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AVAF 209 Structures II III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls 09/25/14 Author: Harry L. Whitehead 1
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls Aerodynamics: The study of objects in motion through the air and the forces that produce or change such motion 09/25/14 Author: Harry L. Whitehead 2
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls The Atmosphere •In order to fly, we need to create an upward force equal to the weight of the aircraft by using the Atmosphere •This force comes from the action of the atmosphere on an airfoil 09/25/14 Author: Harry L. Whitehead 3
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls The Atmosphere •Is made of a mixture of gases •21% Oxygen •78% Nitrogen •Rest is mix of inert gases (Argon, Neon, etc.) 09/25/14 Author: Harry L. Whitehead 4
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls The Atmosphere •Mixture remains constant regardless of altitude •Weight of air changes as altitude changes •Less weight above as we go up = less ATMOSPHERIC PRESSURE exerted on objects 09/25/14 Author: Harry L. Whitehead 5
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY CONDITIONS •International Civil Aeronautics Organization (ICAO) has set standards for test data 09/25/14 Author: Harry L. Whitehead 6
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY CONDITIONS •Allows comparison of test data from one location or day to any other in world 09/25/14 Author: Harry L. Whitehead 7
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Is a force created by the weight of the atmosphere above an object •Is measured in IN-HG, MM-HG, PSI, or MILLIBARS 09/25/14 Author: Harry L. Whitehead 8
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •In-Hg or mm-Hg •A tube is filled with Mercury (Hg) and then inverted in a container of Mercury •Hg will rise and height is measured 09/25/14 Author: Harry L. Whitehead 9
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •In-Hg or mm-Hg •On a Standard Day at SEA LEVEL (zero altitude), the height will be 29.92 inches 29.92 in-Hg) or 760 millimeters (760 mm- Hg) 09/25/14 Author: Harry L. Whitehead 10
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •In-Hg or mm-Hg •This is called an ABSOLUTE SCALE measurement as a VACUUM will form in the top of the tube (= ABSOLUTE ZERO PRESSURE) 09/25/14 Author: Harry L. Whitehead 11
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Atmospheric pressure will decrease by approx. 1 in-Hg for every 1,000 feet increase in altitude •Known as the LAPSE RATE 09/25/14 Author: Harry L. Whitehead 12
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •An ALTIMETER measures absolute pressure and displays the result in Feet Above Sea Level (ASL) •Notice KOLLSMAN WINDOW (adjust to varying local conditions) 09/25/14 Author: Harry L. Whitehead 13
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •Is a measurement of FORCE / AREA •The most common units are POUNDS PER SQUARE INCH 09/25/14 Author: Harry L. Whitehead 14
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •On a Standard Day at Sea Level, the atmosphere pushes on objects with a force of 14.69 pounds per square inch of area 09/25/14 Author: Harry L. Whitehead 15
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •Since ½ of the air in the atmosphere is below 18,000 feet ASL, the pressure there is 7.34 psi 09/25/14 Author: Harry L. Whitehead 16
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •Is measured by an Absolute scale and is labeled PSIA 09/25/14 Author: Harry L. Whitehead 17
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Or a GAUGE scale which uses Atmospheric Pressure as the zero reference (= PSIG) 09/25/14 Author: Harry L. Whitehead 18
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Millibars •Are used by Meteorologists (weather forecasters) •Standard Day at Sea Level is 1013.2 mbs •1 millibar approximately equals .75 in-Hg 09/25/14 Author: Harry L. Whitehead 19
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Celsius (used to be Centigrade) 09/25/14 Author: Harry L. Whitehead 20
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Kelvin (Absolute Celsius) 09/25/14 Author: Harry L. Whitehead 21
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Fahrenheit 09/25/14 Author: Harry L. Whitehead 22
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Rankine (Absolute Fahrenheit) 09/25/14 Author: Harry L. Whitehead 23
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Standard Day at Sea Level: •15o Celsius •59o Fahrenheit •2880 Kelvin •519o Rankine 09/25/14 Author: Harry L. Whitehead 24
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •As we go up in altitude, temperature goes down •3.54o F or 2o C per 1,000 feet •ADIABATIC LAPSE RATE 09/25/14 Author: Harry L. Whitehead 25
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Humidity •Is amount of moisture in air •Measured by RELATIVE HUMIDITY •Is comparison of moisture present to amount air can hold in percent •Maximum amount is directly proportional to temperature (hotter temp. = more moisture at same Relative Humidity %) 09/25/14 Author: Harry L. Whitehead 26
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Humidity •Standard Day is 0% humidity or Dry Air 09/25/14 Author: Harry L. Whitehead 27
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density •Is measure of Mass per unit Volume •Mass is the amount of matter in an object •Can think of it as number of molecules •Weight is the affect of Gravity on a mass •Since we are dealing with objects near the surface of the Earth, Weight and Mass are used interchangeably in Aerodynamics 09/25/14 Author: Harry L. Whitehead 28
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density •Air density is officially measured in SLUGS PER CUBIC FOOT •Standard Day at Sea Level = .002378 slugs/ft3 •Formula symbol is the Greek letter Rho ( r ) •Is a major factor in developing Lift •Varies directly with Atmospheric Pressure and inversely with Temperature 09/25/14 Author: Harry L. Whitehead 29
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Aviation uses DENSITY ALTITUDE as important measure of density affects on flying 09/25/14 Author: Harry L. Whitehead 30
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Is a measure of an aircraft’s performance (necessary takeoff distance, necessary landing distance, weight-carrying capability, etc.) 09/25/14 Author: Harry L. Whitehead 31
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •“The altitude in a Standard Day that has the same density as the Ambient conditions.” •Is the altitude the aircraft thinks it’s at 09/25/14 Author: Harry L. Whitehead 32
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Computed using a Density Altitude Chart •Must know PRESSURE ALTITUDE and Ambient Temperature 09/25/14 Author: Harry L. Whitehead 33
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Pressure Altitude is altitude in the Standard Day whose atmospheric pressure matches the local atmospheric pressure 09/25/14 Author: Harry L. Whitehead 34
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Press. Alt. Example: •Ambient pressure of 28.92 in-Hg •Since pressure decreases 1 in- Hg/1000 feet, Pressure Altitude = 1,000 feet ASL 09/25/14 Author: Harry L. Whitehead 35
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Pressure Altitude can also be determined for the location you are by adjusting the Kollsman window to 29.92 and reading the altitude 09/25/14 Author: Harry L. Whitehead 36
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Pressure = 25.92 in-Hg (= ? feet Pressure Altitude) •= 4,000 feet •SL (29.92) – actual (25.92) = 4 inches x 1000 ft. 09/25/14 Author: Harry L. Whitehead 37
