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To accelerate to specific airspeed ease the cyclic forward to select the attitude, hold the attitude, and then adjust for accuracy. This will increase the airspeed and the altitude will decrease. Pause to let the airspeed stabilize, anticipate the desired airspeed, and then adjust cyclic as necessary to maintain that airspeed. Once again prevent yaw through the use of the tail rotor pedals.
Your instructor will have you practise this several times. Attempt to make cyclic changes small and smooth, avoiding large or abrupt control movements.
POWER CHANGES
Your instructor will describe the relationship between collective and throttle movement as it applies to the helicopter on which you are training. You will note that any change in power causes the helicopter to yaw as a result of the changing torque. The greater is the change in power, the greater the torque effect. You must anticipate this torque reaction whenever changing power and make the appropriate pedal adjustment to maintain coordinated flight.
If training on a helicopter powered by a piston engine your instructor will explain and demonstrate the method of changing manifold pressure while maintaining a constant RPM. To increase the manifold pressure, you must raise the collective. This will increase the pitch on the main rotor blades. It will also cause a decrease in RPM due to increased drag. To prevent this undesired decrease in RPM, always lead with throttle. This action will now result in an increase in manifold pressure while maintaining RPM. Remember that these power changes will cause the helicopter to yaw unless you simultaneously apply corrections to the appropriate tail rotor pedal. On North American helicopters, an increase in power will require left pedal input, the ‘power pedal’, and a decrease in power, a right pedal input. On most European helicopters the right pedal is the power pedal.
To reduce the manifold pressure the opposite will apply. You will lower the collective. This reduction of blade pitch, with the resulting reduction in drag, will cause the RPM to increase. To prevent this increase you must reduce the throttle setting. This in turn will cause a decrease in manifold pressure, while maintaining RPM. Once again you must anticipate the need for an adjustment of the tail rotor pedals to prevent unwanted yaw.
Your instructor will demonstrate that to increase RPM you must increase the throttle and also reduce collective to maintain a constant manifold pressure. To reduce the RPM you will close the throttle slightly and raise the collective to maintain a constant manifold pressure.
Collective pitch is the primary control for manifold pressure while the throttle primarily controls RPM. But since one influences the other you must analyze both the dual tachometer to determine the RPM, and the manifold pressure gauge to determine the power, to decide which control to apply and by how much to get the expected results. For example: if the RPM were low and the manifold pressure low, you would increase the throttle, maintaining the collective setting. The result would be an increase in both RPM and manifold pressure.
The control movements on turbine and on some piston-engined helicopters (RH 22 / 44) are simplified in so far as the governor maintains the RPM. The movements of the collective and pedals are identical to a piston engine helicopter.
STRAIGHT AND LEVEL FLIGHT
We may define straight and level flight as flight at a constant altitude, on a constant heading, with a constant airspeed in co-ordinated flight. Small, smooth, coordinated control movements achieve this condition.
Figure 4-1: Attitudes In Level Flight
As you have seen, once the main rotor has been tilted, the fuselage will tend to parallel that tilt as the helicopter C of G aligns itself with the line of total lift reaction. Your instructor will point out to you the visual cues representative of straight and level flight at cruise airspeed and various other speeds. You should note the position of the disc, in relation to the horizon, as this is one of the important cues in cruise flight. Note also, the power settings used for cruise speed.
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本文链接地址：直升机飞行训练手册 HELICOPTER FLIGHT TRAINING MANUAL(12)
