直升机飞行手册Rotorcraft flying handbook

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Landing Gear ....................................................15-3

Wings ................................................................15-3

Chapter 16—Aerodynamics of the Gyroplane

Autorotation...........................................................16-1

Vertical Autorotation.........................................16-1

Rotor Disc Regions...........................................16-2

Autorotation in Forward Flight ........................16-2

Reverse Flow................................................16-3

Retreating Blade Stall ..................................16-3

Rotor Force............................................................16-3

Rotor Lift ..........................................................16-4

Rotor Drag ........................................................16-4

Thrust.....................................................................16-4

Stability .................................................................16-5

Horizontal Stabilizer.........................................16-5

Fuselage Drag (Center of Pressure)..................16-5

Pitch Inertia.......................................................16-5

Propeller Thrust Line........................................16-5

Rotor Force .......................................................16-6

Trimmed Condition...........................................16-6

Chapter 17—Gyroplane Flight Controls

Cyclic Control .......................................................17-1

Throttle ..................................................................17-1

Rudder ...................................................................17-2

Horizontal Tail Surfaces........................................17-2

Collective Control .................................................17-2

Chapter 18—Gyroplane Systems

Propulsion Systems ...............................................18-1

Rotor Systems .......................................................18-1

Semirigid Rotor System....................................18-1

Fully Articulated Rotor System ........................18-1

Prerotator ...............................................................18-2

Mechanical Prerotator.......................................18-2

Hydraulic Prerotator .........................................18-2

Electric Prerotator.............................................18-3

Tip Jets..............................................................18-3

Instrumentation......................................................18-3

Engine Instruments ...........................................18-3

Rotor Tachometer .............................................18-3

Slip/Skid Indicator ............................................18-4

Airspeed Indicator ............................................18-4

Altimeter ...........................................................18-4

IFR Flight Instrumentation ...............................18-4

Ground Handling...................................................18-4

Chapter 19—Rotorcraft Flight Manual

(Gyroplane)

Using the Flight Manual........................................19-1

Weight and Balance Section .............................19-1

Sample Problem ...........................................19-1

Performance Section.........................................19-2

Sample Problem ...........................................19-2

Height/Velocity Diagram .............................19-3

Emergency Section ...........................................19-3

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Hang Test...............................................................19-4

Chapter 20—Flight Operations

Preflight .................................................................20-1

Cockpit Management........................................20-1

Engine Starting......................................................20-1

Taxiing...................................................................20-1

Blade Flap.........................................................20-1

Before Takeoff.......................................................20-2

Prerotation.........................................................20-2

Takeoff...................................................................20-3

Normal Takeoff.................................................20-3

Crosswind Takeoff ............................................20-4

Common Errors for Normal and

Crosswind Takeoffs ..........................................20-4

Short-Field Takeoff...........................................20-4

x

Common Errors............................................20-4

High-Altitude Takeoff ..................................20-4

Soft-Field Takeoff.............................................20-5

Common Errors............................................20-5

Jump Takeoff................................................20-5

Basic Flight Maneuvers.........................................20-6

Straight-and-Level Flight..................................20-6

Climbs...............................................................20-6

Descents ............................................................20-7

Turns .................................................................20-7

Slips..............................................................20-7

Skids .............................................................20-7

Common Errors During Basic

Flight Maneuvers ..............................................20-8

Steep Turns .......................................................20-8

Common Errors............................................20-8

Ground Reference Maneuvers...............................20-8

Rectangular Course...........................................20-8

S-Turns............................................................20-10

Turns Around a Point......................................20-11

Common Errors During

Ground Reference Maneuvers ........................20-11

Flight at Slow Airspeeds .....................................20-12

Common Errors ..............................................20-12

High Rate of Descent ..........................................20-12

Common Errors ..............................................20-13

Landings ..............................................................20-13

Normal Landing..............................................20-13

Short-Field Landing........................................20-13

Soft-Field Landing..........................................20-14

Crosswind Landing.........................................20-14

High-Altitude Landing....................................20-14

Common Errors During Landing....................20-15

Go-Around...........................................................20-15

Common Errors ..............................................20-15

After Landing and Securing................................20-15

Chapter 21—Gyroplane Emergencies

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Aborted Takeoff.....................................................21-1