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Pressure = 25.92 in-Hg (= ? feet Pressure Altitude) •= 4,000 feet •Temperature = 80o F 09/25/14 Author: Harry L. Whitehead 38
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Density Altitude = 6,500 feet 6,500 09/25/14 Author: Harry L. Whitehead 39
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Also is affected by the Relative Humidity •Water vapor has about 62% of weight of air = higher humidity = less dense air = higher Density Altitude •= only affected by about 5% 09/25/14 Author: Harry L. Whitehead 40
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Generally speaking: BEWARE OF HIGH, HOT AND HUMID CONDITIONS 09/25/14 Author: Harry L. Whitehead 41
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Bernoulli's Principle •“If the total energy of flowing air remains constant, any increase in KINETIC energy creates a decrease in POTENTIAL energy” •Since the LAW OF CONSERVATION OF ENERGY applies, the energies in the flow are only changed 09/25/14 Author: Harry L. Whitehead 42
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Bernoulli's Principle •Kinetic energy is measured as Velocity •Potential energy is measured as Pressure 09/25/14 Author: Harry L. Whitehead 43
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Bernoulli's Principle •In “throat” of venturi: •Velocity goes up so all air gets through in same time = pressure down 09/25/14 Author: Harry L. Whitehead 44
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Newton’s Laws •First Law: •Law of Inertia •A body at rest tends to remain at rest and a body in motion tends to remain in motion, until acted upon by an outside force. 09/25/14 Author: Harry L. Whitehead 45
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Newton’s Laws •Second Law: •Law of Acceleration •Acceleration of a body is directly proportional to the force applied and inversely proportional to the mass of the body or a = F / m •Or more useful to us: F = ma 09/25/14 Author: Harry L. Whitehead 46
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Newton’s Laws •Third Law •Law of Reaction •For every Action there is an Equal and Opposite Reaction 09/25/14 Author: Harry L. Whitehead 47
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •As we looked at before, there are four forces being applied to an airplane in flight: •Lift (up) •Weight (down) •Thrust (forward) •Drag (aft) 09/25/14 Author: Harry L. Whitehead 48
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In order to understand these forces, we need to look at VECTORS: 09/25/14 Author: Harry L. Whitehead 49
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •A Vector is an arrow whose length shows a value and it points in the direction the value is being applied 09/25/14 Author: Harry L. Whitehead 50
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •To combine vectors, we place them with their starting points joined (as on the left below) 09/25/14 Author: Harry L. Whitehead 51
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •And by COMPLETING THE SQUARE we can get the RESULTANT vector (the combination of the other two) 09/25/14 Author: Harry L. Whitehead 52
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •If two forces are exactly opposing each other (such as Lift and Weight) and have the same value, the resultant is zero 09/25/14 Author: Harry L. Whitehead 53
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In STRAIGHT AND LEVEL, UNACCELERATED FLIGHT, Thrust and Drag are equal, Lift and Weight are equal, and the aircraft continues in a straight line with no change in altitude •The forces are said to be in EQUILIBRIUM Author: Harry L. Whitehead 54
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In order to climb, we must increase the Lift Vector so there is no longer an equilibrium between Lift and Weight •The Resultant of the two is an upward force 09/25/14 Author: Harry L. Whitehead 55
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In order to go faster (Accelerate), we must increase the Thrust vector to get a Resultant forward •Etc. 09/25/14 Author: Harry L. Whitehead 56
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •Thrust is created by the POWERPLANT and PROPELLER •Weight is the effect of Gravity on the aircraft •Drag is created by movement of the aircraft •Lift is created by the Airfoils used as Wings 09/25/14 Author: Harry L. Whitehead 57
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •An Airfoil is a specially designed surface which produces a reaction to air flowing across it •Two theories: •Bernoulli’s Principle •Newton’s Laws 09/25/14 Author: Harry L. Whitehead 58
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Subsonic airfoils can be Asymmetrical or Symmetrical •Most airplanes use Asymmetrical wings •Blunt, rounded LEADING EDGE •Max. thickness about 1/3 of distance from L.E. to TRAILING EDGE 09/25/14 Author: Harry L. Whitehead 59
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes 09/25/14 Author: Harry L. Whitehead 60
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes •Early were very thin with definite camber •The Clark-Y was the standard through the 1930s •NACA developed the “modern” asymmetrical shape in the 30s and it was used for decades = smoother airflow and greater lift with less drag 09/25/14 Author: Harry L. Whitehead 61
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes •As aircraft started to get near Mach 1, the subsonic shapes caused shock waves to form and destroy lift and increase drag tremendously •Supersonic airfoils were designed with sharp Leading and Trailing edges and the max thickness about ½ of the chord distance 09/25/14 Author: Harry L. Whitehead 62
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes •Next came the Supercritical design •Reduces the velocity of the air over the upper surface and delays the drag rise occurring with the approach of Mach 1 •NASA developed the GAW series for General Aviation aircraft and give higher lift with lesser drag than the “modern” 09/25/14 Author: Harry L. Whitehead 63
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •This is defined as the angle between the CHORD and the RELATIVE WIND (= opposite the FLIGHT PATH) 09/25/14 Author: Harry L. Whitehead 64
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Don’t confuse this with the ANGLE OF INCIDENCE •The angle formed between the Chord and the Longitudinal Axis of the airplane 09/25/14 Author: Harry L. Whitehead 65
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •If the a is positive = the Leading Edge is higher than the Trailing Edge = generate Lift in the Upward direction •Negative a = downward Lift 09/25/14 Author: Harry L. Whitehead 66
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •As the a increases, the amount of Lift also increases Airfoil simulation 09/25/14 Author: Harry L. Whitehead 67
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •This can be shown graphically using the COEFFICIENT OF LIFT or CL 09/25/14 Author: Harry L. Whitehead 68
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Notice the CL is positive even to a small negative a 09/25/14 Author: Harry L. Whitehead 69
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •And the CL peaks at some positive a 09/25/14 Author: Harry L. Whitehead 70
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Also, the CL starts to drop off if the a gets higher •This is called a STALL and starts at CLmax or CRITICAL a 09/25/14 Author: Harry L. Whitehead 71
