Pre-API

In API it can make a big difference if you are one test ahead. If you have already read and are familiar with the upcoming section you can better pay attention in class. To do that you have to know the first six chapters when you show up. Below is the key information from the first six chapters of Aero 1. Learn this to get that edge. Nothing here is a substitute for digging into and knowing the information in the book.

Fundamentals of Aerodynamics Chapter 1 – Basic Properties of Physics

 * Mathematical Systems:
 * Scalar – a quantity that represents only magnitude (time, temp, volume)
 * Vector – a quantity that represents magnitude and direction (displacement, velocity, acceleration or force)
 * Displacement (s) – the distance and direction of a body’s movement
 * Velocity (V) - the rate of change in speed and direction of a body’s motion
 * Acceleration (a) – is the rate and direction of a body’s change of velocity
 * Force (F) – is a push or pull exerted on a body
 * Mass (m) – the quantity of molecular material that comprises an object
 * Volume (v) – the amount of space occupied by an object
 * Density (p) – mass per unit volume
 * Weight (W) – the force with which a mass is attracted toward the center of the earth by gravity
 * Force (F) – product of mass and acceleration
 * Moment (M) – a vector quantity equal to force (F) times the distance (d) from the point of rotation that is perpendicular to the force
 * Work (W) – a force acting on a body and moves it. Equal to the product of the force and the distance of displacement
 * Power (P) – the rate of doing work or work done per unit time
 * Energy (E) – measures a body’s capability to doing work
 * Potential Energy (P.E.) – body’s ability to do work because of its positive state of being and is a function of mass, gravity and height
 * Kinetic Energy (K.E.) – is the ability of a body to do work because of its motion
 * Newton’s Laws of Motion:
 * First Law – The Law of Equilibrium : a body at rest tends to remain at rest and a body in motion tends to remain in motion (inertia). This motion tends to be in a straight line at constant velocity. Equilibrium is the absence of acceleration. The sum of all the forces ( lift vs weight and thrust vs drag ) all summed around the center of gravity total zero.
 * Trimmed Flight exist when the sum of the moments around the COG totals zero. If you are in equilibrium flight, then you are in trimmed flight but the reverse is not necessarily true!
 * Second Law – An unbalanced force on an a body produces an acceleration in the direction of the force that is directly proportional to the force and the inversely proportional to the mass of the body.
 * Third Law – For every action there is an equal and opposite reaction (thrust versus hot gasses from a jet engine)
 * Properties of the Atmosphere:
 * Static Pressure – the pressure each air particle exerts on another. Atmospheric static pressure decreases 1.0 inches of Hg per 1000 feet of climb.
 * Air Density – the total mass of air particles per unit volume. Air density decreases with an increase in altitude.
 * Temperature – a measure of the average kinetic energy of the air particles. The average lapse rate is the decrease in the airs temperature as you climb at a rate of 2 degrees Celsius per 1000 feet until 36,000 feet. From 35K to 80K feet the air stays at –56.5 degrees Celsius in the Isothermal Layer.
 * Humidity – the amount of water vapor in the air. As humidity increases, air density decreases because water molecules have less mass and approximately the same volume.
 * Viscosity – a measure of the air’s resistance to flow and shearing. How air sticks to a surface. Air viscosity increases with an increase in air temperature.
 * Sound is wave motion not particle motion.
 * Local Speed of Sound – the rate at which sound waves travel through a particular air mass. It is only dependent on air temperature. As the temperature of air increases, the speed of sound increases.
 * Standard Atmosphere:
 * A way of disregarding atmospheric changes and developing a baseline condition. It is a set of reference conditions giving average values of air properties as a function of altitude.
 * The General Gas Law:
 * Demonstrates the relationship between three properties in air: pressure, density and temperature P = density R T
 * Altitude Measurement:
 * Altitude – the height above a given plane of reference
 * True Altitude – the actual height above mean sea level
 * Pressure Altitude – the height above the standard datum plane:pressure is 29.92in-HG
 * Density Altitude – the altitude in the standard atmosphere where the air density is equal to local air density

