Leaving the debate if this were actually possible to that thread, how much damage could a WWII era atomic bomb cause on a US city?
Little Boy with a yield of 13 kilotons but was exploded at 600 m. I’d suspect that the best case for the given scenario would be to detonate the bomb at the shore.
Surface explosions are problematic for many reasons, such as not being able to capitalize on the Mach Stem Formation. Unlike an air burst, only a small percentage of the exploding force would be in the direction of the buildings. Rather than damaging building in 360 degrees from the bomb, a shore blast would be cut in half, at 180 deg. The shock wave would reduced by the buildings it destroyed, rather than coming down from above.
I would presume the target would either be NYC or Washington, DC.
Half the blast goes away from the city, assuming a shoreline hit and not in a narrow harbor. Half also is directed downward causing lots of damage near the point of detonation, but not very far inland. So it could be down to nearly 25% of the immediate effect of the blast.
Marginally more gruesome, but it might be more practical to simply install the nuke inside the U-Boat and set it off in a suicide attack (I guess a Kaiten attack more than a Kamikaze one, to be proper). Maybe you could get fancy and set it on a timer and have the crew abandon ship, first—either to be picked up by another U-Boat, or just paddle ashore and try not to get captured/get captured before an angry mob found you. (Have fun!)
Or, alternately, install the nuke in a towed “barge,” like the ones designed for submarine V2 launches, drop it off on a timer near the target, and skedaddle. I’ll leave speculation as to actually using the V2 to deliver a “Little Boy” sized payload, albeit with a surely more limited range, to others.
I’d certainly be curious as to the other conditions of the OP’s quoted scenario, and if they could be compared to estimates of how close a U-Boat could get to the US coastline at different historical times and conditions. Maybe we could get some old hand Silent Hunter player to run a simulation.
Well, a metric fucktonne of fish would die, since Little Boy weighed 4400kg and the biggest German torpedo had a warhead of 280kg, the torp would just sink to the bottom.
The payload of a V2 was only 1000kg, so no, that wouldn’t have worked either.
The FatMan style of bomb (much better than the Little Boy) weighed 4,670 kg.
So, it wouldnt work, unless a suicide mission and a specially modified sub.
Yes, only a manned sub on a suicide mission. Though maybe only one man was needed to steer it.
Suppose they made a lightweight bomb, what was the range of their torpedoes? Unless there was a timer for detonation they just created one big ass depth charge. It would be a suicide mission for the sub that launched the torpedo when it gets hit by that shockwave. It’s unlikely they’d get a ship close enough to launch a torpedo, and if they could get a plane that far carrying the bomb they’d just drop it on the city, they wouldn’t carry the added load of a torpedo.
Rather than a suicide mission, why not have the guy pilot the bomb into the harbor, leave it on the bottom, swim ashore in the dead of night, and hop a bus to wherever else, and be a hundred miles away when it goes off?
That’s how I’d do it. I do suspect that getting it there would have been problematic- the physics package was around 5’ in diameter, and was extremely heavy. Turning it into a torpedo of some kind, or a mine of some kind would increase that somewhat- probably on the order of turning it into an aerial bomb.
And the Texas City Disaster was on the order of a really tiny nuke- like 3 kilotons or so. That’s 1/5 of the Little Boy yield, and 1/7 that of Fat Man. It still wrecked several entire blocks of the older part of the city (like 1/2 mile from the Grandcamp) and demolished several chemical plants between it and the city proper. The explosion also sent big pieces of the ship flying- the anchors were found 1/2 mile away and 1.5 miles away respectively, and the screw of the High Flyer was found a mile away as well.
The UBoot would have to have a fairly large crew in order to cross the Atlantic. Then getting ashore would mean their arrest and execution, as happened to German Agents who tried that very thing.
Very early Cold War planning played with schemes of using sub-delivered atomic bombs on Russian cities, and decided it was worthless as a tactic. Detonating it in the water or at the surface would do very little damage to the city, and the early atomic bombs were too large to effectively be launched into the air from a sub.
Remember, this is the Nazis we’re talking about. You tell the crew that they’re carrying a top secret new weapon, and their mission is to sail to within 1000 feet of New York Harbor, aim their tubes at the harbor, trigger the weapon, and return to the nearest German-controlled port. Then, after the crew completes the first three of those four steps, you issue press releases back home lauding the courage of those brave Aryans who willingly gave their lives in service of the Fatherland.
More sensible would be for the Germans to use the sub to hijack a US freighter or other boat off the coast, then set it to sail into the port on an incoming tide, where it would explode.
It wouldn’t have to be a full sized U-Boat, it could be something like the British X-Boat mini submarines; put just one man in it to sail it up the target and then leg it.