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Stall is a SEPARATION OF AIRFLOW from the upper wing surface = rapid decrease in lift 09/25/14 Author: Harry L. Whitehead 72
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •This occurs at the same a regardless of speed, aircraft weight, or flight attitude 09/25/14 Author: Harry L. Whitehead 73
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •To eliminate this condition = reduce the a below critical 09/25/14 Author: Harry L. Whitehead 74
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Airspeed •Faster = increased Lift •Lift is increased as the square of the speed •For example: •At 200 mph a wing has 4 times the lift of the same airfoil at 100 mph •At 50 mph the lift is ¼ as much as at 100 mph Airfoil simulation 09/25/14 Author: Harry L. Whitehead 75
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •View of the wing from above or below 09/25/14 Author: Harry L. Whitehead 76
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •Rectangular: excellent slow flight and stall occurs first at root of wing (= good aileron control) 09/25/14 Author: Harry L. Whitehead 77
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •Elliptical: most efficient = least drag for given size but difficult to manufacture and stalls all along Trail. Edge 09/25/14 Author: Harry L. Whitehead 78
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •Modified (or Moderate) Tapered: more efficient than Rectangular and easier to build than Elliptical but still stalls along Trailing Edge 09/25/14 Author: Harry L. Whitehead 79
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •SweptBack (and Delta): Good efficiency at high speed but not very good at low 09/25/14 Author: Harry L. Whitehead 80
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Camber •Curve of the wing •Increased Camber = increased airflow velocity over the top surface and more downwash angle = more lift •It also tends to lower the Critical a •Trailing Edge Flaps use this to allow more lift at a slower airspeed for landing and takeoff Airfoil simulation 09/25/14 Author: Harry L. Whitehead 81
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Aspect Ratio •Is the Ratio of the Wing’s SPAN to the average Chord •Higher Aspect Ratio (“long and skinny”) = increased lift and lower stalling speed •Used on Gliders and TR-1 spy plane 09/25/14 Author: Harry L. Whitehead 82
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Area •Is the total surface area of the wings •Must be sufficient to lift max weight of the aircraft •If wing produces 10.5 pounds of lift per square foot at normal cruise speed = needs Wing Area of 200 square feet to lift 2,100 pounds of weight Airfoil simulation 09/25/14 Author: Harry L. Whitehead 83
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Drag •Is the force opposing Thrust •Is the force trying to hold the aircraft back as it flies and generally limits the maximum airspeed •Is created by any aircraft surface that deflects or interferes with the smooth air flow around the aircraft •Drag is classified as two types: •Induced •Parasite 09/25/14 Author: Harry L. Whitehead 84
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •The Airfoil shape (type of airfoil and amount of Camber) and Wing Area create a force which comes from the same forces as those which create Lift •It is Directly Proportional to the Angle of Attack (a) 09/25/14 Author: Harry L. Whitehead 85
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •As a increases, the high pressure on the bottom of the wing flows around the wing tips and “fills in” some of the low pressure on top •This creates a WINGTIP VORTEX and destroys some of the wing’s lift or increases its drag 09/25/14 Author: Harry L. Whitehead 86
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •The strength of the Vortex is proportional to aircraft speed, weight, and configuration •These can be dangerous for small aircraft flying behind a large aircraft 09/25/14 Author: Harry L. Whitehead 87
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •This effect can be reduced by installing WINGLETS on the tips of the wings •Reduce the Vortex = increased lift and reduced drag 09/25/14 Author: Harry L. Whitehead 88
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •This effect can also be reduced by installing TIP TANKS on the tips of the wings 09/25/14 Author: Harry L. Whitehead 89
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •And/or by installing DROOPED TIPS •Used on STOL (Short Take Off/ Landing) aircraft or those designed for heavy and slow flight 09/25/14 Author: Harry L. Whitehead 90
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •This can also be shown by looking at the COEFFICIENT OF DRAG (CD) of the airfoil •CD is proportional to Angle of Attack (a) and increases as a increases 09/25/14 Author: Harry L. Whitehead 91
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Angle of Attack and Drag •By combining the CL and CD curves we get a “Family” of curves for any given airfoil •Includes a combination known as Lift-to-Drag Ratio (L/D) 09/25/14 Author: Harry L. Whitehead 92
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Angle of Attack and Drag •Peak L/D (L/Dmax) occurs at a given a which is the most efficient a for the airfoil to operate at 09/25/14 Author: Harry L. Whitehead 93
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Angle of Attack and Drag •Unfortunately, this may be at too low an a to generate enough lift to fly (may not be able to fly fast enough) 09/25/14 Author: Harry L. Whitehead 94
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Is the drag produced by the aircraft itself and is proportional to Airspeed •Is disruption of the airflow around the aircraft •4 types: •Form Drag •Skin Friction Drag •Interference Drag •Profile Drag 09/25/14 Author: Harry L. Whitehead 95
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Form Drag •Created by any structure which extends into the airstream •Is directly proportional to the size and shape of the structure •Includes struts, antennas, landing gear, etc. •Streamlining reduces Form Drag 09/25/14 Author: Harry L. Whitehead 96
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Skin Friction Drag •Caused by the roughness of the aircraft’s skin •Includes paint, rivets, skin seams, etc. •Causes small swirls (eddies) of air = drag •Improved by flush riveting and cleaning and waxing the skin 09/25/14 Author: Harry L. Whitehead 97
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Interference Drag •Occurs when various air currents around the aircraft structure intersect and interact with each other •Example: mixing of air where fuselage and wings meet •Improved by installing FAIRINGS 09/25/14 Author: Harry L. Whitehead 98
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Profile Drag •Drag formed by the Frontal Area of the aircraft •Can’t be changed or affected by anything except Retractable Landing Gear 09/25/14 Author: Harry L. Whitehead 99
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Combined Parasite Drag Airspeed Effect •Parasite Drag increases exponentially as airspeed increases •IS LOWEST AT LOW AIRSPEEDS and increases rapidly 09/25/14 Author: Harry L. Whitehead 100
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Can best be reduced by Retractable Landing Gear & streamlining •Weight and complication is more than compensated by decrease in Parasite Drag at higher airspeeds 09/25/14 Author: Harry L. Whitehead 101
