Theory of Flight

• Boundary Layer

  • Very thin layer of air lying over the surface of the wing

  • Includes laminar and turbulent flow, which are separated by the transition point

• Laminar flow

  • Smooth airflow over the wing

  • Initial portion until the boundary layer is tripped at the transition point

  • Laminar flow airfoils reduce the drag by maintaining the laminar flow throughout a greater percentage of the chord

• Conventional Airfoils

  • Thickest airfoils are generally thickest at 25% of the chord

• Aspect ratio

  • Dividing span by the average chord

• Wash in vs wash out

  • Wash in: increasing the angle of incidence at the wing tip relative to the wing root

  • Wash out: decreasing the angle of incidence at the wing tip

• Wing tip modifications designed to increase lift or reduce drag

  • Wing tip fuel tanks

  • Winglets

  • Drooping wing tips

• Slots and slats

  • Slots: auxiliary airfoils that remain fixed on the leading edge

  • Slats: auxiliary airfoils that move out in front of the leading edge at high angles of attack

• Camber

  • Curvature of the airfoil

Instruments

• Pitot static system

  • Pitot static system

    • Connected to the airspeed indicator, altimeter and vertical speed indicator

    • Includes a pitot pressure source and static pressure source

      • Pitot tube measures ram air pressure, or dynamic pressure, by the air rushing in due to the forward movement of the aircraft

      • Static port measures the differences in atmospheric pressure, and are not affected by ram air pressure

    • All instruments are connected to the static pressure source, where only the airspeed indicator is attached to the pitot tube

• Airspeed Indicator errors

  • Density Error

    • Density of air depends on atmospheric pressure and temperature

    • These variables affect the air speed indicator reading as it changes the pressure differential between components within the airspeed indicator

  • Position Error

    • Depends on location of pitot tube on the aircraft

    • Farther back on the aircraft, it may receive more eddies and give a less accurate reading, where as at the front of the aircraft it is in more smooth, laminar flow

  • Lag Error

    • Mechanical error due to friction between working parts

  • Icing or Water Error

    • Blocks the pitot or static pressure sources

• Airspeeds

  • Indicated

    • What is read off the airspeed dial

  • Calibrated

    • Indicated corrected for instrument error

  • Equivalent

    • Calibrated corrected for compressibility factor

  • True

    • Equivalent corrected for the airspeed indicator error due to density and the temperature

    • Actual speed of the airplane through the air mass

  • Mnemonic to remember airspeeds: ICE Tea is a Pretty Cool Drink

    • Moves in a zig zag pattern from I to P to C, and so on to show the different airspeeds (top row) and the factor (bottom row) that changes it to the next airspeed

I C E T

P       C       D

• Density altitude

  • Pressure altitude corrected for temperature

• Precession

  • Tendency of a rotating body, when a force is applied perpendicular to its plane of rotation, to turn in the direction of its rotation 90 degrees to its axis and take up a new plane of rotation parallel to the force applied.

• Mach number

  • Mach number is calculated by dividing the airspeed by the speed of sound

Engine

• Fuel selector valve

  • Use to select desired fuel tank to draw fuel from

  • Use to shut off the flow of fuel from the tanks

• Throttle

  • Forward movement opens the throttle valve, which increases the fuel to air mixture and increases the power being produced by the engine

• Gauges

  • Oil Pressure Gauge

    • Indicates oil pressure supplied by the oil pump to lubricate the engine

  • Oil Temperature Gauge

    • Gives a reading of the temperature of the oil

  • Cylinder Head Temperature Gauge

    • Records the temperature of one or more of the engine cylinder heads

    • Gives a reasonably good indication of the effectiveness of the engine cooling system

  • Carburetor Air Temperature Gauge

    • Indicates temperature of the mixture entering the manifold

    • Or may record temperature of the intake air entering the carburetor

  • Tachometer

    • Shows the speed at which the engine crankshaft is turning in hundreds of revolutions per minute

    • Arcs:

      • Green – good

      • Yellow – caution range

      • Red – danger range

  • Manifold Pressure Gauge

    • Settings are controlled by the throttle

    • Indicates the pressure of the fuel to air mixture in the engine intake manifold between the cylinders and the carburetor

• Pitch

  • Distance a propeller travels forward in one revolution

• Thrust is maintained throughout most of the diameter of the propeller by means of the variation in airfoil sections and the angle of attack

• Increase in Altitude

  • Air becomes less dense so power decreases without corrective action by the pilot

Meteorology

• Surface friction on winds

  • Causes lower wind speeds than would be expected from the pressure gradient

  • Slows down the wind speed due to contact resistance with the ground

• Define air mass

  • Large section of the troposphere with uniform properties of temperature, moisture within the horizontal.

• Anabatic and katabatic winds

  • Anabatic: up slope winds flowing from valleys up the slopes to higher elevations

  • Katabatic: down slope winds flowing from high elevation down to the valleys below

  • Mnemonic: Ana ran up the hill and kicked the cat down

• Gust

  • Rapid and irregular change of wind speed

• Main factors determining weather in an airmass

  • Moisture content

  • Cooling process

  • Stability of the air

• Stable air conditions

  • Stratus clouds

  • Poor visibility

  • Steady precipitation

• Unstable air conditions

  • Cumuloform clouds

  • Good visibility

  • Showering precipitation

• Cold Air Mass

  • More dense so sinks

  • Undercuts warmer air where will ascend over the colder air

Navigation

• Great Circle

  • Shortest distance between two points on the surface of the earth

• Rhumb Line

  • Lines that cuts all meridians at the same angle

  • Allows for constant direction so that the navigator may have a constant heading

• TVMDC Headings

  • Variation is the angle between true and magnetic headings

  • Deviation is the angle between magnetic and compass headings

  • Moving from T -> M -> C add west and subtract east (east is least, west is best)

• Isogonal Line

  • Lines drawn joining places having the same variation

• Agonic Line

  • Joining places of zero variation

• Compass Lead and Lag

  • ANDS – acceleration causes turns to the north, deceleration causes turns to the south

  • Occurs on east and west headings

• Meridians of Longitude

  • Semi-great circles joining the geographical poles of the earth

  • Measured 0 to 180 degrees east and west

• Parallels of Latitude

  • Circles in the Earth’s surface that lie parallel to the equator

  • Measured 0 to 90 degrees north and south of the equator