1.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General </li></ul><ul><li>To insure an airplane has good handling qualities in all flight regimes, we need it to be STABLE, MANEUVERABLE, and CONTROLLABLE </li></ul><ul><li>STABILITY is the characteristic of an airplane in flight that causes it to return to a condition of equilibrium, or steady flight, after it is disturbed. </li></ul>

2.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General </li></ul><ul><li>To insure an airplane has good handling qualities in all flight regimes, we need it to be STABLE, MANEUVERABLE, and CONTROLLABLE </li></ul><ul><li>MANEUVERABLILITY is the characteristic that permits the pilot to easily move the airplane about its axes and to withstand the stress from these moves </li></ul>

3.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General </li></ul><ul><li>To insure an airplane has good handling qualities in all flight regimes, we need it to be STABLE, MANEUVERABLE, and CONTROLLABLE </li></ul><ul><li>CONTROLLABILITY is the capability to respond to the pilot’s control inputs </li></ul>

4.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General </li></ul><ul><li>Unfortunately, these characteristics are at odds with each other </li></ul><ul><li>Increase in one leads to a decrease in another </li></ul><ul><li>= all airplane designs are compromises </li></ul><ul><ul><li>If make it too stable = it’s hard to control </li></ul></ul>

5.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General Types </li></ul><ul><li>2 TYPES OF STABILITY </li></ul><ul><ul><li>STATIC </li></ul></ul><ul><ul><ul><li>The ability of an object to return to its equilibrium state after being disturbed </li></ul></ul></ul><ul><ul><li>DYNAMIC </li></ul></ul><ul><ul><ul><li>The way the object moves after being disturbed </li></ul></ul></ul>

6.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General Types </li></ul><ul><li>3 CONDITIONS OF STABILITY: </li></ul><ul><ul><li>POSITIVE </li></ul></ul><ul><ul><ul><li>The disruption of an object gets less over time </li></ul></ul></ul><ul><ul><li>NEGATIVE </li></ul></ul><ul><ul><ul><li>The disruption gets greater over time </li></ul></ul></ul><ul><ul><li>NUETRAL </li></ul></ul><ul><ul><ul><li>The disruption neither increases or decreases over time </li></ul></ul></ul>

7.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General Types </li></ul><ul><ul><li>The tendency to return to the original equilibrium </li></ul></ul><ul><ul><li>Example: Ball in a trough </li></ul></ul><ul><ul><li>Generally desirable in an airplane but does decrease maneuverability </li></ul></ul><ul><li>Positive Stability: </li></ul>

8.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General Types </li></ul><ul><ul><li>The tendency to move away from the equilibrium </li></ul></ul><ul><ul><li>Example: Ball on a hill </li></ul></ul><ul><ul><li>Undesirable in an airplane </li></ul></ul><ul><li>Negative Stability: </li></ul>

9.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: General Types </li></ul><ul><ul><li>The tendency for the correcting forces to neither increase or decrease over time </li></ul></ul><ul><ul><li>Example: Ball on a flat surface </li></ul></ul><ul><ul><li>Somewhat OK in an airplane </li></ul></ul><ul><li>Nuetral Stability: </li></ul>

10.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>Since we have 3 main axes of an aircraft, we also have 3 main types of Stability: </li></ul><ul><ul><li>LONGITUDINAL </li></ul></ul><ul><ul><li>LATERAL </li></ul></ul><ul><ul><li>DIRECTIONAL </li></ul></ul>

11.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>Is the ability of an aircraft to remain stable ABOUT (OR AROUND) THE LATERAL AXIS </li></ul><ul><li>Is PITCH STABILITY </li></ul><ul><li>Or keeping the Longitudinal Axis stable </li></ul>

12.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>Since the CENTER OF PRESSURE (or CENTER OF LIFT) moves with Angle of Attack changes </li></ul>

13.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>We need to be sure the Center of Gravity doesn’t get behind the Center of Pressure or severe flight problems will occur (such as can’t lower the nose) </li></ul>

14.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>Airplanes are designed so the Center of Pressure or Lift is behind of the Center of Gravity = a downward pitching moment on the nose of the aircraft at all times </li></ul>

15.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>This, coupled with the downward TAIL LOAD created by the HORIZONTAL STABILIZER, create a balanced set of conditions to keep the Longitudinal Axis stable </li></ul>

16.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>If the aircraft gets disturbed so the nose goes up, the Horizontal Stabilizer’s Angle of Attack is decreased and creates less Down Load to compensate </li></ul><ul><ul><li>Hor. Stabs. are usually symmetrical airfoils </li></ul></ul>

17.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>If the aircraft gets disturbed so the nose goes down, the Horizontal Stabilizer’s Angle of Attack is increased and creates more Down Load to compensate </li></ul><ul><li>This is Positive Longitudinal Stability </li></ul>