Fundamentals of Aerodynamics Chapter 2 – Aircraft Terminology

 * Major Components of an Airplane:
 * Aircraft – device used or intended to be used for flight in the air. It is supported by buoyancy of the structure or by the dynamic reaction of the air against the surface
 * Airplane – is a heavier than air fixed wing aircraft that is driven by an engine driven propeller or a gas turbine jet
 * T-34 is a unpressurized low-winged monoplane with tricycle landing gear that is steered by its rudder during taxiing. It is a single engine turbo prop with tandem cockpits.
 * Fuselage – the basic structure of the airplane to which all the other components are attached
 * Truss – consist of a metal or wooden frame over which a light skin is stretched
 * Full Monocoque – extremely light and strong and consist of only a kin shell which is highly stressed but almost impossible to repair if damaged
 * Semi Monocoque – has skin, transverse frame members, and stringers, which all share in stress loads and will reduce damage if sustained. (T-34)
 * Wing – an airfoil attached to the fuselage and is designed to produce lift and contains fuel cells, engine nacelles and landing gear.
 * Ailerons – control surfaces attached to the wing to control roll
 * Flaps – are high lift devices attached to the wing to increase lift at low airspeeds. T-34 has a single mounted wing with slotted flaps integrated into the trailing edge inboard of the ailerons
 * Full Cantilever – all bracing for the wings are internal
 * Empennage – the assembly of stabilizing and control surfaces on the tail of the airplane
 * Rudder – the upright control surface attached to the vertical stabilizer to control yaw
 * Elevators – the horizontal control surfaces attached the horizontal stabilizer to control pitch
 * Landing Gear – taxi’s the plane and permits it to absorb the landing shock
 * Engines - provide the thrust necessary for powered flight. The T-34 is powered by a PT6A-25 turboprop engine
 * Airplane Reference System:
 * Consist of the 3 mutually perpendicular lines intersecting at a point
 * Center of Gravity – the point where the three lines intersect. It is where all the weight is thought of being concentrated. This point moved depending on the load of the plane
 * Longitudinal Axis – passes from the nose to the tail of the airplane and cause roll or lateral control
 * Lateral Axis – passes from wingtip to wingtip and causes pitch or longitude control
 * Vertical Axis – passes vertically through the center of gravity and causes yaw or directional control
 * Dimensions:
 * Wingspan – the length of a wing measured from wingtip to wingtip. The T-34 is 33’5"
 * Chordline – an infinitely long, straight line drawn through the leading and trailing edge of an airfoil.
 * Chord – a measure of the width of the wing or other control surfaces
 * Root Chord – is the length of the wing chord at the centerline of the plane
 * Tip Chord – is the chord measured at the wingtip
 * Average Chord – is the average of every chord from the wing root to the wing tip
 * Wing Area – is 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 – if the wing has straight leading and trailing edges, it is the ration of the tip chord to the root cord
 * Sweep Angle – the angle between the line drawn 25% aft of the leading edge and parallel to the lateral axis
 * Aspect Ratio – the ratio of the wingspan to the average chord. High aspect ratio (35:1) is a glider while Low aspect ration (3:1) is a rocket
 * Wing Load – the ration of the airplane’s weight to the surface area of its wings. There is a reverse relationship between aspect ration and wing loading. High aspect have low wing loading and low aspect have high wing loading.
 * Angle of Incidence – the angle between the airplanes longitudinal axis and the chordline of its wing
 * Dihedral Angle – the angle between the spanwise inclination of the wing and the lateral axis
 * Anhedral Angle is a negative dihedral angle on a plane. The T-34 has a dihedral wings to improve lateral stability.

