Scalar Quantity - A quantity measuring only magnitude.

Vector - A quantity measuring magnitude and direction.

Force - A push or pull exerted on a body.

Mass - Quantity of molecular material of an object.

Volume - Amount of space occupied by an object.

Density - Mass per unit volume.

Weight - The force by which a mass is affected by gravity.

Moment - A force acting over a distance to produce rotation about an axis.

Work - Force acting on a body causing displacement.

Power - Rate of work per unit time.

Energy - A scalar measure of a body’s capacity to do work.

Potential Energy - The ability of a body to do work because of its position.

Kinetic Energy - The ability of a body to do work because of its motion.

An unbalanced force acting on a body produces an acceleration in the direction of the force that is directly proportional to the force and inversely proportional to the mass of the body. F = ma

Static Pressure (Ps) - The pressure each air particle exerts on another.

Air Density (r) - The total mass of air particles per unit volume.

Temperature (T) - A measure of the average kinetic energy of the air particles.

Lapse Rate - The linear decrease of temperature with an increase in altitude at a rate of 2 ° C (3.57 ° F) per 1000 ft of elevation until 36,000 ft.

Humidity - The amount of water vapor in the air.

Viscosity (m) - The air’s resistance to flow and shearing.

Local Speed of Sound (LSOS) - The rate at which sound waves travel through a particular air mass.

Static Pressure (Ps) - 2.92 in-Hg or 1013.2 mb

Temperature (T) – 59 ° F or 15 ° C

Lapse Rate – 3.57° F/1000 ft or 2 ° C/1000 ft

P = r RT

Aircraft - Any device used or intended to be used for flight in the air.

Airplane - A heavier-than-air fixed-wing engine-driven aircraft supported by the dynamic reaction of airflow over its wings.

T-34 - An unpressurized low-winged monoplane and single engine turboprop with tandem cockpits and tricycle landing gear.

Ailerons - Control surfaces attached to the wing to control roll.

Rudder - The upright control surface attached to the vertical stabilizer to control yaw.

Elevators - The horizontal control surfaces attached to the horizontal stabilizer to control pitch.

Fuselage - The basic structure of the airplane to which all other components are attached. The T-34 uses a 28 ft 8 in. semi-monocoque fuselage.

Wing - An airfoil attached to the fuselage designed to produce lift. The T-34 uses full-cantilever wings and has slotted flaps.

Empennage - The assembly of stabilizing control surfaces on the tail. It includes the aft part of the fuselage, the vertical stabilizer and the horizontal stabilizer.

Landing Gear - Permits ground taxi operation and absorbs shock encountered during takeoff and landing. The T-34 steers using its rudder.

Engine - Provides the thrust necessary for powered flight. The T-34 has a PT6A-25 turboprop engine.

Center of Gravity - The point at which all weight is considered to be concentrates, and about which all forces and moments are measured.

Longitudinal Axis - Passes from the nose to the tail of the airplane.

Lateral Axis - Passes from wingtip to wingtip.

Vertical Axis - Passes vertically through the center of gravity.

Roll - Movement of the lateral axis around the longitudinal axis.

Pitch/Longitudinal Control - Movement of the longitudinal axis around the lateral axis.

Yaw/Directional Control - Movement of the longitudinal axis around the vertical axis.

Wingspan (b) - The length of the wing from wingtip to wingtip. The wingspan of the T-34 is 33’5".

Chordline - An infinitely long, straight line through the leading and trailing edges of an airfoil.

Chord - A measure of the width of the wing or other control surface.

Tip Chord (c_T) - Chord measured at the wingtip.

Root Chord (c_R) - The chord at the wing centerline.

Average Chord (c) - The average of every chord from the root to the wingtip.

Wing Area (S) - The apparent surface area of a wing from wingtip to wingtip.

Taper - The reduction in the chord of an airfoil from root to tip. The wings of the T-34 are tapered to reduce weight, improve structural stiffness and reduce wingtip vortices.

Taper Ratio (l) - The ratio of the tip chord to the root chord.

Sweep Angle (L) - The angle between a line drawn 25% aft of the leading edge and a line parallel to the lateral axis.

Aspect Ratio - The ratio of the wingspan to the average chord. The T-34’s aspect ratio is 6.2:1.

Wing Loading - A ratio of an airplane’s weight to the surface area of its wings. The T-34 is 24.5 lbs/ft².

Angle of Incidence - The angle between the airplanes longitudinal axis and the chordline of its wing. The T-34 has a 4° angle of incidence.

Dihedral Angle - The angle between the spanwise inclination of the wing and the lateral axis. The T-34 has dihedral wings at 7° to improve lateral stability.

