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直升机飞行手册Rotorcraft flying handbook [复制链接]

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area. Only after the first two items are assured, should

you try to communicate with anyone.

Another important part of managing workload is recognizing a work overload situation. The first effect of

high workload is that you begin to work faster. As

workload increases, attention cannot be devoted to several tasks at one time, and you may begin to focus on

one item. When you become task saturated, there is no

awareness of inputs from various sources, so decisions

may be made on incomplete information, and the possibility of error increases. [Figure 14-9]

When becoming overloaded, you should stop, think,

slow down, and prioritize. It is important that you

understand options that may be available to decrease

workload. For example, tasks, such as locating an item

on a chart or setting a radio frequency, may be delegated to another pilot or passenger, an autopilot, if

available, may be used, or ATC may be enlisted to

provide assistance.

SITUATIONAL AWARENESS

Situational awareness is the accurate perception of the

operational and environmental factors that affect the

aircraft, pilot, and passengers during a specific period

of time. Maintaining situational awareness requires

an understanding of the relative significance of these

factors and their future impact on the flight. When situationally aware, you have an overview of the total

operation and are not fixated on one perceived significant factor. Some of the elements inside the aircraft

to be considered are the status of aircraft systems, you

as the pilot, and passengers. In addition, an awareness

of the environmental conditions of the flight, such as

spatial orientation of the helicopter, and its relationship to terrain, traffic, weather, and airspace must be

maintained.

To maintain situational awareness, all of the skills

involved in aeronautical decision making are used. For

example, an accurate perception of your fitness can be

achieved through self-assessment and recognition of

hazardous attitudes. A clear assessment of the status of

navigation equipment can be obtained through workload management, and establishing a productive

relationship with ATC can be accomplished by effective resource use.

OBSTACLES TO MAINTAINING SITUATIONAL

AWARENESS

Fatigue, stress, and work overload can cause you to fixate on a single perceived important item rather than

maintaining an overall awareness of the flight situation. A contributing factor in many accidents is a

distraction that diverts the pilot’s attention from monitoring the instruments or scanning outside the

aircraft. Many cockpit distractions begin as a minor

problem, such as a gauge that is not reading correctly,

but result in accidents as the pilot diverts attention to

the perceived problem and neglects to properly control

the aircraft.

Complacency presents another obstacle to maintaining

situational awareness. When activities become routine,

you may have a tendency to relax and not put as much

effort into performance. Like fatigue, complacency

reduces your effectiveness in the cockpit. However,

complacency is harder to recognize than fatigue, since

everything is perceived to be progressing smoothly. For

example, you have just dropped off another group of

fire fighters for the fifth time that day. Without thinking, you hastily lift the helicopter off the ground, not

realizing that one of the skids is stuck between two

rocks. The result is dynamic rollover and a destroyed

helicopter.

OPERATIONAL PITFALLS

There are a number of classic behavioral traps into

which pilots have been known to fall. Pilots, particularly those with considerable experience, as a rule,

always try to complete a flight as planned, please passengers, and meet schedules. The basic drive to meet

or exceed goals can have an adverse effect on safety,

and can impose an unrealistic assessment of piloting

skills under stressful conditions. These tendencies ultimately may bring about practices that are dangerous

and often illegal, and may lead to a mishap. You will

develop awareness and learn to avoid many of these

operational pitfalls through effective ADM training.

[Figure 14-10]

Margin

of Safety

Pilot Capabilities

Task

Requirements

Preflight Takeoff Cruise Approach &

Landing

Taxi Taxi

Time

Figure 14-9. Accidents often occur when flying task requirements exceed pilot capabilities. The difference between

these two factors is called the margin of safety. Note that in

this idealized example, the margin of safety is minimal during

the approach and landing. At this point, an emergency or distraction could overtax pilot capabilities, causing an accident.

14-9

Peer Pressure—Poor decision making may be based upon an emotional response to peers, rather than evaluating a situation

objectively.

Mind Set—A pilot displays mind set through an inability to recognize and cope with changes in a given situation.

Get-There-Itis—This disposition impairs pilot judgment through a fixation on the original goal or destination, combined with a

disregard for any alternative course of action.

Scud Running—This occurs when a pilot tries to maintain visual contact with the terrain at low altitudes while instrument

conditions exist.

Continuing Visual Flight Rules (VFR) into Instrument Conditions—Spatial disorientation or collision with ground/obstacles

may occur when a pilot continues VFR into instrument conditions. This can be even more dangerous if the pilot is not

instrument-rated or current.

Getting Behind the Aircraft—This pitfall can be caused by allowing events or the situation to control pilot actions. A constant

state of surprise at what happens next may be exhibited when the pilot is getting behind the aircraft.

Loss of Positional or Situational Awareness—In extreme cases, when a pilot gets behind the aircraft, a loss of positional or

situational awareness may result. The pilot may not know the aircraft's geographical location, or may be unable to recognize

deteriorating circumstances.

Operating Without Adequate Fuel Reserves—Ignoring minimum fuel reserve requirements is generally the result of

overconfidence, lack of flight planning, or disregarding applicable regulations.

Flying Outside the Envelope—The assumed high performance capability of a particular aircraft may cause a mistaken belief

that it can meet the demands imposed by a pilot's overestimated flying skills.

Neglect of Flight Planning, Preflight Inspections, and Checklists—A pilot may rely on short- and long-term memory,

regular flying skills, and familiar routes instead of established procedures and published checklists. This can be particularly true

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of experienced pilots.

OPERATIONAL PITFALLS

Figure 14-10. All experienced pilots have fallen prey to, or have been tempted by, one or more of these tendencies in their flying

careers.

14-10

autorotation. The first successful example of this type

of aircraft was the British Fairy Rotodyne, certificated

to the Transport Category in 1958. During the 1960s

and 1970s, the popularity of gyroplanes increased with

the certification of the McCulloch J-2 and Umbaugh.

