直升机飞行手册 Helicopter Flying Handbook

时间：2014-11-09 12:30来源：FAA 作者：直升机翻译 点击：次

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See FAA-H-8083-15, Instrument Flying Handbook for a detailed discussion of these three categories. Although this chapter discusses helicopter instrument flying, the concepts in general are similar to airplane attitude instrument flying.
Helicopter Control
Control of the helicopter is the result of accurately interpreting the flight instruments and translating these readings into correct control responses. Helicopter control involves adjustment to pitch, bank, power, and trim in order to achieve a desired flightpath.
Pitch attitude control is control of the movement of the helicopter about its lateral axis. After interpreting the helicopter’s pitch attitude by reference to the pitch instruments (attitude indicator, altimeter, airspeed indicator, and VSI), cyclic control adjustments are made to affect the desired pitch attitude. A pilot transitioning from airplanes to helicopters must understand that the attitude indicator is mounted in the airframe beneath the main rotor system and does not directly indicate what the main rotor system is doing to the flightpath. Therefore, the helicopter can take off and climb with the nose below the horizon. The helicopter can slow down and land with the nose above the horizon.
In contrast, the airplane must be pointed generally in the direction of travel (up or down) since the attitude indicator is firmly attached to the airframe that is firmly attached to the wings. The helicopter tends to fly through the air at some stabilized attitude, an effect developed by the horizontal stabilizer and designed to minimize drag in forward flight. As a helicopter begins to take off, acceleration begins. As the airflow increases over the horizontal stabilizer, it produces a downward force to bring the nose into a stabilized attitude to streamline the airframe into the relative wind. Therefore, the helicopter’s attitude indicator is about level when at a stable airspeed and altitude. A nose-low attitude indicates acceleration, not necessarily a descent, and a nose-high attitude indicates a decelerating attitude, not necessarily a climb.
These effects make the helicopter pilot interpretation of the instruments even more important because the pilot must integrate the results of the entire instrument scan to achieve complete situational awareness of the helicopter’s to flightpath.
Bank attitude control is controlling the angle made by the lateral tilt of the rotor and the natural horizon, or the movement of the helicopter about its longitudinal axis (side to side). After interpreting the helicopter’s bank instruments (attitude indicator, heading indicator, and turn indicator), cyclic control adjustments are made to attain the desired bank attitude.
Power control is the application of collective pitch with corresponding throttle control, where applicable. In straight-and-level flight, changes in collective pitch are made to correct for altitude deviations if the error is more than 100 feet, or the airspeed is off by more than 10 knots. If the error is less than that amount, use a slight cyclic climb or descent. When flying a helicopter by reference to the instruments, pilots should know the approximate power settings required for a particular helicopter in various load configurations and flight conditions.
Force or cyclic trim, in helicopters, refers to the use of the cyclic centering button, if the helicopter is so equipped, to relieve cyclic pressures. Trim also refers to the use of pedal adjustment to center the ball of the turn indicator. Pedal trim is required during all power changes.
The proper adjustment of collective pitch and cyclic friction helps pilots relax during instrument flight. Friction may be adjusted to minimize overcontrolling and to prevent creeping, but not applied to such a degree that control movement is limited. In addition, many helicopters equipped for instrument flight contain stability augmentation systems or an autopilot to help relieve pilot workload.
See FAA-H-8083-15, Instrument Flying Handbook, for a detailed explanation and illustrations concerning helicopter attitude instrument flying.

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