Rotorcraft Flying Handbook, FAA-H-8083-21

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The rotor disc tilts in the direction that pressure is applied to the cyclic pitch control. If the cyclic is moved forward, the rotor disc tilts forward; if the cyclic is moved aft, the disc tilts aft, and so on. Because the rotor disc acts like a gyro, the mechanical linkages for the cyclic control rods are rigged in such a way that they decrease the pitch angle of the rotor blade approximately 90° before it reaches the direction of cyclic displacement, and increase the pitch angle of the rotor blade approximately 90° after it passes the direction of displacement. An increase in pitch angle increases angle of attack; a decrease in pitch angle decreases angle of attack. For example, if the cyclic is moved forward, the angle of attack decreases as the rotor blade passes the right side of the helicopter and increases on the left side. This results in maximum downward deflection of the rotor blade in front of the helicopter and maximum upward deflection behind it, causing the rotor disc to tilt forward. ANTITORQUE PEDALS The antitorque pedals, located on the cabin floor by the pilot’s feet, control the pitch, and therefore the thrust, of the tail rotor blades. [Figure 4-5] . The main purpose of the tail rotor is to counteract the torque effect of the main rotor. Since torque varies with changes in power, the tail rotor thrust must also be varied. The pedals are connected to the pitch change mechanism on the tail rotor gearbox and allow the pitch angle on the tail rotor blades to be increased or decreased. Figure 4-5. Antitorque pedals compensate for changes in torque and control heading in a hover. HEADING CONTROL Besides counteracting torque of the main rotor, the tail rotor is also used to control the heading of the helicopter while hovering or when making hovering turns. Hovering turns are commonly referred to as “pedal turns.” In forward flight, the antitorque pedals are not used to control the heading of the helicopter, except during portions of crosswind takeoffs and approaches. Instead they are used to compensate for torque to put the helicopter in longitudinal trim so that coordinated flight can be maintained. The cyclic control is used to change heading by making a turn to the desired direction. The thrust of the tail rotor depends on the pitch angle of the tail rotor blades. This pitch angle can be positive, negative, or zero. A positive pitch angle tends to move the tail to the right. A negative pitch angle moves the tail to the left, while no thrust is produced with a zero pitch angle. With the right pedal moved forward of the neutral position, the tail rotor either has a negative pitch angle or a small positive pitch angle. The farther it is forward, the larger the negative pitch angle. The nearer it is to neutral, the more positive the pitch angle, and somewhere in between, it has a zero pitch angle. As the left pedal is moved forward of the neutral position, the positive pitch angle of the tail rotor increases until it becomes maximum with full forward displacement of the left pedal. If the tail rotor has a negative pitch angle, tail rotor thrust is working in the same direction as the torque of the main rotor. With a small positive pitch angle, the tail rotor does not produce sufficient thrust to overcome the torque effect of the main rotor during cruise flight. Therefore, if the right pedal is displaced forward of neutral during cruising flight, the tail rotor thrust does not overcome the torque effect, and the nose yaws to the right. [Figure 4-6] With the antitorque pedals in the neutral position, the tail rotor has a medium positive pitch angle. In medium positive pitch, the tail rotor thrust approximately equals the torque of the main rotor during cruise flight, so the helicopter maintains a constant heading in level flight. Tail Moves Negative or Low Positive Pitch Medium Positive Pitch High Positive Pitch Tail Moves Figure 4-6. Tail rotor pitch angle and thrust in relation to pedal positions during cruising flight. 4-3
If the left pedal is in a forward position, the tail rotor has a high positive pitch position. In this position, tail rotor thrust exceeds the thrust needed to overcome torque effect during cruising flight so the helicopter yaws to the left. The above explanation is based on cruise power and airspeed. Since the amount of torque is dependent on the amount of engine power being supplied to the main rotor, the relative positions of the pedals required to counteract torque depend upon the amount of power being used at any time. In general, the less power being used, the greater the requirement for forward displacement of the right pedal; the greater the power, the greater the forward displacement of the left pedal. The maximum positive pitch angle of the tail rotor is generally somewhat greater than the maximum negative pitch angle available. This is because the primary purpose of the tail rotor is to counteract the torque of the main rotor. The capability for tail rotors to produce thrust to the left (negative pitch angle) is necessary, because during autorotation the drag of the transmission tends to yaw the nose to the left, or in the same direction the main rotor is turning. 4-4
Page 2: ROTORCRAFT FLYING HANDBOOK 2000 U.S
Page 6 and 7: HELICOPTER Chapter 1—Introduction
Page 8 and 9: Technique..........................
Page 10 and 11: Collision Avoidance at Night.......
