Lesson 2-2aLesson 2-2aPrinciples of FlightPrinciples of Flight

The Forces of FlightThe Forces of Flight

How many forces are present when an aircraft How many forces are present when an aircraft is cruising at constant speed and altitude?is cruising at constant speed and altitude?

a.a. 00

b.b. 22

c.c. 44

d.d. 66

Chapter 1, Lesson 2

LiftLift

Lift is produced almost entirely by moving air Lift is produced almost entirely by moving air over and under the wingsover and under the wings The profile of a wing is called an airfoil The profile of a wing is called an airfoil

Changing the airflow on the surface of the Changing the airflow on the surface of the airfoil (or wing) will increase or decrease the airfoil (or wing) will increase or decrease the amount of liftamount of lift

Bernoulli’s PrincipleBernoulli’s Principle

Faster airflow causes a decrease in air pressureFaster airflow causes a decrease in air pressure Air flowing over the curved upper surface of a wing Air flowing over the curved upper surface of a wing

speeds upspeeds up Increase in speed reduces pressure above the wing Increase in speed reduces pressure above the wing

and produces the upward lifting force and produces the upward lifting force

AirfoilsAirfoils

Can be wings or propeller blades Can be wings or propeller blades Parts of airfoil Include leading and trailing Parts of airfoil Include leading and trailing

edges, camber and chord lineedges, camber and chord line

Wind Tunnels, cont.Wind Tunnels, cont. The Wright Brothers tested more than 200 The Wright Brothers tested more than 200

wing shapes in a tunnel before the successfulwing shapes in a tunnel before the successful 1902 glider1902 glider

Researchers can carefully control airflow Researchers can carefully control airflow conditions and measure the forces on an conditions and measure the forces on an aircraft modelaircraft model

Activity Activity Bernoulli’s Principle in ActionBernoulli’s Principle in Action

Let’s do a quick experiment to demonstrate Let’s do a quick experiment to demonstrate Bernoulli’s Principle in action using a funnel Bernoulli’s Principle in action using a funnel and a ping-pong balland a ping-pong ball

Effect of Angle ofEffect of Angle of Attack on Flight Attack on Flight

If a plane alters pitch—the up and down movement of If a plane alters pitch—the up and down movement of the plane’s nose—the angle of attack on its wings will the plane’s nose—the angle of attack on its wings will changechange

As angle of attack increases, wings generate more As angle of attack increases, wings generate more lifting forcelifting force

Critical Angle of AttackCritical Angle of Attack

Point at which a plane stalls—around 15Point at which a plane stalls—around 15⁰⁰

Chapter 1, Lesson 1 Reproduced from NASA/Glenn Research Center

How Lift is GeneratedHow Lift is Generated

Air flows over top of wing reducing Air flows over top of wing reducing pressure on top surface relative to pressure on top surface relative to bottom surface of wingbottom surface of wing

Lift depends on aircraft’s shape, Lift depends on aircraft’s shape, size, and velocitysize, and velocity

To increase lift:To increase lift: Increase aircraft’s forward speed Increase aircraft’s forward speed Increase airfoil’s angle of attack (up to Increase airfoil’s angle of attack (up to

stall angle)stall angle) Increase surface area of airfoil Increase surface area of airfoil

Chapter 1, Lesson 2Chapter 1, Lesson 2 Reproduced from NASA/Glenn Research Center

Airfoil CamberAirfoil Camber The curve in an airfoil is the camberThe curve in an airfoil is the camber In most airfoils the upper surface curves In most airfoils the upper surface curves

more than the lower surfacemore than the lower surface Airfoil’s thickness is the maximum Airfoil’s thickness is the maximum

distance between the upper and lower distance between the upper and lower wing surfaceswing surfaces

Airfoil Types, Airfoil Types, Purpose, and FunctionPurpose, and Function

Aircraft weight, speed, Aircraft weight, speed, and purpose determine and purpose determine wing’s shapewing’s shape

Streamlined airfoils Streamlined airfoils don’t create enough liftdon’t create enough lift

Teardrop shaped airfoils Teardrop shaped airfoils have no lift at zero angle have no lift at zero angle of attack of attack

Airfoil Types, Airfoil Types, Purpose, and FunctionPurpose, and Function

See handout of conventional airfoils

The FuselageThe Fuselage The fuselage is the aircraft bodyThe fuselage is the aircraft body Fuselage vary in shape to fit the missionFuselage vary in shape to fit the mission Fuselage must be strong enough to Fuselage must be strong enough to

withstand torquewithstand torque

Chapter 1, Lesson 3Chapter 1, Lesson 3 Courtesy of USAF/CMSgt Gary Emery

Wing Position and PartsWing Position and Parts

Wing position Wing position depends on depends on aircraft’s missionaircraft’s mission

