Aerodynamics

1
Aerodynamics

• Lecture 1
• Chapter 1

2
What is Aerodynamics?

• How does the text define Aerodynamics?

3
Aerodynamics defined-

• Is the science that deals with the motion of air
  and the forces on bodies moving through the air.
• The term aerodynamics implies the explanation of
  why and how airplanes fly.

4
Why do we need Aerodynamics?

• Pilots, Technicians, and others with an interest
  in aviation have a need to understand the
  behavior of the air and its effect on the
  airplane.

5
Chapter 1

• History of Flight

6
Greek Mythology

• The story of Daedalus and his son Icarus.
• They utilized flight as a means of escape from
  the island of Crete where they were imprisoned.
• Icarus flew too close to the sun and the heat
  melted the wax in his wings.
• He fell to the sea and suffered one of the first
  fatal crashes in history.

7
What famous artist dreamed of flight?

• He cut off his ear.

8
Leonardo da Vinci

• He was obsessed with the idea of transforming the
  muscle-power of man into lift and thrust through
  a flapping device called the ornithopter. (figure
  1-3 p. 3)

9
Aerostatics

• How does a balloon fly?
• The buoyancy principle discovered by Archimedes.
• The pressure in any fluid, liquid, or gas,
  increases in depth.
• Explain the phrase, high to low look out below?

10
Example

• A small chunk of fluid within a larger container
  of fluid.
• The pressure on the bottom of the surface is
  greater than the pressure on the top of the
  surface.
• If the chunk of fluid had no weight , it would be
  pushed upward by the increased pressure of the
  bottom however, the weight of this chunk of
  fluid added to the pressure force on the top
  surface balances out the increased
  pressure.(Static or still)

11
Example

• Now suppose that this chunk of fluid is replaced
  by a container filled with a fluid lighter than
  the surrounding fluid.
• The total weight of the container and the fluid
  inside it must be considered.
• This total weight must be less than the weight of
  the amount of fluid displaces in order for it to
  rise.

12
Balloons

• The previous example is the principle that causes
  a balloon to ascend.
• Heated or lighter-than-air gas is placed inside
  the balloon.
• When the resulting weight of the balloon and the
  gas inside it is less than the surrounding air,
  the balloon ascends.

13
Why does the balloon not rise to the top of the
atmosphere?

• The balloon, which has a gas of a certain density
  inside, rising in the atmosphere.
• Eventually it will reach an altitude where the
  density of the outside of the balloon and the
  density inside the balloon are the same.
• At this point the forces are again in balance and
  the pressure is not great enough to push the
  balloon upward. (figure 1-7, p.7)

14
Balloons

• Balloons are referred to as aerostatic vehicles,
  which means that they will lift in a static air
  mass.
• The balloon has no mechanism to move horizontally
  in this air mass. (only velocity and wind
  direction)

15
Joseph Etienne Montgolfier

• The brothers designed and built the first hot air
  balloon in France in June of 1783.(figure 1-4,p.
  4)
• They did not know what caused their balloon to
  ascend. (they thought burning wood released some
  unknown gas that mysteriously caused objects to
  rise.)
• The principles of lighter than air soon became
  known and both hot-air and hydrogen-filled
  balloon flights were launched before the end of
  that year.

16
Hot Air Vs. Lighter than Air Gas

• Hot air may be used at lower altitudes, however,
  at higher altitudes the temperature decreases
  causing the hot air to cool.
• Lighter than Air Gas is used in high altitude
  flight.

17
Compressibility

• Remember that air is compressible unlike water.
• Air is compressed by its own weight.
• Because all of the air is above the surface, the
  highest compression and highest density altitude
  occurs at the surface.
• As you go up in altitude, there is less air above
  causing the compression at that altitude
  therefore the air is less dense.

18
Airship

• A lighter-than air craft with propulsive
  capability.
• Fuel is required only to provide propulsion and
  not lift, as it is with other types of aircraft.

19
Heavier-Than Air Flight

• Men attempted to emulate the birds, wing flapping
  and gliding.
• One of the first persons to recognize the
  fixed-wing mode of flight was an English
  nobleman, Sir George Cayley.
• He was the first to recognize the importance of
  stability and control in an aircraft and designed
  his tail sections accordingly.

20
Sir George Cayley

• In 1853 Cayley designed and built a
  human-carrying glider.
• His coachman was pressed into service as the
  pilot and made the 1st manned flight of a
  heavier-than air craft in history.
• The coachman promptly resigned after the
  experiment.
• Cayleys work was published however it was not
  recognized until recently.

21
Otto Lilienthal

• A German engineer that approached the idea of
  flight with scientific reasoning and analysis.
• Lilienthal made many successful glider flights
  but crashed before he was able to achieve his
  ultimate goal of powered flight.
• Figure 1-8 on p. 9 shows Lilienthals design.

22
Octave Chanute

• A Chicago engineer, was experimenting with
  gliders around the same time as Lilenthal.
• Chanute was also scientific in his approach and
  contributed significantly to the structural
  soundness of aircraft design.
• Figure 1-9, p. 9 shows Chanute experimenting with
  gliders.

23
The men who recognized all of the problems
involved with flight?

• They worked in a bicycle shop!

24
Wilbur Orville Wright

• Their procedure was methodical and scientific in
  the approach.
• They studied the successes and failures of others
  especially Lilenthal and Chanute.
• They tackled one problem at a time construction
  techniques, devising controls, teaching
  themselves to fly, increasing the efficiency of
  design.

25
December 17, 1903

• Worlds First Sustained, Controlled, and Powered
  Flight!
• Where?
• Who was the pilot?
• How did they decide who would pilot?

26
The Science of Aerodynamics

• Gliders are ______________ machines.
• The study of moving air and the forces that it
  produces is referred to as ____________, meaning
  literally, air in motion
• Aerostatic means _____ ____ ______.

27
Classical Theory of Flight

• Scientists began around 1910 to look into the
  physical principles of winged flight including
  behavior of wings airfoils.
• Frederick Lancaster in England
• Ludwig Prandtl in Germany
• Joukowsky in Russia
• These men were scientists with the intent to
  explain physical behavior not interested in
  developing aircraft.

28
Quiz on Lecture 1

• Please take out a sheet of paper. Include todays
  date and your name.

29
Quiz on Lecture 1

• Please explain how a balloon ascends to 10,000
  feet and remains at this altitude?
• How did Cayleys approach to achieving manned
  flight differ from Da Vincis?
• What was the key to the Wright brothers success?
  
• What did scientists like Lancaster, Prandtl,
  Jaoukowsky contribute to the development of the
  first airplane?
• Why do we need to study aerodynamics?