直升機(jī)教員手冊(cè) Helicopter Instructor’s Handbook
時(shí)間：2014-11-10 08:35來源：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. Coordination Most beginning students have difficulty relating the effect one control has on another. The most obvious of these is the change in torque as power is changed, requiring the use of antitorque pedal pressure as power is varied. Less obvious is the effect of a power change on pitch attitude in forward flight due to gyroscopic precession and differential lift on the advancing and retreating blades. As power is increased with the collective, the nose tends to pitch up; as power is decreased, the nose pitches down. As speed is increased, the nose of the helicopter tends to rise and begin a roll towards the retreating blade. These effects can be most disconcerting to the student unless the instructor thoroughly explains and demonstrates them. Scan To correct a deviation, it must first be recognized. Most beginning students tend to devote all of their attention to a specific problem. For example, full attention may be devoted to an altitude problem while the helicopter drifts off heading or the airspeed changes. Students may also fail to see other aircraft or obstacles in the vicinity if their attention is fixed on a single item. Some instructors find it helpful to call out or point to the items that should be included in the scan pattern. This helps the student build a good habitual scan. It is important that the student be taught to include the engine instruments in the scan, so an impending engine problem does not go undetected. Kinesthesia The sense of motion and pressure changes through nerve endings and muscular sensations is scientifically named kinesthesia, but is commonly called seat-of-the-pants flying. This sense can be developed more rapidly if the instructor calls attention to the sensations as they occur. Development of this sense enables a student to become aware of changes in the helicopter’s attitude more quickly. Point out to the student the importance of the other senses as well. The sounds of the engine, rotor, and transmission give information of rpm and possible mechanical problems. Seeing (vision) allows us to fly safely, maintaining level flight with the horizon and/ or the instruments. Unusual smells while in flight may be indications of something getting hot or burning within the helicopter. Touch may be the pressure-counterpressure that we exert on the antitorque pedals or the amount of cyclic input to maintain flight profiles. Normal Climb The objectives in practicing climbs are to achieve proficiency in establishing a climb attitude and airspeed, setting climb power while maintaining a specified rpm, and coordinating the use of flight controls. Proficiency is also gained by understanding the techniques used in leveling off at a designated altitude and establishing level cruise flight. Instructional Points For both climbs and descents, focus on: 1. Transitioning from one power setting to another (cruise power to climb power, then back to cruise power; for the descent, cruise power to approach power, then back to cruise power, if desired). 2. Coordinating the controls as a result of a power change. 3. Clearing the helicopter above or below prior to initiating a climb or descent. To enter a constant airspeed climb from cruise airspeed, simultaneously increase the collective and throttle rpm to obtain climb power. Adjust antitorque pedals to maintain helicopter in yaw trim. Note: In a counterclockwise rotor system, a left pedal input is required for an increase in torque (right pedal for a torque decrease). An increase in power causes the helicopter to start climbing, and only slight back pressure on the cyclic is required to change from a level to a climb attitude. NOTE: Discuss with the student how helicopter design affects climb and descent attitudes. For example, some helicopters are designed to increase the usable CG range of the helicopter at higher airspeeds. Nose-high or nose-low attitudes are also based on load conditions or aircraft designs. Therefore, climb attitude is slightly different from one helicopter design to the other. Point out to the student that simply pulling aft cyclic (while in cruise flight) initiates a climb and, in a short period of time, airspeed lowers and a descent begins. If the available lift/thrust is completely converted to vertical lift by using aft cyclic, the helicopter will begin descending when it slows enough to lose translational lift. This is not the coordinated climb that you are attempting to achieve. While in cruise flight, forward cyclic initiates a descent and, in a short period of time, your airspeed increases. However, depending on altitude, this could result in retreating blade stall. These types of maneuvers are discouraged during training so the student can learn to control the helicopter within stated parameters. This results in a better trained pilot with better skills. As the airspeed approaches normal climb airspeed, adjust the cyclic to hold this airspeed. Throughout the maneuver, maintain climb attitude, heading, and airspeed with the cyclic; climb power and rpm with the collective and throttle; and yaw trim with the antitorque pedals. To level off from a climb, start adjusting the attitude to the level flight attitude a few feet prior to reaching the desired altitude. The amount of lead depends on the rate of climb at the time of level off (the higher the rate of climb, the more the lead). Generally, the lead is 10 percent of the climb rate. For example, if your climb rate is 500 feet per minute, you should lead the level-off by 50 feet. To begin the level-off, adjust cyclic to adjust and maintain a cruise flight attitude. You should maintain climb power until the airspeed approaches the desired cruising airspeed, then lower the collective to obtain cruising power and adjust the throttle to obtain and maintain cruising rpm. Throughout the level-off, maintain yaw trim and heading with the antitorque pedals. The instructor should remind the student of the effects of inertia, which require some lead time and efforts. Just as one applies the brakes in a car before a stop sign, a pilot should apply control inputs prior to the desired point, be that an altitude or heading. |
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