The latter becoming the Air & Space 18A.

There are several aircraft under development using the

free spinning rotor to achieve rotary wing takeoff performance and fixed wing cruise speeds. The gyroplane

offers inherent safety, simplicity of operation, and outstanding short field point-to-point capability.

TYPES OF GYROPLANES

Because the free spinning rotor does not require an

antitorque device, a single rotor is the predominate

configuration. Counter-rotating blades do not offer

any particular advantage. The rotor system used in a

gyroplane may have any number of blades, but the

most popular are the two and three blade systems.

Propulsion for gyroplanes may be either tractor or

pusher, meaning the engine may be mounted on the

front and pull the aircraft, or in the rear, pushing it

through the air. The powerplant itself may be either

reciprocating or turbine. Early gyroplanes were

often a derivative of tractor configured airplanes

with the rotor either replacing the wing or acting in

conjunction with it. However, the pusher configuration is generally more maneuverable due to the

placement of the rudder in the propeller slipstream,

and also has the advantage of better visibility for the

pilot. [Figure 15-1]

15-1

January 9th, 1923, marked the first officially observed

flight of an autogyro. The aircraft, designed by Juan de

la Cierva, introduced rotor technology that made forward flight in a rotorcraft possible. Until that time,

rotary-wing aircraft designers were stymied by the

problem of a rolling moment that was encountered

when the aircraft began to move forward. This rolling

moment was the product of airflow over the rotor disc,

causing an increase in lift of the advancing blade and

decrease in lift of the retreating blade. Cierva’s successful design, the C.4, introduced the articulated rotor, on

which the blades were hinged and allowed to flap. This

solution allowed the advancing blade to move upward,

decreasing angle of attack and lift, while the retreating

blade would swing downward, increasing angle of

attack and lift. The result was balanced lift across the

rotor disc regardless of airflow. This breakthrough was

instrumental in the success of the modern helicopter,

which was developed over 15 years later. (For more

information on dissymmetry of lift, refer to Chapter 3—

Aerodynamics of Flight.) On April 2, 1931, the Pitcairn

PCA-2 autogyro was granted Type Certificate No. 410

and became the first rotary wing aircraft to be certified

in the United States. The term “autogyro” was used to

describe this type of aircraft until the FAA later designated them “gyroplanes.”

By definition, the gyroplane is an aircraft that achieves

lift by a free spinning rotor. Several aircraft have used

the free spinning rotor to attain performance not available in the pure helicopter. The “gyrodyne” is a hybrid

rotorcraft that is capable of hovering and yet cruises in

Figure 15-1. The gyroplane may have wings, be either tractor or pusher configured, and could be turbine or propeller powered.

Pictured are the Pitcairn PCA-2 Autogyro (left) and the Air & Space 18A gyroplane.

15-2

When direct control of the rotor head was perfected,

the jump takeoff gyroplane was developed. Under the

proper conditions, these gyroplanes have the ability to

lift off vertically and transition to forward flight. Later

developments have included retaining the direct control rotor head and utilizing a wing to unload the rotor,

which results in increased forward speed.

COMPONENTS

Although gyroplanes are designed in a variety of configurations, for the most part the basic components are the

same. The minimum components required for a functional gyroplane are an airframe, a powerplant, a rotor

system, tail surfaces, and landing gear. [Figure 15-2] An

optional component is the wing, which is incorporated

into some designs for specific performance objectives.

AIRFRAME

The airframe provides the structure to which all other

components are attached. Airframes may be welded

tube, sheet metal, composite, or simply tubes bolted

together. A combination of construction methods may

also be employed. The airframes with the greatest

strength-to-weight ratios are a carbon fiber material or

Powerplant

Rotor

Airframe

Landing Gear

Tail

Surfaces

Direct Control—The capacity for

the pilot to maneuver the aircraft

by tilting the rotor disc and, on

some gyroplanes, affect changes in

pitch to the rotor blades. These

equate to cyclic and collective control, which were not available in

earlier autogyros.

Unload—To reduce the component of weight supported by the

rotor system.

Prerotate—Spinning a gyroplane

rotor to sufficient r.p.m. prior to

flight.

the welded tube structure, which has been in use for a

number of years.

POWERPLANT

The powerplant provides the thrust necessary for forward

flight, and is independent of the rotor system while in

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flight. While on the ground, the engine may be used as

a source of power to prerotate the rotor system. Over

the many years of gyroplane development, a wide

variety of engine types have been adapted to the gyroplane. Automotive, marine, ATV, and certificated

aircraft engines have all been used in various

gyroplane designs. Certificated gyroplanes are

required to use FAA certificated engines. The cost of a

new certificated aircraft engine is greater than the cost

of nearly any other new engine. This added cost is the

primary reason other types of engines are selected for

use in amateur built gyroplanes.

ROTOR SYSTEM

The rotor system provides lift and control for the gyroplane. The fully articulated and semi-rigid teetering

rotor systems are the most common. These are

explained in-depth in Chapter 5—Main Rotor System.

The teeter blade with hub tilt control is most common

in homebuilt gyroplanes. This system may also employ

a collective control to change the pitch of the rotor

blades. With sufficient blade inertia and collective

pitch change, jump takeoffs can be accomplished.

TAIL SURFACES

The tail surfaces provide stability and control in the pitch

and yaw axes. These tail surfaces are similar to an airplane empennage and may be comprised of a fin and

rudder, stabilizer and elevator. An aft mounted duct

enclosing the propeller and rudder has also been used.

Many gyroplanes do not incorporate a horizontal tail

surface.

On some gyroplanes, especially those with an enclosed

cockpit, the yaw stability is marginal due to the large

fuselage side area located ahead of the center of gravity. The additional vertical tail surface necessary to

compensate for this instability is difficult to achieve as

the confines of the rotor tilt and high landing pitch attitude limits the available area. Some gyroplane designs

incorporate multiple vertical stabilizers and rudders to

add additional yaw stability.

