The Henschel Hs 117 Schmetterling (“Butterfly”) was a radio-guided German surface-to-air missile project. The operator used a telescopic sight and a joystick to guide the missile by radio control. When it reached the distance of about 20m to the bomber, its 41kg warhead was detonated by acoustic and photoelectric proximity fuses, destroying the bomber in question.
It was a long-range missile with operational range of 32km and a maximum altitude of 9km – sufficient for intercepting Allied strategic bombers.
Hs 117 was developed in 1941 by Professor Herbert A. Wagner (who was previously responsible for the Henschel Hs 293 anti-ship missile). However, the shortsighted Reich Air Ministry (RLM), rejected the design saying that there was no need for more anti-aircraft weapons. It was a monumental blunder that ultimately could have well led to the defeat of Germany in World War II.
Predictably, by mid-1943 the large-scale bombing of Germany caused the RLM to change its mind, and Henschel was given a contract to develop and manufacture it. The team was led by Dr. Herbert Wagner, and it produced a weapon somewhat resembling a bottlenose dolphin with swept wings and cruciform tail.
In May 1944, 59 Hs 117 missiles were tested (both surface-to-air and air-to-air versions – the latter from beneath a Heinkel He 111 bomber); over half the trials failed.
However, mass production (3,000 units) was ordered in December 1944, with deployment to start in March 1945. Operational missiles were to be launched from a 37mm gun carriage making it a highly mobile weapon.
Thus, of all the experimental German antiaircraft missiles of World War II, the Schmetterling (Butterfly) came closest to deployment. It was hoped that the first operational unit would enter service in March, but the war ended before the Hs 117 began operations.
The Hs 117H was an air-launched variant, designed to be launched from a Dornier Do 217, Junkers Ju 188, or Junkers Ju 388. This version was designed to attack enemy aircraft up to 5 km above and 10km away from the launching aircraft.
The guidance system was the same as for the ground-launched version, however the controller would reside in a nearby parent aircraft. Work on the Hs 117H continued into 1945, and the project was one of few to survive a savage cut in January 1945, but it was never used operationally.
After the war, the Soviet Union reverse-engineered the Schmetterling and tested it under the R-102 designation until in 1951 the decision was made to cancel all German-derived surface-to-air missiles in favor of new approaches.