Accelerate/Stop Distance..................................21-1

Lift-off at Low Airspeed and

High Angle of Attack ............................................21-1

Common Errors ................................................21-2

Pilot-Induced Oscillation (PIO) ............................21-2

Buntover (Power Pushover) ..................................21-3

Ground Resonance ................................................21-3

Emergency Approach and Landing.......................21-3

Emergency Equipment and Survival Gear............21-4

Chapter 22—Gyroplane Aeronautical Decision

Making

Impulsivity.............................................................22-1

Invulnerability .......................................................22-1

Macho....................................................................22-2

Resignation............................................................22-2

Anti-Authority .......................................................22-3

Glossary.................................................................G-1

Index........................................................................I-1

1-1

Helicopters come in many sizes and shapes, but most

share the same major components. These components

include a cabin where the payload and crew are carried; an airframe, which houses the various components, or where components are attached; a powerplant

or engine; and a transmission, which, among other

things, takes the power from the engine and transmits it

to the main rotor, which provides the aerodynamic

forces that make the helicopter fly. Then, to keep the

helicopter from turning due to torque, there must be

some type of antitorque system. Finally there is the

landing gear, which could be skids, wheels, skis, or

floats. This chapter is an introduction to these components. [Figure 1-1]

THE MAIN ROTOR SYSTEM

The rotor system found on helicopters can consist of a

single main rotor or dual rotors. With most dual rotors,

the rotors turn in opposite directions so the torque from

one rotor is opposed by the torque of the other. This

cancels the turning tendencies. [Figure 1-2]

In general, a rotor system can be classified as either

fully articulated, semirigid, or rigid. There are variations and combinations of these systems, which will be

discussed in greater detail in Chapter 5—Helicopter

Systems.

FULLY ARTICULATED ROTOR SYSTEM

A fully articulated rotor system usually consists of

three or more rotor blades. The blades are allowed to

flap, feather, and lead or lag independently of each

other. Each rotor blade is attached to the rotor hub by a

horizontal hinge, called the flapping hinge, which permits the blades to flap up and down. Each blade can

move up and down independently of the others. The

flapping hinge may be located at varying distances

from the rotor hub, and there may be more than one.

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The position is chosen by each manufacturer, primarily

with regard to stability and control.

Payload—The term used for passengers, baggage, and cargo.

Torque—In helicopters with a single, main rotor system, the tendency of the helicopter to turn in

the opposite direction of the main

rotor rotation.

Blade Flap—The upward or

downward movement of the rotor

blades during rotation.

Blade Feather or Feathering—The

rotation of the blade around the

spanwise (pitch change) axis.

Blade Lead or Lag—The fore and

aft movement of the blade in the

plane of rotation. It is sometimes

called hunting or dragging.

Landing Gear

Tail Rotor

System

Main Rotor

System

Cabin

Airframe

Transmission

Powerplant

Figure 1-2. Helicopters can have a single main rotor or a dual rotor system.

Figure 1-1. The major components of a helicopter are the

cabin, airframe, landing gear, powerplant, transmission, main

rotor system, and tail rotor system.

1-2

Each rotor blade is also attached to the hub by a vertical hinge, called a drag or lag hinge, that permits each

blade, independently of the others, to move back and

forth in the plane of the rotor disc. Dampers are normally incorporated in the design of this type of rotor

system to prevent excessive motion about the drag

hinge. The purpose of the drag hinge and dampers is to

absorb the acceleration and deceleration of the rotor

blades.

The blades of a fully articulated rotor can also be feathered, or rotated about their spanwise axis. To put it

more simply, feathering means the changing of the

pitch angle of the rotor blades.