Figure 15-2. Gyroplanes typically consist of five major components. A sixth, the wing, is utilized on some designs.

15-3

LANDING GEAR

The landing gear provides the mobility while on the

ground and may be either conventional or tricycle.

Conventional gear consists of two main wheels, and one

under the tail. The tricycle configuration also uses two

mains, with the third wheel under the nose. Early autogyros, and several models of gyroplanes, use conventional gear, while most of the later gyroplanes

incorporate tricycle landing gear. As with fixed wing

aircraft, the gyroplane landing gear provides the ground

mobility not found in most helicopters.

WINGS

Wings may or may not comprise a component of the

gyroplane. When used, they provide increased performance, increased storage capacity, and increased

stability. Gyroplanes are under development with

wings that are capable of almost completely unloading the rotor system and carrying the entire weight

of the aircraft. This will allow rotary wing takeoff

performance with fixed wing cruise speeds. [Figure

15-3]

Figure 15-3. The CarterCopter uses wings to enhance

performance.

15-4

16-1

Helicopters and gyroplanes both achieve lift through

the use of airfoils, and, therefore, many of the basic

aerodynamic principles governing the production of lift

apply to both aircraft. These concepts are explained in

depth in Chapter 2—General Aerodynamics, and constitute the foundation for discussing the aerodynamics

of a gyroplane.

AUTOROTATION

A fundamental difference between helicopters and

gyroplanes is that in powered flight, a gyroplane rotor

system operates in autorotation. This means the rotor

spins freely as a result of air flowing up through the

blades, rather than using engine power to turn the

blades and draw air from above. [Figure 16-1] Forces

are created during autorotation that keep the rotor

blades turning, as well as creating lift to keep the aircraft aloft. Aerodynamically, the rotor system of a

gyroplane in normal flight operates like a helicopter

rotor during an engine-out forward autorotative

descent.

VERTICAL AUTOROTATION

During a vertical autorotation, two basic components

contribute to the relative wind striking the rotor blades.

[Figure 16-2] One component, the upward flow of air

through the rotor system, remains relatively constant

for a given flight condition. The other component is the

rotational airflow, which is the wind velocity across the

blades as they spin. This component varies significantly based upon how far from the rotor hub it is

measured. For example, consider a rotor disc that is 25

feet in diameter operating at 300 r.p.m. At a point one

foot outboard from the rotor hub, the blades are traveling in a circle with a circumference of 6.3 feet. This

equates to 31.4 feet per second (f.p.s.), or a rotational

blade speed of 21 m.p.h. At the blade tips, the circumference of the circle increases to 78.5 feet. At the same

operating speed of 300 r.p.m., this creates a blade tip

Direction of Flight

Relative Wind Relative Wind

Direction of Flight

Figure 16-1. Airflow through the rotor system on a gyroplane is reversed from that on a powered helicopter. This airflow is the

medium through which power is transferred from the gyroplane engine to the rotor system to keep it rotating.

ResultantRelativeWind

Wind due to Blade Rotation

Upward

Airflow

Figure 16-2. In a vertical autorotation, the wind from the

rotation of the blade combines with the upward airflow to

produce the resultant relative wind striking the airfoil.

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16-2

speed of 393 feet per second, or 267 m.p.h. The result

is a higher total relative wind, striking the blades at a

lower angle of attack. [Figure 16-3]

ROTOR DISC REGIONS

As with any airfoil, the lift that is created by rotor

blades is perpendicular to the relative wind. Because

the relative wind on rotor blades in autorotation shifts

from a high angle of attack inboard to a lower angle of

attack outboard, the lift generated has a higher forward

component closer to the hub and a higher vertical component toward the blade tips. This creates distinct

regions of the rotor disc that create the forces necessary for flight in autorotation. [Figure 16-4] The

autorotative region, or driving region, creates a total

aerodynamic force with a forward component that

exceeds all rearward drag forces and keeps the blades

spinning. The propeller region, or driven region, generates a total aerodynamic force with a higher vertical

component that allows the gyroplane to remain aloft.

Near the center of the rotor disc is a stall region where

the rotational component of the relative wind is so low

that the resulting angle of attack is beyond the stall

limit of the airfoil. The stall region creates drag against

the direction of rotation that must be overcome by the

forward acting forces generated by the driving region.

AUTOROTATION IN FORWARD FLIGHT

As discussed thus far, the aerodynamics of autorotation

apply to a gyroplane in a vertical descent. Because

gyroplanes are normally operated in forward flight, the

component of relative wind striking the rotor blades as

a result of forward speed must also be considered. This

component has no effect on the aerodynamic principles

that cause the blades to autorotate, but causes a shift in

the zones of the rotor disc.

As a gyroplane moves forward through the air, the forward speed of the aircraft is effectively added to the

ResultantRelativeWind

Rotational Airflow (267 m.p.h. or 393 f.p.s.)

Upward Airflow

(17 m.p.h. or 25 f.p.s.)

TIP

Rotor Speed: 300 r.p.m.

F

Resultant

RelativeWind

Rotational Airflow

(21 m.p.h. or 31 f.p.s.)

Upward Airflow

(17 m.p.h. or 25 f.p.s.)

HUB

VERTICAL AUTOROTATION

Figure 16-3. Moving outboard on the rotor blade, the rotational velocity increasingly exceeds the upward component of airflow,

resulting in a higher relative wind at a lower angle of attack.

