Here's another weird contraption from the Deutsches Museum in Munich, the Bachstelze. It is a small, unpowered autogyro meant as a spotter for German U-boats. The small craft can be quickly assembled on the rear deck of a Uboat, and will then be towed by it. The forward speed of the uboat is enough to spin the rotor and let it climb, at which point the pilot will serve as a lookout, spotting targets for the uboat. The pilot has an intercom system to talk to the crew as well as a compass and binoculars to call in contacts. Landing is done via autorotation, the same principle helicopters use when their engine fails. The craft can even land when the uboat is stopped.

This could've been a very useful craft in the early stages of the war in the Atlantic, but the Bachstelze only reached regular production in autumn 1942. But by summer 1943 the mid atlantic gap (where so far there was no real allied air cover) got closed by very long range aircraft such as the B-24 Liberator. The biggest downside of the Bachstelze being that its use prolonged emergency dive times it didn't get much use.