SEMIRIGID ROTOR SYSTEM

A semirigid rotor system allows for two different

movements, flapping and feathering. This system is

normally comprised of two blades, which are rigidly

attached to the rotor hub. The hub is then attached to

the rotor mast by a trunnion bearing or teetering hinge.

This allows the blades to see-saw or flap together. As

one blade flaps down, the other flaps up. Feathering is

accomplished by the feathering hinge, which changes

the pitch angle of the blade.

RIGID ROTOR SYSTEM

The rigid rotor system is mechanically simple, but

structurally complex because operating loads must be

absorbed in bending rather than through hinges. In this

system, the blades cannot flap or lead and lag, but they

can be feathered.

ANTITORQUE SYSTEMS

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TAIL ROTOR

Most helicopters with a single, main rotor system

require a separate rotor to overcome torque. This is

accomplished through a variable pitch, antitorque rotor

or tail rotor. [Figure 1-3]. You will need to vary the

thrust of the antitorque system to maintain directional

control whenever the main rotor torque changes, or to

make heading changes while hovering.

FENESTRON

Another form of antitorque rotor is the fenestron or

“fan-in-tail” design. This system uses a series of rotating blades shrouded within a vertical tail. Because the

blades are located within a circular duct, they are less

likely to come into contact with people or objects.

[Figure 1-4]

NOTAR®

The NOTAR® system is an alternative to the antitorque

rotor. The system uses low-pressure air that is forced

into the tailboom by a fan mounted within the helicopter. The air is then fed through horizontal slots, located

on the right side of the tailboom, and to a controllable

rotating nozzle to provide antitorque and directional

control. The low-pressure air coming from the horizontal slots, in conjunction with the downwash from the

main rotor, creates a phenomenon called “Coanda

Effect,” which produces a lifting force on the right side

of the tailboom. [Figure 1-5]

LANDING GEAR

The most common landing gear is a skid type gear,

which is suitable for landing on various types of surfaces. Some types of skid gear are equipped with

dampers so touchdown shocks or jolts are not transmitted to the main rotor system. Other types absorb the

shocks by the bending of the skid attachment arms.

Landing skids may be fitted with replaceable heavyduty skid shoes to protect them from excessive wear

and tear.

Helicopters can also be equipped with floats for water

operations, or skis for landing on snow or soft terrain.

Wheels are another type of landing gear. They may be

in a tricycle or four point configuration. Normally, the

Tail Rotor Thrust

to Compensate for Torque

Torque

Torque

Blade Rotation

Figure 1-3. The antitorque rotor produces thrust to oppose

torque and helps prevent the helicopter from turning in the

opposite direction of the main rotor.

Figure 1-4. Compared to an unprotected tail rotor, the fenestron antitorque system provides an improved margin of

safety during ground operations.

1-3

nose or tail gear is free to swivel as the helicopter is

taxied on the ground.

POWERPLANT

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A typical small helicopter has a reciprocating engine,

which is mounted on the airframe. The engine can be

mounted horizontally or vertically with the transmission supplying the power to the vertical main rotor

shaft. [Figure 1-6]

Another engine type is the gas turbine. This engine is

used in most medium to heavy lift helicopters due to its

large horsepower output. The engine drives the main

transmission, which then transfers power directly to the

main rotor system, as well as the tail rotor.

FLIGHT CONTROLS

When you begin flying a helicopter, you will use four

basic flight controls. They are the cyclic pitch control;

the collective pitch control; the throttle, which is

usually a twist grip control located on the end of the

collective lever; and the antitorque pedals. The collective and cyclic controls the pitch of the main rotor

blades. The function of these controls will be explained

in detail in Chapter 4—Flight Controls. [Figure 1-7]

Figure 1-5. While in a hover, Coanda Effect supplies approximately two-thirds of the lift necessary to maintain directional

control. The rest is created by directing the thrust from the

controllable rotating nozzle.