Driven Region

Driving Region

Stall

Region

Driven Region

(Propeller)

Driving Region

(Autorotative)

Stall Region

F

VERTICAL AUTOROTATION

Rotational

Relative Wind

Lift

Lift

TAF

TAF

Total

Aerodynamic

Force Aft

of Axis of

Rotation

Drag

Chord Line

Inflow Up

Through Rotor

Resultant

Relative Wind

Total

Aerodynamic

Force

Forward

of Axis of

Rotation

Drag

Inflow

Axis of

Rotation

Axis of

Rotation

Axis of

Rotation

(Blade is Stalled)

TAF

Drag

Inflow

Lift

Figure 16-4. The total aerodynamic force is aft of the axis of

rotation in the driven region and forward of the axis of rotation in the driving region. Drag is the major aerodynamic

force in the stall region. For a complete depiction of force

vectors during a vertical autorotation, refer to Chapter 3—

Aerodynamics of Flight (Helicopter), Figure 3-22.

16-3

relative wind striking the advancing blade, and subtracted from the relative wind striking the retreating

blade. To prevent uneven lifting forces on the two sides

of the rotor disc, the advancing blade teeters up,

decreasing angle of attack and lift, while the retreating

blade teeters down, increasing angle of attack and lift.

(For a complete discussion on dissymmetry of lift, refer

to Chapter 3—Aerodynamics of Flight.) The lower

angles of attack on the advancing blade cause more of

the blade to fall in the driven region, while higher

angles of attack on the retreating blade cause more of

the blade to be stalled. The result is a shift in the rotor

regions toward the retreating side of the disc to a degree

directly related to the forward speed of the aircraft.

[Figure 16-5]

REVERSE FLOW

On a rotor system in forward flight, reverse flow occurs

near the rotor hub on the retreating side of the rotor

disc. This is the result of the forward speed of the aircraft exceeding the rotational speed of the rotor blades.

For example, two feet outboard from the rotor hub, the

blades travel in a circle with a circumference of 12.6

feet. At a rotor speed of 300 r.p.m., the blade speed at

the two-foot station is 42 m.p.h. If the aircraft is being

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operated at a forward speed of 42 m.p.h., the forward

speed of the aircraft essentially negates the rotational

velocity on the retreating blade at the two-foot station.

Moving inboard from the two-foot station on the

retreating blade, the forward speed of the aircraft

increasingly exceeds the rotational velocity of the

blade. This causes the airflow to actually strike the

trailing edge of the rotor blade, with velocity increasing toward the rotor hub. [Figure 16-6] The size of the

area that experiences reverse flow is dependent prima-

rily on the forward speed of the aircraft, with higher

speed creating a larger region of reverse flow. To some

degree, the operating speed of the rotor system also has

an effect on the size of the region, with systems operating at lower r.p.m. being more susceptible to reverse

flow and allowing a greater portion of the blade to

experience the effect.

RETREATING BLADE STALL

The retreating blade stall in a gyroplane differs from

that of a helicopter in that it occurs outboard from the

rotor hub at the 20 to 40 percent position rather than at

the blade tip. Because the gyroplane is operating in

autorotation, in forward flight there is an inherent stall

region centered inboard on the retreating blade. [Refer

to figure 16-5] As forward speed increases, the angle of

attack on the retreating blade increases to prevent dissymmetry of lift and the stall region moves further

outboard on the retreating blade. Because the stalled

portion of the rotor disc is inboard rather than near the

tip, as with a helicopter, less force is created about the

aircraft center of gravity. The result is that you may feel

a slight increase in vibration, but you would not experience a large pitch or roll tendency.

ROTOR FORCE

As with any heavier than air aircraft, the four forces

acting on the gyroplane in flight are lift, weight, thrust

and drag. The gyroplane derives lift from the rotor and

Forward

Driven Region

Driving Region

Stall

Region

Retreating

Side

Advancing

Side

Figure 16-5. Rotor disc regions in forward autorotative flight.

Forward

Flight at

42 kt

42kt

42kt

42kt

42kt

2'

Area of

Reverse flow

42kt

Rotor Speed 300 r.p.m.

Figure 16-6. An area of reverse flow forms on the retreating

blade in forward flight as a result of aircraft speed exceeding

blade rotational speed.

16-4

rotor blades turn, rapid changes occur on the airfoils

depending on position, rotor speed, and aircraft speed.

A change in the angle of attack of the rotor disc can

effect a rapid and substantial change in total rotor drag.

Rotor drag can be divided into components of induced

drag and profile drag. The induced drag is a product of

lift, while the profile drag is a function of rotor r.p.m.

Because induced drag is a result of the rotor providing

lift, profile drag can be considered the drag of the rotor

when it is not producing lift. To visualize profile drag,

consider the drag that must be overcome to prerotate

the rotor system to flight r.p.m. while the blades are

producing no lift. This can be achieved with a rotor system having a symmetrical airfoil and a pitch change

capability by setting the blades to a 0° angle of attack.

A rotor system with an asymmetrical airfoil and a built

in pitch angle, which includes most amateur-built

teeter-head rotor systems, cannot be prerotated without

having to overcome the induced drag created as well.

THRUST

Thrust in a gyroplane is defined as the component of

total propeller force parallel to the relative wind. As

with any force applied to an aircraft, thrust acts around

the center of gravity. Based upon where the thrust is

applied in relation to the aircraft center of gravity, a relatively small component may be perpendicular to the

relative wind and can be considered to be additive to

lift or weight.

In flight, the fuselage of a gyroplane essentially acts as

a plumb suspended from the rotor, and as such, it is

thrust directly from the engine through a propeller.

[Figure 16-7]

The force produced by the gyroplane rotor may be

divided into two components; rotor lift and rotor drag.

The component of rotor force perpendicular to the

flight path is rotor lift, and the component of rotor force

parallel to the flight path is rotor drag. To derive the

total aircraft drag reaction, you must also add the drag

of the fuselage to that of the rotor.

ROTOR LIFT

Rotor lift can most easily be visualized as the lift

required to support the weight of the aircraft. When an

airfoil produces lift, induced drag is produced. The

most efficient angle of attack for a given airfoil produces the most lift for the least drag. However, the airfoil of a rotor blade does not operate at this efficient

angle throughout the many changes that occur in each

revolution. Also, the rotor system must remain in the

autorotative (low) pitch range to continue turning in

order to generate lift.

