Major Kevin A. Gore, USAF (Ret)

• Aerospace Science II
• Principles of Flight
• Lesson 1

Students will Learn About

• The Theory of flight
• Airfoils and flight
• Newton's laws of motion and aircraft design
• Bernouilli's principle, airfoils,and flight
• The effect of relative wind on flight
• The effect of angle of attack on flight

The Theory of Flight
Humans flew in their imaginations long before doing so in reality. Ancient legends tell of winged horses and huge birds lifting people up into the skies. In these stories living men sprouted wings, and dying ones flew up to heaven in reward for leading heroics lives. Such stories stretch back thousands of years to the earliest civilizations.

This is what man dreamed of....

• Freedom like the birds....

Getting off the Ground

• What is perhaps the earliest recorded case of a human being successfully flying with the aid of a mechanism is found in the Chinese Book of Sui (AD 636).
• Flight by balloon, or lighter than air flight, did not occur until more than 1,000 years after the Book of Sui. In 1783, the French Montgolfiers brothers built the first hot air balloon.

GETTING OFF THE GROUND cont.

• It took centuries of experimenting, of trying and failing, before people understood how things fly. They slowly had to develop a theory of flight.

Aerodynamics

• This long word comes from two Greek words, aerios and dynamis, which translate into air - force
• Aerodynamics is the way an object moves through the air

Airfoils and flight

• For an object to fly, you need a force to lift it.
• One object that creates this lifting force is an airfoil. An airfoil is a structure -such as a wing or propeller blade - that when exposed to a flow of air generates a force.

Airfoils and Flight cont.

• The front edge of an airfoil is called the leading edge. This edge cuts through the air ahead. The rear edge is the trailing edge.
• The typical airfoil has a rounded leading edge and a sharp trailing edge.

Airfoils and Flight cont.

• In general, an airfoils' upper and lower surfaces curve. The curve of an airfoil is its camber. In most aircraft the camber is greater on the upper surface than on the lower

Airfoils and wind tunnels

• Aircraft designers - including the Wright Brothers, use wind tunnels to test models of new aircraft.
• Wind tunnels are controlled spaces for testing airflow over a wing, aircraft, or other object
• In a wind tunnel, a researcher can carefully control the airflow conditions, which affect the forces on an aircraft.

Airfoils and Wind Tunnels cont.

• The Wright Brothers built one to test airfoils after their 1901 glider failed to produce enough lift.
• They tested more than 200 wing shapes in designing their successful 1902 glider. That glider led to the 1903 powered Wright Flyer.

Newton's first laws motion

newton's second law of motion

Newton's third law of motion

Bernoulli's principle, airfoil, and flight

• According to this principle, an increase in the rate of airflow causes a decrease in air pressure.
• Air pressure is the force exerted by the air on a unit of surface. In other words when air moves faster, its pressure drops.
• For example, when air flows through a pipe, the pressure is lower in the narrow sections of the pipe because the airflow is faster.

The effect of relative wind on flight

• The concept of relative wind, often abbreviated RW, is also key to understanding flight. Relative wind is the motion of air as it relates to the aircraft within it.
• To determine relative wind, you ignore air disturbances at the aircraft's surface and consider only the movement of air at a distance from the plane.

Relative wind cont.

• The speed of relative wind depends not only on an aircraft's speed, but also on the direction it is flying.
• For example, suppose a plane takes off directly into a 15 knot headwind...If the plane's speed relative to the ground is 100 knots, then the relative wind will be 115 knots

The effect of angle of attack on flight

• The angle between the direction of the relative wind and the chord line of an airfoil is the angle of attack
• If a plane continues along the same line of motion, but alters its pitch - the up and down movement of the plane's nose - the angle of attack on its wings will change

The effect of angle of attack on flight cont.

• As the angle of attack increases, the wings generate more lifting force, but only up to a certain point - the critical angle of attack.
• The critical angle of attack is the point at which a plane stalls. A stall is a rapid reduction in lifting force caused by exceeding the critical angle of attack.

Summary

• The Theory of flight
• Airfoils and flight
• Newton's 3 laws of motion
• Bernoulli's principle, airfoils, and flight
• The effect of relative wind on flight
• The effect of angle of attack on flight

These laws and principles you've read about in this lesson make up the basic theory of flight.

You need to understand them in order to fly an airplane safely, to decide whether it is safe to fly in conditions, or to create a successful aircraft design.

Questions to answer after Lesson 1

• In what year was the first manned ballon flight?
• What is aerodynamics?
• Which edge of an airffoil is rounded? Which is sharp?
• What did the Wright brothers discover using a wind tunnel?
• What is another name for Newton's first law?
• What does F=ma mean?

Questions cont.

• 7. What is an example in aviation of Newton's third law in action?
• 8. Why does an airfoils shape create a lifting force?
• 9. The speed of relative wind depends on the aircraft's speed and what else?
• 10. At about how many degrees does a plane reach its critical angle of attack?

Differentiation

Differentiation

• Students who do not pass assessment with will be asked to click on the link shown on previous slide. That way, they will be allowed to review those areas they may have missed on the assessment.

Assessment (Formative)

• Students will be shown the 10 questions on the slide to be answered with their own paper
• Students in JROTC could also use the Classroom Performance System to answer the 10 questions (optional).

Technology Resources

• Haikudeck.com website
• Aerospace Science II curriculum textbook, The Science of Flight, A Gateway to New Horizons, Jones and Bartlett Learning, Copyright 2012..
• Newton's First Law (slide 13) video, courtesy of You Tube
• Newton's Second Law (slide 14) video , courtesy of You Tube.
• Newton's Third Law (slide 15) video, courtesy of You Tube
• Video with Microflier and Geese (Slide 4) courtesy of You Tube

Results of Formative Review (80% passing)

• Score -10/10- 3 students
• Score- 09/10 - 2 students
• Score- 08/10- 2 students
• Score- 06/10-2 students
• Score- 05/10- 1 student
• 3 students would need to view the link and retake the assessment.

Results of assessment by percentage