Main Rotor

Wake

Rotating

Nozzle

Downwash

Air

Jet

Lift

Air Intake

Main

Rotor

Main

Transmission

Antitorque

Rotor

Engine

Figure 1-6. Typically, the engine drives the main rotor through

a transmission and belt drive or centrifugal clutch system.

The antitorque rotor is driven from the transmission.

Cyclic

Throttle

Collective

Antitorque

Pedals

Figure 1-7. Location of flight controls.

1-4

2-1

There are four forces acting on a helicopter in flight.

They are lift, weight, thrust, and drag. [Figure 2-1] Lift

is the upward force created by the effect of airflow as it

passes around an airfoil. Weight opposes lift and is

caused by the downward pull of gravity. Thrust is the

force that propels the helicopter through the air.

Opposing lift and thrust is drag, which is the retarding

force created by development of lift and the movement

of an object through the air.

AIRFOIL

Before beginning the discussion of lift, you need to be

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aware of certain aerodynamic terms that describe an

airfoil and the interaction of the airflow around it.

An airfoil is any surface, such as an airplane wing or a

helicopter rotor blade, which provides aerodynamic

force when it interacts with a moving stream of air.

Although there are many different rotor blade airfoil

designs, in most helicopter flight conditions, all airfoils

perform in the same manner.

Engineers of the first helicopters designed relatively

thick airfoils for their structural characteristics.

Because the rotor blades were very long and slender, it

was necessary to incorporate more structural rigidity

into them. This prevented excessive blade droop when

the rotor system was idle, and minimized blade twisting while in flight. The airfoils were also designed to

be symmetrical, which means they had the same camber (curvature) on both the upper and lower surfaces.

Symmetrical blades are very stable, which helps keep

blade twisting and flight control loads to a minimum.

[Figure 2-2] This stability is achieved by keeping the

center of pressure virtually unchanged as the angle of

attack changes. Center of pressure is the imaginary

point on the chord line where the resultant of all aerodynamic forces are considered to be concentrated.

Today, designers use thinner airfoils and obtain the

required rigidity by using composite materials. In addition, airfoils are asymmetrical in design, meaning the

upper and lower surface do not have the same camber.

Normally these airfoils would not be as stable, but this

can be corrected by bending the trailing edge to produce

the same characteristics as symmetrical airfoils. This is

called “reflexing.” Using this type of rotor blade allows

the rotor system to operate at higher forward speeds.

One of the reasons an asymmetrical rotor blade is not

as stable is that the center of pressure changes with

changes in angle of attack. When the center of pressure

lifting force is behind the pivot point on a rotor blade, it

tends to cause the rotor disc to pitch up. As the angle of

attack increases, the center of pressure moves forward.

If it moves ahead of the pivot point, the pitch of the

rotor disc decreases. Since the angle of attack of the

rotor blades is constantly changing during each cycle

of rotation, the blades tend to flap, feather, lead, and

lag to a greater degree.

When referring to an airfoil, the span is the distance

from the rotor hub to the blade tip. Blade twist refers to

a changing chord line from the blade root to the tip.

Figure 2-2. The upper and lower curvatures are the same on a

symmetrical airfoil and vary on an asymmetrical airfoil.

Asymmetrical

Symmetrical

Lift

Weight

Drag

Thrust

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Figure 2-1. Four forces acting on a helicopter in forward flight.

2-2

Twisting a rotor blade causes it to produce a more even

amount of lift along its span. This is necessary because

rotational velocity increases toward the blade tip. The

leading edge is the first part of the airfoil to meet the

oncoming air. [Figure 2-3] The trailing edge is the aft

portion where the airflow over the upper surface joins

the airflow under the lower surface. The chord line is

an imaginary straight line drawn from the leading to

the trailing edge. The camber is the curvature of the airfoil’s upper and lower surfaces. The relative wind is the

wind moving past the airfoil. The direction of this wind

is relative to the attitude, or position, of the airfoil and

is always parallel, equal, and opposite in direction to

the flight path of the airfoil. The angle of attack is the

angle between the blade chord line and the direction of

the relative wind.