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Some gyroplanes use small wings for creating lift when

operating at higher cruise speeds. The lift provided by

the wings can either supplement or entirely replace

rotor lift while creating much less induced drag.

ROTOR DRAG

Total rotor drag is the summation of all the drag forces

acting on the airfoil at each blade position. Each blade

position contributes to the total drag according to the

speed and angle of the airfoil at that position. As the

Lift

Resultant

Thrust

Resultant

Thrust

Lift

Resultant

Drag

Rotor

Drag

Fuselage

Drag

Resultant

Weight

Weight

Figure 16-7. Unlike a helicopter, in forward powered flight the resultant rotor force of a gyroplane acts in a rearward direction.

16-5

subject to pendular action in the same way as a helicopter. Unlike a helicopter, however, thrust is applied

directly to the airframe of a gyroplane rather than being

obtained through the rotor system. As a result, different

forces act on a gyroplane in flight than on a helicopter.

Engine torque, for example, tends to roll the fuselage

in the direction opposite propeller rotation, causing it

to be deflected a few degrees out of the vertical plane.

[Figure 16-8] This slight “out of vertical” condition is

usually negligible and not considered relevant for most

flight operations.

STABILITY

Stability is designed into aircraft to reduce pilot workload and increase safety. A stable aircraft, such as a typical general aviation training airplane, requires less

attention from the pilot to maintain the desired flight

attitude, and will even correct itself if disturbed by a

gust of wind or other outside forces. Conversely, an

unstable aircraft requires constant attention to maintain

control of the aircraft.

Reactive

Torque on

Fuselage

Torque

Applied to

Propeller

Figure 16-8. Engine torque applied to the propeller has an

equal and opposite reaction on the fuselage, deflecting it a

few degrees out of the vertical plane in flight.

Pendular Action—The lateral or

longitudinal oscillation of the fuselage due to it being suspended

from the rotor system. It is similar

to the action of a pendulum.

Pendular action is further discussed in Chapter 3—

Aerodynamics of Flight.

There are several factors that contribute to the stability

of a gyroplane. One is the location of the horizontal

stabilizer. Another is the location of the fuselage drag

in relation to the center of gravity. A third is the

inertia moment around the pitch axis, while a fourth is

the relation of the propeller thrust line to the vertical

location of the center of gravity (CG). However, the

one that is probably the most critical is the relation of

the rotor force line to the horizontal location of the

center of gravity.

HORIZONTAL STABILIZER

A horizontal stabilizer helps in longitudinal stability,

with its efficiency greater the further it is from the

center of gravity. It is also more efficient at higher

airspeeds because lift is proportional to the square of

the airspeed. Since the speed of a gyroplane is not very

high, manufacturers can achieve the desired stability

by varying the size of the horizontal stabilizer, changing the distance it is from the center of gravity, or by

placing it in the propeller slipstream.

FUSELAGE DRAG

(CENTER OF PRESSURE)

If the location, where the fuselage drag or center of

pressure forces are concentrated, is behind the CG,

the gyroplane is considered more stable. This is especially true of yaw stability around the vertical axis.

However, to achieve this condition, there must be a

sufficient vertical tail surface. In addition, the gyroplane needs to have a balanced longitudinal center of

pressure so there is sufficient cyclic movement to

prevent the nose from tucking under or lifting, as

pressure builds on the frontal area of the gyroplane as

airspeed increases.

PITCH INERTIA

Without changing the overall weight and center of

gravity of a gyroplane, the further weights are placed

from the CG, the more stable the gyroplane. For example, if the pilot's seat could be moved forward from the

CG, and the engine moved aft an amount, which keeps

the center of gravity in the same location, the gyroplane

becomes more stable. A tightrope walker applies this

same principle when he uses a long pole to balance

himself.

PROPELLER THRUST LINE

Considering just the propeller thrust line by itself, if the

thrust line is above the center of gravity, the gyroplane

has a tendency to pitch nose down when power is

applied, and to pitch nose up when power is removed.

The opposite is true when the propeller thrust line is

below the CG. If the thrust line goes through the CG or

16-6

nearly so there is no tendency for the nose to pitch up

or down. [Figure 16-9]

ROTOR FORCE

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Because some gyroplanes do not have horizontal stabilizers, and the propeller thrust lines are different, gyroplane manufacturers can achieve the desired stability

by placing the center of gravity in front of or behind the

rotor force line. [Figure 16-10]

Suppose the CG is located behind the rotor force line in

forward flight. If a gust of wind increases the angle of

attack, rotor force increases. There is also an increase

in the difference between the lift produced on the

advancing and retreating blades. This increases the

flapping angle and causes the rotor to pitch up. This

pitching action increases the moment around the center

of gravity, which leads to a greater increase in the angle

of attack. The result is an unstable condition.

If the CG is in front of the rotor force line, a gust of

wind, which increases the angle of attack, causes the

rotor disc to react the same way, but now the increase

in rotor force and blade flapping decreases the

moment. This tends to decrease the angle of attack, and

creates a stable condition.

TRIMMED CONDITION

As was stated earlier, manufacturers use a combination

of the various stability factors to achieve a trimmed

gyroplane. For example, if you have a gyroplane where

the CG is below the propeller thrust line, the propeller

thrust gives your aircraft a nose down pitching moment

when power is applied. To compensate for this pitching

moment, the CG, on this type of gyroplane, is usually

located behind the rotor force line. This location produces a nose up pitching moment.

Conversely, if the CG is above the propeller thrust line,

the CG is usually located ahead of the rotor force line.

Of course, the location of fuselage drag, the pitch inertia, and the addition of a horizontal stabilizer can alter

where the center of gravity is placed.