Steady Airflow - Exists when static pressure, density, temperature and velocity remain constant over time.

Streamline - The path that air particles follow in steady airflow.

Streamtube - A collection of many streamlines which contains a flow like a tube with solid walls.

r ₁A₁V₁ = r ₂A₂V₂ Velocity and area in a streamtube are inversely related.

P_T = P_S + q If static pressure increases, dynamic pressure decreases. Static Pressure (P_S) is a measure of potential energy per unit volume. Dynamic Pressure (q) is the pressure of a fluid resulting from its motion. Total Pressure (P_T) is the sum of static and dynamic pressure.

Pitot Tube - The device on the wing or nose that measures Total Pressure.

Static Pressure Port - The device on the fuselage that measures static pressure.

Black Box - The device that collects both readings and determines Dynamic pressure.

Indicated Airspeed (IAS) - The instrument indication for the dynamic pressure the airplane is creating during flight.

Calibrated Airspeed (CAS) - Indicated airspeed corrected for instrument error.

Equivalent Airspeed (EAS) - Calibrated airspeed corrected for compressibility error.

True Airspeed (TAS) - The actual velocity at which an airplane moves though an air mass. TAS is IAS corrected for the difference between local air density and the density of the air at sea level on a standard day. TAS = (r ₀/r )^1/2 * IAS

Ground Speed (GS) - The airplane’s actual speed over the ground. It is TAS corrected for movement of the air mass.

GS = TAS ± HW/TW

Mach Number (M) - The ratio of the airplane’s true airspeed to the local speed of sound.

Critical Mach Number (M_CRIT) - The free airstream Mach Number that produces the first evidence of local sonic flow.

M = TAS/LSOS The higher the altitude, the lower the speed of sound, so for any given TAS, the Mach Number will be higher.

Pitch Attitude (q) - The angle between an airplane’s longitudinal axis and the horizon.

Flight Path - The path described by an 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.

Angle of Attack (a ) - 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 of an airfoil.

Positive Camber Airfoil - An airfoil with a mean camber line above the chordline.

Negative Camber Airfoil - An airfoil with a mean camber line below the chordline.

Symmetric Airfoil - An airfoil with a mean camber line coincident with the chordline.

Aerodynamic Center - The point along the chordline where all changes in the aerodynamic force take place. (Approximately 25% of the length of the chord from the leading edge)

Airfoil Thickness - The height of the airfoil and point of maximum thickness, corresponding to the aerodynamic center.

Spanwise Flow - Airflow that travels along the span of the wing, parallel to the leading edge. It produces no lift.

Chordwise Flow - Air flowing at right angles to the leading edge of the airfoil. It is the only airflow that produces lift.

Aerodynamic Force (AF) - A force that is the result of pressure and friction distribution over an airfoil, and can be resolved into two components, lift and drag.

Lift - The component of aerodynamic force acting perpendicular to the relative wind.

Drag - The component of aerodynamic force acting parallel to and in the same direction as the relative wind.

Symmetric Airfoils - As air strikes the leading edge, its velocity will slow to near zero (leading edge stagnation point) creating 100% static pressure. As the airflow separates to either side of the airfoil, the static pressure decreases and dynamic pressure and velocity increase to a maximum at the point of greatest thickness of the airfoil. The velocity begins to slow again and stagnates at the trailing edge again creating an area of 100% static pressure. The upper surface lift (lift) is equal to the lower surface lift (drag) at zero angle of attack.

Positively Cambered Airfoils - These also have leading and trailing edge stagnation points and come to a maximum velocity at the point of greatest thickness of the airfoil. However, the positive camber creates an area of lower static pressure and higher dynamic pressure above the airfoil. This creates greater lift than drag at zero angle of attack.

L = qSC_L = 1/2r V²SC_L Lift is a product of dynamic pressure (q) the surface area of the airfoil (S) and the coefficient of lift (C_L). The coefficient of lift includes angle of attack, shape of the airfoil, aspect ratio, viscosity and compressibility.

Laminar Flow - Smooth airflow movement along in streamlines.

Turbulent Flow - Disorganized and irregular airflow movement following laminar flow.

Laminar Flow - Produces little friction, but is easily separated from the surface.

Turbulent Flow - Produces higher friction drag, but adheres to the upper surface of the airfoil and delays boundary layer separation.

AOA indicators (T-34 left wing)

Rudder Pedal Shakers (T-34)

AOA indexer (T-34)

Buffeting (T-34)

Solve for velocity in the lift equation and change lift to weight, we get V_S = (2W/r SC_Lmax)^1/2 and

IAS_S = (2W/r ₀SC_Lmax)^1/2 as weight increases, stall speed increases. An increase in altitude increases true stall speed, however indicated stall speed remains unchanged. As thrust increases, stall speed decreases. Power-on stall speed is 9 knots less in the T-34.

