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AVAF 209 Structures II III. Basic Aerodynamics A. B. C. D. E. F. 7/20/2015 The Atmosphere Physics The Airfoil Lift & Drag Stability Large Aircraft Flight Controls 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 7/20/2015 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 7/20/2015 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.) 7/20/2015 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 7/20/2015 Author: Harry L. Whitehead 5 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY CONDITIONS •International Civil Aeronautics Organization (ICAO) has set standards for test data 7/20/2015 Author: Harry L. Whitehead 6 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY CONDITIONS •Allows comparison of test data from one location or day to any other in world 7/20/2015 Author: Harry L. Whitehead 7 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 8 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 9 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 mmHg) 7/20/2015 Author: Harry L. Whitehead 10 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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) 7/20/2015 Author: Harry L. Whitehead 11 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 12 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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) 7/20/2015 Author: Harry L. Whitehead 13 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Pressure •PSI •Is a measurement of FORCE / AREA •The most common units are POUNDS PER SQUARE INCH 7/20/2015 Author: Harry L. Whitehead 14 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 15 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 16 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Pressure •PSI •Is measured by an Absolute scale and is labeled PSIA 7/20/2015 Author: Harry L. Whitehead 17 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Pressure •Or a GAUGE scale which uses Atmospheric Pressure as the zero reference (= PSIG) 7/20/2015 Author: Harry L. Whitehead 18 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 19 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Temperature •Four scales used: •Celsius (used to be Centigrade) 7/20/2015 Author: Harry L. Whitehead 20 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Temperature •Four scales used: •Kelvin (Absolute Celsius) 7/20/2015 Author: Harry L. Whitehead 21 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Temperature •Four scales used: •Fahrenheit 7/20/2015 Author: Harry L. Whitehead 22 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Temperature •Four scales used: •Rankine (Absolute Fahrenheit) 7/20/2015 Author: Harry L. Whitehead 23 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Temperature •Standard Day at Sea Level: •15o Celsius •59o Fahrenheit •2880 Kelvin •519o Rankine 7/20/2015 Author: Harry L. Whitehead 24 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 25 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 %) 7/20/2015 Author: Harry L. Whitehead 26 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Humidity •Standard Day is 0% humidity or Dry Air 7/20/2015 Author: Harry L. Whitehead 27 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 28 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 ( ) •Is a major factor in developing Lift •Varies directly with Atmospheric Pressure and inversely with Temperature 7/20/2015 Author: Harry L. Whitehead 29 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Aviation uses DENSITY ALTITUDE as important measure of density affects on flying 7/20/2015 Author: Harry L. Whitehead 30 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Is a measure of an aircraft’s performance (necessary takeoff distance, necessary landing distance, weight-carrying capability, etc.) 7/20/2015 Author: Harry L. Whitehead 31 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 32 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Computed using a Density Altitude Chart •Must know PRESSURE ALTITUDE and Ambient Temperature 7/20/2015 Author: Harry L. Whitehead 33 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Pressure Altitude is altitude in the Standard Day whose atmospheric pressure matches the local atmospheric pressure 7/20/2015 Author: Harry L. Whitehead 34 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Press. Alt. Example: •Ambient pressure of 28.92 in-Hg •Since pressure decreases 1 inHg/1000 feet, Pressure Altitude = 1,000 feet ASL 7/20/2015 Author: Harry L. Whitehead 35 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 36 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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. 7/20/2015 Author: Harry L. Whitehead 37 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Pressure = 25.92 in-Hg (= ? feet Pressure Altitude) •= 4,000 feet •Temperature = 80o F 7/20/2015 Author: Harry L. Whitehead 38 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Dens. Alt. Example: •Density Altitude = 6,500 feet 6,500 7/20/2015 Author: Harry L. Whitehead 39 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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% 7/20/2015 Author: Harry L. Whitehead 40 Basic Aerodynamics The Atmosphere III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •STANDARD DAY •Density Altitude •Generally speaking: BEWARE OF HIGH, HOT AND HUMID CONDITIONS 7/20/2015 Author: Harry L. Whitehead 41 Basic Aerodynamics Laws of Physics which affect Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •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 7/20/2015 Author: Harry L. Whitehead 42 Basic Aerodynamics Laws of Physics which affect Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Bernoulli's Principle •Kinetic energy is measured as Velocity •Potential energy is measured as Pressure 7/20/2015 Author: Harry L. Whitehead 43 Basic Aerodynamics Laws of Physics which affect Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Bernoulli's Principle •In “throat” of venturi: •Velocity goes up so all air gets through in same time = pressure down 7/20/2015 Author: Harry L. Whitehead 44 Basic Aerodynamics Laws of Physics which affect Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •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. 