Propeller Thrust

Propeller Thrust

Center of Gravity Center of Gravity

High Profile Low Profile

RotorForce

RotorForce

Figure 16-9. A gyroplane which has the propeller thrust line above the center of gravity is often referred to as a low profile gyroplane. One that has the propeller thrust line below or at the CG is considered a high profile gyroplane.

Figure 16-10. If the CG is located in front of the rotor force line, the gyroplane is more stable than if the CG is located behind the

rotor force line.

Blade Flapping—The upward or downward movement of the rotorblades during rotation.

17-1

Due to rudimentary flight control systems, early gyroplanes

suffered from limited maneuverability. As technology

improved, greater control of the rotor system and more

effective control surfaces were developed. The modern

gyroplane, while continuing to maintain an element of

simplicity, now enjoys a high degree of maneuverability as a result of these improvements.

CYCLIC CONTROL

The cyclic control provides the means whereby you are

able to tilt the rotor system to provide the desired

results. Tilting the rotor system provides all control for

climbing, descending, and banking the gyroplane. The

most common method to transfer stick movement to

the rotor head is through push-pull tubes or flex cables.

[Figure 17-1] Some gyroplanes use a direct overhead

stick attachment rather than a cyclic, where a rigid control is attached to the rotor hub and descends over and

in front of the pilot. [Figure 17-2] Because of the

nature of the direct attachment, control inputs with this

system are reversed from those used with a cyclic.

Pushing forward on the control causes the rotor disc to

tilt back and the gyroplane to climb, pulling back on

the control initiates a descent. Bank commands are

reversed in the same way.

THROTTLE

The throttle is conventional to most powerplants, and

provides the means for you to increase or decrease

engine power and thus, thrust. Depending on how

the control is designed, control movement may or

may not be proportional to engine power. With many

gyroplane throttles, 50 percent of the control travel

may equate to 80 or 90 percent of available power.

This varying degree of sensitivity makes it necessary

Figure 17-1. A common method of transferring cyclic control inputs to the rotor head is through the use of push-pull tubes,

located outboard of the rotor mast pictured on the right.

Figure 17-2. The direct overhead stick attachment has been

used for control of the rotor disc on some gyroplanes.

17-2

for you to become familiar with the unique throttle

characteristics and engine responses for a particular

gyroplane.

RUDDER

The rudder is operated by foot pedals in the cockpit

and provides a means to control yaw movement of the

aircraft. [Figure 17-3] On a gyroplane, this control is

achieved in a manner more similar to the rudder of an

airplane than to the antitorque pedals of a helicopter.

The rudder is used to maintain coordinated flight, and

at times may also require inputs to compensate for

propeller torque. Rudder sensitivity and effectiveness

are directly proportional to the velocity of airflow over

the rudder surface. Consequently, many gyroplane

rudders are located in the propeller slipstream and

provide excellent control while the engine is developing

thrust. This type of rudder configuration, however, is

less effective and requires greater deflection when the

engine is idled or stopped.

HORIZONTAL TAIL SURFACES

The horizontal tail surfaces on most gyroplanes are

not controllable by the pilot. These fixed surfaces, or

stabilizers, are incorporated into gyroplane designs to

increase the pitch stability of the aircraft. Some gyroplanes use very little, if any, horizontal surface. This

translates into less stability, but a higher degree of

maneuverability. When used, a moveable horizontal

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surface, or elevator, adds additional pitch control of the

aircraft. On early tractor configured gyroplanes, the

elevator served an additional function of deflecting the

propeller slipstream up and through the rotor to assist

in prerotation.

COLLECTIVE CONTROL

The collective control provides a means to vary the

rotor blade pitch of all the blades at the same time, and

is available only on more advanced gyroplanes. When

incorporated into the rotor head design, the collective

allows jump takeoffs when the blade inertia is sufficient. Also, control of in-flight rotor r.p.m. is available

to enhance cruise and landing performance. A simple

two position collective does not allow unlimited control

of blade pitch, but instead has one position for prerotation

and another position for flight. This is a performance

compromise but reduces pilot workload by simplifying

control of the rotor system.

Figure 17-3. Foot pedals provide rudder control and operation is similar to that of an airplane.

18-1

rotating portion of the head to the non-rotating torque

tube. The torque tube is mounted to the airframe

through attachments allowing both lateral and longitudinal movement. This allows the movement through

which control is achieved.

FULLY ARTICULATED ROTOR SYSTEM

The fully articulated rotor system is found on some

gyroplanes. As with helicopter-type rotor systems, the

articulated rotor system allows the manipulation of

Coning Angle—An angular

deflection of the rotor blades

upward from the rotor hub.

Undersling—A design characteristic that prevents the distance

between the rotor mast axis and

the center of mass of each rotor

blade from changing as the

blades teeter. This precludes

Coriolis Effect from acting on the

speed of the rotor system.

Undersling is further explained

in Chapter 3—Aerodynamics of

Flight, Coriolis Effect (Law of

Conservation of Angular

Momentum).

Gyroplanes are available in a wide variety of designs

that range from amateur built to FAA-certificated aircraft. Similarly, the complexity of the systems integrated in gyroplane design cover a broad range. To

ensure the airworthiness of your aircraft, it is important

that you thoroughly understand the design and operation of each system employed by your machine.

PROPULSION SYSTEMS

Most of the gyroplanes flying today use a reciprocating

engine mounted in a pusher configuration that drives

either a fixed or constant speed propeller. The engines

used in amateur-built gyroplanes are normally proven

powerplants adapted from automotive or other uses.

Some amateur-built gyroplanes use FAA-certificated aircraft engines and propellers. Auto engines, along with

some of the other powerplants adapted to gyroplanes,

operate at a high r.p.m., which requires the use of a reduction unit to lower the output to efficient propeller speeds.

Early autogyros used existing aircraft engines, which

drove a propeller in the tractor configuration. Several

amateur-built gyroplanes still use this propulsion configuration, and may utilize a certificated or an uncertificated engine. Although not in use today, turboprop

and pure jet engines could also be used for the propulsion of a gyroplane.