Fundamentals of Aerodynamics Chapter 3 – Basic Aerodynamic Properties

 * Properties of Airflow:
 * The atmosphere us a uniform mixture of gases with the properties of a fluid. The flow of this fluid changes with static pressure, density, temperature and velocity
 * Steady Airflow – exist if every point in the airflow consistently follow these four principles over time. A particle of air follows the exact same path and velocity as the particle in front of it
 * Streamline – the path that air particles follow in steady airflow
 * Streamtube – is a collection of many streamlines which contains a flow much like a tube with solid walls
 * Continuity Equation:
 * An equation stating that the air flowing thru A1 in a stream tube must equal the air flowing thru A2 in a streamtube. The velocity and the area in a streamtube are inversely related
 * Bernoulli’s Equation:
 * Gives the relationship between the pressure and the velocity of steady airflow
 * Dynamic Pressure (q) – is the pressure of a fluid resulting from its motion and is equal to _ p V 2
 * Total Pressure (Pt) – also called the head pressure; the sum of the static and dynamic pressures
 * Airspeed Measurements:
 * We need to know airspeed to find out if we have sufficient dynamic pressure to create lift but not so much as to damage and we need to know the velocity to navigate
 * Pitot-Static System – the measure of total pressure and static pressure on the airplane, subtracting static pressure from the total pressure results in dynamic pressure
 * Pitot Tube – is a device that collects total pressure. The static pressure port is the device that collects ambient static pressure. This results in a reading of the airplane’s knots of indicated airspeed
 * Indicated Airspeed – is the instrumental indication of the dynamic pressure the airplane is creating during flight
 * Instrumental Error – is caused by the ram effect of air in the pitot tube resulting in higher than normal airspeed indications at airspeeds approaching the speed of sound
 * Calibrated Airspeed – the corrected airspeed taking in account the instrumental error
 * Compressibility Error – caused by the ram effect of air in the pitot tube resulting in higher than normal airspeed indications at airspeeds approaching the speed of sound
 * Equivalent Airspeed – the true airspeed at sea level on a standard day that produces the same dynamic pressure as the actual flight condition. Found by correcting calibrated airspeed for compressibility error
 * True Airspeed – the actual velocity at which an airplane moves through an airmass. Found by correcting EAS for density. TAS will only equal IAS on standard days at sea level conditions. If IAS remains constant while climbing from sea level to a higher altitude, the TAS must increase
 * ICE-T – used to remember the order of airspeeds
 * Ground Speed – a measure of the airplane’s actual speed over the ground. It is the TAS of the plane through the air mass corrected with the movement of air.
 * Mach Number:
 * As a plane approaches the speed of sound it begins to suffer from the effects of compressibility. The closer it gets, the greater the pressure wall forms called a shock wave. The Mach Number is the ratio of the airplane’s TAS to the Local Speed of Sound
 * Critical Mach Number – the free stream Mach Number that produces the first evidence of local sonic flow