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Total Drag •Induced Drag is also somewhat dependent on Airspeed (indirectly) •Since it is Inversely Proportional to a and since the a is highest at low airspeeds = Induced Drag is highest at low airspeeds and drops off rapidly 09/25/14 Author: Harry L. Whitehead 102
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Total Drag •By combining the two Drag curves, we get Total Drag •At low airspeeds, Induced Drag predominates so curve goes down •At higher airspeeds, Parasite Drag predominates so curve goes up 09/25/14 Author: Harry L. Whitehead 103
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Total Drag •At some airspeed it will be at its lowest value = most efficient airspeed to fly at = best Lift/Drag Ratio or L/Dmax •However, like L/Dmax when looking at the a curve, it may not be possible to operate at this airspeed 09/25/14 Author: Harry L. Whitehead 104
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Design Considerations •Other factors affect the structure and design of an aircraft while in flight besides just Lift and Drag •These are: •Load Factor •Propeller Factors •Engine Torque •Gyroscopic Precession •Asymmetrical Thrust •Spiraling Slipstream 09/25/14 Author: Harry L. Whitehead 105
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor Author: Harry L. Whitehead 106 •Load Factor is a function of Banking an aircraft •You can also think of it as creating a curved flight path = CENTRIFUGAL FORCE puts more downward force (LOAD) on the structure
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •So in order to maintain altitude = need to pull back on the yoke or stick and increase the engine’s power to increase the overall Lift component 09/25/14 Author: Harry L. Whitehead 107
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •Load Factor is the Ratio of the load supported by the wings to the actual weight of the aircraft •Below about 20o Bank Angle it is equal to 1G in force •= the weight is not being increased 09/25/14 Author: Harry L. Whitehead 108
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •As the Bank Angle increases above that the “G-force” also goes up exponentially •For example: at about 60o of Bank, the Load Factor is 2 •The wings feel the aircraft weighs twice as much as normal 09/25/14 Author: Harry L. Whitehead 109
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •The FAA establishes LIMIT LOAD FACTORS for airplanes to be designed to •= the maximum Load Factor the aircraft can withstand without permanent deformation or structural damage 09/25/14 Author: Harry L. Whitehead 110
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •For a NORMAL CATEGORY airplane = 3.8 positive Gs and 1.52 negative Gs •For a UTILITY CATEGORY = 4.4 positive Gs and 1.76 negative Gs 09/25/14 Author: Harry L. Whitehead 111
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •For an ACROBATIC CATEGORY airplane = 6 positive Gs and 3 negative Gs 09/25/14 Author: Harry L. Whitehead 112
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Torque •Torque is a force applied to the airplane from the Reaction to the spinning Propeller (Newton’s 3rd Law) •It causes a roll to the left = opposite of the normal rotation of U.S. designed engines 09/25/14 Author: Harry L. Whitehead 113
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Torque •On single-engine airplanes, it’s common to use aileron trim tabs to compensate • On multi-engine airplanes, it’s common for the engines to rotate in opposite directions which cancels out the Torque Effect Author: Harry L. Whitehead 114
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •A rotating Propeller also acts like a GYROSCOPE and exhibits two gyroscopic characteristics: •RIGIDITY IN SPACE •PRECESSION 09/25/14 Author: Harry L. Whitehead 115
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •Precession is the phenomenon which says that any force applied to a Gyroscope is felt 90o later in direction of rotation 09/25/14 Author: Harry L. Whitehead 116
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •Any rapid change in aircraft pitch = a precessive force applied to the prop. •Most commonly felt by Conventional Gear airplanes just prior to Takeoff when the tail wheel is raised 09/25/14 Author: Harry L. Whitehead 117
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •This causes a downward force (action) applied to the prop •Which causes a reaction 90o later = yaw to the left 09/25/14 Author: Harry L. Whitehead 118
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •At high aircraft angles of attack and during rapid climbs, the prop blades see differing angles of attack during their rotation 09/25/14 Author: Harry L. Whitehead 119
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •The side of the prop “disk” on which the prop blade is descending has a higher a than the ascending blade = more lift •NOTE: rotation is clockwise as viewed from the pilot’s seat 09/25/14 Author: Harry L. Whitehead 120
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •This change in a comes from the vertical movement and a corresponding change in Relative Wind of the airfoil 09/25/14 Author: Harry L. Whitehead 121
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •Since the airfoil (prop) is rotating in addition to flying, the Relative Wind is now made of two factors: 09/25/14 Author: Harry L. Whitehead 122
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •The Flight Path vector and a vertical (rotation) vector •Descending blade (right side) = vertical vector is down 09/25/14 Author: Harry L. Whitehead 123
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •Which gives us a new Relative Wind and a higher a 09/25/14 Author: Harry L. Whitehead 124
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •Since the descending (right) side of the prop has a higher a it is also producing more Thrust •The opposite occurs on the ascending side and it produces less Thrust • = tendency to yaw to left in rapid climb 09/25/14 Author: Harry L. Whitehead 125
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Spiraling Slipstream •On a single-engine airplane, the SLIPSTREAM from the propeller “wraps” itself around the fuselage in a Spiraling manner •It will generally then strike the left side of the Vertical Stabilizer and cause a yaw to the left 09/25/14 Author: Harry L. Whitehead 126
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Spiraling Slipstream •Since this is a function of how much air the prop is pushing which is directly proportional to the Thrust being produced = more yaw at higher power settings 09/25/14 Author: Harry L. Whitehead 127
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Spiraling Slipstream •It’s not uncommon to find the Vertical Stabilizer installed with a slight offset to the left to cause a constant compensating force •This is usually set up to balance the Slipstream affect during Cruise flight 09/25/14 Author: Harry L. Whitehead 128
Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls 09/25/14 Author: Harry L. Whitehead 129

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Basicaerodynamics tostability-091209082823-phpapp01

  • 1. AVAF 209 Structures II III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls 09/25/14 Author: Harry L. Whitehead 1
  • 2. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls Aerodynamics: The study of objects in motion through the air and the forces that produce or change such motion 09/25/14 Author: Harry L. Whitehead 2
  • 3. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls The Atmosphere •In order to fly, we need to create an upward force equal to the weight of the aircraft by using the Atmosphere •This force comes from the action of the atmosphere on an airfoil 09/25/14 Author: Harry L. Whitehead 3
