Warm-Up – 9/23 – 10 minutes Utilizing your notes and past knowledge answer the following questions: What is the axis of flight that runs from the nose tip to the tail of the aircraft? Describes what happens to an aircraft when the CG moves rearward. When flaps are extended during takeoff, what do they provide to the aircraft? What are the two ways to steer an aircraft while on the ground? What instrument is used to display attitude?

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Warm-Up – 9/23 – 10 minutes Utilizing your notes and past knowledge answer the following questions: What is the axis of flight that runs from the nose tip to the tail of the aircraft? Describes what happens to an aircraft when the CG moves rearward. When flaps are extended during takeoff, what do they provide to the aircraft? What are the two ways to steer an aircraft while on the ground? What instrument is used to display attitude?

Lift and Basic Aerodynamics The longitudinal or roll axis extends through the aircraft from nose to tail, with the line passing through the CG.

Warm-Up – 9/23 – 10 minutes Utilizing your notes and past knowledge answer the following questions: What is the axis of flight that runs from the nose tip to the tail of the aircraft? Describes what happens to an aircraft when the CG moves rearward. When flaps are extended during takeoff, what do they provide to the aircraft? What are the two ways to steer an aircraft while on the ground? What instrument is used to display attitude?

Lift and Basic Aerodynamics The position of the CG of an aircraft determines the stability of the aircraft in flight. As the CG moves rearward (towards the tail) the aircraft becomes more and more dynamically unstable.

Warm-Up – 9/23 – 10 minutes Utilizing your notes and past knowledge answer the following questions: What is the axis of flight that runs from the nose tip to the tail of the aircraft? Describes what happens to an aircraft when the CG moves rearward. When flaps are extended during takeoff, what do they provide to the aircraft? What are the two ways to steer an aircraft while on the ground? What instrument is used to display attitude?

Major Components Wings The flaps are normally flush with the wing’s surface during cruising flight. When extended, the flaps move simultaneously downward to increase the lifting force of the wing for takeoffs and landings.

Warm-Up – 9/23 – 10 minutes Utilizing your notes and past knowledge answer the following questions: What is the axis of flight that runs from the nose tip to the tail of the aircraft? Describes what happens to an aircraft when the CG moves rearward. When flaps are extended during takeoff, what do they provide to the aircraft? What are the two ways to steer an aircraft while on the ground? What instrument is used to display attitude?

Major Components Landing Gear Most aircraft are steered by moving the rudder pedals, whether nosewheel or tailwheel. Additionally, some aircraft are steered by using differential braking (alternating the application of brakes on one side then the other).

Warm-Up – 9/23 – 10 minutes Utilizing your notes and past knowledge answer the following questions: What is the axis of flight that runs from the nose tip to the tail of the aircraft? Describes what happens to an aircraft when the CG moves rearward. When flaps are extended during takeoff, what do they provide to the aircraft? What are the two ways to steer an aircraft while on the ground? What instrument is used to display attitude?

Instrumentation: Control The control instruments display immediate attitude and power changes, and are calibrated to permit adjustments in precise increments. The instrument for attitude display is the attitude indicator.

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THIS DAY IN AVIATION September 23 1910 — Peruvian Georges Chavez, who flies over the Simplon Pass between Italy and Switzerland, makes the first airplane flight over the Alps.

THIS DAY IN AVIATION September 23 1911 — Earl Ovington carries the first airmail in the United States in a Blériot monoplane from Nassau Boulevard Aerodome, Long Island to Mineola, Long Island.

THIS DAY IN AVIATION September 23 1913 — French pilot, Roland Garros, becomes the first person to fly across the Mediterranean, a distance of 470 miles. He lands in Tunisia 7 hours and 53 minutes after taking off from France, which is of particular note because he only had enough fuel for 8 hours of flight.

THIS DAY IN AVIATION September 23 1921 — Day and night of bombardment tests resulted in sinking of the battleship USS Alabama.

THIS DAY IN AVIATION September 23 1928 — Eleven over 23 entrants finish in Los Angeles-Cincinnati Air Derby. Robert A. Drake wins Class A Race in American Moth plane (American Cirrus), Charles W. Holman wins Class B Race in Laird (Wright Whirlwind), and Arthur Goebel wins the non-stop race in a Lockheed Vega (Pratt & Whitney Wasp), his time 15 hours 17 minutes 30 seconds.

THIS DAY IN AVIATION September 23 1934 — The Gordon Bennett Balloon Race is won by F. Hynek and W. Pomaski of Poland, traveling 826.77 miles from Warsaw to Anna, Russia.

