Heeresversuchsanstalt Peenemünde
After training with the 4th U-boat Flotilla, from May 1942, "U-511" was used for testing the possibility of launching "Wurfkörper 42" artillery rockets from U-boats. In cooperation with the commanding officer's brother Ernst Steinhoff of the Peenemünde Army Research Center, a rack of six rockets were mounted on deck, and were successfully launched while on the surface and while submerged up to a depth of . However, the rockets were not particularly accurate and the racks on the deck had a negative effect on the U-boat's underwater handling and performance, so the project was abandoned.