The Physics of Flight

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The Physics of Flight
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Ancient Dreamers

• Legends of flight attempts date to 2000 B.C.
• Many believed flying was for the mythical gods
• Others tried to copy bird flight-unsuccessfully
• Chinese invented kites about 1000 B.C.
• 17th century A.D. kites carried soldiers aloft
• Leonardo da Vinci, 15th century Italian artist
• First recorded scientific study of aeronautics
• Experimented to prove feasibility of mechanical
  flight
• Drew sketches and plans to construct flying
  machines

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Ancient Dreamers

• Leonardo da Vinci
• Daedalis 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.
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The Quest for Flight

• By 17th Century, ancient ideas inspired
  scientific theories and experiments
• Characteristics of the atmosphere and the
  discovery of gasses and properties led to
  lighter-than-air balloon experiments
• Airships needed power and direction control
• Glider flying increased the understanding of
  flight forces, wing geometry controls

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Definition Aerodynamics

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

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Bernoullis Principle

• According to Bernoullis Principle, as the
  velocity of a fluid increases the pressure
  exerted by the fluid decreases.

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Air Flow Past a Wing

• The air speed is greater over the upper surface,
  as indicated by the closer streamlines, the air
  pressure is lower there and the wing is lifted

• When the wing is angled upward, air deflected
  from its lower surface provides additional lift.
• If the angle is too great, turbulence reduces
  lift and increases drag.

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Powered Flight Breakthrough

• Experiments showed basic ingredients of flight
  are sufficient power, lift , control
• Wrights successfully applied theories of lift
  and drag to practical use in powered gliders
• Progress (and a conventional designs) came with
  lighter materials and drag reduction

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Breakthrough
The Main Events

• Sir Hiram Maxim
• power, lift, control
• Wright brothers
• Glen Curtiss
• Improved designs, promoted 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.
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World War I
The Main Events

• War speeds up technology development
• Airplane speed, loads increased
• Large manufacturing base developed

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

• Veteran pilots kept interest alive
• Commercial aviation catches on
• Dramatic design advances
• Beginning of rocket flight
• Invention of the jet engine

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Four Forces of Flight

• Lift
• Weight
• Thrust
• Drag

Source NASA Glen Research Center
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Forces on an Airplane
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Lift

• Lift is an aerodynamic force
• Lift must exceed weight for flight
• Generated by motion of aircraft through air
• Created by the effects of airflow past wing
• 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.

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Weight

• Weight is not constant
• varies with passengers, cargo, fuel load
• decreases as fuel is consumed or payload
  off-loaded
• Direction is constant toward earths center
• May be assumed concentrated at the center of
  gravity

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Drag

• An aerodynamic force
• Drag is also called air resistance.
• the force that pulls the plane backward.
• Two broad drag classifications
• Parasite drag drag created by airplane design
• Induced drag by-product of lift generation
• Acts through the center of pressure

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Thrust

• Forward-acting force opposes drag
• Direction of thrust depends on design
• Propulsion systems produce thrust
• Equal to drag in straight, constant speed flight

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Stability

• Center of Gravity
• Center of Pressure
• Longitudinal Stability
• Lateral Stability
• Directional Stability

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Definition Aeronautics

• Aeronautics is the design and construction of
• aircraft and
• The theory and practice of aircraft navigation

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Definition Aerospace Engineering

• Aerospace engineering is closely allied to
  aeronautics and aeronautical engineering but
• Includes the study and development of rocket
  engines, satellites, and spacecraft

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Activities and Exercises

• Build gliders for flight control experiments
• Worksheets