THIS DAY IN AVIATION September 25 1903 — The Wright brothers arrive at Kitty Hawk, North Carolina to begin tests of their first powered aircraft.

THIS DAY IN AVIATION September 25 1918 - Capt. Eddie Rickenbacker, 94th Aero squadron, attacks seven enemy aircraft, shooting down two and is awarded the first Medal of Honor given for air activity.

THIS DAY IN AVIATION September 27 1913 — Katherine Stinson becomes the first woman in the United States to make an official airmail flight.

THIS DAY IN AVIATION September 27 1922 — Dr. Albert Taylor and Leo Young, scientists at the US Naval Aircraft Radio Laboratory, make the first successful detections of objects by “radio observation.” They use wireless waves to detect objects not visible due to weather or darkness. This insight leads to the advent of radar.

THIS DAY IN AVIATION September 27 1956 — The first piloted airplane to exceed Mach 3 is the rocket-powered Bell X-2.

THIS DAY IN AVIATION September 27 1991 — SAC forces stand down from Alert status.

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Chapter 3 – Principles of Flight FAA – Pilot’s Handbook of Aeronautical Knowledge

Today’s Mission Requirements Identify in writing the fundamental physical laws governing the forces acting on an aircraft in flight. Describe in writing the effect these natural laws and forces have on the performance characteristics of an aircraft. Describe in writing the means a pilot must understand the principles involved and learn to use or counteract these natural forces. EQ: Describe the importance of Aeronautical Knowledge for the student pilot learning to fly.

Sporty’ s Learn to Fly

Introduction To control an aircraft, be it an airplane, helicopter, glider, or balloon, the pilot must understand the principles involved and learn to use or counteract these natural forces.

Today’s Mission Requirements Discuss the layers of the atmosphere, its composition and height. Describe the atmospheric properties of pressure, temperature, and density EQ: Explain the basics of aeronautics and aerodynamics.

Airdynamics

The Realm of Flight The science of aerodynamics involves the study of airflow around an aircraft, passage of air through a jet engine and even the thrust of energy from a rocket motor.

The Realm of Flight The layers of the atmosphere: Troposphere, stratosphere, mesosphere, thermosphere, and exosphere The atmosphere is a mixture of gases 79% nitrogen 21% oxygen 1% of other gases The atmosphere extends to about 100 miles (approx. 528,000 ft)

Pressure Top layer of atmosphere has less pressure Pressure is greatest at Earth’s surface Pressure decreases with increase in altitude “Standard Pressure” is 14.7 psi or 29.92 inches

Temperature Temperature is a measure of energy The hotter the air, the more energy it has inside and the faster the molecules move around. Temperature decreases approx 3 ½ degrees for every 1,000 ft increase in altitude Decrease occurs up to about 38,000 ft

Density Density of air means how many molecules are squeezed into a given volume. Higher density air is squeezed more tightly than lower density air. Cool day at sea level, air is dense – aircraft perform very well.

Density Air at higher altitudes has less pressure – it is also less dense. Density is also related to temperature. As air is heated, the molecules move farther apart Which means there is a decrease in density On a hot day, aircraft in high altitudes have difficulty taking off – air is too thin

Structure of the Atmosphere The atmosphere is composed of 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases, such as argon or helium.

Structure of the Atmosphere The heavier elements, such as oxygen, settle to the surface of the Earth, while the lighter elements are lifted up to the region of higher altitude. Most of the atmosphere’s oxygen is contained below 35,000 feet altitude.

Atmospheric Pressure Pilots are mainly concerned with atmospheric pressure.

Atmospheric Pressure It is one of the basic factors in weather changes, helps to lift an aircraft, and actuates some of the important flight instruments.

Atmospheric Pressure These instruments are the altimeter, airspeed indicator, vertical speed indicator, and manifold pressure gauge.

Atmospheric Pressure Air is very light, but it has mass and is affected by the attraction of gravity. It has weight It has force It is a fluid substance Its effect on bodies within the air is called pressure.

Atmospheric Pressure Under standard conditions at sea level, the average pressure exerted by the weight of the atmosphere is approximately 14.70 pounds per square inch (psi) of surface, or 1,013.2 millibars (mb).

Atmospheric Pressure The standard atmosphere at sea level is: temperature of 59 °F or 15 °C surface pressure of 29.92 inches of mercury

Atmospheric Pressure A standard temperature lapse rate is one in which the temperature decreases at the rate of approximately 3.5 °F or 2 °C per thousand feet up to 36,000 feet which is approximately -65 °F or -55 °C.