Fundamentals of Aerodynamics Chapter 4 – Lift and Stalls

 * Airfoil Terminology:
 * Pitch Attitude (θ ) – 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 and is equal in magnitude and opposite in the direction to the flight path
 * Angle of Attack (α ) – the angle between the relative wind and the chordline of an airfoil
 * Flight path, relative wind, and angle of attack should never be inferred from the pitch attitude
 * Mean Camber Line – Line drawn halfway between the upper and lower surfaces
 * Airfoil Positive / Negative / Symmetrical Camber – determines whether the mean camber lines is above or below or equal to the chordline
 * Airfoil Thickness – is the height of the airfoil profile. The point of maximum thickness corresponds to the aerodynamic center
 * Spanwise Flow – Airflow that travels along the span of the wing, parallel to the leading edge and is normally from root to tip. This airflow is not accelerated over the wing and therefore produces no lift
 * Chordwise Flow – is air flowing at right angles to the leading edge of an airfoil and is the only flow accelerated over the wing producing lift
 * Aerodynamic Force – a force that is the result of pressure and friction distribution over an airfoil and can be resolve into lift and drag
 * Lift – the component of aerodynamic force acting perpendicular to the wind
 * Drag – the component of the aerodynamic force acting parallel to and in the same direction as the relative wind
 * Leading Edge Stagnation Point – the area of high static pressure where the air strikes the leading edge of the airfoil and its velocity is slow to near 0
 * Trailing Edge Stagnation Point – the point where the upper and lower airflows
 * meet. The velocity slows to near zero, forming an area of high static pressure
 * Aerodynamic Force Equation – a product of dynamic pressure (q), the surface area of the airfoil (S), and a variable (Cf) which is the coefficient of aerodynamic force AF = _ ρ V2 S Cf
 * Lift – controlled by eight factors that affect aerodynamic force
 * Density, Velocity, and Surface Area
 * Angle of Attack and Shape Effects
 * Aspect Ratio (deals with the shape of the wing), Viscosity (affects the aerodynamic force by decreasing the velocity of the airflow immediately adjacent to the wing’s surface), and Compressibility (air compresses when it hits the wing)
 * An increase in density or velocity will produce greater lift
 * An increase in wing surface area produces greater lift
 * Flaps are devices used to change the camber of an airfoil and are used during take off and landings
 * Velocity and Angle of Attack are inversely related in level flight
 * Clmax is the most effective AOA and remains constant regardless of weight, dynamic pressure, bank angle, etc
 * The Boundary Layer – the layer of airflow over a surface that demonstrates local airflow retardation due to viscosity, it is usually no more than 1mm thick at the leading edge of the airfoil and grows in thickness as it moves aft over the surface
 * Laminar Flow – the air molecules move smoothly along in streamlines and this layer produces little friction but is easily separated from the surface
 * Turbulent Flow – streamlines break up and the flow is disorganized and irregular, this produces high friction drag, but adheres to the upper surface of the airfoil
 * Favorable Pressure Gradient – assist the boundary layer in adhering to the surface by maintaining its high kinetic energy
 * Adverse Pressure Gradient – impedes the flow of the boundary layer
 * If the boundary doesn’t have significant kinetic energy to overcome the adverse pressure gradient, the lower levels of the boundary layer will stagnate. The boundary will separate from the surface and cause the airfoil to lose the suction pressure that creates lift
 * Stalls – a condition of flight where an increase in AOA has resulted in a decrease in Cl
 * Regardless to flight speed and air conditions, the wing will always stall beyond the same AOA
 * The only cause of a stall is excessive AOA
 * The only action necessary for stall recovery is to decrease the AOA below ClmaxAOA
 * The T-34C AOA indicator is calibrated so that the airplane stalls between 29.0 and 29.5 units AOA regardless of airspeed, nose attitude, weight, or altitude. It is self adjusting to account for differences in full flap or no flap stalls. The T-34 also contains AOA indexer and rudder shakers that receive their input from an AOA probe on the left wing. The rudder pedal shakers are activated and airframe buffeting will occur at 26.5 units of AOA. Stalls at idle in a clean configuration are characterized by a nose down pitch with a slight rolling tendency at near full aft stick. The effect of the landing gear on stalls is negligible, however extending the flaps will aggravate the stall characteristics by increasing the rolling tendency. Increased power will degrade the stall characteristics by increasing nose up stall attitude, increased buffeting and increased roll tendency.
