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A Bell UH-1 Iroquois helicopter. A helicopter is a powered rotorcraft with rotors driven by the engine(s) throughout the flight, allowing it to take off and land vertically, hover, and fly forward, backward, or laterally. Helicopters have several different configurations of one or more main rotors.
Abrasion strips on helicopter rotor blades are made of metal, often titanium or nickel, which are very hard, but less hard than sand. When a helicopter flies low to the ground in desert environments, sand striking the rotor blade can cause erosion. At night, sand hitting the metal abrasion strip causes a visible corona or halo around the rotor ...
In 2017, 926 civil helicopters were shipped for $3.68 billion, led by Airbus Helicopters with $1.87 billion for 369 rotorcraft, Leonardo Helicopters with $806 million for 102 (first three-quarters only), Bell Helicopter with $696 million for 132, then Robinson Helicopter with $161 million for 305.
He had developed a small helicopter model with coaxial rotors in July 1754 and demonstrated it to the Russian Academy of Sciences. [1] In 1859, the British Patent Office awarded the first helicopter patent to Henry Bright for his coaxial design. From this point, coaxial helicopters developed into fully operational machines as we know them today ...
Later that year, during the leftist Asturias revolt in October, an autogyro made a reconnaissance flight for the loyal troops, marking the first military employment of a rotorcraft. [20] When improvements in helicopters made them practical, autogyros became largely neglected. Also, they were susceptible to ground resonance. [16]
Since the rotors can be configured to be more efficient for propulsion (e.g. with root-tip twist) and it avoids a helicopter's issues of retreating blade stall, the tiltrotor can achieve higher cruise speeds and takeoff weights than helicopters. A tiltrotor aircraft differs from a tiltwing in that only the rotor pivots rather than the entire wing.
One such rotorcraft was the American Boeing/Sikorsky RAH-66 Comanche, a stealthy aerial reconnaissance helicopter which was canceled in 2004. Another example is the Sikorsky S-67 Blackhawk , which, in 1974, had a Fenestron for testing purposes used for 29 flight hours. [ 16 ]
The attack helicopters have only to rise from cover briefly to fire their missiles before returning to a concealed location. [7] Late-development of attack helicopters, such as the Mil Mi-28N, the Kamov Ka-52, and the AH-64D Longbow, incorporate sensors and command and control systems to relieve the requirement for scout helicopters.