Lesson 2-2a Principles of Flight

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Lesson 2-2aPrinciples of Flight
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The Forces of Flight
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• How many forces are present when an aircraft is
  cruising at constant speed and altitude?
• a. 0
• b. 2
• c. 4
• d. 6

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Lift

• Lift is produced almost entirely by moving air
  over and under the wings
• The profile of a wing is called an airfoil
• Changing the airflow on the surface of the
  airfoil (or wing) will increase or decrease the
  amount of lift

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Bernoullis Principle

• Faster airflow causes a decrease in air pressure
• Air flowing over the curved upper surface of a
  wing speeds up
• Increase in speed reduces pressure above the wing
  and produces the upward lifting force

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Airfoils

• Can be wings or propeller blades
• Parts of airfoil Include leading and trailing
  edges, camber and chord line

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Wind Tunnels, cont.

• The Wright Brothers tested more than 200 wing
  shapes in a tunnel before the successful 1902
  glider
• Researchers can carefully control airflow
  conditions and measure the forces on an aircraft
  model

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Activity Bernoullis Principle in Action

• Lets do a quick experiment to demonstrate
  Bernoullis Principle in action using a funnel
  and a ping-pong ball

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Effect of Angle of Attack on Flight

• If a plane alters pitchthe up and down movement
  of the planes nosethe angle of attack on its
  wings will change
• As angle of attack increases, wings generate more
  lifting force

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Critical Angle of Attack

• Point at which a plane stallsaround 15

Reproduced from NASA/Glenn Research Center
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How Lift is Generated

• Air flows over top of wing reducing pressure on
  top surface relative to bottom surface of wing
• Lift depends on aircrafts shape, size, and
  velocity
• To increase lift
• Increase aircrafts forward speed
• Increase airfoils angle of attack (up to stall
  angle)
• Increase surface area of airfoil

Reproduced from NASA/Glenn Research Center
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Airfoil Camber

• The curve in an airfoil is the camber
• In most airfoils the upper surface curves more
  than the lower surface
• Airfoils thickness is the maximum distance
  between the upper and lower wing surfaces

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Airfoil Types, Purpose, and Function

• Aircraft weight, speed, and purpose determine
  wings shape
• Streamlined airfoils dont create enough lift
• Teardrop shaped airfoils have no lift at zero
  angle of attack

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Airfoil Types, Purpose, and Function

• See handout of conventional airfoils

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The Fuselage

• The fuselage is the aircraft body
• Fuselage vary in shape to fit the mission
• Fuselage must be strong enough to withstand
  torque

Courtesy of USAF/CMSgt Gary Emery
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Wing Position and Parts

• Wing position depends on aircrafts mission
• Main internal parts are spars, ribs and stringers
• Fuel tanks usually part of wing

Reproduced from US Department of
Transportation/Federal Aviation Administration
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Wing Angles

• Dihedral angles give aircraft roll stability and
  level flight
• Large commercial airliner wings have dihedral
  angles
• Fighter aircraft have anhedral angles

Modified from NASA/Glenn Research Center
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The Role of Stabilizers and Rudders

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• Stabilizers are on the aircrafts tail
• Stabilizers keep aircraft stable so it can
  maintain straight flight path
• Vertical stabilizer prevents the nose of plane
  from roving side to size
• Horizontal stabilizer keeps plane from bobbing up
  and down

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The Role of Stabilizers and Rudders, cont.

• Rudder is the hinged piece on the vertical
  stabilizer
• Lets pilot steer the aircraft by moving the tail
  left or right
• Elevators are the hinged flaps on the horizontal
  stabilizer
• Lets pilot steer the aircraft by moving the tail
  up or down

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The Positions of Flaps, Spoilers, and Slats on
Aircraft

• Flaps are hinged device at wings trailing edge
  that produces lift
• Spoiler is small, flat plate that attaches the
  tops of wings it increases drag
• Slat is moveable, hinged parts that pivot down to
  generate more force

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Primary and Secondary Controls

• Primary Controls make aircraft controllable and
  safe to fly
• Rudders, elevators, and ailerons
• Secondary controls let the pilot maintain more
  control over aircrafts performance
• Flaps, slats, and spoilers

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Primary Flight Controls

• Pilot uses primary flight controls to control
  aircraft yaw, pitch, and roll
• Rudders control yaw or side-to-side motion of
  aircraft
• Elevators control pitch or up and down motion of
  aircraft
• Ailerons control roll or banking of the wings

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How Ailerons Work

• Aileron is a small hinged section on the outboard
  portion of each wing
• Ailerons operate in opposite direction on the
  wings, causing one to increase lift (point
  aileron down), one to decrease lift (point
  aileron up)

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Secondary Flight Controls

• Used primarily in more challenging flight
  conditions where low speeds are required
  (take-off and landing)
• Flaps are on trailing edge of wings and
  increase/decrease lift and drag on both wings at
  the same time
• Slats are on the leading edge of the wings and
  also increase/decrease lift and drag on both
  wings at the same time
• Spoilers reduce lift and increase drag and can
  be used on both wings at same time or on one wing
  and not the other

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Spoilers

• Spoilers are small, flat plates that attach to
  the tops of the wings with hinges
• Raising spoilers on both wings slows aircraft in
  any phase of flight
• Raising spoilers on only one wing causes a
  rolling motion

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Activity Airplane Parts and Functions

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