 * Stall Speeds – the minimum true airspeed required to maintain level flight at ClmaxAOA. It is greatly controlled by weight (as weight decreases, stall speed decreases), altitude (an increase in altitude, increases stall speed), power and maneuvering
 * Power On Stall Speed – is less than power off stall speed because at high pitch attitude, part of the weight of the airplane is actually being supported by the vertical component of the thrust vector
 * The T-34 Power On Stall Speed is 9 knots less than its Power Off Stall Speed
 * High Lift Devices – affect stall speeds since they increase Cl as we approach ClmaxAOA. The primary purpose of high lift devices is to reduce takeoff and landing speeds by reducing stall speed. There are two types: those that delay boundary layer separation and those that increase camber.
 * Boundary Layer Control (BLC) Devices – 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. As the air flows through the nozzle, the potential energy is converted into kinetic energy. There are many types of BLC devices but we will concentrate on slots
 * Fixed Slots – are gaps located at the leading edge of a wing that allow air to flow from below the wing to the upper surface. High pressure air from the leading edge stagnation point is directed through the slot, which acts as a nozzle converting the static pressure into dynamic pressure. The high kinetic energy air leaving the nozzle increases the energy of the boundary layer and delays separation
 * Slats – moveable leading edge sections and used to make automatic slots. When the slat deploys, it opens a slot
 * Camber Change – increasing the camber of an airfoil increases Clmax . Extending flaps increases the airfoil’s positive camber thus shifting its zero lift point to the left.
 * Plain Flap – a simple hinge 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 and creates a lot of drag because the turbulent air between the wing and the deflected surface
 * Slotted Flap – similar to plain flap, but moves away from the wing to open a narrow slot between the flap and the wing for BLC.
 * Fowler Flap – used extensively on larger airplanes. When extended, it moves down increasing the camber and aft causing a significant increase in wing area as well as a slot for BLC
 * Leading Edge Flaps – devices that change the wing camber at the leading edge of the airfoil.
 * Stall Pattern / Wing Design – the most desirable pattern on a wing is one that begins at the root. The primary reason for a root first stall pattern is to maintain aileron effectiveness until the wing is fully stalled.
 * Rectangular Wing – lift distortion is due to low lift coefficients at the tip and high lift coefficients at the root. It has a strong root stall tendency
 * Highly Tapered Wing – is desirable from the standpoint of structural weight, stiffness, and wingtip vortices. They produce most of the lift towards that tip
 * Swept Wings – are used on high speed aircraft because they reduce drag and allow the airplane to fly at higher mach numbers. They have similar lift distribution as that of Tapered and have strong tip stall tendency and rapidly progresses over the rest of the wing
 * Elliptical Wings – has an even distribution of lift from the root to the tip and produces minimum induced drag. All section stall at the same AOA.
 * Moderate Taper Wings – have a lift distribution and stall pattern that is similar to elliptical. The T-34 uses tapered wings because they reduce weight, improve stiffness, and reduce wingtip vortices. The stall is undesirable and as the stall progresses, the pilot will lose lateral control
 * Geometric Twist – is a decrease in angle of incidence from wing root to tip. T-34 is geometrically twisted at 3.1 degrees
 * Aerodynamic Twist – is a decrease in camber from wing root to tip. The T-34 is aerodynamically twisted to create a reduced camber at the tip
 * Stall Fences – redirect airflow along the chord, thereby delaying tip stall and enabling the wing to achieve higher AOAs without stalling
 * Stall Strip – a sharply angled piece of metal mounted on the leading edge of the root to induce a stall at the wing root. T-34s have stall strips located near the root at the leading edge

