In 1947 Anton Flettner, a former German teacher and inventor, was brought to the United States as part of Operation Paperclip. He was the developer of the former German helicopter Flettner Fl 282 "Kolibri" (Hummingbird), which had the principle of counter-rotating side-by-side intermeshing (combing) rotors, as the means to solve the problem of torque compensation, normally countered in single rotor helicopters by a tail rotor or vented blower exhaust. Anton Flettner stayed in the United S