National Geographic : 1953 Dec
© National Geographic Society 773 Color by Luis Marden and American Helicopter ' Navy's Skyshark Need Not Turn on Its Belly to Bite Driven by turbines, two propellers rotating in opposite directions elimi nate torque, a force which tends to roll a plane in the direction opposite to the propeller's spin. This Douglas attack bomber operates from carriers and short runways. Exhaust from turbine tail pipes gives added thrust. <- Army's Jet Jeep Lifts Twice Its Own Weight + This pocket-size helicopter (the Jet Jeep) folds up for trailer transport. Pulse-jet engines at rotor tips operate on the fluttering-Venetian-blind principle used by Hitler's buzz bombs. The machine weighs 400 pounds, flies on one engine in emergency, burns anything from kerosene to high octane gasoline, and takes off in zero weather in less than 30 seconds. Engines have only one moving part, and the craft uses not a single gear.