  • 4. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls The Atmosphere •Is made of a mixture of gases •21% Oxygen •78% Nitrogen •Rest is mix of inert gases (Argon, Neon, etc.) 09/25/14 Author: Harry L. Whitehead 4
  • 5. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls The Atmosphere •Mixture remains constant regardless of altitude •Weight of air changes as altitude changes •Less weight above as we go up = less ATMOSPHERIC PRESSURE exerted on objects 09/25/14 Author: Harry L. Whitehead 5
  • 6. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY CONDITIONS •International Civil Aeronautics Organization (ICAO) has set standards for test data 09/25/14 Author: Harry L. Whitehead 6
  • 7. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY CONDITIONS •Allows comparison of test data from one location or day to any other in world 09/25/14 Author: Harry L. Whitehead 7
  • 8. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Is a force created by the weight of the atmosphere above an object •Is measured in IN-HG, MM-HG, PSI, or MILLIBARS 09/25/14 Author: Harry L. Whitehead 8
  • 9. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •In-Hg or mm-Hg •A tube is filled with Mercury (Hg) and then inverted in a container of Mercury •Hg will rise and height is measured 09/25/14 Author: Harry L. Whitehead 9
  • 10. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •In-Hg or mm-Hg •On a Standard Day at SEA LEVEL (zero altitude), the height will be 29.92 inches 29.92 in-Hg) or 760 millimeters (760 mm- Hg) 09/25/14 Author: Harry L. Whitehead 10
  • 11. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •In-Hg or mm-Hg •This is called an ABSOLUTE SCALE measurement as a VACUUM will form in the top of the tube (= ABSOLUTE ZERO PRESSURE) 09/25/14 Author: Harry L. Whitehead 11
  • 12. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Atmospheric pressure will decrease by approx. 1 in-Hg for every 1,000 feet increase in altitude •Known as the LAPSE RATE 09/25/14 Author: Harry L. Whitehead 12
  • 13. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •An ALTIMETER measures absolute pressure and displays the result in Feet Above Sea Level (ASL) •Notice KOLLSMAN WINDOW (adjust to varying local conditions) 09/25/14 Author: Harry L. Whitehead 13
  • 14. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •Is a measurement of FORCE / AREA •The most common units are POUNDS PER SQUARE INCH 09/25/14 Author: Harry L. Whitehead 14
  • 15. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •On a Standard Day at Sea Level, the atmosphere pushes on objects with a force of 14.69 pounds per square inch of area 09/25/14 Author: Harry L. Whitehead 15
  • 16. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •Since ½ of the air in the atmosphere is below 18,000 feet ASL, the pressure there is 7.34 psi 09/25/14 Author: Harry L. Whitehead 16
  • 17. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •PSI •Is measured by an Absolute scale and is labeled PSIA 09/25/14 Author: Harry L. Whitehead 17
  • 18. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Or a GAUGE scale which uses Atmospheric Pressure as the zero reference (= PSIG) 09/25/14 Author: Harry L. Whitehead 18
  • 19. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Pressure •Millibars •Are used by Meteorologists (weather forecasters) •Standard Day at Sea Level is 1013.2 mbs •1 millibar approximately equals .75 in-Hg 09/25/14 Author: Harry L. Whitehead 19
  • 20. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Celsius (used to be Centigrade) 09/25/14 Author: Harry L. Whitehead 20
  • 21. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Kelvin (Absolute Celsius) 09/25/14 Author: Harry L. Whitehead 21
  • 22. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Fahrenheit 09/25/14 Author: Harry L. Whitehead 22
  • 23. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Four scales used: •Rankine (Absolute Fahrenheit) 09/25/14 Author: Harry L. Whitehead 23
  • 24. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •Standard Day at Sea Level: •15o Celsius •59o Fahrenheit •2880 Kelvin •519o Rankine 09/25/14 Author: Harry L. Whitehead 24
  • 25. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Temperature •As we go up in altitude, temperature goes down •3.54o F or 2o C per 1,000 feet •ADIABATIC LAPSE RATE 09/25/14 Author: Harry L. Whitehead 25
  • 26. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Humidity •Is amount of moisture in air •Measured by RELATIVE HUMIDITY •Is comparison of moisture present to amount air can hold in percent •Maximum amount is directly proportional to temperature (hotter temp. = more moisture at same Relative Humidity %) 09/25/14 Author: Harry L. Whitehead 26
  • 27. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Humidity •Standard Day is 0% humidity or Dry Air 09/25/14 Author: Harry L. Whitehead 27
  • 28. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density •Is measure of Mass per unit Volume •Mass is the amount of matter in an object •Can think of it as number of molecules •Weight is the affect of Gravity on a mass •Since we are dealing with objects near the surface of the Earth, Weight and Mass are used interchangeably in Aerodynamics 09/25/14 Author: Harry L. Whitehead 28
  • 29. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density •Air density is officially measured in SLUGS PER CUBIC FOOT •Standard Day at Sea Level = .002378 slugs/ft3 •Formula symbol is the Greek letter Rho ( r ) •Is a major factor in developing Lift •Varies directly with Atmospheric Pressure and inversely with Temperature 09/25/14 Author: Harry L. Whitehead 29
  • 30. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Aviation uses DENSITY ALTITUDE as important measure of density affects on flying 09/25/14 Author: Harry L. Whitehead 30
  • 31. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Is a measure of an aircraft’s performance (necessary takeoff distance, necessary landing distance, weight-carrying capability, etc.) 09/25/14 Author: Harry L. Whitehead 31
  • 32. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •“The altitude in a Standard Day that has the same density as the Ambient conditions.” •Is the altitude the aircraft thinks it’s at 09/25/14 Author: Harry L. Whitehead 32
  • 33. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Computed using a Density Altitude Chart •Must know PRESSURE ALTITUDE and Ambient Temperature 09/25/14 Author: Harry L. Whitehead 33
  • 34. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Pressure Altitude is altitude in the Standard Day whose atmospheric pressure matches the local atmospheric pressure 09/25/14 Author: Harry L. Whitehead 34
  • 35. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Press. Alt. Example: •Ambient pressure of 28.92 in-Hg •Since pressure decreases 1 in- Hg/1000 feet, Pressure Altitude = 1,000 feet ASL 09/25/14 Author: Harry L. Whitehead 35
  • 36. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Pressure Altitude can also be determined for the location you are by adjusting the Kollsman window to 29.92 and reading the altitude 09/25/14 Author: Harry L. Whitehead 36
  • 37. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Pressure = 25.92 in-Hg (= ? feet Pressure Altitude) •= 4,000 feet •SL (29.92) – actual (25.92) = 4 inches x 1000 ft. 09/25/14 Author: Harry L. Whitehead 37
  • 38. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Pressure = 25.92 in-Hg (= ? feet Pressure Altitude) •= 4,000 feet •Temperature = 80o F 09/25/14 Author: Harry L. Whitehead 38
  • 39. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Density Altitude = 6,500 feet 6,500 09/25/14 Author: Harry L. Whitehead 39
