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Back to: "P"parasite drag
- Definição1
- The part of total drag created by the form or shape of helicopter parts.
- Fonte1
- FEDERAL AVIATION ADMINISTRATION. Helicopter flying handbook (FAA-H8083-21A). Washington, DC: FAA, 2012.
- Fonte2
- FEDERAL AVIATION ADMINISTRATION. Rotorcraft flying handbook (FAA-H-8083-21). Washington, DC: FAA, 2000. Disponível em: http://www.faa.gov/library/manuals/aircraft/media/faa-h-8083 -21.pdf. Acesso em: 10 fev. 2012.
- Nota adicional1
- Parasite drag is present any time the helicopter is moving through the air. This type of drag increases with airspeed. Non-lifting components of the helicopter, such as the cabin, rotor mast, tail, and landing gear, contribute to parasite drag. Any loss of momentum by the airstream, due to such things as openings for engine cooling, creates additional parasite drag. Because of its rapid increase with increasing airspeed, parasite drag is the major cause of drag at higher airspeeds. Parasite drag varies with the square of the velocity; therefore, doubling the airspeed increases the parasite drag four times.
- Contexto
- COMMENT: There are two basic types of drag called parasite drag and induced drag. Parasite drag is caused by friction between the air and the aircraft surface, aerials, landing gear, etc. Induced drag is produced by lift.
- As airspeed increases, parasite drag increases, while induced drag decreases. Profile drag remains relatively constant throughout the speed range with some increase at higher airspeeds. Combining all drag forces results in a total drag curve. The low point on the total drag curve shows the airspeed at which drag is minimized. This is the point where the lift-to-drag ratio is greatest and is referred to as L/Dmax. At this speed, the total lift capacity of the helicopter, when compared to the total drag of the helicopter, is most favorable. This is important in helicopter performance.
- Subárea1
- Aerodynamics
- Related Term
- drag
- Narrower Term
- form drag
- Português
- arrasto parasita
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