7/20/2015 Author: Harry L. Whitehead 45 Basic Aerodynamics Laws of Physics which affect Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •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 7/20/2015 Author: Harry L. Whitehead 46 Basic Aerodynamics Laws of Physics which affect Aerodynamics III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Newton’s Laws •Third Law •Law of Reaction •For every Action there is an Equal and Opposite Reaction 7/20/2015 Author: Harry L. Whitehead 47 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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) 7/20/2015 Author: Harry L. Whitehead 48 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Flight Forces •In order to understand these forces, we need to look at VECTORS: 7/20/2015 Author: Harry L. Whitehead 49 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Flight Forces •A Vector is an arrow whose length shows a value and it points in the direction the value is being applied 7/20/2015 Author: Harry L. Whitehead 50 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Flight Forces •To combine vectors, we place them with their starting points joined (as on the left below) 7/20/2015 Author: Harry L. Whitehead 51 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Flight Forces •And by COMPLETING THE SQUARE we can get the RESULTANT vector (the combination of the other two) 7/20/2015 Author: Harry L. Whitehead 52 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 53 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 55 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Flight Forces •In order to go faster (Accelerate), we must increase the Thrust vector to get a Resultant forward •Etc. 7/20/2015 Author: Harry L. Whitehead 56 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 57 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 58 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 59 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •There are many basic airfoil shapes 7/20/2015 Author: Harry L. Whitehead 60 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 61 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 •Supersonic airfoils were designed with sharp Leading and Trailing edges and the max thickness about ½ of the chord distance Author: Harry L. Whitehead 62 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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” 7/20/2015 Author: Harry L. Whitehead 63 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •This is defined as the angle between the CHORD and the RELATIVE WIND (= opposite the FLIGHT PATH) 7/20/2015 Author: Harry L. Whitehead 64 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •Don’t confuse this with the ANGLE OF INCIDENCE •The angle formed between the Chord and the Longitudinal Axis of the airplane 7/20/2015 Author: Harry L. Whitehead 65 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •If the is positive = the Leading Edge is higher than the Trailing Edge = generate Lift in the Upward direction •Negative = downward Lift 7/20/2015 Author: Harry L. Whitehead 66 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •As the increases, the amount of Lift also increases Airfoil simulation 7/20/2015 Author: Harry L. Whitehead 67 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •This can be shown graphically using the COEFFICIENT OF LIFT or CL 7/20/2015 Author: Harry L. Whitehead 68 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •Notice the CL is positive even to a small negative 7/20/2015 Author: Harry L. Whitehead 69 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •And the CL peaks at some positive 7/20/2015 Author: Harry L. Whitehead 70 Basic Aerodynamics The Airfoil III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •Also, the CL starts to drop off if the gets higher •This is called a STALL and starts at CLmax or CRITICAL 7/20/2015 Author: Harry L. Whitehead 71 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •Stall is a SEPARATION OF AIRFLOW from the upper wing surface = rapid decrease in lift 7/20/2015 Author: Harry L. Whitehead 72 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •This occurs at the same regardless of speed, aircraft weight, or flight attitude 7/20/2015 Author: Harry L. Whitehead 73 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •In order to generate Lift, an Airfoil must have an ANGLE OF ATTACK () •To eliminate this condition = reduce the below critical 7/20/2015 Author: Harry L. Whitehead 74 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 75 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Other Factors Affecting Lift: •Wing Planform •View of the wing from above or below 7/20/2015 Author: Harry L. Whitehead 76 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Other Factors Affecting Lift: •Wing Planform •Rectangular: excellent slow flight and stall occurs first at root of wing (= good aileron control) 7/20/2015 Author: Harry L. Whitehead 77 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 78 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 79 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Other Factors Affecting Lift: •Wing Planform •SweptBack (and Delta): Good efficiency at high speed but not very good at low 7/20/2015 Author: Harry L. Whitehead 80 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 •Trailing Edge Flaps use this to allow more lift at a slower airspeed for landing and takeoff Airfoil