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The FAA states "The height–velocity diagram or H/V curve is a graph charting the safe/unsafe flight profiles relevant to a specific helicopter. As operation outside the safe area of the chart can be fatal in the event of a power or transmission failure it is sometimes referred to as the dead man's curve ."
In aerodynamics, the flight envelope, service envelope, or performance envelope of an aircraft or spacecraft refers to the capabilities of a design in terms of airspeed and load factor or atmospheric density, often simplified to altitude. [1] [2] The term is somewhat loosely applied, and can also refer to other measurements such as maneuverability.
Helicopters with fly-by-wire systems allow a cyclic-style controller to be mounted to the side of the pilot seat. The cyclic is used to control the main rotor in order to change the helicopter's direction of movement. In a hover, the cyclic controls the movement of the helicopter forward, back, and laterally.
For an overloaded helicopter that can only hover IGE it may be possible to climb away from the ground by translating to forward flight first while in ground effect. [11] The ground-effect benefit disappears rapidly with speed but the induced power decreases rapidly as well to allow a safe climb. [ 12 ]
As with fixed-wing aircraft, a helicopter may be properly loaded for takeoff, but near the end of a long flight when the fuel tanks are almost empty, the CG may have shifted enough for the helicopter to be out of balance laterally or longitudinally. [1] For helicopters with a single main rotor, the CG is usually close to the main rotor mast.
Its comprises helicopter aerodynamics, stability, control, structural dynamics, vibration, and aeroelastic and aeromechanical stability. [1] By studying the forces in helicopter flight, improved helicopter designs can be made, though due to the scale and speed of the dynamics, physical testing is non-trivial and expensive.
The Bell 407 is a four-blade, single-engine, civil utility helicopter. A derivative of the Bell 206L-4 LongRanger, the 407 uses the four-blade, soft-in-plane design rotor with composite hub developed for the United States Army's OH-58D Kiowa Warrior instead of the two-blade, semi-rigid, teetering rotor of the 206L-4.
Aircraft performance refers to the ability of airplanes and helicopters to accomplish certain useful things. [1] It is an important consideration when designing and testing aircraft, to ensure the aircraft can be operated in an efficient and economic manner. [ 2 ]