Fixed Slots - Gaps located at the leading edge of a wing that allow air to flow from below the wing to the upper surface.

Automatic Slots - Moveable leading edge sections also called slats.

Fixed Slots – High pressure air from the leading edge stagnation point is directed through the slot, converting the static pressure to dynamic pressure. The air increases the energy on the boundary layer and delays separation.

Automatic Slots – are deployed by the pilot or automatically when separation begins to occur.

Plain Flap – A simple hinged portion of the trailing edge that is forced down into the airstream to increase the camber of the airfoil.

Split Flap – A plate deflected from the lower surface of the airfoil that creates drag by creating turbulent airflow between the bottom of the wing and the deflected surface.

Slotted Flap – Is similar to a plain flap, but moves away from the wing to open a narrow slot between the flap an the wing for better boundary layer control. The T-34 uses this kind of flap.

Fowler Flap – an extended flap that increases the wing area of the plane while moving down to increase the camber of the airfoil. It also opens a slot to increase boundary layer control. This type of flap is primarily used in larger airplanes.

Plain Flap – A simple hinged portion on the leading edge of the airfoil that tilts down to increase camber.

Slotted Flap – is similar to the plain flap but moves away from the wing to open a narrow slot between the flap an the wing for better boundary layer control.

Moderate Taper (l = 0.5) – Even stall tendency.

Elliptical – Even stall tendency.

Rectangular (l = 1.0) – (The only naturally occurring) Root stall tendency.

Swept – Tip stall tendency.

High Taper (l = 0.25) – Tip stall tendency.

Geometric Twist – A decrease in angle of incidence from wing root to wingtip.

Aerodynamic Twist – A decrease in camber from wing root to wingtip.

Stall Fences – Strips that redirect airflow over the chord, rather than the root.

Stall Strips – A sharply angled piece of metal mounted on the leading edge of the root section.

Total Drag – is the composite of parasite drag and induced drag. It is the total force that is parallel to the relative wind and acts in the same direction.

Parasite Drag – All drag not associated with the production of lift.

Induced Drag – That portion of total drag associated with the production of lift.

Form – Caused by airflow separation from the surface and the wake caused by separation.

Friction – A retarding force created in the boundary layer caused by viscosity that increases with surface area.

Interference – Is caused by the mixing of streamlines between one or more components.

Form – Streamlining surfaces of the plane reduces separation and decreases the pressure differential that causes drag.

Friction – Can be reduced by smoothing exposed surfaces through painting, cleaning, waxing and polishing and by using flush riveting.

Interference – Can be minimized by proper fairing and filleting

D_P = ½ r V²ƒ = qƒ An increase in density will increase drag, an increase in velocity will increase drag, and an increase in equivalent parasite area (ƒ) will increase drag.

D_I = KL²/r V²b² as lift increases drag increases, as weight increases drag increases, as density increases drag decreases, and as velocity increases induced drag decreases.

Thrust is a component of power. P_R=T_RV/325

Thrust Required – The thrust required to overcome drag

Power Required – The amount of power required to produce thrust required

Thrust Required – As velocity increases from zero to L/D_MAX, thrust required decreases. Beyond L/D_MAX thrust required increases.

Power Required – As velocity increase from zero, power required decreases, then begins to increase at some velocity less than the velocity at L/D_MAX.

Thrust Available – The amount of thrust that the airplane’s engines are producing at a given throttle setting, velocity and density.

Power Available – The amount of power that the airplane’s engine is actually producing at a given throttle setting, velocity and density.

Thrust Available – As the throttle is reduced, thrust available decreases. Thrust available is unaffected by an increase in velocity, and as density decreases thrust available also decreases.

Power Available – As the throttle is reduced, power available decreases. Power available increases linearly with an increase in velocity, and as density decreases power available also decreases.

Thrust Available – As the throttle is reduced, thrust available decreases. Thrust available decreases with an increase in velocity, and as density decreases thrust available also decreases.

Power Available – As the throttle is reduced, power available decreases. Power available will initially increase then decrease with an increase in velocity, and as density decreases power available also decreases.

Thrust Horsepower (THP) – The horsepower that is converted to thrust by the propeller.

Shaft Horsepower (SHP) – Engine output.

Propeller Efficiency (p.e.) – The ability of the propeller to turn engine output into thrust.

THP = SHP * p.e. Thrust horsepower is the engine output multiplied by the propeller efficiency.

Thrust Excess – The difference between thrust available and thrust required when thrust available is greater than thrust required.

Power Excess - The difference between power available and power required when power available is greater than power required.