Helicopter Flying Handbook (FAA-H-8083-21B) Flashcards

500 Flashcards covering the Helicopter Flying Handbook (FAA-H-8083-21B), including dynamics, aerodynamics, configurations, and procedures, systems, and human factors.

Helicopter

An aircraft that is lifted and propelled by one or more horizontal rotors, each consisting of two or more rotor blades.

Rotorcraft

A category of aircraft, also called rotary-wing aircraft, that derives its source of lift from rotor blades rotating around a mast.

Gustave de Ponton d’Amécourt

The person who coined the French word hélicoptère in $1861$, derived from Greek helix/helikos and pteron.

Igor Sikorsky

Designer of the first helicopter to reach full-scale production in $1942$, the single main rotor with an antitorque tail rotor configuration.

Sikorsky VS-300

The specific helicopter design that incorporated a variable pitch antitorque tail rotor and became the recognized convention for helicopter design.

Turbine Age

An era in helicopter development beginning in $1951$ marked by the use of turbo-shaft engines which provided high horsepower with low weight.

Charles H. Kaman

The individual who modified a $K-225$ helicopter with the world's first turbo-shaft engine on December $11, 1951$.

Kaman K-225

The first turbine-powered helicopter in the world.

Navy HTK-1

A modified Kaman helicopter that became the first twin-turbine helicopter to fly on March $26, 1954$.

Sud Aviation Alouette II

The first helicopter produced with a turbine engine.

Turbo-shaft engine

A lightweight turbine engine that is the preferred powerplant for modern helicopters due to its high performance and reliability.

Rotor System

The rotating part of a helicopter that generates lift, consisting of a mast, hub, and rotor blades.

Mast

A hollow cylindrical metal shaft extending upwards from and driven by the transmission to which the hub is attached.

Hub

The attachment point for rotor blades at the top of the mast.

Semirigid Rotor System

A classification of rotor systems where blades are attached to the hub, typically on a teetering hinge, and move as a unit.

Rigid Rotor System

A rotor system where the blades are attached to the hub without flapping or lead/lag hinges; motions are accommodated by blade bending.

Fully Articulated Rotor System

A rotor system allowing each blade to lead/lag, flap, and feather independently of other blades.

Newton’s Third Law of Motion

Every action has an equal and opposite reaction; applied to helicopters, it explains why the fuselage turns opposite the rotor rotation (torque).

Traditional Tail Rotor

The most common antitorque control used to neutralize the twisting momentum of a single main rotor.

Fenestron

Also called a fantail, an antitorque design featuring a series of blades shrouded within a circular duct in the vertical tail.

NOTAR®

A ‘no tail rotor’ antitorque system utilizing the Coanda effect and a direct jet thruster for directional control.

Tandem Rotor

A dual-rotor configuration with two large horizontal rotor assemblies each canceling out the other’s torque via counter-rotation.

Coaxial Rotors

A pair of rotors mounted on the same mast turning in opposite directions, one above the other.

Kamov

A Russian helicopter design bureau noted for producing coaxial rotor configurations.

Intermeshing Rotors

A set of two rotors turning in opposite directions with masts mounted at an angle so blades intermesh without colliding.

Synchropter

Another name for an intermeshing rotor configuration.

Flettner Fl 282 Kolibri

A small anti-submarine warfare helicopter developed in Germany using intermeshing rotors.

HH-43 Huskie

An American Kaman Aircraft production used by the USAF for firefighting, featuring intermeshing rotors.

Kaman K-MAX

A dedicated sky crane design with intermeshing rotors used for construction work.

Intermediate Gearbox

A component used on some large helicopters to angle the tail rotor drive shaft to the top of a pylon or vertical fin.

Primary Flight Controls

The four main inputs for a helicopter: cyclic, collective, antitorque pedals, and throttle.

Cyclic Control

The stick used to vary the pitch of rotor blades throughout each revolution to tilt the rotor disk and control direction of travel.

Robinson T-bar

A unique cyclic control system found on Robinson helicopters.

Collective Pitch Control

The lever on the left of the pilot's seat that changes the pitch angle of all main rotor blades simultaneously to control lift.

Antitorque Pedals

Pedals located at the feet that control the pitch of tail rotor blades to manage the aircraft's heading.

Throttle

A control, often a twist grip on the collective, used to maintain engine power and keep rotor $RPM$ within allowable limits.

Hovering

A flight condition where the helicopter maintains a constant position over a selected point, typically a few feet above the ground.

Horizontal Stabilizer

An airfoil that helps level the helicopter during forward flight to minimize drag.

Balanced Flight

Coordinated flight achieved by applying pedal input in the direction necessary to center the ball in the turn and bank indicator.

Weight

The force created by gravity acting on the mass of an object.

Static Pressure

Pressure at sea level exerted equally on all surfaces ($2,116\,lb/ft^2$) that does not create useful force unless a differential exists.

Dynamic Pressure

Pressure existing in the direction of air movement which increases as air velocity increases.

Aerodynamic Force

The force created by air moving over an object, categorized into lift and drag.

Lift

The portion of aerodynamic force measured perpendicular to the air flowing around an airfoil used to oppose weight.

Drag

The portion of aerodynamic force measured as resistance parallel to the relative wind that retards forward movement.

Thrust

The force produced by the rotor that opposes drag and determines direction of movement.

Angle of Attack (AOA)

The angle measured between the airfoil chord line and the resultant relative wind.