Atmospheric Pressure Since aircraft performance is compared and evaluated with respect to the standard atmosphere, all aircraft instruments are calibrated for the standard atmosphere.

Pressure Altitude Pressure altitude is 29.92 "Hg as measured by a barometer. An altimeter is essentially a sensitive barometer calibrated to indicate altitude in the standard atmosphere.

Pressure Altitude Pressure altitude is important as a basis for determining airplane performance

Pressure Altitude The pressure altitude can be determined by either of two methods: 1. Setting the barometric scale of the altimeter to 29.92 and reading the indicated altitude. 2. Applying a correction factor to the indicated altitude according to the reported altimeter setting.

Density Altitude Aircraft operate in a nonstandard atmosphere and the term density altitude is used for correlating aerodynamic performance in the nonstandard atmosphere.

Density Altitude The density of air has significant effects on the aircraft’s performance because as air becomes less dense, it reduces: • Power because the engine takes in less air. • Thrust because a propeller is less efficient in thin air. • Lift because the thin air exerts less force on the airfoils.

Density Altitude As the density of the air increases (lower density altitude), aircraft performance increases and conversely as air density decreases (higher density altitude), aircraft performance decreases. A decrease in air density means a high density altitude; an increase in air density means a lower density altitude.

Density Altitude Density altitude is used in calculating aircraft performance.

Density Altitude A known density occurs for any one temperature and pressure altitude.

Density Altitude The density of the air has a pronounced effect on aircraft and engine performance.

Density Altitude Regardless of the actual altitude at which the aircraft is operating, it will perform as though it were operating at an altitude equal to the existing density altitude.

Density Altitude Air density is affected by changes in altitude, temperature, and humidity. High density altitude refers to thin air while low density altitude refers to dense air.

Density Altitude The conditions that result in a high density altitude are high elevations, low atmospheric pressures, high temperatures, high humidity, or some combination of these factors.

Density Altitude Lower elevations, high atmospheric pressure, low temperatures, and low humidity are more indicative of low density altitude.

Density Altitude Effect of Pressure on Density When air is compressed, a greater amount of air can occupy a given volume. Conversely, when pressure on a given volume of air is decreased, the air expands and occupies a greater space.

Density Altitude Effect of Pressure on Density If the pressure is doubled, the density is doubled; if the pressure is lowered, the density is lowered. This is true only at a constant temperature.

Density Altitude Effect of Temperature on Density The density of air varies inversely with temperature. This is true only at a constant pressure.

Density Altitude Effect of Temperature on Density In the atmosphere, both temperature and pressure decrease with altitude, and have conflicting effects upon density. Pilots can expect the density to decrease with altitude.

Density Altitude Effect of Humidity on Density Humidity may become an important factor in the performance of an aircraft. Water vapor is lighter than air; consequently, moist air is lighter than dry air.

Density Altitude Effect of Humidity on Density As the water content of the air increases, the air becomes less dense, increasing density altitude and decreasing performance.

Density Altitude Effect of Humidity on Density Humidity, also called relative humidity, refers to the amount of water vapor contained in the atmosphere, and is expressed as a percentage of the maximum amount of water vapor the air can hold.

Density Altitude Effect of Humidity on Density This amount varies with temperature. Warm air holds more water vapor, while colder air holds less.

Density Altitude Effect of Humidity on Density Perfectly dry air has a relative humidity of zero percent Saturated air, which cannot hold any more water vapor, has a relative humidity of 100 percent.

Airfoil Design Notice that there is a difference in the curvatures (called cambers) of the upper and lower surfaces of the airfoil.

Airfoil Design The camber of the upper surface is more pronounced than that of the lower surface, which is usually somewhat flat.

Airfoil Design The chord line is a straight line drawn through the profile connecting the extremities of the leading and trailing edges.

Airfoil Design The distance from this chord line to the upper and lower surfaces of the wing denotes the magnitude of the upper and lower camber at any point.

Airfoil Design The mean camber line is equidistant at all points from the upper and lower surfaces.

Airfoil Design An airfoil is constructed in such a way that its shape takes advantage of the air’s response to certain physical laws.

Airfoil Design This develops two actions from the air mass: a positive pressure lifting action from the air mass below the wing, and a negative pressure lifting action from lowered pressure above the wing.

Airfoil Design If a wing is constructed in such a form that it causes a lift force greater than the weight of the aircraft, the aircraft will fly.

Airfoil Design Different airfoils have different flight characteristics.

