They were nearly picked as a stick to beat Boeing with. There was never any real risk of the atomic bombs being carried by a British aircraft that couldn't fly high enough or fast enough to survive the delivery.They were well involved in trying out air-to-air refueling and were nearly picked to drop the atomic bombs on Japan until the above mentioned converted B-29's were converted.
B-29s were dropping Grand Slams on U-boat pens in May 1946. Yes, you read that date right. If there was an operational need to drop them over Japan (and I'd suggest that would most likely be shutting down LoCs during an invasion), then they could do the job perfectly well. Unless politics demanded that the slower, lower-flying, shorter-ranged bombers of Tiger Force be used.
The Disney and Tallboy concepts (Grand Slam was originally Tallboy Large) were actually very different.Yeah, I can see these being used in Japan. They are much lighter and smaller than Tall & Grand. Anyone has the dimensions of the B-29's bomb bay? I'd love to know if it could carry one (or more?) internally. That would give it at least a payload of 3 (wing, wing, bay) while saving a lot of weight, so no loss of range/performance other than that caused by drag of the bomsb.
Tallboy was designed to penetrate deep into the earth adjacent to a target, then destroy it by disrupting the ground it stood on. It wasn't actually designed to directly penetrate hard targets, though it could do a decent job through sheer size and explosive power. Against the thickest roofs of submarine pens, they only penetrated part-way, but the explosive effect finished the job.
Disney was a direct penetrator in a similar performance class to the BLU-113, and considerably outperformed the Tallboy concept against hard targets. Once it had penetrated, the charge would go off inside the bunker, potentially doing more damage. Though it had to hit first, which was a bit of an issue.