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Stephan Petroczy and Theodore von Karman designed a captive helicopter for observation, not transportation

Stephan Petroczy and Theodore von Karman designed a captive helicopter for observation, not transportation. The craft had two coaxial rotors and was powered with three 120-hp (89-kW) LeRhone engines. Although it rose to a height of 164 feet (50 meters) and remained aloft for an hour, it was always held by cables and could not move horizontally.

Credits - Hiller Aviation Museum