  • 40. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Also is affected by the Relative Humidity •Water vapor has about 62% of weight of air = higher humidity = less dense air = higher Density Altitude •= only affected by about 5% 09/25/14 Author: Harry L. Whitehead 40
  • 41. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Atmosphere Controls •STANDARD DAY •Density Altitude •Generally speaking: BEWARE OF HIGH, HOT AND HUMID CONDITIONS 09/25/14 Author: Harry L. Whitehead 41
  • 42. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Bernoulli's Principle •“If the total energy of flowing air remains constant, any increase in KINETIC energy creates a decrease in POTENTIAL energy” •Since the LAW OF CONSERVATION OF ENERGY applies, the energies in the flow are only changed 09/25/14 Author: Harry L. Whitehead 42
  • 43. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Bernoulli's Principle •Kinetic energy is measured as Velocity •Potential energy is measured as Pressure 09/25/14 Author: Harry L. Whitehead 43
  • 44. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Bernoulli's Principle •In “throat” of venturi: •Velocity goes up so all air gets through in same time = pressure down 09/25/14 Author: Harry L. Whitehead 44
  • 45. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Newton’s Laws •First Law: •Law of Inertia •A body at rest tends to remain at rest and a body in motion tends to remain in motion, until acted upon by an outside force. 09/25/14 Author: Harry L. Whitehead 45
  • 46. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Newton’s Laws •Second Law: •Law of Acceleration •Acceleration of a body is directly proportional to the force applied and inversely proportional to the mass of the body or a = F / m •Or more useful to us: F = ma 09/25/14 Author: Harry L. Whitehead 46
  • 47. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Laws of Physics which affect Controls Aerodynamics •Newton’s Laws •Third Law •Law of Reaction •For every Action there is an Equal and Opposite Reaction 09/25/14 Author: Harry L. Whitehead 47
  • 48. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •As we looked at before, there are four forces being applied to an airplane in flight: •Lift (up) •Weight (down) •Thrust (forward) •Drag (aft) 09/25/14 Author: Harry L. Whitehead 48
  • 49. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In order to understand these forces, we need to look at VECTORS: 09/25/14 Author: Harry L. Whitehead 49
  • 50. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •A Vector is an arrow whose length shows a value and it points in the direction the value is being applied 09/25/14 Author: Harry L. Whitehead 50
  • 51. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •To combine vectors, we place them with their starting points joined (as on the left below) 09/25/14 Author: Harry L. Whitehead 51
  • 52. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •And by COMPLETING THE SQUARE we can get the RESULTANT vector (the combination of the other two) 09/25/14 Author: Harry L. Whitehead 52
  • 53. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •If two forces are exactly opposing each other (such as Lift and Weight) and have the same value, the resultant is zero 09/25/14 Author: Harry L. Whitehead 53
  • 54. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In STRAIGHT AND LEVEL, UNACCELERATED FLIGHT, Thrust and Drag are equal, Lift and Weight are equal, and the aircraft continues in a straight line with no change in altitude •The forces are said to be in EQUILIBRIUM Author: Harry L. Whitehead 54
  • 55. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In order to climb, we must increase the Lift Vector so there is no longer an equilibrium between Lift and Weight •The Resultant of the two is an upward force 09/25/14 Author: Harry L. Whitehead 55
  • 56. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •In order to go faster (Accelerate), we must increase the Thrust vector to get a Resultant forward •Etc. 09/25/14 Author: Harry L. Whitehead 56
  • 57. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Flight Forces •Thrust is created by the POWERPLANT and PROPELLER •Weight is the effect of Gravity on the aircraft •Drag is created by movement of the aircraft •Lift is created by the Airfoils used as Wings 09/25/14 Author: Harry L. Whitehead 57
  • 58. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •An Airfoil is a specially designed surface which produces a reaction to air flowing across it •Two theories: •Bernoulli’s Principle •Newton’s Laws 09/25/14 Author: Harry L. Whitehead 58
  • 59. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •Subsonic airfoils can be Asymmetrical or Symmetrical •Most airplanes use Asymmetrical wings •Blunt, rounded LEADING EDGE •Max. thickness about 1/3 of distance from L.E. to TRAILING EDGE 09/25/14 Author: Harry L. Whitehead 59
  • 60. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes 09/25/14 Author: Harry L. Whitehead 60
  • 61. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes •Early were very thin with definite camber •The Clark-Y was the standard through the 1930s •NACA developed the “modern” asymmetrical shape in the 30s and it was used for decades = smoother airflow and greater lift with less drag 09/25/14 Author: Harry L. Whitehead 61
  • 62. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes •As aircraft started to get near Mach 1, the subsonic shapes caused shock waves to form and destroy lift and increase drag tremendously •Supersonic airfoils were designed with sharp Leading and Trailing edges and the max thickness about ½ of the chord distance 09/25/14 Author: Harry L. Whitehead 62
  • 63. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •There are many basic airfoil shapes •Next came the Supercritical design •Reduces the velocity of the air over the upper surface and delays the drag rise occurring with the approach of Mach 1 •NASA developed the GAW series for General Aviation aircraft and give higher lift with lesser drag than the “modern” 09/25/14 Author: Harry L. Whitehead 63
  • 64. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •This is defined as the angle between the CHORD and the RELATIVE WIND (= opposite the FLIGHT PATH) 09/25/14 Author: Harry L. Whitehead 64
  • 65. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Don’t confuse this with the ANGLE OF INCIDENCE •The angle formed between the Chord and the Longitudinal Axis of the airplane 09/25/14 Author: Harry L. Whitehead 65
  • 66. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •If the a is positive = the Leading Edge is higher than the Trailing Edge = generate Lift in the Upward direction •Negative a = downward Lift 09/25/14 Author: Harry L. Whitehead 66
  • 67. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •As the a increases, the amount of Lift also increases Airfoil simulation 09/25/14 Author: Harry L. Whitehead 67
  • 68. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •This can be shown graphically using the COEFFICIENT OF LIFT or CL 09/25/14 Author: Harry L. Whitehead 68
  • 69. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Notice the CL is positive even to a small negative a 09/25/14 Author: Harry L. Whitehead 69
  • 70. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •And the CL peaks at some positive a 09/25/14 Author: Harry L. Whitehead 70
  • 71. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight The Airfoil Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Also, the CL starts to drop off if the a gets higher •This is called a STALL and starts at CLmax or CRITICAL a 09/25/14 Author: Harry L. Whitehead 71
