Aero I Ch. 4

Front 1

Define pitch attitude, flight path, relative wind, angle of attack, mean camber line,
positive camber airfoil, negative camber airfoil, symmetric airfoil, aerodynamic
center, airfoil thickness, spanwise flow, chordwise flow, aerodynamic force, lift
and drag.

Back 1

Pitch Attitude: the angle between an airplane’s longitudinal axis and the horizon
Flight path: is the path described by the airplane's center of gravity as it moves through an air mass.
Relative wind: the airflow the airplane experiences as it moves through the air. It is equal in magnitude and opposite in direction to the flight path.
Angle of Attack: the angle between the relative wind and the chordline of an airfoil.
Mean Camber Line: A line drawn halfway between the upper and lower surfaces.
Positive Camber Airfoil: the airfoil is positive if the mean camber line is above the chordline.
Negative Camber: If the camber line is below the chordline, it has negative camber.
Symmetric: Mean camber line is coincident with the chordline
Aerodynamic Center: the point along the chordline around which all changes in the aerodynamic force takes place.
Airfoil Thickness: the height of the airfoil profile.
Spanwise Flow: airflow that travels along the span of the wing, parallel to the leading edge.
Chordwise Flow: air flowing at right angles to the leading edge of an airfoil.
Aerodynamic Force: the net force that results from pressure and friction distribution over an airfoil, and
comes from two components, lift and drag.
Lift: the component of the aerodynamic force acting perpendicular to the relative wind.
Drag: the component of the AF acting parallel to and in the same direction as the relative wind.

Front 2

Describe the effects on dynamic pressure, static pressure, and the aerodynamic
force as air flows around a cambered airfoil and a symmetric airfoil.

Back 2

Symmetric: At zero angle of attack, produces identical velocity increases and static pressure decreases on both the upper and lower surfaces. Since there is no pressure differential perpendicular to the relative wind, the airfoil produces zero net lift.
Cambered: area above the wing is smaller than area below the wing so the velocity will be faster above the wing than below. Therefore, the dynamic pressure will be higher on top, meaning the static pressure will be lower as well. The higher static pressure from the bottom of the airfoil will causing a lifting force (High to Low Static pressure)

Front 3

Describe the effects of changes in angle of attack on the pressure distribution
and aerodynamic force of cambered and symmetric airfoils.

Back 3

Symmetric: In order to create lift, there must be an angle of attack greater than zero
Cambered: Increasing AOA will creat even less of an area above the airfoil, increasing the velocity, increasing the Dynamic pressure which decreases the static pressure, causing a pressure differential between the airfoil, which increases lift.

Front 4

Describe the effects of changes in density, velocity, surface area, camber, and
angle of attack on lift.

Back 4

L=qSC=1/2pV^2SC
They are directly related.

Front 5

List the factors affecting lift that the pilot can directly control.

Back 5

Velocity, camber, and angle of attack

Front 6

Compare and contrast the coefficients of lift generated by cambered and
symmetric airfoils.

Back 6

Positive Camber: Highest CLmax, lowest AOA
Symmetric: Lower CLmax but higher AOA
Negative: Lowest CLmax but highest AOA

Front 7

Describe the relationships between weight, lift, velocity, and angle of attack in
order to maintain straight and level flight, using the lift equation.

Back 7

Lift=Weight in straight and level flight
Angle of Attack and Velocity are inversely related so in order to maintain straight and level flight while increasing AOA, velocity must decrease. Otherwise, lift will be greater than weight and the airplane will climb.

Front 8

Define boundary layer.

Back 8

The layer of airflow over a surface that demonstrates local airflow retardation due to viscosity.

Front 9

List and describe the types of boundary layer airflow.

Back 9

Laminar Flow: the air moves smoothly along in streamlines. Produces very little friction, but is easily separated from the surface.
Turbulent flow: the streamlines break up and the flow is disorganized and irregular. Higher friction drag but adheres better to the upper surface of the airfoil, delaying boundary layer separation.

Front 10

State the advantages and disadvantages of each type of boundary layer airflow.

Back 10

Laminar: produces very little friction drag, but easily separates from the surface.
Turbulent: produces high friction drag but adheres better to the surface, delaying boundary layer seperation.

Front 11

State the cause and effects of boundary layer separation.

Back 11

As the air flows aft from the point of maximum thickness (lower static pressure) toward the trailing edge (higher static pressure), it encounters an adverse pressure gradient which impedes the flow of the boundary layer.

Front 12

Define stall and state the cause of a stall.

Back 12

A condition of flight which an increase in AOA results in a decrease in CL. The only cause of a stall is excessive AOA.

