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the new attitude is established, other instruments become
primary, and the attitude indicator usually becomes the
supporting instrument.
Aircraft Control
Controlling a helicopter is the result of accurately interpreting
the flight instruments and translating these readings
into correct control responses. Aircraft control involves
adjustment to pitch, bank, power, and trim in order to achieve
a desired flight path.
Pitch attitude control is controlling the movement of
the helicopter about its lateral axis. After interpreting
the helicopter’s pitch attitude by reference to the pitch
instruments (attitude indicator, altimeter, airspeed
indicator, and vertical speed indicator (VSI)), cyclic control
adjustments are made to affect the desired pitch attitude. In
this chapter, the pitch attitudes depicted are approximate
and vary with different helicopters.
Bank attitude control is controlling the angle made by the
lateral tilt of the rotor and the natural horizon, or the movement
of the helicopter about its longitudinal axis. After interpreting
the helicopter’s bank instruments (attitude indicator, heading
indicator, and turn indicator), cyclic control adjustments are
made to attain the desired bank attitude.
Power control is the application of collective pitch with
corresponding throttle control, where applicable. In straightand-
level flight, changes of collective pitch are made to
correct for altitude deviation if the error is more than 100
feet, or the airspeed is off by more than 10 knots. If the error
is less than that amount, a pilot should use a slight cyclic
climb or descent.
In order to fly a helicopter by reference to the instruments, it
is important to know the approximate power settings required
for a particular helicopter in various load configurations and
flight conditions.
Trim, in helicopters, refers to the use of the cyclic centering
button, if the helicopter is so equipped, to relieve all
possible cyclic pressures. Trim also refers to the use of pedal
adjustment to center the ball of the turn indicator. Pedal trim
is required during all power changes.
The proper adjustment of collective pitch and cyclic friction
helps a pilot relax during instrument flight. Friction should
be adjusted to minimize overcontrolling and to prevent
creeping, but not applied to such a degree that control
movement is limited. In addition, many helicopters equipped
for instrument flight contain stability augmentation systems
or an autopilot to help relieve pilot workload.
Straight-and-Level Flight
Straight-and-level unaccelerated flight consists of maintaining
the desired altitude, heading, airspeed, and pedal trim.
Pitch Control
The pitch attitude of a helicopter is the angular relation of
its longitudinal axis to the natural horizon. If available, the
attitude indicator is used to establish the desired pitch attitude.
In level flight, pitch attitude varies with airspeed and center of
gravity (CG). At a constant altitude and a stabilized airspeed,
the pitch attitude is approximately level. [Figure 6-2]
Attitude Indicator
The attitude indicator gives a direct indication of the pitch
attitude of the helicopter. In visual flight, attain the desired
pitch attitude by using the cyclic to raise and lower the nose
6-4
Figure 6-3. The initial pitch correction at normal cruise is one bar
width or less.
Figure 6-2. The flight instruments for pitch control are the airspeed indicator, attitude indicator, altimeter, and vertical speed
indicator.
of the helicopter in relation to the natural horizon. During
instrument flight, follow exactly the same procedure in
raising or lowering the miniature aircraft in relation to the
horizon bar.
There is some delay between control application and resultant
instrument change. This is the normal control lag in the
helicopter and should not be confused with instrument lag.
The attitude indicator may show small misrepresentations
of pitch attitude during maneuvers involving acceleration,
deceleration, or turns. This precession error can be detected
quickly by cross-checking the other pitch instruments.
If the miniature aircraft is properly adjusted on the ground, it
may not require readjustment in flight. If the miniature aircraft
is not on the horizon bar after level off at normal cruising
airspeed, adjust it as necessary while maintaining level flight
with the other pitch instruments. Once the miniature aircraft
has been adjusted in level flight at normal cruising airspeed,
leave it unchanged so it gives an accurate picture of pitch
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Instrument Flying Handbook仪表飞行手册上(118)
