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直升機(jī)飛行手冊(cè) Helicopter Flying Handbook

時(shí)間：2014-11-09 12:30來源：FAA 作者：直升機(jī)翻譯 點(diǎn)擊：次

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Helicopters with low inertia rotor systems settle immediately. Keep a level attitude and ensure a vertical descent with cyclic control while maintaining heading with the pedals. Any lateral movement must be avoided to prevent dynamic rollover. As rotor rpm decays, cyclic response decreases, so compensation for winds will change, requiring more cyclic input. At approximately 1 foot AGL, apply upward collective pitch control, as necessary, to slow the descent and cushion the landing without arresting the rate of descent above the surface. Usually, the full amount of collective pitch is required just as the landing gear touches the surface. As upward collective pitch control is applied, the throttle must be held in the idle detent position to prevent the engine from re-engaging.
Helicopters with high inertia rotor systems settle more slowly after the throttle is closed. When the helicopter has settled to approximately 1 foot AGL, apply upward collective pitch control while holding the throttle in the idle detent position to slow the descent and cushion the landing. The timing of collective pitch control application and the rate at which it is applied depend upon the particular helicopter being used, its gross weight, and the existing atmospheric conditions. Cyclic control is used to maintain a level attitude and to ensure a vertical descent. Maintain heading with antitorque pedals.
When the weight of the helicopter is entirely resting on the landing gear, cease application of upward collective. When the helicopter has come to a complete stop, lower the collective pitch to the full-down position.
The timing of the collective pitch is a most important consideration. If it is applied too soon, the remaining rpm may not be sufficient to make a soft landing. On the other hand, if collective pitch control is applied too late, surface contact may be made before sufficient blade pitch is available to cushion the landing. The collective must not be used to hold the helicopter off the surface, causing a blade stall. Low rotor rpm and ensuing blade stall can result in a total loss of rotor lift allowing the helicopter to fall to the surface and possibly resulting in blade strikes to the tail boom and other airframe damage such as landing gear damage, transmission mount deformation, and fuselage cracking.
Common Errors
1. Failure to use sufficient proper antitorque pedal when power is reduced.
2. Failure to stop all sideward or backward movement prior to touchdown.
3. Failure to apply up-collective pitch properly, resulting in a hard touchdown.
4. Failure to touch down in a level attitude.
5. Failure to roll the throttle completely to idle.
6. Failure to hover at a safe altitude for the helicopter type, atmospheric conditions, and the level of training/ proficiency of the pilot.
7. Failure to go around if not within limits and specified criteria for safe autorotation.
Height/Velocity Diagram
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 driveline failure, it is sometimes referred to as the dead man’s curve by helicopter pilots. By carefully studying the height/velocity diagram, a pilot is able to avoid the combinations of altitude and airspeed that may not allow sufficient time or altitude to enter a stabilized autorotative descent. A pilot may want to refer to this diagram during the remainder of the discussion on the height/velocity diagram. [Figure 11-3]
Av oid.o pera tion.i n.sha ded. areas
S moot h.ha rd.su rface
A
B
Figure 11-3. Height/velocity diagram.
0. 10.20.30.40.50.60.70.80.90.100
Indicated.airspeed.(knots) (corrected.for.instrument.error)
Height.above.surface.(feet)
In the simplest explanation, the H/V curve is a diagram in which the shaded areas should be avoided, as the pilot may be unable to complete an autorotation landing without damage. The H/V curve usually contains a takeoff profile, where the diagram can be traversed from 0 height and 0 speed to cruise, without entering the shaded areas or with minimum exposure to shaded areas.

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