直升機教員手冊 Helicopter Instructor’s Handbook
時間：2014-11-10 08:35來源：FAA 作者：直升機翻譯 點擊：次
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To view this page ensure that Adobe Flash Player version 9.0.124 or greater is installed. Common Student Difficulties Attitude As in straight-and-level flight, students frequently have difficulty visualizing and establishing the proper attitude for the climb. Use whatever references are available in the helicopter, such as the tip-path plane, canopy crossbars, or any other structural reference. Depending on the helicopter, horizontal stabilizer, and rate of change in altitude, the climb attitude may be the same as the cruise attitude, or slightly higher. Overcontrolling The difficulty in establishing the correct climb airspeed may be the result of overcontrolling. Since establishing the correct airspeed is usually accomplished by a series of pitch attitude adjustments, students may not hold the attitude long enough for the airspeed to stabilize. This leads to excessive maneuvering while chasing the airspeed. At this point, frustration and tension begin to build. When it becomes apparent that the student is getting frustrated, the instructor can try one of the following three things; have the student return to straight-and-level flight, take over for a brief demonstration while the student relaxes, or allow the student to continue climbing until they achieve a stabilized climb and perceive the sight picture and control pressures. If climbing to an altitude is too complicated, just strive for a coordinated climb at first. Instructors should never be afraid to break any maneuver down to it component parts and allow the student to practice those individual skills until they are ready to assemble those skills into a complete maneuver. Coordination In the process of beginning a climb, all controls are utilized. Each control input causes something else to change, and a beginning student may have difficulty, not only in accomplishing the actions in the proper sequence, but also in compensating for control inputs. During the level-off, some students have a tendency to decrease power before adjusting attitude (cyclic) for cruise flight. Talk the student through the maneuver to remove any doubt about what is to be accomplished, as well as how and when it is done. Scan The scan pattern mentioned in straight-and-level flight becomes more important when the flight condition is constantly changing. Several things are happening at once and the task becomes more difficult unless the student has rehearsed the actions and reactions of the helicopter. Normal Descent A normal descent is a maneuver in which the helicopter loses altitude at a controlled rate in a controlled attitude. The objective in practicing descents is to gain proficiency in establishing the attitude necessary to maintain the desired airspeed, setting power as required to maintain the desired rate of descent while maintaining a constant rotor rpm and correcting for changing torque. Instructional Points To establish a normal descent from straight-and-level flight at cruising airspeed, lower the collective to obtain proper power, adjust the throttle to maintain rpm (a slight amount of cyclic adjustment is normally necessary to maintain desired airspeed), and adjust antitorque pedals to maintain heading. Throughout the maneuver, maintain descending attitude and airspeed with the cyclic, descending power and rpm with the collective and throttle, and yaw trim with the antitorque pedals. To level off from the descent, lead the desired altitude by approximately 10 percent of the rate of descent. For example, a descent rate of 500 feet per minute would require a 50-foot lead. At this point, increase the collective to obtain cruising power, adjust the throttle to maintain rpm, adjust antitorque pedals to maintain yaw trim, and adjust the cyclic to obtain cruising airspeed and a level flight attitude. Common Student Difficulties Attitude Visualization of pitch attitude may be difficult for the student in the initial stages of flight training. Make use of any available reference points on the helicopter in order to maintain some sort of visual reference. Helicopter attitude is primary for acceleration and deceleration control. The airspeed indicator is going to be the primary indicator for airspeed control. If the airspeed is slow, then the nose must be lowered to accelerate the helicopter until the airspeed increases. As the airspeed increases, the pilot must plan on indicator delays and allow the helicopter attitude to stabilize and neutralize equilibrium at the desired airspeed. The descent attitude may be the same as the level attitude was once the helicopter is stabilized in the descent. Coordination The student may have difficulty adjusting throttle and antitorque pedals while simultaneously adjusting the collective to set descent power. Emphasize that power is to be changed slowly and smoothly to minimize coordination problems. Scan It is common for a student to concentrate on one factor to the exclusion of others. Students have difficulty with two areas in this maneuver: maintaining a constant angle of descent and leading the level-off sufficiently. These two problems often result in recovery below the desired altitude. Turns Turns are practiced to develop skill in establishing and maintaining a desired angle of bank, while holding the pitch attitude that is appropriate to the desired maneuver. Level turns are practiced first, using bank angles of approximately 15–20°. [Figure 10-2] As the student is developing his or her skills, turns should be practiced at different airspeeds. As the student progresses, turns at VH or VNE should be added to the program as well as turns below effective translational lift. Care should be exercised to avoid LTE at low altitudes. If possible, a demonstration of LTE at higher altitudes is a good teaching point for the new student. Instructional Points Before making any turns, make sure the student clears the area in the direction of the turn, as well as above and below the helicopter. To enter a turn from straight-and-level flight, apply sideward pressure on the cyclic in the direction the turn is to be made. This is the only control movement needed to start the turn. Antitorque pedals are not used to assist the turn. Airplane pilots transitioning to helicopters attempt to use the antitorque pedals as they would a rudder pedal. Use the pedals only to compensate for torque to keep the helicopter in yaw trim. |
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