Front 13

Define and state the importance of CLmax and CLmax AOA.

Back 13

CLmax is the highest value of CL.
CLmaxAOA (critical angle of attack) is the stalling angle of attack.

Front 14

State the procedures for stall recovery.

Back 14

Add power, relax back stick pressure, and roll wings level.
(Max, relax, level)

Front 15

List common methods of stall warning, and identify those used on the T-34C.

Back 15

AOA Indicators, rudder pedal shakers, stick shakers, horns, buzzers, warning lights and other devices.
T-34C: AOA indicator, AOA indexer, and rudder shakers.

Front 16

State the stalling angle of attack of the T-34C.

Back 16

Between 29.0 and 29.5 units AOA

Front 17

Define stall speed.

Back 17

The minimum true airspeed required to maintain level flight at CLmaxAOA

TAS=V=(2W/pSCLmax)^(1/2)

Front 18

Describe the effects of weight, altitude, and thrust on true and indicated stall speed, using the appropriate equation.

Back 18

TAS=V=(2W/pSCLmax)^(1/2)
IASs=(2W/p0SCLmax)^(1/2)
More weight increases the stall speed.
Higher altitude decreases density, which increases stall speed, except IASstall is constant.
Thrust decreases stall speed because thrust can help support weight.

Front 19

State the purpose of high lift devices.

Back 19

To reduce takeoff and landing speeds by reducing stall speeds.

Front 20

State the effect of boundary layer control devices on the coefficient of lift, stalling
AOA, and stall speed.

Back 20

Increases CL, AOA
Decreases stall speed.
Only at high AOA's

Front 21

Describe different types of boundary layer control devices.

Back 21

Slots: operate by allowing the high static pressure air beneath the wing to be accelerated through a nozzle and injected into the boundary layer on the upper surface of the airfoil. Its PE turns into KE. Using the extra KE, the turbulent boundary layer is able to overcome the adverse pressure gradient. Helps for higher AOA's.
-Fixed slots
-Slats (automatic slots): have moveable leading edges

Front 22

Describe the operation of boundary layer control devices.

Back 22

Delay boundary layer separation by allowing the high static pressure air beneath the wing to be accelerated through a nozzle and injected into the boundary layer on the upper surface of the airfoil. Its PE turns into KE. Using the extra KE, the turbulent boundary layer is able to overcome the adverse pressure gradient. Helps for high AOA.

Front 23

State the effect of flaps on the coefficient of lift, stalling AOA, and stall speed.

Back 23

Higher CLmax, less of an AOA. Stall speed increases.

Front 24

Describe different types of flaps.

Back 24

Plain flap: simple hinged portion of the trailing edge that is forced down in the airstream to increase camber.
Split: A plate deflected from the lower surface of the airfoil. Lot of drag.
Slotted: similar to the plain flap but moves away from the wing to open a narrow slot between the flap and wing for boundary layer control.
Fowler: Moves down, increasing the camber, and aft, causing a significant increase in wing area as well as opening one or more slots for boundary layer control.

Front 25

State the methods used by each type of flap to increase the coefficient of lift.

Back 25

Plain flap: increases camber
split flap: increases camber
Slotted: increase camber and boundary layer control
fowler: increase camber

Front 26

State the stall pattern exhibited by rectangular, elliptical, moderate taper, high
taper, and swept wing planforms.

Back 26

Rectangular: stalls at root
Ellipticall: stalls everywhere
Moderate Taper: stalls everywhere
High Taper: stalls at tip
Swept Wing: stalls at tip

Front 27

State the advantages and disadvantages of tapering the wings of the T-34C.

Back 27

Reduces weight, improve stiffness, and reduces wingtip vortices.
Even stall progression. Could lose lateral control.

Front 28

State the purpose of wing tailoring.

Back 28

Used to create a root to tip stall progression and give the pilot some stall warning while ensuring that the ailerons remain effective up to a complete stall.

Front 29

Describe different methods of wing tailoring.

Back 29

Geometric Twist: a decrease in angle of incidence from wing root to wing tip.
Aerodynamic Twist: a gradual change in airfoil shape that increases CLmaxAOA to a higher value from the root to the tip.
Stall Fences: redirect the airflow along the chord, thereby delaying tip stall and enabling the wing to achieve a higher AOA without stalling.
Stall Strip: a piece of metal mounted on the leading edge of the root section to induce a stall at the wing root.

Front 30

State the types of wing tailoring used on the T-34C.

Back 30

Geometric Twist: 3.1'
Aerodynamic Twist
Stall strips