The Physics of FlightThe Physics of Flight

Ancient DreamersAncient Dreamers Legends of flight attempts date to 2000 B.C.Legends of flight attempts date to 2000 B.C.

– Many believed flying was for the mythical godsMany believed flying was for the mythical gods– Others tried to copy bird flight-unsuccessfullyOthers tried to copy bird flight-unsuccessfully

Chinese invented kites about 1000 B.C.Chinese invented kites about 1000 B.C.– 1717thth century A.D. kites carried soldiers aloft century A.D. kites carried soldiers aloft

Leonardo da Vinci, 15Leonardo da Vinci, 15thth century Italian artist century Italian artist– First recorded scientific study of aeronauticsFirst recorded scientific study of aeronautics– Experimented to prove feasibility of mechanical Experimented to prove feasibility of mechanical

flightflight– Drew sketches and plans to construct flying Drew sketches and plans to construct flying

machinesmachines

Ancient DreamersAncient Dreamers

Leonardo da Leonardo da VinciVinci

Daedalis & IcarusDaedalis & Icarus

Italian artist and scientist Leonardo da Vinci (1452-1519) gathered data on the flight of birds and developed concepts of the propeller, the parachute, and heavier-than-air craft.

The Quest for FlightThe Quest for Flight

By 17th Century, ancient ideas inspired By 17th Century, ancient ideas inspired scientific theories and experimentsscientific theories and experiments

Characteristics of the atmosphere and the Characteristics of the atmosphere and the discovery of gasses and properties led to discovery of gasses and properties led to lighter-than-air balloon experimentslighter-than-air balloon experiments

Airships needed power and direction Airships needed power and direction controlcontrol

Glider flying increased the understanding Glider flying increased the understanding of flight forces, wing geometry & controlsof flight forces, wing geometry & controls

Definition: AerodynamicsDefinition: Aerodynamics

AerodynamicsAerodynamics is is a branch of fluid a branch of fluid mechanics that mechanics that deals with the deals with the motion of air and motion of air and other gaseous other gaseous fluids, and with the fluids, and with the forces acting on forces acting on bodies in motion bodies in motion relative to such relative to such fluidsfluids

Bernoulli’s Principle Bernoulli’s Principle According to Bernoulli’s Principle, as According to Bernoulli’s Principle, as

the velocity of a fluid increases the the velocity of a fluid increases the pressure exerted by the fluid pressure exerted by the fluid decreases. decreases.

Air Flow Past a WingAir Flow Past a Wing The air speed is greater over the upper The air speed is greater over the upper

surface, as indicated by the closer surface, as indicated by the closer streamlines, the air pressure is lower there streamlines, the air pressure is lower there and the wing is liftedand the wing is lifted

When the wing is angled upward, air deflected When the wing is angled upward, air deflected from its lower surface provides additional lift.from its lower surface provides additional lift.

If the angle is too great, turbulence reduces lift If the angle is too great, turbulence reduces lift and increases drag.and increases drag.

Powered Flight Powered Flight BreakthroughBreakthrough

Experiments showed basic ingredients Experiments showed basic ingredients of flight are: sufficient power, lift , of flight are: sufficient power, lift , controlcontrol

Wright’s successfully applied theories Wright’s successfully applied theories of lift and drag to practical use in of lift and drag to practical use in powered gliderspowered gliders

Progress (and a conventional designs) Progress (and a conventional designs) came with lighter materials and drag came with lighter materials and drag reductionreduction

BreakthroughBreakthrough

Sir Hiram MaximSir Hiram Maxim– power, lift, controlpower, lift, control

Wright brothersWright brothers Glen Curtiss Glen Curtiss

– Improved designs, Improved designs, promoted aviationpromoted aviation

December 17, 1903, near Kitty Hawk, North Carolina, Wilbur and Orville Wright made the world's first successful powered, free, controlled, sustained flights in a heavier-than-air craft.

The Main Events

World War IWorld War I

War speeds up War speeds up technology technology developmentdevelopment

Airplane speed, Airplane speed, loads increasedloads increased

Large Large manufacturing manufacturing base developedbase developed

Congressional medal of Honor winner Captain Eddie Rickenbacker went on to be a pioneer in civil aviation, too

The Main Events

After the WarAfter the War

Veteran pilots kept interest Veteran pilots kept interest alivealive

Commercial aviation Commercial aviation catches oncatches on

Dramatic design advancesDramatic design advances Beginning of rocket flightBeginning of rocket flight Invention of the jet engineInvention of the jet engine

Four Forces of FlightFour Forces of Flight

LiftLift WeightWeight ThrustThrust DragDrag

Source: NASA Glen Research Center

Forces on an AirplaneForces on an Airplane

LiftLift Lift is an aerodynamic forceLift is an aerodynamic force Lift must exceed weight for flightLift must exceed weight for flight Generated by motion of aircraft Generated by motion of aircraft

through airthrough air Created by the effects of airflow past Created by the effects of airflow past

wingwing The top of an airplane wing is

curved, so that air has to travel further to reach the trailing end of the wing.

Therefore, the air on the underside of the plane is exerting more pressure, causing the plane to lift.

WeightWeight

Weight is not constantWeight is not constant– varies with passengers, varies with passengers,

cargo, fuel loadcargo, fuel load– decreases as fuel is decreases as fuel is

consumed or payload off-consumed or payload off-loadedloaded

Direction is constant Direction is constant toward earth’s centertoward earth’s center

May be assumed May be assumed concentrated at the center concentrated at the center of gravityof gravity

DragDrag An aerodynamic forceAn aerodynamic force Drag is also called air resistance. the force that pulls the plane backward. Two broad drag classificationsTwo broad drag classifications

– Parasite drag: drag created by airplane Parasite drag: drag created by airplane designdesign

– Induced drag: by-product of lift generationInduced drag: by-product of lift generation Acts through the center of pressureActs through the center of pressure

ThrustThrust

Forward-acting force opposes dragForward-acting force opposes drag Direction of thrust depends on designDirection of thrust depends on design Propulsion systems produce thrustPropulsion systems produce thrust Equal to drag in straight, constant Equal to drag in straight, constant

speed flightspeed flight

StabilityStability

Center of GravityCenter of Gravity Center of PressureCenter of Pressure Longitudinal StabilityLongitudinal Stability Lateral StabilityLateral Stability Directional StabilityDirectional Stability

Definition: AeronauticsDefinition: Aeronautics

AeronauticsAeronautics is the is the design and design and construction of construction of

aircraft and aircraft and The theory and The theory and

practice of aircraft practice of aircraft navigationnavigation

Definition: Aerospace EngineeringDefinition: Aerospace Engineering

Aerospace Aerospace engineeringengineering is is closely allied to closely allied to aeronautics and aeronautics and aeronautical aeronautical engineering but engineering but

Includes the study Includes the study and development of and development of rocket engines, rocket engines, satellites, and satellites, and spacecraftspacecraft

Activities and ExercisesActivities and Exercises

Build gliders for flight control Build gliders for flight control experimentsexperiments

WorksheetsWorksheets