Focke-Wulf_Triebflugel

The Focke-Wulf Triebflügel, or Triebflügeljäger, literally meaning "thrust-wing hunter", was a German concept for an aircraft designed in 1944, during the final phase of World War II as a defence against the ever-increasing Allied bombing raids on central Germany. It was a vertical take-off and landing tailsitter interceptor design for local defense of important factories or areas which had small or no airfields.

The Triebflügel had only reached wind-tunnel testing when the Allied forces reached the production facilities. No complete prototype was ever built

https://en.wikipedia.org/wiki/Focke-Wulf_Triebflügel

Rather a hare-brained concept. But working on something like this took time from useful ideas - which was good for the free world.