  • 72. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •Stall is a SEPARATION OF AIRFLOW from the upper wing surface = rapid decrease in lift 09/25/14 Author: Harry L. Whitehead 72
  • 73. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •This occurs at the same a regardless of speed, aircraft weight, or flight attitude 09/25/14 Author: Harry L. Whitehead 73
  • 74. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK (a) •To eliminate this condition = reduce the a below critical 09/25/14 Author: Harry L. Whitehead 74
  • 75. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Airspeed •Faster = increased Lift •Lift is increased as the square of the speed •For example: •At 200 mph a wing has 4 times the lift of the same airfoil at 100 mph •At 50 mph the lift is ¼ as much as at 100 mph Airfoil simulation 09/25/14 Author: Harry L. Whitehead 75
  • 76. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •View of the wing from above or below 09/25/14 Author: Harry L. Whitehead 76
  • 77. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •Rectangular: excellent slow flight and stall occurs first at root of wing (= good aileron control) 09/25/14 Author: Harry L. Whitehead 77
  • 78. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •Elliptical: most efficient = least drag for given size but difficult to manufacture and stalls all along Trail. Edge 09/25/14 Author: Harry L. Whitehead 78
  • 79. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •Modified (or Moderate) Tapered: more efficient than Rectangular and easier to build than Elliptical but still stalls along Trailing Edge 09/25/14 Author: Harry L. Whitehead 79
  • 80. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Planform •SweptBack (and Delta): Good efficiency at high speed but not very good at low 09/25/14 Author: Harry L. Whitehead 80
  • 81. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Camber •Curve of the wing •Increased Camber = increased airflow velocity over the top surface and more downwash angle = more lift •It also tends to lower the Critical a •Trailing Edge Flaps use this to allow more lift at a slower airspeed for landing and takeoff Airfoil simulation 09/25/14 Author: Harry L. Whitehead 81
  • 82. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Aspect Ratio •Is the Ratio of the Wing’s SPAN to the average Chord •Higher Aspect Ratio (“long and skinny”) = increased lift and lower stalling speed •Used on Gliders and TR-1 spy plane 09/25/14 Author: Harry L. Whitehead 82
  • 83. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Factors Affecting Lift: •Wing Area •Is the total surface area of the wings •Must be sufficient to lift max weight of the aircraft •If wing produces 10.5 pounds of lift per square foot at normal cruise speed = needs Wing Area of 200 square feet to lift 2,100 pounds of weight Airfoil simulation 09/25/14 Author: Harry L. Whitehead 83
  • 84. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Drag •Is the force opposing Thrust •Is the force trying to hold the aircraft back as it flies and generally limits the maximum airspeed •Is created by any aircraft surface that deflects or interferes with the smooth air flow around the aircraft •Drag is classified as two types: •Induced •Parasite 09/25/14 Author: Harry L. Whitehead 84
  • 85. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •The Airfoil shape (type of airfoil and amount of Camber) and Wing Area create a force which comes from the same forces as those which create Lift •It is Directly Proportional to the Angle of Attack (a) 09/25/14 Author: Harry L. Whitehead 85
  • 86. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •As a increases, the high pressure on the bottom of the wing flows around the wing tips and “fills in” some of the low pressure on top •This creates a WINGTIP VORTEX and destroys some of the wing’s lift or increases its drag 09/25/14 Author: Harry L. Whitehead 86
  • 87. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •The strength of the Vortex is proportional to aircraft speed, weight, and configuration •These can be dangerous for small aircraft flying behind a large aircraft 09/25/14 Author: Harry L. Whitehead 87
  • 88. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •This effect can be reduced by installing WINGLETS on the tips of the wings •Reduce the Vortex = increased lift and reduced drag 09/25/14 Author: Harry L. Whitehead 88
  • 89. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •This effect can also be reduced by installing TIP TANKS on the tips of the wings 09/25/14 Author: Harry L. Whitehead 89
  • 90. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •And/or by installing DROOPED TIPS •Used on STOL (Short Take Off/ Landing) aircraft or those designed for heavy and slow flight 09/25/14 Author: Harry L. Whitehead 90
  • 91. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Induced Drag •This can also be shown by looking at the COEFFICIENT OF DRAG (CD) of the airfoil •CD is proportional to Angle of Attack (a) and increases as a increases 09/25/14 Author: Harry L. Whitehead 91
  • 92. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Angle of Attack and Drag •By combining the CL and CD curves we get a “Family” of curves for any given airfoil •Includes a combination known as Lift-to-Drag Ratio (L/D) 09/25/14 Author: Harry L. Whitehead 92
  • 93. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Angle of Attack and Drag •Peak L/D (L/Dmax) occurs at a given a which is the most efficient a for the airfoil to operate at 09/25/14 Author: Harry L. Whitehead 93
  • 94. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Angle of Attack and Drag •Unfortunately, this may be at too low an a to generate enough lift to fly (may not be able to fly fast enough) 09/25/14 Author: Harry L. Whitehead 94
  • 95. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Is the drag produced by the aircraft itself and is proportional to Airspeed •Is disruption of the airflow around the aircraft •4 types: •Form Drag •Skin Friction Drag •Interference Drag •Profile Drag 09/25/14 Author: Harry L. Whitehead 95
  • 96. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Form Drag •Created by any structure which extends into the airstream •Is directly proportional to the size and shape of the structure •Includes struts, antennas, landing gear, etc. •Streamlining reduces Form Drag 09/25/14 Author: Harry L. Whitehead 96
  • 97. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Skin Friction Drag •Caused by the roughness of the aircraft’s skin •Includes paint, rivets, skin seams, etc. •Causes small swirls (eddies) of air = drag •Improved by flush riveting and cleaning and waxing the skin 09/25/14 Author: Harry L. Whitehead 97
  • 98. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Interference Drag •Occurs when various air currents around the aircraft structure intersect and interact with each other •Example: mixing of air where fuselage and wings meet •Improved by installing FAIRINGS 09/25/14 Author: Harry L. Whitehead 98
  • 99. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Profile Drag •Drag formed by the Frontal Area of the aircraft •Can’t be changed or affected by anything except Retractable Landing Gear 09/25/14 Author: Harry L. Whitehead 99
  • 100. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Combined Parasite Drag Airspeed Effect •Parasite Drag increases exponentially as airspeed increases •IS LOWEST AT LOW AIRSPEEDS and increases rapidly 09/25/14 Author: Harry L. Whitehead 100