Fundamentals of Aerodynamics Chapter 5 – Drag

 * Drag – is the component of the aerodynamic force that is parallel to the relative wind, and acts in the same direction. The coefficient of drag is low and nearly constant at very low angles of attack. As AOA increases, the coefficient rapidly increases. It is never zero and is a combination of parasite drag and induced drag.
 * Parasite Drag - all drag that is not associated with the production of lift. It is composed of form drag, friction drag and interference drag
 * Form Drag – also called pressure or profile drag, is caused by the airflow separation from a surface and the wake that is created in that separation. Primarily based on the shape of the object. It temporarily is significant until the aircraft velocity decreased to match the higher angle of attack. To reduce form drag, surfaces exposed to the airstream are streamlined like a teardrop. This reduces the size of high static pressure leading edge stagnation points and reduces the size of the low static pressure wake
 * Friction Drag – is due to viscosity and is a retarding force. Turbulent flow creates more friction drag than laminar flow. It is reduced by making sure the plane’s surfaces are smooth. This is done by painting, cleaning, waxing or polishing, using flush rivets
 * Interference Drag – generated by the mixing of streamlines between one or more components. It can be minimized by proper fairing and filleting which allows the streamlines to meet gradually rather than abruptly
 * Equivalent Parasite Area (f) – a mathematically computed value equal to the area of a flat plate perpendicular to the relative wind that would produce the same amount of drag as form drag, friction drag and interference drag combined. It is NOT the cross sectional area of the plane. It varies directly with velocity squared
 * Induced Drag
 * Infinite Wing – ideal situation where the wing tip is against a wall and the relative wind is only flowing chordwise, creating lift
 * Upwash – the wind hits the leading edge and wants to take the shortest route around the leading edge. This results in some of the air that should of passed under the wing to flow up and over the leading edge. This increases lift because it increases the average angle of attack on the wing
 * Downwash – the air on top of the wing that flows down and under the trailing edge. It decreases lift by reducing the average AOA on the wing
 * For an infinite wing, the upwash exactly balances the downwash resulting in no net change in lift. Upwash and downwash exist anytime an airfoil produces lift
 * Finite Wing – Up and Downwash will not be equal. Once the air reaches the wingtips, it flows around it and the upper surface of the wing. There, it combines with the chordwise flow that has already produced lift and adds to the downwash. Downwash approximately doubles by this process to the spanwise airflow moving around the wingtip
 * Induced Drag – the portion of total drag associated with the production of lift.
 * Average Relative Wind – because downwash is twice as much as upwash on a finite wing, the relative wind will have a downward slant compared to the free airstream
 * Effective Lift – The perpendicular component of total lift. It is less than total lift because total lift is inclined
 * In level flight where lift is constant, induced drag varies inversely with velocity, and directly with the AOA
 * Total Drag – the combined total of parasite and induced drag
 * Lift to Drag Ratio – an airfoil produces lift, but will always have drag. An airfoil that produces more lift and less drag is desirable. The larger the ratio, the more efficient the air foil
 * L/DmaxAOA produces the minimum total drag. It is located at the bottom of the total drag curve and any movement away from this will increase drag
 * L/DmaxAOA parasite drag and induced drag are equal. At velocities below max, the planes is affected primarily by induced drag, while at higher velocities, parasite drag takes over
 * L/DmaxAOA produces the greatest ratio of lift to drag. This is not the maximum amount of lift!
 * L/DmaxAOA is the most efficient AOA. L/D is the efficiency of the wing not the engine!
 * An increase in weight or altitude will increase L/Dmax airspeed, but not affect L/Dmax or L/DmaxAOA. A change in configuration may have a large effect on L/Dmax and L/Dmax Airspeed. The effect of configuration on L/DmaxAOA will depend on what causes the change and how much change is produced

Fundamentals of Aerodynamics Chapter 6 – Thrust and Power

 * Thrust and Power Curves
 * Thrust Required – is the amount of thrust that is required to overcome drag and can be found on the total drag curve. It is expressed in pounds
 * Power Required – the rate of doing work. The amount of power that is required to produce thrust required
 * Thrust Available – the amount of thrust that the airplane’s engines are actually producing at a given throttle setting, velocity and density.
 * Power Available - the amount of power that an airplane’s engine is actually producing at a given throttle setting, velocity and density
 * Shaft Horse Power is the output of the engine.
 * Thrust Horse Power is propeller output or the horsepower that is converted to thrust by the propeller
 * Propeller Efficiency is the ability of the propeller to turn engine output into thrust
 * The T-34 has a constant-speed, variable-pitch propeller. Propeller efficiency will decrease as altitude increases. As the air density decreases, the blade angle will increase so that the prop takes a bigger bite of air to maintain a constant 2200rpms. This is much more efficient than a fixed prop
 * Thrust Excess – occurs if thrust available is greater than thrust required at a particular velocity