Paranoid uses for starship

[Rakaydos]

32 minutes ago, 55delta said:

I was going to bring this thread back to point out how difficult to hide and ineffective an orbital laser weapon would be. But I thought of something better.

Imagine that someone was crazy enough to make Starship into a nuclear bomb (instead of using a better, purpose-built ICBM.) That is, a Starship loaded with a single nuclear device (as opposed to a MIRV) somehow fitting into its cargo bay and used as a ICBM. If the whole cargo section could be used, and that such a nuclear device could be built and installed, how power could a Starship nuclear weapon be?

For this thread, we dont care about practical reality, so lets pull out the big numbers.

"Even more efficient than fission, nuclear fusion would liberate 6.46 × 10¹⁴ Joules of energy per kilogram of hydrogen fuel, meaning it would take a mere 867 tonnes of hydrogen to power the world"

"TNT has an energy density of 4.6 million J/kg. This means that setting off one kilo of TNT releases 4.6 million Joules of energy,"

...running some numbers...

"Sir, we estimate that starship could carry  a 140 megaton Fusion Bomb, almost 6 times more powerful than the largest nuclear bomb ever deployed."

wait, that's the reusable numbers. 250 tons expendable... call it 225 megaton thermonuclear weapon. 9 times larger... so round up an call it an "Order of magnitude improvement."

Edited October 22, 2021 by Rakaydos

[GuessingEveryDay]

Tsar Bomba was only 2 meters wide, and 8 meters long. This includes the fins, so we can definitely get rid of that, but you would probably have at least enough room for 7 Tsar Bombas. The payload would be called Nuclear Pluto.

[Rakaydos]

7 minutes ago, GuessingEveryDay said:

Tsar Bomba was only 2 meters wide, and 8 meters long. This includes the fins, so we can definitely get rid of that, but you would probably have at least enough room for 7 Tsar Bombas. The payload would be called Nuclear Pluto.

That's a MERV. (multiple independant reentry vehicals), which the person disallowed.

How much did the Tsar bomba mass? that might be more of a restriction, though the weight might be difficult to find when explosions are measured in the equivilant weight of TNT.

Edit: 27 tons, so an expendable could carry 9 50-megaton bombs. I probably slipped a digit in my previous post.

Edited October 22, 2021 by Rakaydos

[kerbiloid]

Tsar didn't have a bomb, because it was developed much later.

But AN602 which was meant had an aerodynamic shape, so its dimensions don't tell much 

***

https://en.wikipedia.org/wiki/B41_nuclear_bomb

is more cylindric, it's 1.32 m in diameter, 3.76 m in length, its mass is 4.84 t, its yield 25 Mt.

Density ~= 4.84 / (3.76 * pi * 1.32² / 4) ~= 1 t/m³.

yield/mass = 25 / 4.84 ~= 5 Mt / t.

***

Starship cargo section is ~9 m in diameter and nearly same in length.

To load.unload the warhead, the cargo bay should be a 9 / sqrt(2) ~= 6 m wide. (square in  the circle)

The warhead is cylindric, so its diameter ~= 6 m.

Volume ~= 9 * pi * 6² / 4 ~= 250 m³.

Mass ~= 250 t.

Yield ~= 1 250 Mt.

Area of destruction is (1250 / 1)^2/3 ~= 116 times greater than 1 Mt has.

I.e. 10 times less effective than a MIRV could be.

[55delta]

On 10/22/2021 at 6:29 AM, kerbiloid said:

Tsar didn't have a bomb, because it was developed much later.

But AN602 which was meant had an aerodynamic shape, so its dimensions don't tell much 

***

https://en.wikipedia.org/wiki/B41_nuclear_bomb

is more cylindric, it's 1.32 m in diameter, 3.76 m in length, its mass is 4.84 t, its yield 25 Mt.

Density ~= 4.84 / (3.76 * pi * 1.32² / 4) ~= 1 t/m³.

yield/mass = 25 / 4.84 ~= 5 Mt / t.

***

Starship cargo section is ~9 m in diameter and nearly same in length.

To load.unload the warhead, the cargo bay should be a 9 / sqrt(2) ~= 6 m wide. (square in  the circle)

The warhead is cylindric, so its diameter ~= 6 m.

Volume ~= 9 * pi * 6² / 4 ~= 250 m³.

Mass ~= 250 t.

Yield ~= 1 250 Mt.

Area of destruction is (1250 / 1)^2/3 ~= 116 times greater than 1 Mt has.

I.e. 10 times less effective than a MIRV could be.

If AN602 was a 'statement' of Soviet nuclear power, then a +1000 Mt weapons sounds like an 'immediate ransom demand.' As the AN602 was deliberately limited to keep the aircraft from immediate destruction and keep the (relatively) nearly civilians from encountering radioactive fallout, I don't think there's anywhere on the planet you could test a 1250 Mt weapon if you care about...anything. I don't know the limits of nuclear bombs, but I would guess you couldn't put one together without it melting down on final assembly. Regardless, MIRVs are more destructive and more efficient. But it makes for some scary numbers of a paranoid general to show his friends. I mean, the accusation, without evidence, that Starship/Superheavy is a weapon has been made.