ROTOR SYSTEMS

SEMIRIGID ROTOR SYSTEM

Any rotor system capable of autorotation may be utilized

in a gyroplane. Because of its simplicity, the most widely

used system is the semirigid, teeter-head system. This

system is found in most amateur-built gyroplanes.

[Figure 18-1] In this system, the rotor head is mounted

on a spindle, which may be tilted for control. The rotor

blades are attached to a hub bar that may or may not

have adjustments for varying the blade pitch. Aconing

angle, determined by projections of blade weight,

rotor speed, and load to be carried, is built into the hub

bar. This minimizes hub bar bending moments and

eliminates the need for a coning hinge, which is used

in more complex rotor systems. A tower block provides the undersling and attachment to the rotor head

by the teeter bolt. The rotor head is comprised of a

bearing block in which the bearing is mounted and

onto which the tower plates are attached. The spindle

(commonly, a vertically oriented bolt) attaches the

Figure 18-1. The semirigid, teeter-head system is found on

most amateur-built gyroplanes. The rotor hub bar and blades

are permitted to tilt by the teeter bolt.

Tower Plates

Hub Bar

Tower Block

Bearing Block

Teeter Bolt

Spindle Bolt

Torque Tube

Fore / Aft Pivot Bolt

Lateral Pivot Bolt

18-2

rotor blade pitch while in flight. This system is significantly more complicated than the teeter-head, as it

requires hinges that allow each rotor blade to flap,

feather, and lead or lag independently. [Figure 18-2]

When used, the fully articulated rotor system of a gyroplane is very similar to those used on helicopters, which

is explained in depth in Chapter 5—Helicopter Systems,

Main Rotor Systems. One major advantage of using a

fully articulated rotor in gyroplane design is that it usually allows jump takeoff capability. Rotor characteristics

required for a successful jump takeoff must include a

method of collective pitch change, a blade with sufficient

inertia, and a prerotation mechanism capable of approximately 150 percent of rotor flight r.p.m.

Incorporating rotor blades with high inertia potential is

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desirable in helicopter design and is essential for jump

takeoff gyroplanes. A rotor hub design allowing the

rotor speed to exceed normal flight r.p.m. by over

50 percent is not found in helicopters, and predicates a

rotor head design particular to the jump takeoff

gyroplane, yet very similar to that of the helicopter.

PREROTATOR

Prior to takeoff, the gyroplane rotor must first achieve

a rotor speed sufficient to create the necessary lift.

This is accomplished on very basic gyroplanes by initially spinning the blades by hand. The aircraft is then

taxied with the rotor disc tilted aft, allowing airflow

through the system to accelerate it to flight r.p.m.

More advanced gyroplanes use a prerotator, which

provides a mechanical means to spin the rotor. Many

prerotators are capable of only achieving a portion of

the speed necessary for flight; the remainder is

gained by taxiing or during the takeoff roll. Because

of the wide variety of prerotation systems available,

you need to become thoroughly familiar with the

characteristics and techniques associated with your

particular system.

MECHANICAL PREROTATOR

Mechanical prerotators typically have clutches or belts

for engagement, a drive train, and may use a transmission to transfer engine power to the rotor. Friction

drives and flex cables are used in conjunction with an

automotive type bendix and ring gear on many gyroplanes. [Figure 18-3]

The mechanical prerotator used on jump takeoff gyroplanes may be regarded as being similar to the helicopter

main rotor drive train, but only operates while the aircraft is firmly on the ground. Gyroplanes do not have an

antitorque device like a helicopter, and ground contact is

necessary to counteract the torque forces generated by

the prerotation system. If jump takeoff capability is

designed into a gyroplane, rotor r.p.m. prior to liftoff

must be such that rotor energy will support the aircraft through the acceleration phase of takeoff. This

combination of rotor system and prerotator utilizes

the transmission only while the aircraft is on the

ground, allowing the transmission to be disconnected

from both the rotor and the engine while in normal

flight.

HYDRAULIC PREROTATOR

The hydraulic prerotator found on gyroplanes uses

engine power to drive a hydraulic pump, which in turn

drives a hydraulic motor attached to an automotive type

bendix and ring gear. [Figure 18-4] This system also

requires that some type of clutch and pressure regulation be incorporated into the design.

Figure 18-2. The fully articulated rotor system enables the

pilot to effect changes in pitch to the rotor blades, which is

necessary for jump takeoff capability.

Figure 18-3. The mechanical prerotator used by many gyroplanes uses a friction drive at the propeller hub, and a flexible cable that runs from the propeller hub to the rotor mast.

When engaged, the bendix spins the ring gear located on the

rotor hub.

18-3

ELECTRIC PREROTATOR

The electric prerotator found on gyroplanes uses an

automotive type starter with a bendix and ring gear

mounted at the rotor head to impart torque to the rotor

system. [Figure 18-5] This system has the advantage of

simplicity and ease of operation, but is dependent on

having electrical power available. Using a “soft start”

device can alleviate the problems associated with the

high starting torque initially required to get the rotor

system turning. This device delivers electrical pulses to

the starter for approximately 10 seconds before connecting uninterrupted voltage.

TIP JETS

Jets located at the rotor blade tips have been used in several applications for prerotation, as well as for hover

flight. This system has no requirement for a transmission

or clutches. It also has the advantage of not imparting

torque to the airframe, allowing the rotor to be powered

in flight to give increased climb rates and even the ability

to hover. The major disadvantage is the noise generated

by the jets. Fortunately, tip jets may be shut down while

operating in the autorotative gyroplane mode.

INSTRUMENTATION

The instrumentation required for flight is generally

related to the complexity of the gyroplane. Some gyroplanes using air-cooled and fuel/oil-lubricated engines

may have limited instrumentation.

