Sep 2012 Lesson 2.2 Theory of Flight Wing Design

Reference From the Ground Up Chapter 2.1.2: Design of the Wing Pages

Introduction There are many different airfoil designs. The type of operation for which an airplane is intended has a direct influence on the design and shape of the wing for that airplane.There are many different airfoil designs. The type of operation for which an airplane is intended has a direct influence on the design and shape of the wing for that airplane. Normally, an airplane designed for slow speed uses a thick airfoil and a thin airfoil is best for high speed.Normally, an airplane designed for slow speed uses a thick airfoil and a thin airfoil is best for high speed.

Outline Camber & PlanformCamber & Planform Angle of IncidenceAngle of Incidence Wingtips and Wing FencesWingtips and Wing Fences Wash OutWash Out Flaps & SpoilersFlaps & Spoilers

Wing Design Conventional AirfoilsConventional Airfoils –Thick, for stronger structure –Camber is farther rearward, which Increases lifting capability over more of wing and decreases drag –For larger, slower aircraft (such as cargo planes) –Thickest at 25% chord

Wing Design Laminar Flow AirfoilsLaminar Flow Airfoils –Usually thin –Leading edge more pointed and upper and lower surfaces nearly symmetrical –For smaller, faster aircraft (such as fighter jets) –Thickest at 50% chord

Planform Planform – Shape of wing as seen from abovePlanform – Shape of wing as seen from above Aspect Ratio – Ratio of wing span to Chord (or MAC)Aspect Ratio – Ratio of wing span to Chord (or MAC) High Aspect Ratio creates more lift and less induced dragHigh Aspect Ratio creates more lift and less induced drag

Angle of Incidence Angle that wing is attached to fuselageAngle that wing is attached to fuselage Angle between wing and longitudinal axis (or the horizontal)Angle between wing and longitudinal axis (or the horizontal) Longitudinal Axis Angle of Incidence

Wing Tip Design Different wing tip devices disrupt vortices, thus decreases induced drag. Some devices:Different wing tip devices disrupt vortices, thus decreases induced drag. Some devices: –Wing tip tanks –Wing tip plates –Droop wing tip –Winglets

Wing Fences Small fin-like surfaces on upper surface of wingSmall fin-like surfaces on upper surface of wing Control and straighten airflow, reduce wing vortices, and therefore reduce induced dragControl and straighten airflow, reduce wing vortices, and therefore reduce induced drag Provide better slow speed handling and stall characteristicsProvide better slow speed handling and stall characteristics

Wash-Out Wash-Out - Twist in the wing so wing tip has smaller angle of incidence than wing rootWash-Out - Twist in the wing so wing tip has smaller angle of incidence than wing root Reduces tendency of wing to stall suddenlyReduces tendency of wing to stall suddenly Wing tips stall last, so ailerons remain effectiveWing tips stall last, so ailerons remain effective

Flaps and Spoilers Slats - Airfoils on leading edge that pull out at high angle of attacks. They help improve lateral control by smoothing out turbulent airflowSlats - Airfoils on leading edge that pull out at high angle of attacks. They help improve lateral control by smoothing out turbulent airflow Slots - Passageways in leading edge. At high angles of attack, air flows through holes smoothing out turbulent airflowSlots - Passageways in leading edge. At high angles of attack, air flows through holes smoothing out turbulent airflow Leading Edge Flap – Increase camber and increase liftLeading Edge Flap – Increase camber and increase lift

Flaps and Spoilers

Spoilers - Devices fitted into wing that increase drag and decrease liftSpoilers - Devices fitted into wing that increase drag and decrease lift Speed Brakes – Devices on wing or fuselage that increase dragSpeed Brakes – Devices on wing or fuselage that increase drag

Flaps and Spoilers Flaps are high lift devices that increase the camber of the wing. Flaps give you:Flaps are high lift devices that increase the camber of the wing. Flaps give you: –Better Take-off Performance –Steeper Approach Angles –Lower Approach/Landing Speeds

Next Lesson Theory of Flight Airplane Axes From the Ground Up Chapters 2.1.3, 2.1.4: The Axes of an Airplane, Stability Pages 23 – 26