Some had tilting jet engines, like the EWR VJ 101C. Some, such as the Bell X-22, used tilting ducted fans, while others used tilting propellers-for example, the Vought-Hiller-Ryan XC-142A and Canadair CL-84. One approach was to design an aircraft whose thrust could be tilted vertically for takeoff and landing and horizontally for forward flight, during which time the vehicle would produce its lift from fixed wings. In the 1950s, aircraft designers began to look at other configurations to achieve vertical takeoff and landing and reach forward speeds greater than 450 km/h. At 300 km/h, the wind on the advancing side would reach 1100 km/h, while the wind on the opposite side would be 500 km/h. The relative speed of the wind on the retreating side gets lower and lower the faster the aircraft flies. By the time the helicopter reached 150 km/h, you would feel a wind speed of 950 km/h on the advancing side, versus 650 km/h on the retreating side. If the helicopter were to fly forward, you would note that the wind was stronger on what’s called the advancing side, when the rotor was moving in the same direction as the helicopter, but that it would be noticeably weaker when the rotor was on the retreating side. If the helicopter were hovering, you’d feel a constant 800-km/h wind in your face as the rotor spun around. That’s easy to see if you imagine a miniature version of yourself perched on the tip of a helicopter rotor blade. When a helicopter flies forward, the rotor blades experience a dramatic variation in airspeed. Army UH-60 Black Hawk engine’s output of 20 900 revolutions per minute turns the main rotor only 258 times per minute, a ratio of 81 to 1.īut here’s the catch. A helicopter also needs a powerful engine and a large transmission to reduce the engine’s rotation rate to something appropriate for the large rotors. Each blade must withstand the forces of rotation, which can amount to many times the weight of the aircraft on each blade. The lift generated by the rotor blades can be angled using the helicopter’s flight controls, allowing it to fly sideways, pivot, or even backward.Ĭompared with the fixed wings of an airplane, a helicopter’s rotating blades make for a much more complicated design. It manipulates the air flowing over its spinning rotor blades, allowing the body of the aircraft to hover. Once a plane is airborne, its speed is limited only by the amount of thrust its engines can provide.Ī helicopter generates lift quite differently.
That creates enough extra lift for the airplane to take off. At a certain speed, the pilot pitches the nose up slightly, increasing the angle of the wing to the air. When an airplane barrels down a runway, air flows over the wings to produce lift. The reason why becomes clear when you consider the difference between how helicopters and airplanes fly.
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To take a crack at the speed record, we had to make some fundamental changes to conventional helicopter design.
Today’s working helicopters tend to top out at around 270 km/h. The Westland Lynx was a good start, but it was more like a race car than a family sedan-impressive but not quite practical for routine missions. A Curtiss biplane bested that speed in 1923. The world speed record for a helicopter, claimed by a modified Westland Lynx in 1986, is 400 kilometers per hour. When roads are impassable, bridges have been destroyed, and the electricity has been knocked out, helicopters can still deliver supplies and rescue people. And the best sound a wounded soldier can hear is that telltale rotor beat, just minutes before being evacuated to a hospital. It can float next to a mountain to search for the lost. It can deftly maneuver through tight spots and alight in remote places.
To paraphrase helicopter pioneer Igor Sikorsky: If you’re in trouble, an airplane can fly over and drop flowers, but a helicopter can save your life. Speed Demon: Sikorsky’s X2 experimental helicopter is, unofficially, the fastest on Earth.
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