18.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LONGITUDINAL STABILITY </li></ul><ul><li>The Horizontal Stabilizer will be installed at some particular Angle of Incidence so it can do its job correctly </li></ul><ul><ul><li>This may be negative, positive, or zero </li></ul></ul>

19.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LATERAL STABILITY </li></ul><ul><li>Is the ability of an aircraft to remain stable ABOUT (OR AROUND) THE LONGITUDINAL AXIS </li></ul><ul><li>Is ROLL STABILITY </li></ul><ul><li>Or keeping the Lateral Axis stable </li></ul>

20.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LATERAL STABILITY </li></ul><ul><li>Provided mostly by wing DIHEDRAL </li></ul><ul><ul><li>This is the upward angle between the wing and the Lateral Axis </li></ul></ul>

21.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LATERAL STABILITY </li></ul><ul><li>Provided mostly by wing DIHEDRAL </li></ul><ul><ul><li>As an airplane is upset so a wing drops, it starts to SIDESLIP toward the low wing </li></ul></ul>

22.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LATERAL STABILITY </li></ul><ul><li>Provided mostly by wing DIHEDRAL </li></ul><ul><ul><li>This slipping motion plus the downward movement of the wing add downward vectors to the Angle of Attack production and lead to an increase in  on the lower wing = more lift on that wing </li></ul></ul>

23.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LATERAL STABILITY </li></ul><ul><li>Provided mostly by wing DIHEDRAL </li></ul><ul><ul><li>On the wing moving up, the upward vector reduces the  = less lift </li></ul></ul>

24.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LATERAL STABILITY </li></ul><ul><li>Provided mostly by wing DIHEDRAL </li></ul><ul><ul><li>These two changes to lift create a rolling force in the direction to restore the wings to level = Positive Lateral Stability </li></ul></ul>

25.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>LATERAL STABILITY </li></ul><ul><li>A HIGH-WING Airplane will not need as much Dihedral as a LOW-WING Airplane </li></ul><ul><li>since the Center of Gravity is below the Center of Lift it tends to right itself naturally (it’s inherently more Laterally Stable) </li></ul>

26.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>Is the ability of an aircraft to remain stable ABOUT (OR AROUND) THE VERTICAL AXIS </li></ul><ul><li>Is YAW STABILITY </li></ul><ul><li>Or keeping the Vertical Axis stable </li></ul>

27.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>Provided by the VERTICAL STABILIZER and Fuselage </li></ul><ul><ul><li>To be Directionally Stable, an aircraft must have more surface area behind the CG than in front so it acts like a Weather Vane </li></ul></ul>

28.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>Provided by the VERTICAL STABILIZER and Fuselage </li></ul><ul><ul><li>When the aircraft yaws (= SIDESLIP), the Vert. Stab. creates lift in the restoring direction and the sides of the fuselage offer a surface for the wind to push against </li></ul></ul>

29.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>Is also improved by SWEEPBACK of the wings </li></ul>

30.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>Is also improved by SWEEPBACK of the wings </li></ul><ul><ul><li>When yawing (SIDESLIP), the wing which is moving forward has a larger effective wing area = more drag to push it back </li></ul></ul>

31.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>But sweepback can cause a small problem: Dutch Roll </li></ul><ul><ul><li>If the aircraft’s wing drops it will tend to yaw into the low wing and the dihedral and sweepback will combine to return the wings to level quickly </li></ul></ul>

32.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>But sweepback can cause a small problem: Dutch Roll </li></ul><ul><ul><li>As the low wing moves up the Lateral Stability will return the aircraft to straight flight = the low wing will be moving faster than the high wing = more lift </li></ul></ul>

33.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>But sweepback can cause a small problem: Dutch Roll </li></ul><ul><ul><li>= that wing will now rise and the process will repeat in the opposite direction </li></ul></ul>

34.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>But sweepback can cause a small problem: Dutch Roll </li></ul><ul><ul><li>The resulting low level oscillation (“Dutch Roll”) doesn’t affect aircraft flight safety but is uncomfortable for passengers </li></ul></ul>

35.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Aircraft Stability <ul><li>Stability: About the Aircraft Axes </li></ul><ul><li>DIRECTIONAL STABILITY </li></ul><ul><li>But sweepback can cause a small problem: Dutch Roll </li></ul><ul><ul><li>Aircraft susceptible to this usually have YAW DAMPERS connected to the rudder controls to automatically apply corrective rudder action </li></ul></ul>