RELATIVE WIND

Relative wind is created by the motion of an airfoil

through the air, by the motion of air past an airfoil, or by

a combination of the two. Relative wind may be

affected by several factors, including the rotation of the

rotor blades, horizontal movement of the helicopter,

flapping of the rotor blades, and wind speed and direction.

For a helicopter, the relative wind is the flow of air with

respect to the rotor blades. If the rotor is stopped, wind

blowing over the blades creates a relative wind. When

the helicopter is hovering in a no-wind condition, relative wind is created by the motion of the rotor blades

through the air. If the helicopter is hovering in a wind,

the relative wind is a combination of the wind and the

motion of the rotor blades through the air. When the

helicopter is in forward flight, the relative wind is a

combination of the rotation of the rotor blades and the

forward speed of the helicopter.

BLADE PITCH ANGLE

The pitch angle of a rotor blade is the angle between its

chord line and the reference plane containing the rotor

hub. [Figure 2-4] You control the pitch angle of the blades

with the flight controls. The collective pitch changes each

rotor blade an equal amount of pitch no matter where it is

located in the plane of rotation (rotor disc) and is used to

change rotor thrust. The cyclic pitch control changes the

pitch of each blade as a function of where it is in the plane

of rotation. This allows for trimming the helicopter in

pitch and roll during forward flight and for maneuvering

in all flight conditions.

ANGLE OF ATTACK

When the angle of attack is increased, air flowing over

the airfoil is diverted over a greater distance, resulting

in an increase of air velocity and more lift. As angle of

attack is increased further, it becomes more difficult for

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air to flow smoothly across the top of the airfoil. At this

point the airflow begins to separate from the airfoil and

enters a burbling or turbulent pattern. The turbulence

results in a large increase in drag and loss of lift in the

area where it is taking place. Increasing the angle of

attack increases lift until the critical angle of attack is

reached. Any increase in the angle of attack beyond this

point produces a stall and a rapid decrease in lift.

[Figure 2-5]

Angle of attack should not be confused with pitch

angle. Pitch angle is determined by the direction of the

relative wind. You can, however, change the angle of

attack by changing the pitch angle through the use of

the flight controls. If the pitch angle is increased, the

angle of attack is increased, if the pitch angle is

reduced, the angle of attack is reduced. [Figure 2-6]

Axis-of-Rotation—The imaginary

line about which the rotor rotates.

It is represented by a line drawn

through the center of, and perpendicular to, the tip-path plane.

Tip-Path Plane—The imaginary

circular plane outlined by the

rotor blade tips as they make a

cycle of rotation.

Aircraft Pitch—When referenced

to a helicopter, is the movement of

the helicopter about its lateral, or

side to side axis. Movement of the

cyclic forward or aft causes the

nose of the helicopter to move up

or down.

Aircraft Roll—Is the movement of

the helicopter about its longitudinal, or nose to tail axis. Movement

of the cyclic right or left causes the

helicopter to tilt in that direction.

Figure 2-3. Aerodynamic terms of an airfoil.

Trailing

Edge

ChordLine

Angleof

Attack

FLIGHT PATH

RELATIVE WIND

Upper

Camber

Lower

Camber

Leading

Edge

Axis of Rotation

Reference Plane

Pitch

Angle

ChordLine

Figure 2-4. Do not confuse the axis of rotation with the rotor

mast. The only time they coincide is when the tip-path plane

is perpendicular to the rotor mast.

2-3

LIFT

MAGNUS EFFECT

The explanation of lift can best be explained by looking

at a cylinder rotating in an airstream. The local velocity

near the cylinder is composed of the airstream velocity

and the cylinder’s rotational velocity, which decreases

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with distance from the cylinder. On a cylinder, which is

rotating in such a way that the top surface area is rotating

in the same direction as the airflow, the local velocity at

the surface is high on top and low on the bottom.