ENGINE INSTRUMENTS

All but the most basic engines require monitoring

instrumentation for safe operation. Coolant temperature, cylinder head temperatures, oil temperature, oil

pressure, carburetor air temperature, and exhaust gas

temperature are all direct indications of engine operation and may be displayed. Engine power is normally

indicated by engine r.p.m., or by manifold pressure on

gyroplanes with a constant speed propeller.

ROTOR TACHOMETER

Most gyroplanes are equipped with a rotor r.p.m. indicator. Because the pilot does not normally have direct

control of rotor r.p.m. in flight, this instrument is most

useful on the takeoff roll to determine when there is sufficient rotor speed for liftoff. On gyroplanes not

equipped with a rotor tachometer, additional piloting

skills are required to sense rotor r.p.m. prior to takeoff.

Figure 18-4. This prerotator uses belts at the propeller hub to drive a hydraulic pump, which drives a hydraulic motor on the

rotor mast.

Figure 18-5. The electric prerotator is simple and easy to use,

but requires the availability of electrical power.

18-4

Certain gyroplane maneuvers require you to know precisely the speed of the rotor system. Performing a jump

takeoff in a gyroplane with collective control is one

example, as sufficient rotor energy must be available

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for the successful outcome of the maneuver. When

variable collective and a rotor tachometer are used,

more efficient rotor operation may be accomplished by

using the lowest practical rotor r.p.m. [Figure 18-6]

SLIP/SKID INDICATOR

A yaw string attached to the nose of the aircraft and a

conventional inclinometer are often used in gyroplanes

to assist in maintaining coordinated flight. [Figure 18-7]

AIRSPEED INDICATOR

Airspeed knowledge is essential and is most easily

obtained by an airspeed indicator that is designed for

accuracy at low airspeeds. Wind speed indicators

have been adapted to many gyroplanes. When no air-

speed indicator is used, as in some very basic

amateur-built machines, you must have a very acute

sense of “q” (impact air pressure against your body).

ALTIMETER

For the average pilot, it becomes increasingly difficult

to judge altitude accurately when more than several

hundred feet above the ground. A conventional altimeter may be used to provide an altitude reference when

flying at higher altitudes where human perception

degrades.

IFR FLIGHT INSTRUMENTATION

Gyroplane flight into instrument meteorological conditions requires adequate flight instrumentation and navigational systems, just as in any aircraft. Very few

gyroplanes have been equipped for this type of operation.

The majority of gyroplanes do not meet the stability

requirements for single-pilot IFR flight. As larger and

more advanced gyroplanes are developed, issues of IFR

flight in these aircraft will have to be addressed.

GROUND HANDLING

The gyroplane is capable of ground taxiing in a manner

similar to that of an airplane. A steerable nose wheel,

which may be combined with independent main wheel

brakes, provides the most common method of control.

[Figure 18-8] The use of independent main wheel

brakes allows differential braking, or applying more

braking to one wheel than the other to achieve tight

radius turns. On some gyroplanes, the steerable nose

wheel is equipped with a foot-operated brake rather

than using main wheel brakes. One limitation of this

system is that the nose wheel normally supports only a

fraction of the weight of the gyroplane, which greatly

reduces braking effectiveness. Another drawback is the

Figure 18-6. A rotor tachometer can be very useful to determine when rotor r.p.m. is sufficient for takeoff.

Figure 18-7. A string simply tied near the nose of the gyroplane that can be viewed from the cockpit is often used to

indicate rotation about the yaw axis. An inclinometer may

also be used.

Figure 18-8. Depending on design, main wheel brakes can be

operated either independently or collectively. They are considerably more effective than nose wheel brakes.

18-5

inability to use differential braking, which increases

the radius of turns.

The rotor blades demand special consideration during

ground handling, as turning rotor blades can be a hazard to those nearby. Many gyroplanes have a rotor

brake that may be used to slow the rotor after landing,

or to secure the blades while parked. A parked gyroplane should never be left with unsecured blades,

because even a slight change in wind could cause the

blades to turn or flap.

18-6

19-1

As with most certificated aircraft manufactured after

March 1979, FAA-certificated gyroplanes are required

to have an approved flight manual. The flight manual

describes procedures and limitations that must be

adhered to when operating the aircraft. Specification

for Pilot’s Operating Handbook, published by the

General Aviation Manufacturers Association (GAMA),

provides a recommended format that more recent gyroplane flight manuals follow. [Figure 19-1]

This format is the same as that used by helicopters,

which is explained in depth in Chapter 6—Rotorcraft

Flight Manual (Helicopter).

Amateur-built gyroplanes may have operating limitations but are not normally required to have an approved

flight manual. One exception is an exemption granted

by the FAA that allows the commercial use of

two-place, amateur-built gyroplanes for instructional

purposes. One of the conditions of this exemption is to

have an approved flight manual for the aircraft. This

manual is to be used for training purposes, and must be

carried in the gyroplane at all times.

USING THE FLIGHT MANUAL

The flight manual is required to be on board the aircraft

to guarantee that the information contained therein is

readily available. For the information to be of value,

you must be thoroughly familiar with the manual and

be able to read and properly interpret the various charts

and tables.

WEIGHT AND BALANCE SECTION

The weight and balance section of the flight manual

contains information essential to the safe operation of

the gyroplane. Careful consideration must be given to

the weight of the passengers, baggage, and fuel prior to

each flight. In conducting weight and balance computations, many of the terms and procedures are similar to

those used in helicopters. These are further explained

in Chapter 7—Weight and Balance. In any aircraft,

failure to adhere to the weight and balance limitations prescribed by the manufacturer can be

extremely hazardous.

SAMPLE PROBLEM

As an example of a weight and balance computation,

assume a sightseeing flight in a two-seat, tandem-configured gyroplane with two people aboard. The pilot,

seated in the front, weighs 175 pounds while the rear

seat passenger weighs 160 pounds. For the purposes of

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