Transcript Aerodynamics - Delta State University

Aerodynamics
Lecture 1
Chapter 1
What is Aerodynamics?
How does the text define
Aerodynamics?
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.
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.
Chapter 1
History of Flight
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.
What famous artist dreamed of
flight?
He cut off his ear.
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)
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?”
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)
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.
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.
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)
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)
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.
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.
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.
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.
Heavier-Than Air Flight
• Men attempted to emulate the birds, wing
flapping and gliding.
– One of the first persons to recognize the fixedwing 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.
Sir George Cayley
• In 1853 Cayley designed and built a humancarrying 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.
– Cayley’s work was published however it was
not recognized until recently.
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 Lilienthal’s design.
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.
The men who recognized all of
the problems involved with
flight?
They worked in a bicycle shop!
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.
December 17, 1903
• World’s First Sustained, Controlled, and
Powered Flight!
– Where?
– Who was the pilot?
• How did they decide who would pilot?
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 _____ ____ ______.
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.
Quiz on Lecture 1
Please take out a sheet of paper.
Include today’s date and your name.
Quiz on Lecture 1
• Please explain how a balloon ascends to 10,000
feet and remains at this altitude?
• How did Cayley’s approach to achieving manned
flight differ from Da Vinci’s?
• What was the key to the Wright brother’s success?
• What did scientists like Lancaster, Prandtl,&
Jaoukowsky contribute to the development of the
first airplane?
• Why do we need to study aerodynamics?