Meanwhile, work had resumed in France where in 1920 Etienne Oehmichen flew a helicopter somewhat similar to Cornu's, although it required a cylindrical balloon above it to offset instability and insufficient engine power. Two years later, Oemichen was able to dispense with the gasbag and fly free. In 1923 he made the first hovering flight of more than five minutes, and the next year he negotiated a one-kilometer course to set a distance record for helicopters.