simulation 7/20/2015 Author: Harry L. Whitehead 81 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 82 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 83 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 84 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 () 7/20/2015 Author: Harry L. Whitehead 85 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Induced Drag •As 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 7/20/2015 Author: Harry L. Whitehead 86 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 87 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 88 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Induced Drag •This effect can also be reduced by installing TIP TANKS on the tips of the wings 7/20/2015 Author: Harry L. Whitehead 89 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 90 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 () and increases as increases 7/20/2015 Author: Harry L. Whitehead 91 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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) 7/20/2015 Author: Harry L. Whitehead 92 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Angle of Attack and Drag •Peak L/D (L/Dmax) occurs at a given which is the most efficient for the airfoil to operate at 7/20/2015 Author: Harry L. Whitehead 93 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Angle of Attack and Drag •Unfortunately, this may be at too low an to generate enough lift to fly (may not be able to fly fast enough) 7/20/2015 Author: Harry L. Whitehead 94 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 95 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 96 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 97 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 98 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 99 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Parasite Drag •Combined Parasite Drag Airspeed Effect •Parasite Drag increases exponentially as airspeed increases •IS LOWEST AT LOW AIRSPEEDS and increases rapidly 7/20/2015 Author: Harry L. Whitehead 100 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 101 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Total Drag •Induced Drag is also somewhat dependent on Airspeed (indirectly) •Since it is Inversely Proportional to and since the is highest at low airspeeds = Induced Drag is highest at low airspeeds and drops off rapidly 7/20/2015 Author: Harry L. Whitehead 102 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 103 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 curve, it may not be possible to operate at this airspeed 7/20/2015 Author: Harry L. Whitehead 104 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 105 Basic Aerodynamics Lift and Drag •Load Factor •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 Author: III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls Harry L. Whitehead 106 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 107 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 108 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 109 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 110 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 111 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Load Factor •For an ACROBATIC CATEGORY airplane = 6 positive Gs and 3 negative Gs 7/20/2015 Author: Harry L. Whitehead 112 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 113 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Propeller Factors: Gyroscopic Precession •A rotating Propeller also acts like a GYROSCOPE and exhibits two gyroscopic characteristics: •RIGIDITY IN SPACE •PRECESSION 7/20/2015 Author: Harry L. Whitehead 115 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 116 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 117 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 118 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 119 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Propeller Factors: Asymmetrical Thrust •The side of the prop “disk” on which the prop blade is descending has a higher than the ascending blade = more lift •NOTE: rotation is clockwise as viewed from the pilot’s seat 7/20/2015 Author: Harry L. Whitehead 120 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Propeller Factors: Asymmetrical Thrust •This change in comes from the vertical movement and a corresponding change in Relative Wind of the airfoil 7/20/2015 Author: Harry L. Whitehead 121 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Propeller Factors: Asymmetrical Thrust •Since the airfoil (prop) is rotating in addition to flying, the Relative Wind is now made of two factors: 7/20/2015 Author: Harry L. Whitehead 122 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Propeller Factors: Asymmetrical Thrust •The Flight Path vector and a vertical (rotation) vector •Descending blade (right side) = vertical vector is down 7/20/2015 Author: Harry L. Whitehead 123 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Propeller Factors: Asymmetrical Thrust •Which gives us a new Relative Wind and a higher 7/20/2015 Author: Harry L. Whitehead 124 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls •Propeller Factors: Asymmetrical Thrust •Since the descending (right) side of the prop has a higher 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 7/20/2015 Author: Harry L. Whitehead 125 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 126 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 127 Basic Aerodynamics Lift and Drag III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight 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 7/20/2015 Author: Harry L. Whitehead 128 Basic Aerodynamics 7/20/2015 III. Basic Aerodynamics A. The Atmosphere B. Physics C. The Airfoil D. Lift & Drag E. Stability F. Large Aircraft Flight Controls Author: Harry L. Whitehead 129