Page 12 and 13: Helicopters come in many sizes and
Page 14 and 15: Main Rotor Wake Air Jet Downwash Li
Page 16 and 17: There are four forces acting on a h
Page 18 and 19: Increased Local Velocity (Decreased
Page 20 and 21: Load Factor - "G's" 9 8 7 6 5 4 3 2
Page 22 and 23: Once a helicopter leaves the ground
Page 24 and 25: otation and blade deceleration take
Page 26 and 27: lift and thrust are greater than we
Page 28 and 29: Relative Wind Retreating Side Blade
Page 30 and 31: Bank Angle Vertical Component of Li
Page 32 and 33: percent of the radius. In the drive
Page 34 and 35: Note: In this chapter, it is assume
Page 38 and 39: By knowing the various systems on a
Page 40 and 41: If the first and second stage turbi
Page 42 and 43: The horizontal hinge, called the fl
Page 44 and 45: RECIPROCATING ENGINES Fuel is deliv
Page 46 and 47: incorporated to prevent excessive v
Page 48 and 49: depends on the temperature of the o
Page 50 and 51: Title 14 of the Code of Federal Reg
Page 52 and 53: l0 5 l5 20 25 30 35 MANIFOLD PRESSU
Page 54 and 55: It is vital to comply with weight a
Page 56 and 57: sive forward displacement of cyclic
Page 58 and 59: Once you are satisfied that the tot
Page 60 and 61: Basic Empty Weight Pilot Fwd Passen
Page 62 and 63: Your ability to predict the perform
Page 64 and 65: Approximate Density Altitude - Thou
Page 66 and 67: the entire flight operation. Being
Page 68 and 69: From the previous chapters, it shou
Page 70 and 71: 2. brief passengers on the best way
Page 72 and 73: VERTICAL TAKEOFF TO A HOVER A verti
Page 74 and 75: Control pressures and direction of
Page 76 and 77: HOVER TAXI A "hover taxi" is used w
Page 78 and 79: 3. Assuming an extreme nose-down at
Page 80 and 81: tain altitude and r.p.m. As the tor
Page 82 and 83: Start Turn At Boundary Turn More Th
Page 84 and 85: the helicopter is being crabbed int
Page 86 and 87:
APPROACHES An approach is the trans
Page 88 and 89:
The maneuvers presented in this cha
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TECHNIQUE Refer to figure 10-2. To
Page 92 and 93:
COMMON ERRORS 1. Failing to maintai
Page 94 and 95:
Figure 10-7. Slope takeoff. be cons
Page 96 and 97:
made in the forward portion of the
Page 98 and 99:
Today helicopters are quite reliabl
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After touchdown and after the helic
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HEIGHT ABOVE SURFACE - FEET 500 450
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helicopter, while the relative airf
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When performing slope takeoff and l
Page 108 and 109:
the main rotor blades having an ang
Page 110 and 111:
WEATHERCOCK STABILITY (120-240°) I
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LOW FREQUENCY VIBRATIONS Low freque
Page 114 and 115:
Attitude instrument flying in helic
Page 116 and 117:
ways. If the ram air inlet is clogg
Page 118 and 119:
to true north. Because the aircraft
Page 120 and 121:
AIRCRAFT CONTROL Controlling the he
Page 122 and 123:
vertical speed indicator immediatel
Page 124 and 125:
POWER CONTROL DURING STRAIGHT-AND-
Page 126 and 127:
50 60 70 80 40 TORQUE 90 30 100 20
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to the approximate setting for the
Page 130 and 131:
used, the rate of cross-check must
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AUTOROTATIONS Both straight-ahead a
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{ { Flying at night can be a very p
Page 136 and 137:
White Red Red White Green Red Green
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you are operating off-airport, you
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Aeronautical decision making (ADM)
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THE DECISION-MAKING PROCESS An unde
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Night VFR Accident Rate Per 100,000
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STRESSORS Physical Stress—Conditi
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OPERATIONAL PITFALLS Peer Pressure
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January 9th, 1923, marked the first
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LANDING GEAR The landing gear provi
Page 154 and 155:
Helicopters and gyroplanes both ach
Page 156 and 157:
elative wind striking the advancing
Page 158 and 159:
subject to pendular action in the s
Page 160 and 161:
Due to rudimentary flight control s
Page 162 and 163:
Gyroplanes are available in a wide
Page 164 and 165:
Figure 18-4. This prerotator uses b
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inability to use differential braki
Page 168 and 169:
As with most certificated aircraft
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8 TOTAL TAKEOFF DISTANCE TO CLEAR 5
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The diversity of gyroplane designs
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minimize the length of the ground r
Page 176 and 177:
adjust the fuel/air mixture to achi
Page 178 and 179:
maximum performance is desired, two
Page 180 and 181:
Start Turn At Boundary Turn More Th
Page 182 and 183:
Shallowest Bank UPPER HALF OF CIRCL
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of failing to monitor and maintain
Page 186 and 187:
for the gyroplane. When using the s
Page 188 and 189:
Gyroplanes are quite reliable, howe
Page 190 and 191:
BUNTOVER (POWER PUSHOVER) As you le
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As with any aircraft, the ability t
Page 194 and 195:
leaves few places to safely land in
Page 196 and 197:
GLOSSARY ABSOLUTE ALTITUDE—The ac
Page 198 and 199:
FREE TURBINE—A turboshaft engine
Page 200 and 201:
TRANSLATIONAL LIFT—The additional
Page 202 and 203:
A ABORTED TAKEOFF, GYROPLANE 21-1 A
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turn indicators, 12-4 GYROSCOPIC PR
Page 206 and 207:
R RAPID DECELERATION 10-3 RECIPROCA
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Rotorcraft Flying Handbook, FAA-H-8083-21

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