36.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Large aircraft, like small, control the aircraft about the same 3 axes: Lateral, Longitudinal, and Vertical </li></ul><ul><li>Major differences: </li></ul><ul><ul><li>More control surfaces </li></ul></ul><ul><ul><li>Hydraulic actuated </li></ul></ul><ul><ul><ul><li>Power-boosted </li></ul></ul></ul><ul><ul><ul><ul><li>Hydraulic cylinder in parallel with control rods </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pilot moves surface and valve to actuate hydraulic cylinder to help </li></ul></ul></ul></ul>

37.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Large aircraft, like small, control the aircraft about the same 3 axes: Lateral, Longitudinal, and Vertical </li></ul><ul><li>Major differences: </li></ul><ul><ul><li>More control surfaces </li></ul></ul><ul><ul><li>Hydraulic actuated </li></ul></ul><ul><ul><ul><li>Power-boosted </li></ul></ul></ul><ul><ul><ul><ul><li>Boosting is typically about 14:1 ratio </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Disadvantage: in transonic speed range shock waves form on controls and cause buffeting which is fed back into cockpit </li></ul></ul></ul></ul>

38.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Large aircraft, like small, control the aircraft about the same 3 axes: Lateral, Longitudinal, and Vertical </li></ul><ul><li>Major differences: </li></ul><ul><ul><li>More control surfaces </li></ul></ul><ul><ul><li>Hydraulic actuated </li></ul></ul><ul><ul><ul><li>Irreversibles </li></ul></ul></ul><ul><ul><ul><ul><li>Used to keep buffet from reaching cockpit </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Hyd. Cylinders in series with control rods </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Also need “feedback” system to give pilot the feel of the controls </li></ul></ul></ul></ul>

39.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul>

40.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Uses Irreversible system with 2 separate hydraulic systems, Standby system, and manual backup of Primary Controls (servo tabs) </li></ul>

41.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Primary Controls: Roll </li></ul><ul><ul><li>Ailerons and Spoilers </li></ul></ul><ul><ul><ul><li>4 ailerons and 14 spoilers </li></ul></ul></ul>

42.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Primary Controls: Roll </li></ul><ul><ul><li>Inboard ailerons and 10 flight spoilers do high speed flight with outboard ailerons locked in neutral position </li></ul></ul>

43.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Primary Controls: Roll </li></ul><ul><ul><li>When trailing edge flaps are deployed, outboard ailerons unlocked = all ailerons and flight spoilers work </li></ul></ul>

44.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Primary Controls: Pitch </li></ul><ul><ul><li>Elevators for normal pitch action </li></ul></ul><ul><ul><li>Movable Horizontal Stab. for trim action </li></ul></ul>

45.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Primary Controls: Yaw </li></ul><ul><ul><li>2 independent rud ders with anti-balance (anti-servo) tabs </li></ul></ul>

46.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Primary Controls: Yaw </li></ul><ul><ul><li>Also receives input from the Yaw Dampers to counteract Dutch Roll </li></ul></ul>

47.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Auxiliary Lift Devices: Trailing Ed ge Flaps </li></ul><ul><ul><li>Triple-slotted Fowler Flaps </li></ul></ul><ul><ul><li>Take-off = only back, Landing = back and down </li></ul></ul>

48.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Auxiliary Lift Devices: Leading Edge Flaps </li></ul><ul><ul><li>Krueger-type </li></ul></ul><ul><ul><li>Increase area and camber </li></ul></ul>

49.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Auxiliary Lift Devices: Leading Edge Slats </li></ul><ul><ul><li>Increase camber </li></ul></ul><ul><ul><li>Inboard flaps stall first = retain aileron control </li></ul></ul>

50.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Secondary Controls (Tabs): </li></ul><ul><ul><li>Ailerons have Balance Tabs which also act as Trim Tabs </li></ul></ul>

51.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Secondary Controls (Tabs): </li></ul><ul><ul><li>Elevators have Servo Tabs which also act as Trim Tabs </li></ul></ul>

52.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Secondary Controls (Tabs): </li></ul><ul><ul><li>Rudders have Anti-balance (anti-servo) Tabs which also act as Trim Tabs </li></ul></ul>

53.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 727 </li></ul><ul><li>Secondary Controls (Tabs): </li></ul><ul><ul><li>These Tabs also serve as manual backups in case of total hydraulic failure </li></ul></ul>

54.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 747 </li></ul>

55.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Boeing 757 </li></ul>

56.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Lockheed L-1011 </li></ul>

57.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>Large Aircraft Controls <ul><li>Example: Airbus A320 </li></ul>

58.
Basic Aerodynamics <ul><li>III. Basic Aerodynamics </li></ul><ul><ul><li>The Atmosphere </li></ul></ul><ul><ul><li>Physics </li></ul></ul><ul><ul><li>The Airfoil </li></ul></ul><ul><ul><li>Lift & Drag </li></ul></ul><ul><ul><li>Stability </li></ul></ul><ul><ul><li>Large Aircraft Flight Controls </li></ul></ul>