As shown in figure 2-7, at point “A,” a stagnation point

exists where the airstream line that impinges on the surface splits; some air goes over and some under. Another

stagnation point exists at “B,” where the two air

streams rejoin and resume at identical velocities. We

now have upwash ahead of the rotating cylinder and

downwash at the rear.

The difference in surface velocity accounts for a difference in pressure, with the pressure being lower on the

top than the bottom. This low pressure area produces

an upward force known as the “Magnus Effect.” This

mechanically induced circulation illustrates the relationship between circulation and lift.

An airfoil with a positive angle of attack develops air

circulation as its sharp trailing edge forces the rear

stagnation point to be aft of the trailing edge, while the

front stagnation point is below the leading edge.

[Figure 2-8]

BERNOULLI’S PRINCIPLE

Air flowing over the top surface accelerates. The airfoil

is now subjected to Bernoulli’s Principle or the “venturi

effect.” As air velocity increases through the constricted

portion of a venturi tube, the pressure decreases.

Axis of Rotation

Reference Plane

Pitch

Angle

ChordLine

Angleof

Attack

RELATIVE WIND

Figure 2-6. Angle of attack may be greater than, less than, or

the same as the pitch angle.

Figure 2-5. As the angle of attack is increased, the separation

point starts near the trailing edge of the airfoil and progresses forward. Finally, the airfoil loses its lift and a stall

condition occurs.

LIFT

STALL

8°

12-16°

Figure 2-7. Magnus Effect is a lifting force produced when a

rotating cylinder produces a pressure differential. This is the

same effect that makes a baseball curve or a golf ball slice.

B A

Increased Local Velocity

(Decreased pressure)

Decreased Local Velocity

Downwash Upwash

Figure 2-8. Air circulation around an airfoil occurs when the

front stagnation point is below the leading edge and the aft

stagnation point is beyond the trailing edge.

Leading Edge

Stagnation Point

Trailing Edge

Stagnation Point

B

A

Steady-State Flight—A condition

when an aircraft is in straightand-level, unaccelerated flight,

and all forces are in balance.

2-4

ward. According to Newton’s Third Law of Motion,

“for every action there is an equal and opposite reaction,” the air that is deflected downward also produces

an upward (lifting) reaction.

Since air is much like water, the explanation for this

source of lift may be compared to the planing effect of

skis on water. The lift which supports the water skis

(and the skier) is the force caused by the impact pressure and the deflection of water from the lower surfaces

of the skis.

Under most flying conditions, the impact pressure and

the deflection of air from the lower surface of the rotor

blade provides a comparatively small percentage of the

total lift. The majority of lift is the result of decreased

pressure above the blade, rather than the increased

pressure below it.

WEIGHT

Normally, weight is thought of as being a known, fixed

value, such as the weight of the helicopter, fuel, and

occupants. To lift the helicopter off the ground vertically, the rotor system must generate enough lift to

overcome or offset the total weight of the helicopter

and its occupants. This is accomplished by increasing

the pitch angle of the main rotor blades.

The weight of the helicopter can also be influenced by

aerodynamic loads. When you bank a helicopter while

maintaining a constant altitude, the “G” load or load

factor increases. Load factor is the ratio of the load supported by the main rotor system to the actual weight of

the helicopter and its contents. In steady-state flight,

the helicopter has a load factor of one, which means the

main rotor system is supporting the actual total weight

of the helicopter. If you increase the bank angle to 60°,

while still maintaining a constant altitude, the load factor increases to two. In this case, the main rotor system

has to support twice the weight of the helicopter and its

contents. [Figure 2-11]

Disc loading of a helicopter is the ratio of weight to the

total main rotor disc area, and is determined by dividing the total helicopter weight by the rotor disc area,

which is the area swept by the blades of a rotor. Disc

area can be found by using the span of one rotor blade

as the radius of a circle and then determining the area

the blades encompass during a complete rotation. As

the helicopter is maneuvered, disc loading changes.

The higher the loading, the more power you need to

maintain rotor speed.

Leading Edge

Stagnation Point

B