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. To maintain a hover over a point, have the student look for minute changes in the helicopter’s attitude and altitude by checking the rotor disk changes against the horizon. When these changes are noticed, the student should make the necessary control inputs before the helicopter starts to move from the point. To detect small variations in altitude or position, the student’s main area of visual attention needs to be some distance from the aircraft, using various points on the helicopter or the tip-path plane as a reference. Looking too close or looking down leads to overcontrolling. Obviously, in order to remain over a certain point, the student should know where the point is, but his or her attention should not be focused there. Note: Helicopter pilots tend to use their peripheral vision more than most pilots. At some distance out in front of the helicopter, the horizon is used for attitude control. Peripheral vision is mainly used close in, near the helicopter, enabling the helicopter pilot to discern the clues of movement from a point (stationary reference). At some point during pilot training, many pilots learn to view the horizon with their peripheral vision and view the landing area with their center vision. Inexperienced students that attempt this at the beginning of their training tend to concentrate only on their intended landing area (tunnel vision). They pay little or no attention to the clues of movement close to the helicopter or their attitude on the horizon. This can lead to loss of control. After a student gains experience, he or she develops a certain “feel” for the helicopter. The student feels and sees small deviations, so corrections can be made before the helicopter actually moves. A certain relaxed looseness develops, and controlling the helicopter becomes second nature, rather than a mechanical response. [Figure 10-5] Common Student Difficulties Failure To Position Controls Properly The beginning student rarely knows how to position the controls so the helicopter lifts off the ground in a level attitude with no tendency to turn. Have the student check the tip-path plane of the rotor before raising the collective, looking forward and to each side to see that it is level. Visualizing Attitude The problems of visualizing attitude in the early stages of training can be compounded in hovering flight by looking at a point that is too close to the helicopter. This is a natural tendency when trying to stay over a spot. The student should pick a point well in front of the helicopter, so the horizon is within normal peripheral vision. This makes it easier to perceive the helicopter’s attitude while keeping the exact position in view. Overcontrolling The natural tendency to overcontrol is accentuated by the responsiveness of the helicopter and the student’s eagerness to get back over the takeoff spot immediately. While the ultimate objective in hovering is to stay exactly over a spot, the problem of overcontrolling can be alleviated by simply having the student stay within a general area, with the stated objective of gently stopping any drift that develops. Note: Remind the student of Newton’s first law of motion. An object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This is often referred to as “the law of inertia.” The student can get ahead of the helicopter and make control inputs before the helicopter has had time to completely respond to any inputs. This is the normal progression of the student gaining experience and getting the “feel” of the helicopter. RPM Control In the initial attempts at hovering, the student usually does not check rpm and make the necessary corrections. On helicopters equipped with a governor or correlator, rpm control is considerably easier. Periodically call attention to the rpm, and point out that changes in engine rpm can also be heard. Coordination It is not uncommon for a student, particularly a student transitioning from airplanes, to attempt to gain altitude by applying rearward cyclic pressure, or attempt to turn by using lateral cyclic. To correct this tendency, many instructors operate one or two of the controls while allowing the student to concentrate on the reaction produced by the remaining control. For example, the instructor can operate the pedals and collective while the student experiments with the reactions produced by cyclic inputs. Tension Tension is the natural result of a student’s efforts to perform satisfactorily. The initial stage of training requires a great deal of patience on the part of the instructor and a lot of positive reinforcement and encouragement for the student. When tension builds to a point where the student is incapable of performing with an acceptable degree of proficiency, the instructor should take over and allow the student to relax for several moments. Usually, it is best to land and talk over the problems and to ensure neither the student nor instructor compares the student’s performance with the instructor’s performance. After encouragement and constructive criticism, another takeoff can be performed. Hovering Height Many beginning students have a tendency to hover too high or too low. Hovering too high can create a hazardous flight condition, while hovering too low creates a risk of touching the ground with lateral movement and possible dynamic rollover. Abrupt aft cyclic movement can also lead to the tail guard/stinger striking the ground and, in worse cases, the tail rotor. To help avoid this problem, continually reinforce what the correct height should look like and continuously remind the student that a good scan helps prevent unwanted altitude changes. Hovering Turn Demonstrate how a hovering turn is accomplished by manipulating the antitorque pedals while the helicopter remains over a designated spot at a constant altitude. [Figure 10-6] The turn should be made at a low, constant rate through varying degrees of heading. |
