Hellmuth Walter (26 August 1900 in Wedel near Hamburg – 16 December 1980 in Upper Montclair, New Jersey) was a German engineer who pioneered research into rocket engines and gas turbines. His most noteworthy contributions were rocket motors for the Messerschmitt Me-163 and Bachem Ba 349 interceptor aircraft, JATO units used for a variety of Luftwaffe aircraft during World War II, and a revolutionary new propulsion system for submarines known as air-independent propulsion (AIP).
After working for some time at the Germaniawerft shipyard in Kiel, Walter branched out on his own in 1934 to form his own company, Hellmuth Walter Kommanditgesellschaft (HWK, or Walter-Werke), to further research and development of his ideas. That same year, he made a proposal to the Oberkommando der Kriegsmarine (OKM – Naval High Command) suggesting that a submarine powered by an AIP engine would have considerable speed advantages over the conventional combination of diesel engine(s) for surface running and electric motor(s) while submerged. The proposal was met with much skepticism, but Walter persisted, and in 1937 showed his plans to Admiral Karl Dönitz, who was able to assist in obtaining a contract to produce a prototype. Construction started in 1939 on a small research submarine designated the V-80. When it was launched in 1940, the submarine demonstrated a top speed of 23 knots submerged, twice that of any submarine in the world at the time. Despite these spectacular results, problems with the production, supply, and safe handling of hydrogen peroxide prevented wide-scale implementation of Walter’s revolutionary engine. In the end, only a handful of German Type XVII submarines were built using this engine, and none saw combat.
After the end of the war, Kapitan zur See Rochus Mauer was showing Lt. Commander Julius Lemp the new Type XXI U-boat. Mauer mentioned that while the streamlined hull had been worked out a couple of years earlier, Dr. Walther had come up with a new hydrogen peroxide-powered engine which would have revolutionized propulsion if it worked properly. However, with Walther's political connections with people in the government, the development team had wasted time on trying to come up with ways to prevent the new engine from catching fire. He lamented they had wasted two years on boats with good hulls and death-trap propulsion systems.