wound rocket motor casing would take the missile's fuel mass fraction to 0.9 to 0.95. So essentially 90-95% of the rocket's mass will be the mass of the combustible fuel. The rest 5-10% is the weight of the payload, payload bus, electronics, inter-staging & stage separation equipment etc.
I assumed A-5's all-up-weight is 55 tons. Since the Indian defence industry has been making/using composites for some time I went with the 95% figure for my calculations. That gives me a fuel mass of 49.5 tons & 5.5 tons of non-fuel mass. ISRO's POEM satellite bus is about 920 kgs. I assume A-5's payload bus will have similar weight. We have no data on the weight of electronics & the staging equipment. I assume its around 500 kg, let's say 580 kgs.
So, 580 + 920 kg= 1.5 tons. Subtracting 1.5 tons from the non-fuel mass of 5.5 tons, we get around 4 tons of throw weight.
You see what I do in my free time.
Well, DRDO gives A5 throw weight as 1 ton, and 3 tons for the notional A6.
We evidently improved on the A5 stages since last decade (MIRV test was obviously with what many called the "A5 Mk.II") with both propulsion & composite advancements, so I'd assume we increased the throw weight since then...but I doubt we already reached the 3-ton capacity of the notional A6.
Let alone 4 tons.
This was for the initial A5 with maraging steel stages.
The notional A6 is now the A5-MIRV
56,000 kg all-up-weight, all composite stages, 3 tons of throw weight. The figures just don't add up. Much like the how the range figures didn't used to add up. I get a feeling that the true figures of throw weight will be revealed in may be decade or so.
We evidently improved on the A5 stages since last decade (MIRV test was obviously with what many called the "A5 Mk.II") with both propulsion & composite advancements, so I'd assume we increased the throw weight since then...but I doubt we already reached the 3-ton capacity of the notional A6.
Let alone 4 tons.
Not an unreasonable assumption, but if so why wouldn't we just call it A6?
As the technology improves, it's likely that the tentative goals of the definitive land-based long range deterrence platform have also kept evolving. It's probable that the real A6 is yet to emerge.
Especially if the rumours surrounding the latest test having only 3 MIRVs is true. It's likely we would want to aim for a 6-10 MIRV solution as the definitive standard, which should then serve the nuclear deterrence against China for the next ~30 years at least.
Because we can't keep spending on a new missile every 5 years, eventually we'll have to settle on a definitive solution that serves the purpose for several decades like the US has. Occasional upgrades/technology-insertion notwithstanding.
Right now our tech and R&D is rapidly evolving, but that should come to a head soon.
Rather than the throw weight, I suspect it's the range that's being understated.
The A5 with old stages and the notional A6 having the same 5,000-km range should make it obvious. That's a hard cap for land-based missiles that GOI did not give DRDO the permission to cross - at least on paper.
Project names in this country are a mess. Remember the Arjun, Arjun Mk1, Arjun Mk1A, Arjun Mk2, NGMBT saga?
It is likely that the A6 shown in that old slide was an internal designation.
The blast yield of each MIRV also matters. If we can have 6-10 MIRVs, each warhead at a 200-250 kT thermo-nuclear then that would be deterrence enough. It is hard to estimate the level of miniaturization we have achieved on the bomb design front.
Agreed.
Range and payload are inversely related. If you were to artificially cap the range to 5000 km while making the missile more powerful, lightweight etc., the throw weight would invariably rise.
Anyway, I think we have gone off topic for long enough. Let's stop or take this to the appropriate thread.
CAD line diagram of what seems to the be the S4 & S4* subs:
H I Sutton have managed to get most things right about the Arihant class:
H I Sutton have managed to get most things right about the Arihant class:
K-5 and A-5 may share design similarities, but it doesn't make sense to marinize the A-5 when it's going to be used from land, the added expenses will be too much.
If they have SLBM'ed the 1.4m dia article ie A4 class , why not the higher dia class after all. I am quite sure K5 with all composite stages would be mirror of A5 so range would be in similar vein. Tough ask is possibly the canisterisation & gas dynamics inside canister silo for underwater launch.
Say in future, can they launch a marinised version of A1P of 1190mm dia , maybe slightly less for the SLBM and multi packed in the bigger generation subs (S5 and above). Obviously its probably a century away almost, but the actual SSBN classes would continue to be upscaled? Arihant the ATV with 4 silo to finally reaching 16 silos at a later gen of SSBN. Then the silo tube dia becomes higher to accommodate future very long range systems as well as multipacking smaller missile classes?
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K-4 and A-4 are entirely different though. And A-5 is much longer.
Agni-P can be put to better use on future destroyers rather than SSBNs, although that's an option on some future SSNs with a dedicated anti-ship role. An Mk2 model can be smaller and lighter.
Thoughts ?
ps: I personally stay away from this kind of snooping, not my liking for the really sensitive assets with high degree of secrecy around it. My interest is on different part, mfg, rocketry, weaponisation, progress etc related.
ps: I personally stay away from this kind of snooping, not my liking for the really sensitive assets with high degree of secrecy around it. My interest is on different part, mfg, rocketry, weaponisation, progress etc related.
It's easy. The S5 is a 12,000+ ton class SSBN that will require more space to build. Future SSNs will be of the current Arihant size (around 6000 tons). Therefore, the current facility at SBC will be used for SSNs, and a new facility will be used for SSBNs.