  • 101. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Parasite Drag •Can best be reduced by Retractable Landing Gear & streamlining •Weight and complication is more than compensated by decrease in Parasite Drag at higher airspeeds 09/25/14 Author: Harry L. Whitehead 101
  • 102. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Total Drag •Induced Drag is also somewhat dependent on Airspeed (indirectly) •Since it is Inversely Proportional to a and since the a is highest at low airspeeds = Induced Drag is highest at low airspeeds and drops off rapidly 09/25/14 Author: Harry L. Whitehead 102
  • 103. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Total Drag •By combining the two Drag curves, we get Total Drag •At low airspeeds, Induced Drag predominates so curve goes down •At higher airspeeds, Parasite Drag predominates so curve goes up 09/25/14 Author: Harry L. Whitehead 103
  • 104. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Total Drag •At some airspeed it will be at its lowest value = most efficient airspeed to fly at = best Lift/Drag Ratio or L/Dmax •However, like L/Dmax when looking at the a curve, it may not be possible to operate at this airspeed 09/25/14 Author: Harry L. Whitehead 104
  • 105. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Other Design Considerations •Other factors affect the structure and design of an aircraft while in flight besides just Lift and Drag •These are: •Load Factor •Propeller Factors •Engine Torque •Gyroscopic Precession •Asymmetrical Thrust •Spiraling Slipstream 09/25/14 Author: Harry L. Whitehead 105
  • 106. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor Author: Harry L. Whitehead 106 •Load Factor is a function of Banking an aircraft •You can also think of it as creating a curved flight path = CENTRIFUGAL FORCE puts more downward force (LOAD) on the structure
  • 107. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •So in order to maintain altitude = need to pull back on the yoke or stick and increase the engine’s power to increase the overall Lift component 09/25/14 Author: Harry L. Whitehead 107
  • 108. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •Load Factor is the Ratio of the load supported by the wings to the actual weight of the aircraft •Below about 20o Bank Angle it is equal to 1G in force •= the weight is not being increased 09/25/14 Author: Harry L. Whitehead 108
  • 109. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •As the Bank Angle increases above that the “G-force” also goes up exponentially •For example: at about 60o of Bank, the Load Factor is 2 •The wings feel the aircraft weighs twice as much as normal 09/25/14 Author: Harry L. Whitehead 109
  • 110. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •The FAA establishes LIMIT LOAD FACTORS for airplanes to be designed to •= the maximum Load Factor the aircraft can withstand without permanent deformation or structural damage 09/25/14 Author: Harry L. Whitehead 110
  • 111. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •For a NORMAL CATEGORY airplane = 3.8 positive Gs and 1.52 negative Gs •For a UTILITY CATEGORY = 4.4 positive Gs and 1.76 negative Gs 09/25/14 Author: Harry L. Whitehead 111
  • 112. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Load Factor •For an ACROBATIC CATEGORY airplane = 6 positive Gs and 3 negative Gs 09/25/14 Author: Harry L. Whitehead 112
  • 113. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Torque •Torque is a force applied to the airplane from the Reaction to the spinning Propeller (Newton’s 3rd Law) •It causes a roll to the left = opposite of the normal rotation of U.S. designed engines 09/25/14 Author: Harry L. Whitehead 113
  • 114. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Torque •On single-engine airplanes, it’s common to use aileron trim tabs to compensate • On multi-engine airplanes, it’s common for the engines to rotate in opposite directions which cancels out the Torque Effect Author: Harry L. Whitehead 114
  • 115. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •A rotating Propeller also acts like a GYROSCOPE and exhibits two gyroscopic characteristics: •RIGIDITY IN SPACE •PRECESSION 09/25/14 Author: Harry L. Whitehead 115
  • 116. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •Precession is the phenomenon which says that any force applied to a Gyroscope is felt 90o later in direction of rotation 09/25/14 Author: Harry L. Whitehead 116
  • 117. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •Any rapid change in aircraft pitch = a precessive force applied to the prop. •Most commonly felt by Conventional Gear airplanes just prior to Takeoff when the tail wheel is raised 09/25/14 Author: Harry L. Whitehead 117
  • 118. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Gyroscopic Precession •This causes a downward force (action) applied to the prop •Which causes a reaction 90o later = yaw to the left 09/25/14 Author: Harry L. Whitehead 118
  • 119. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •At high aircraft angles of attack and during rapid climbs, the prop blades see differing angles of attack during their rotation 09/25/14 Author: Harry L. Whitehead 119
  • 120. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •The side of the prop “disk” on which the prop blade is descending has a higher a than the ascending blade = more lift •NOTE: rotation is clockwise as viewed from the pilot’s seat 09/25/14 Author: Harry L. Whitehead 120
  • 121. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •This change in a comes from the vertical movement and a corresponding change in Relative Wind of the airfoil 09/25/14 Author: Harry L. Whitehead 121
  • 122. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •Since the airfoil (prop) is rotating in addition to flying, the Relative Wind is now made of two factors: 09/25/14 Author: Harry L. Whitehead 122
  • 123. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •The Flight Path vector and a vertical (rotation) vector •Descending blade (right side) = vertical vector is down 09/25/14 Author: Harry L. Whitehead 123
  • 124. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •Which gives us a new Relative Wind and a higher a 09/25/14 Author: Harry L. Whitehead 124
  • 125. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Asymmetrical Thrust •Since the descending (right) side of the prop has a higher a it is also producing more Thrust •The opposite occurs on the ascending side and it produces less Thrust • = tendency to yaw to left in rapid climb 09/25/14 Author: Harry L. Whitehead 125
  • 126. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Spiraling Slipstream •On a single-engine airplane, the SLIPSTREAM from the propeller “wraps” itself around the fuselage in a Spiraling manner •It will generally then strike the left side of the Vertical Stabilizer and cause a yaw to the left 09/25/14 Author: Harry L. Whitehead 126
  • 127. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Spiraling Slipstream •Since this is a function of how much air the prop is pushing which is directly proportional to the Thrust being produced = more yaw at higher power settings 09/25/14 Author: Harry L. Whitehead 127
  • 128. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Lift and Drag Controls •Propeller Factors: Spiraling Slipstream •It’s not uncommon to find the Vertical Stabilizer installed with a slight offset to the left to cause a constant compensating force •This is usually set up to balance the Slipstream affect during Cruise flight 09/25/14 Author: Harry L. Whitehead 128
  • 129. Basic Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls 09/25/14 Author: Harry L. Whitehead 129