直升机教员手册 Helicopter Instructor’s Handbook
时间：2014-11-10 08:35来源：FAA 作者：直升机翻译 点击：次
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To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. Throughout the maneuver, maintain a constant ground speed and path over the ground with the cyclic, a constant heading with the antitorque pedals, altitude with the collective, and the proper rpm with the throttle. To stop the forward movement, apply rearward cyclic pressure so that the helicopter glides to a halt at a hover, taking care not to lower the tail rotor into the ground. As forward motion stops, return the cyclic to the neutral position to prevent rearward movement. Forward movement can also be stopped by simply applying rearward pressure to level the helicopter and let it drift to a stop. Common Student Difficulties Altitude Control The student may not understand that an airspeed of about 5 knots requires the most power to maintain altitude as ground effect diminishes and translational lift has not begun to help. As the helicopter begins to move forward in a calm wind, it also tends to sink. The student may think this is caused by too much forward cyclic, and the resulting correction causes a helicopter to stop. Point out that a slight amount of increased collective is required as forward motion starts. This usually alleviates the problem. Note: Moving forward requires forward thrust, whereas at a stationary hover, only enough thrust is needed to overcome the wind. Begin a forward hover by diverting some lift to thrust, if that lift is not restored, the hovering altitude decreases. The more lift diverted to thrust, the lower the hover altitude, or the more collective must be increased, with the power increase sufficient to maintain rpm with more antitorque needed as well. Sideward Drift Drift to the side of the planned ground track can be the result of concentration on trying to maintain the heading and altitude. If the ground track is being maintained by reference to a line on the ground, the student may be looking too close to the helicopter and may not notice changes in the altitude. If the student has trouble maintaining the specified ground track, refocus attention to reference points that are farther away from the helicopter. Hovering Sideward Sideward flight begins in a hover and is performed at a constant heading, altitude, and airspeed. Instructional Points Explain to the student that the risk of dynamic rollover is highest during sideward hovering maneuvers. Maintain adequate landing gear height. Also ensure that sufficient clearance exists for the expected and possible path of the tail rotor for sideward hovering. Before starting sideward flight, make sure the student clears the area. This may require some clearing turns. Then have the student pick two points of reference in a line in the direction of sideward flight to help maintain the proper ground track. These reference points should be kept in line throughout the maneuver. [Figure 10-9] Reference point 1 Figure 10-9.The key to hovering sideward is establishing at least two reference points that help maintain a straight track over the ground while keeping a constant heading. The maneuver is begun at a normal hovering altitude by applying cyclic toward the side in which the movement is desired. As the movement begins, return the cyclic toward the neutral position to keep the groundspeed low. Throughout the maneuver, maintain a constant groundspeed and ground track with cyclic. Maintain heading, perpendicular to the ground track in this maneuver, with the antitorque pedals, and a constant altitude with collective. Use the throttle to maintain the proper operating rpm. As with all maneuvers, instructors should emphasize the importance of scanning. Viewing objects or obstacles while flying sideways can be deceptive. From a distance, trees and wires may look smaller or higher than they actually are. Terrain may look flat until you hover closer to it and quickly realize that it slopes up and you could possibly contact it with either the landing gear or tail rotor. To stop the sideward movement, apply cyclic pressure in the direction opposite to that of movement and hold it until the helicopter stops. As motion stops, return the cyclic to the neutral position to prevent movement in the opposite direction. Applying sufficient opposite cyclic pressure to level the helicopter may also stop sideward movement. The helicopter then drifts to a stop. Common Student Difficulties Speed Control In sideward flight, lateral cyclic input controls speed. If the student is looking primarily to the side in an attempt to maintain the track, roll attitude can be difficult to maintain. Scan must be continuous if the correct attitude is to be maintained. The student must continuously check to the side, then look in front to check attitude. This is followed by a check of the rpm, then a look back to the side. Drift Drift can also be an attitude problem. If the student concentrates too much to the side, pitch attitude can deviate from level, resulting in drift from the desired track. Heading As the helicopter begins to move sideward, the nose tends to weathercock into the direction of flight. Again, this may not be noticed if the student is concentrating his or her attention in the direction of flight. Hovering Rearward Rearward hovering is conducted using reference points ahead of the helicopter to maintain track. Altitude and heading should remain constant, and groundspeed should be no faster than a brisk walk. Instructional Points Before beginning the maneuver, make sure the area behind the helicopter is clear. This is accomplished by making a 90° clearing turn. Choose two reference points in front of, and in line with, the helicopter as if hovering forward. The movement of the helicopter should be such that these points remain in line. Begin the maneuver from a normal hovering altitude by applying rearward pressure on the cyclic. Once the movement has begun, position the cyclic to maintain a low groundspeed (no faster than a brisk walk). Throughout the maneuver, maintain constant groundspeed and ground track with the cyclic, a constant heading with the antitorque petals, constant altitude with the collective, and the proper rpm with the throttle. |
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