Looking a bit more detailed into WW2 projects which were abandoned during WW2 - personally looking more into WW2 German projects - there seems to be some pretty interesting stuff in there in terms of experimental defence technology or just defence concepts in general.
Personally, one of my favourite concepts of the time being the idea to tow a water-tight launch canister behind a U-boat containing a V-2, i've attached some images of the sort of layout they would have had. The idea was that it would allow Germany to launch attacks on the United States, each U-boat would tow the containers along horizontally then when they were going to be launched then they would be rotated vertically using certain methods to alter the buoyancy of the top, the hatch opened and away they go.
The first image being the general idea of what the whole setup would look like and then a more detailed look at the actual launch canister. One of the more interesting points - bar the fact that the launching technician apparently is containd in the canister itself too - was that it's designed to release the exhaust gases up and outwards of the container, like what we see on modern hot-launch VLS.
The closest the Germans actually got to launching rockets from submarines were firing Wurfgerat 41's submerged up to a depth of 15 meters, this was actually acheived with test firings from U-511 in mid-1942.
Then there's things like the V-3 cannon which would involve firing a projectile and as it was travelling down the barrel, alternate sub-chambers along the barrel would detonate charges to accelerate the projectile faster and faster, you need a mahoosive barrel to do this. Come to think of it, it's similar in concept to the railgun where each individual element is electrified in turn & creates the field as the metal projectile down the barrel riding the EM forces.
EDIT: The following multi-charge diagrams i've added aren't the actual V-3 cannon (they're actually earlier examples of the theory), but they adequately demonstrate the concept of the gun.
Personally, one of my favourite concepts of the time being the idea to tow a water-tight launch canister behind a U-boat containing a V-2, i've attached some images of the sort of layout they would have had. The idea was that it would allow Germany to launch attacks on the United States, each U-boat would tow the containers along horizontally then when they were going to be launched then they would be rotated vertically using certain methods to alter the buoyancy of the top, the hatch opened and away they go.
The first image being the general idea of what the whole setup would look like and then a more detailed look at the actual launch canister. One of the more interesting points - bar the fact that the launching technician apparently is containd in the canister itself too - was that it's designed to release the exhaust gases up and outwards of the container, like what we see on modern hot-launch VLS.
The closest the Germans actually got to launching rockets from submarines were firing Wurfgerat 41's submerged up to a depth of 15 meters, this was actually acheived with test firings from U-511 in mid-1942.
Then there's things like the V-3 cannon which would involve firing a projectile and as it was travelling down the barrel, alternate sub-chambers along the barrel would detonate charges to accelerate the projectile faster and faster, you need a mahoosive barrel to do this. Come to think of it, it's similar in concept to the railgun where each individual element is electrified in turn & creates the field as the metal projectile down the barrel riding the EM forces.
EDIT: The following multi-charge diagrams i've added aren't the actual V-3 cannon (they're actually earlier examples of the theory), but they adequately demonstrate the concept of the gun.