Airfoil Design No one airfoil has been found that satisfies every flight requirement. The weight, speed, and purpose of each aircraft dictate the shape of its airfoil.

Airfoil Design The most efficient airfoil for producing the greatest lift is one that has a concave, or “scooped out” lower surface.

Airfoil Design As a fixed design, this type of airfoil sacrifices too much speed while producing lift and is not suitable for high-speed flight.

Airfoil Design Advancements in engineering have made it possible for today’s high-speed jets to take advantage of the concave airfoil’s high lift characteristics.

Airfoil Design Leading edge (Kreuger) flaps and trailing edge (Fowler) flaps, when extended from the basic wing structure, literally change the airfoil shape into the classic concave form, thereby generating much greater lift during slow flight conditions.

Airfoil Design An airfoil that is perfectly streamlined and offers little wind resistance sometimes does not have enough lifting power to take the airplane off the ground.

Airfoil Design Thus, modern airplanes have airfoils that strike a medium between extremes in design. The shape varies according to the needs of the airplane for which it is designed.

Breaking the Speed of Sound

Viscosity Fluid’s resistance to flow Honey is more viscous than water. The greater the density of air, the greater the resistance Viscous drag happens when an object is placed in the path of moving air.

Laminar Flow The flow pattern around a moving object is either smooth or turbulent. The smooth, and more desirable flow is called laminar. Laminar flow is given careful consideration when designing new aircraft.

The Speed of Sound in Air Sound waves travel like ripples in water. Sound travels in all directions.

The Speed of Sound in Air Austrian physicist Ernst Mach determined the mathematical value for the speed of sound Speed of sound varies with altitude because temperature decreases with an increase in height Chuck Yeager in the X-1 broke the speed of sound Oct 14, 1947

Airfoil – Designs that Capture the Energy of the Wind Leading Edge meets relative wind first Camber can be either positive or negative Trailing edge is at the rear of the wing

Airfoil – Designs that Capture the Energy of the Wind Chord is an imaginary line that connects the leading with the trailing edge The Relative Wind is opposite the flight path Angle of Attack Is the angle between the chord line and the oncoming relative wind

A Third Dimension The high-pressure area on the bottom of an airfoil pushes around the tip to the low-pressure area on the top. This action creates a rotating flow called a tip vortex

A Third Dimension The vortex flows behind the airfoil creating a downwash that extends back to the trailing edge of the airfoil. This downwash results in an overall reduction in lift for the affected portion of the airfoil.

A Third Dimension To counteract this action. Winglets can be added to the tip of an airfoil to reduce this flow. The winglets act as a dam preventing the vortex from forming. Winglets can be on the top or bottom of the airfoil.

A Third Dimension Another method of countering the flow is to taper the airfoil tip, reducing the pressure differential and smoothing the airflow around the tip.

How Wings Work

Aerodynamics Aerodynamics concerns the motion of air and other gaseous fluids and other forces acting on objects in motion through the air (gases). In effect, Aerodynamics is concerned with the object (aircraft), the movement (Relative Wind), and the air (Atmosphere).

Newton’s Laws of Motion Newton's three laws of motion are: Inertia - A body at rest will remain at rest. and a body in motion will remain in motion at the same speed and direction until affected by some external force. Nothing starts or stops without an outside force to bring about or prevent motion. Hence, the force with which a body offers resistance to change is called the force of inertia.

Newton’s Laws of Motion Newton's three laws of motion are: Acceleration - The force required to produce a change in motion of a body is directly proportional to its mass and the rate of change in its velocity. Acceleration refers either to an increase or a decrease in velocity, although Deceleration is commonly used to indicate a decrease.

Newton’s Laws of Motion Newton's three laws of motion are: Action / Reaction - For every action there is an equal and opposite reaction. If an interaction occurs between two bodies, equal forces in opposite directions will be imparted to each body.

Who is Daniel Bernoulli? Dutch-born physicist – born in 1738 Discovered a relationship between the pressure and speed of a fluid in motion Specifically – as velocity of a fluid increases, the pressure decreases

Who is Daniel Bernoulli? For Lift to occur - The pressure on top of the airfoil must be less than the pressure below. The airfoil has no choice but to move upward.

Who is Daniel Bernoulli? Camber determines the amount of lift an airfoil will produce at a given speed The thicker or more pronounced the camber – the more lift. At low speeds its best to have a high-lift airfoil.

Summary Modern general aviation aircraft have what may be considered high performance characteristics. Therefore, it is increasingly necessary that pilots appreciate and understand the principles upon which the art of flying is based.

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Questions / Comments