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Dissymmetry of lift in an American-style helicopter. Consider a single-rotor helicopter in still air. For a stationary (hovering) helicopter, whose blades of length of r metres are rotating at ω radians per second, the blade tip is moving at a speed rω meters per second. As the blades rotate, the speed of the blade-tips relative to the air ...
Overhead view of helicopter rotors. The rotor tips travel much faster than the inner sections, so produce more lift. (For the purposes of this article, the demarcated circular regions are irrelevant and should be ignored.) A helicopter rotor blade is an airfoil, which is driven through the air to create lift. The lift generated is proportional ...
Flapback [1]: 3:28 or blowback [2]: 2–14, 2–20, 2–21 [3] is the tilting of a helicopter rotor disc, usually aft (backwards), which occurs in several circumstances. In normal operating circumstances, forward flight results in flapback caused by dissymmetry of lift and the transverse flow effect.
A coaxial-rotor aircraft is an aircraft whose rotors are mounted one above the other on concentric shafts, with the same axis of rotation, but turning in opposite directions (contra-rotating). This rotor configuration is a feature of helicopters produced by the Russian Kamov helicopter design bureau .
A tandem-rotor aircraft is an aircraft with two large helicopter rotor assemblies mounted one in front of the other in the horizontal plane. This configuration is mainly used for large cargo helicopters. [ 1 ]
The pre-production aircraft were used to develop mission kits and configurations for offshore and SAR roles, enabling these to be immediately certified and available for customer selection. [4] In August 2013, the fifth prototype was dispatched to the UK, so that AgustaWestland's UK branch could begin work on certifying the type for SAR ...
The Pentagon said on Monday that the U.S. State Department has approved the potential sale of Apache helicopters and related logistics and support to South Korea for an estimated $3.5 billion.
The USMC also used the helicopter for combat support, search and rescue (SAR), casualty evacuation and Tactical Recovery of Aircraft and Personnel (TRAP). The Sea Knight also functioned as the US Navy 's standard medium-lift utility helicopter prior to the type being phased out of service in favor of the MH-60S Knighthawk during the early 2000s.