Transcript The Physics of Flight

The Physics of Flight
Ancient Dreamers
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Legends of flight attempts date to 2000 B.C.
– Many believed flying was for the mythical gods
– Others tried to copy bird flight-unsuccessfully
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Chinese invented kites about 1000 B.C.
– 17th century A.D. kites carried soldiers aloft
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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
Ancient Dreamers
Leonardo da Vinci
 Daedalis & Icarus
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Italian artist and scientist Leonardo da Vinci (14521519) gathered data on the flight of birds and
developed concepts of the propeller, the parachute,
and heavier-than-air craft.
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
Bernoulli’s Principle
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According to Bernoulli’s Principle, as the
velocity of a fluid increases the pressure
exerted by the fluid decreases.
Air Flow Past a Wing
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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
 Wright’s 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
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Sir Hiram Maxim
– power, lift, control
Wright brothers
 Glen Curtiss
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– 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.
World War I
The Main Events
War speeds up
technology
development
 Airplane speed,
loads increased
 Large manufacturing
base developed
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Congressional medal of Honor winner Captain Eddie
Rickenbacker went on to be a pioneer in civil aviation, too
After the War
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Veteran pilots kept interest alive
Commercial aviation catches on
Dramatic design advances
Beginning of rocket flight
Invention of the jet engine
Four Forces of Flight
Lift
 Weight
 Thrust
 Drag
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Source: NASA Glen Research Center
Forces on an Airplane
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
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Weight is not constant
– varies with passengers, cargo,
fuel load
– decreases as fuel is consumed
or payload off-loaded
Direction is constant toward
earth’s center
 May be assumed concentrated
at the center of gravity
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Drag
An aerodynamic force
 Drag is also called air resistance.
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the force that pulls the plane backward.
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Two broad drag classifications
– Parasite drag: drag created by airplane design
– Induced drag: by-product of lift generation
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Acts through the center of pressure
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
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Aeronautics is the
design and
construction of
aircraft and
 The theory and
practice of aircraft
navigation
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
Activities and Exercises
Build gliders for flight control experiments
 Worksheets
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