Pacific War, WW2 Ideas introduced that did - and didn't - work.

Ideas that Didn't Work Sea planes on destroyers. Seaplanes were so valuable aboard battleships and cruisers for scouting, anti-submarine and communications that five destroyers were ordered to be equipped to carry them in May 1940. The idea turned out to be impractical and several planned installations were cancelled and those installed were ordered removed in Oct 1943. Athwartship, hanger deck catapults. Those authorized for installation on 11 carriers were removed after 17Feb42 and replaced with a second flight …

…Locks, Panama Canal, but was diverted to attack the US anchorage at Ulithi just as the war ended. The I-400 series of submarine had an energy absorbing skin, snorkel, radar, degaussing, and a range of 1-1/2 times around the world of four months duration. Several conventionally large subs carried a single scout aircraft used for reconnaissance of allied bases such as Pearl Harbor. One fire-bombed a forest in Oregon, twice, fortunately, during a rainy season.