Bernoulli’s Principle

The principle stating that as the velocity of a fluid increases, the internal pressure of the fluid decreases.

Venturi Effect

The reduction in fluid pressure that results when a fluid flows through a constricted section of a pipe (or over an airfoil).

Total Pressure

The sum of static pressure and dynamic pressure ($PT = PD + PS$).

Impact Pressure

Pressure provided by the deflection of air from the lower surface of the rotor blade, contributing a small percentage of total lift.

Load Factor

The actual load on the rotor blades divided by the gross weight of the helicopter, often expressed in ‘G’s.

30-degree Bank Load

At this bank angle, the apparent increase in gross weight is approximately $16\%$, which for a $1,600\,lb$ helicopter is $1,856\,lb$.

60-degree Bank Load

At this bank angle, the load on the rotor disk is twice the gross weight ($2\,G$).

Solidity Ratio

The mathematical ratio of the total rotor blade area to the total rotor disk area.

Profile Drag

Drag originating from the frictional resistance of blades passing through the air, consisting of form drag and skin friction.

Form Drag

Drag resulting from the turbulent wake caused by the separation of airflow from the surface of a structure.

Skin Friction

Drag caused by surface roughness and the thin layer of air clinging to that surface.

Induced Drag

Drag generated by the airflow circulation (vortices) around the rotor blade as it creates lift; it is the major cause of drag at low airspeeds.

Parasite Drag

Drag caused by non-lifting components (cabin, landing gear) which increases with the square of the velocity.

L/DMAX

The point on the total drag curve where the lift-to-drag ratio is greatest and total drag is minimized.

Airfoil

Any surface producing more lift than drag when passing through the air at a suitable angle.

Blade Span

The length of the rotor blade from the center of rotation to the tip of the blade.

Chord Line

A straight line intersecting the leading and trailing edges of the airfoil.

Chord

The length of the chord line from leading edge to trailing edge.

Mean Camber Line

A line drawn halfway between the upper and lower surfaces of the airfoil.

Camber

The curvature of an airfoil, specifically the curvature of the mean camber line.

Leading Edge

The front edge of an airfoil.

Flightpath Velocity

The speed and direction of the airfoil passing through the air (rotational velocity plus/minus directional airspeed).

Relative Wind

The airflow relative to an airfoil created by the movement of the airfoil through the air.

Trailing Edge

The rearmost edge of an airfoil.

Induced Flow

The downward flow of air through the rotor disk, also known as downwash.

Resultant Relative Wind

Rotational relative wind modified by induced flow (downwash).

Angle of Incidence (AOI)

A mechanical angle between the chord line of a blade and the rotor hub, also called blade pitch angle.

Center of Pressure

The point along the chord line through which all aerodynamic forces are considered to act.

Symmetrical Airfoil

An airfoil having identical upper and lower surfaces that produces no lift at zero angle of attack.

Nonsymmetrical Airfoil (Cambered)

An airfoil with different upper and lower curvatures that can produce positive lift at zero angle of attack.

Blade Twist

A design feature providing higher pitch angles at the root and lower pitch angles at the tip to distribute lifting force evenly.

Rotor Blade Root

The inner end of the blade and the point that attaches to the hub.

Rotor Blade Tip

The farthest outboard section of the rotor blade.

Tip-Path Plane

The imaginary plane formed by the rotation of the rotor blade tips.

Rotational Relative Wind

Wind flowing opposite the physical flightpath of the airfoil, striking the leading edge at $90^\circ$ to the hub.

Downward Velocity

Air velocity that is highest at the blade tip where speed is highest and zero at the center of the mast.

Total Aerodynamic Force (TAF)

The resultant vector of lift and drag acting on the airfoil.

Flat Pitch

A blade pitch setting where no lift or induced flow is being produced.

In Ground Effect (IGE)

Increased rotor efficiency caused by airflow interference with the ground at a height of about one rotor diameter or less.

Out of Ground Effect (OGE)

A hover condition above the altitude of ground effect influence requiring higher pitch angles and more power.

Critical Angle of Attack

The angle beyond which the airflow separates from the airfoil, producing a stall and rapid decrease in lift.

Feathering

The rotation of the blade about its longitudinal axis caused by collective or cyclic inputs.

Collective Feathering

Changing the angle of incidence equally and in the same direction on all rotor blades simultaneously.

Cyclic Feathering

Changing the blade’s AOA differentially around the rotor disk to control attitude.

Flapping

The up and down movement of rotor blades about a hinge to compensate for dissymmetry of lift.

Teetering Hinge

A hinge used in semi-rigid rotor systems that allows blades to flap as a unit.

Translating Tendency (Drift)

The tendency of a single-rotor helicopter to move in the direction of the tail rotor thrust while hovering.

Left Skid Low

A hover attitude caused by the rotor mast being tilted or the helicopter hanging to counteract translating tendency.

Inherent Sideslip

The small angle a helicopter makes with the wind in forward flight when rotors are level.

Pendular Action

The oscillation of the helicopter fuselage suspended from the rotor mast like a pendulum.

Mast Bumping

A condition in semirigid rotors where stops contact the mast due to excessive flapping during low-G or high-maneuver conditions.

Coning

The upward sweep of rotor blades caused by the combination of centrifugal force and lift during takeoff.

Coriolis Effect

Also called the Law of Conservation of Angular Momentum, where a rotating body speed changes as mass moves closer to the axis.