Main internal Main internal parts are spars, parts are spars, ribs and stringersribs and stringers

Fuel tanks usually Fuel tanks usually part of wingpart of wing

Chapter 1, Lesson 3Reproduced from US Department of Transportation/Federal Aviation Administration

Wing AnglesWing Angles

Dihedral angles give Dihedral angles give aircraft roll stability aircraft roll stability and level flightand level flight

Large commercial Large commercial airliner wings have airliner wings have dihedral anglesdihedral angles

Fighter aircraft Fighter aircraft have anhedral have anhedral anglesangles

Chapter 1, Lesson 3 Modified from NASA/Glenn Research Center

The Role of StabilizersThe Role of Stabilizers and Rudders and Rudders  

Stabilizers are on the aircraft’s tail Stabilizers are on the aircraft’s tail Stabilizers keep aircraft stable so it Stabilizers keep aircraft stable so it can maintain straight flight pathcan maintain straight flight pathVertical stabilizer prevents the Vertical stabilizer prevents the nose of plane from roving side to nose of plane from roving side to sizesizeHorizontal stabilizer keeps plane Horizontal stabilizer keeps plane from bobbing up and downfrom bobbing up and down

The Role of Stabilizers The Role of Stabilizers and Rudders, cont.and Rudders, cont.

RudderRudder is the hinged piece on the vertical is the hinged piece on the vertical stabilizerstabilizer Lets pilot steer the aircraft by moving the tail left or Lets pilot steer the aircraft by moving the tail left or

rightright ElevatorsElevators are the hinged flaps on the horizontal are the hinged flaps on the horizontal

stabilizerstabilizer Lets pilot steer the aircraft by moving the tail up or Lets pilot steer the aircraft by moving the tail up or

downdown

The Positions of Flaps, The Positions of Flaps, Spoilers, and Slats on Aircraft Spoilers, and Slats on Aircraft

Flaps are hinged device at wing’s Flaps are hinged device at wing’s trailing edge that produces lifttrailing edge that produces lift

Spoiler is small, flat plate that Spoiler is small, flat plate that attaches the tops of wings; it attaches the tops of wings; it increases dragincreases drag

Slat is moveable, hinged parts Slat is moveable, hinged parts that pivot down to generate more that pivot down to generate more forceforce

Primary and Secondary ControlsPrimary and Secondary Controls

Primary Controls Primary Controls make aircraft controllable and safe to fly Rudders, elevators, and aileronsRudders, elevators, and ailerons

Secondary controls Secondary controls let the pilot maintain more control over aircraft’s performance Flaps, slats, and spoilersFlaps, slats, and spoilers

Primary Flight ControlsPrimary Flight Controls

Pilot uses primary flight controls to Pilot uses primary flight controls to control aircraft yaw, pitch, and rollcontrol aircraft yaw, pitch, and roll Rudders control yaw or side-to-side Rudders control yaw or side-to-side

motion of aircraftmotion of aircraft Elevators control pitch or up and Elevators control pitch or up and

down motion of aircraftdown motion of aircraft Ailerons control roll or banking of Ailerons control roll or banking of

the wingsthe wings

How Ailerons WorkHow Ailerons Work Aileron is a small hinged section on the outboard portion of Aileron is a small hinged section on the outboard portion of

each wingeach wing Ailerons operate in opposite direction on the wings, Ailerons operate in opposite direction on the wings,

causing one to increase lift (point aileron down), one to causing one to increase lift (point aileron down), one to decrease lift (point aileron up)decrease lift (point aileron up)

Secondary Flight ControlsSecondary Flight Controls

Used primarily in more challenging Used primarily in more challenging flight conditions where low speeds are flight conditions where low speeds are required (take-off and landing)required (take-off and landing)

FlapsFlaps are on trailing edge of wings are on trailing edge of wings and increase/decrease lift and drag on and increase/decrease lift and drag on both wings at the same timeboth wings at the same time

SlatsSlats are on the leading edge of the are on the leading edge of the wings and also increase/decrease lift wings and also increase/decrease lift and drag on both wings at the same and drag on both wings at the same timetime

SpoilersSpoilers reduce lift and increase drag reduce lift and increase drag and can be used on both wings at same and can be used on both wings at same time or on one wing and not the othertime or on one wing and not the other

Spoilers Spoilers

Spoilers are small, flat plates Spoilers are small, flat plates that attach to the tops of the that attach to the tops of the wings with hingeswings with hinges

Raising spoilers on both wings Raising spoilers on both wings slows aircraft in any phase of slows aircraft in any phase of flightflight

Raising spoilers on only one Raising spoilers on only one wing causes a rolling motion wing causes a rolling motion

Activity: Activity: Airplane Parts and FunctionsAirplane Parts and Functions

Label the airplane parts Label the airplane parts    Define their function in flightDefine their function in flight