直升機(jī)飛行手冊(cè) Helicopter Flying Handbook
時(shí)間：2014-11-09 12:30來(lái)源：FAA 作者：直升機(jī)翻譯 點(diǎn)擊：次
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To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. Technique The maneuver requires a high degree of coordination of all controls. It is practiced at an altitude that permits a safe clearance between the tail rotor and the surface throughout the maneuver, especially at the point where the pitch attitude is highest. The altitude at completion should be no higher than the maximum safe hovering altitude prescribed by that particular helicopter’s manufacturer. In selecting an altitude at which to begin the maneuver, take into account the overall length of the helicopter and its height-velocity diagram. Even though the maneuver is called a rapid deceleration or quick stop, it is performed slowly and smoothly with the primary emphasis on coordination. During training, always perform this maneuver into the wind [Figure 10-3, position 1]. After leveling off at an altitude between 25 and 40 feet, depending upon the manufacturer’s recommendations, accelerate to the desired entry speed, which is approximately 45 knots for most training helicopters (position 2). The altitude chosen should be high enough to avoid danger to the tail rotor during the flare, but low enough to stay out of the hazardous areas of that helicopter’s height-velocity diagram throughout the maneuver. In addition, this altitude should be low enough that the helicopter can be brought to a hover during the recovery. 1. Figure 10-3.Rapid deceleration or quick stop. At position 3, initiate the deceleration by applying aft cyclic to reduce forward groundspeed. Simultaneously, lower the collective, as necessary, to counteract any climbing tendency. The timing must be exact. If too little collective is taken out for the amount of aft cyclic applied, the helicopter climbs. If too much downward collective is applied, the helicopter will descend. A rapid application of aft cyclic requires an equally rapid application of down collective. As collective pitch is lowered, apply proper antitorque pedal pressure to maintain heading, and adjust the throttle to maintain rpm. The G loading on the rotor system depends on the pitch-up attitude. If the attitude is too high, the rotor system may stall and cause the helicopter to impact the surface. After attaining the desired speed (position 4), initiate the recovery by lowering the nose and allowing the helicopter to descend to a normal hovering altitude in level flight and zero groundspeed (position 5). During the recovery, increase collective pitch, as necessary, to stop the helicopter at normal hovering altitude, adjust the throttle to maintain rpm, and apply proper antitorque pedal pressure, as necessary, to maintain heading. During the maneuver, visualize rotating around the tail rotor until a normal hovering altitude is reached. Common Errors 1. Initiating the maneuver by lowering the collective without aft cyclic pressure to maintain altitude. 2. Initially applying aft cyclic stick too rapidly, causing the helicopter to balloon (climb). 3. Failing to effectively control the rate of deceleration to accomplish the desired results. 4. Allowing the helicopter to stop forward motion in a tail-low attitude. 5. Failing to maintain proper rotor rpm. 6. Waiting too long to apply collective pitch (power) during the recovery, resulting in excessive manifold pressure or an overtorque situation when collective pitch is applied rapidly. 7. Failing to maintain a safe clearance over the terrain. 8. Using antitorque pedals improperly, resulting in erratic heading changes. 9. Using an excessively nose-high attitude. Steep Approach A steep approach is used primarily when there are obstacles in the approach path that are too high to allow a normal approach. A steep approach permits entry into most confined areas and is sometimes used to avoid areas of turbulence around a pinnacle. An approach angle of approximately 13° to 15° is considered a steep approach. [Figure 10-4] Caution must be exercised to avoid the parameters for settling with power (20–100 percent of available power applied, airspeed of less than 10 knots, and a rate of descent greater than 300 fpm). For additional information on settling with power, refer to Chapter 11, Helicopter Emergencies and Hazards. |
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