Just as well that Starship is currently a poor choice as a missile. I believe, for most ICBMs you want them to re-enter the atmosphere quickly to limit potential interception. Since you want a pointed nose for that, as well as no landing equipment, I think someone would notice if a Starship was re-configured for use it as an ICBM.

[SOXBLOX]

2 hours ago, 55delta said:

I don't know the limits of nuclear bombs, but I would guess you couldn't put one together without it melting down on final assembly.

It's true, you can't have one single mass of plutonium larger than a certain mass, but I can see multiple cores being feasible. The W-87 (?) has a peanut shaped physics package, where the secondary is beside, rather than wrapped around, the primary. Something acts like a conduit to focus the energy on the secondary. I think it would be difficult, but possible, to have multiple primaries all pumping energy into one giant secondary.

That said, one primary might actually be enough anyways.

[kerbiloid]

4 hours ago, 55delta said:

I don't think there's anywhere on the planet you could test a 1250 Mt weapon if you care about...anything.

Its radius of destruction is just (1250 / 58)^1/3 ~= 3 times greater than the 58 Mt one's.

Its mushroom height would exceed the 58 Mt's 64 km much, because it's limited by the atmosphere presence. 64 km was almost at the Karman line.
So, its fireball would be visible only in ~1200 km radius or so.

This means that it could be tested a little closer to the North Pole, or maybe even there.

5 hours ago, 55delta said:

I don't know the limits of nuclear bombs, but I would guess you couldn't put one together without it melting down on final assembly.

Theoretically, none. Physically, while the material strength allows.

1 000 Mt charges were researched not once by the parties in the atompunk era.

[DDE]

15 hours ago, 55delta said:

I don't know the limits of nuclear bombs, but I would guess you couldn't put one together without it melting down on final assembly.

Most of the increase in yield is achieved through better implosion, not more fissile material.

[55delta]

8 hours ago, DDE said:

Most of the increase in yield is achieved through better implosion, not more fissile material.

Yes, it is true. But that 1250 Mt yield is coming from a 250 t bomb. If a 250 t bomb can be assembled, it would have to be done with incredible planning and care. If the plutonium concentration gets too high...well...there's a lot of plutonium there and now some of it is melting down. That sounds to me like something very horrible and thankfully no one wants to, or needs to, try it.

19 hours ago, kerbiloid said:

Its radius of destruction is just (1250 / 58)^1/3 ~= 3 times greater than the 58 Mt one's.

Its mushroom height would exceed the 58 Mt's 64 km much, because it's limited by the atmosphere presence. 64 km was almost at the Karman line.
So, its fireball would be visible only in ~1200 km radius or so.

This means that it could be tested a little closer to the North Pole, or maybe even there.

I wasn't thinking in terms of space where the blast itself wouldn't harm someone. I was thinking more in terms of radioactive fallout, that such a detonate might expel to unprecedented distances and possibly in higher concentrations. Remember that the Tsar Bomba test limited the fallout by using a tamper that dropped the yield from an expected 100 Mt to 50 Mt. Although I suppose you could try to limit the test to 500 Mt or so. Assuming even testing such a weapon didn't cause more diplomatic incidences than it was worth.

[SunlitZelkova]

8 minutes ago, 55delta said:

Assuming even testing such a weapon didn't cause more diplomatic incidences than it was worth.

Regarding tactical feasibility, one has to ask really how necessary "bigger" weapons are in the first place.

Most targets can already be destroyed by a 25 megaton weapon (within R-36 capability). This is why they abandoned a super heavy ICBM to lift an RDS-220 class weapon. The US never felt it needed anything on its ICBMs larger than about 9 megatons IIRC. What sort of target will require a weapon so large it needs Starship?

In addition, this weapon would not be a secret. Fueling operations would take time and be detectable by different recon assets, and it will still be detectable via radar once it reenters. Russia and China both already need to contend with "next door" nuclear neighbors anyways and thus presumably have contingency plans to launch under ultra short notice (like 3 minutes, and reentry would take longer anyways for Starship).

[DDE]

11 hours ago, SunlitZelkova said:

This is why they abandoned a super heavy ICBM to lift an RDS-220 class weapon.

If we abandoned it, than what's UR-500 Proton.

[kerbiloid]

http://www.astronautix.com/n/n11962.html

[JoeSchmuckatelli]

You guys are really over thinking this: much more likely to be the destabilizing power of dropping 100t of Shinsegae catalogs over the entire country of NK every 30 days. 

[SunlitZelkova]

11 hours ago, DDE said:

If we abandoned it, than what's UR-500 Proton.

Doh! I confused it with the UR-200... which also flew.

From what I have read despite the original UR-500 having flown multiple times, funding was never received to develop the siloes/basing, and thus it could be considered "abandoned" as a weapon. I may be wrong though.

[kerbiloid]

5 hours ago, SunlitZelkova said:

From what I have read despite the original UR-500 having flown multiple times, funding was never received to develop the siloes/basing, and thus it could be considered "abandoned" as a weapon. I may be wrong though.

Both types of launchpads (silo and on-ground) were built and tested on Baikonur before the cancelling.

Edited October 26, 2021 by kerbiloid