Aerospace Education

Module 1Introduction to Flight

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• Chapter 1 – Flight• Chapter 2 – To Fly By the lifting Power of Rising Air• Chapter 3 – Balloons, They Create Their Own Thermals• Quiz• Credits

Chapter 1

“Flight”

The Principle of Lift

The principle of lift mainly owes it’s discovery to Daniel Bernoulli. Using a venturi, he discovered that when you increase the speed of a fluid, which behaves like the air around us, it’s pressure drops, this is known as Bernoulli’s Principle. It’s this discovery that is the main idea behind the theory of airfoil lift, the type of lift which modern aircraft use to fly. Airfoil lift works because when the air below an airfoil (a wing) is unaffect, but the air going over the top travels faster due to the wing, the wing will lift because the air beneath the wing has a higher pressure than the air going above it.

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The Principle of Lift

Bernoulli used a venturi tube(right) to prove that air moving at a higher velocity has a lower pressure. The tube’s restriction in the middle is designed to speed up the air travelling through it.

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The Principle of Lift

Bernoulli’s findings are not the only ones which affect an aircraft in flight. Sir Isaac Newton’s 3 Laws of Motion also affect an aircraft while it’s flying. Newton’s first law explains why an aircraft, which is sitting on a runway at an airport start’s moving when it’s engines start. Newton’s second law explains why we need control surfaces to change the direction the aircraft is flying. Finally, Newton’s third law explains why lift works, the oncoming air which flows over and under the wings is the action and the reaction to this action is the lift which is produced.

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The Principle of Lift

Newton’s Three Laws of Motion1. An object at rest will remain at rest until acted

upon by some outside force.2. A force acting upon a body causes it to accelerate

in the direction of the force. Acceleration is directly proportional to the force and inversely proportional to the mass of the body being accelerated.

3. For every action, there is an equal and opposite reaction.

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The Principle of Lift

Engineers use a mathematical equation to determine how much lift is being produced.

Lift = CL x R x ½V^2 x A• CL = Coefficient of Lift, this takes into consideration the angle of

attack and airfoil design. It’s best determined in a wind tunnel• R = The density of the air, the greater density, the more lift is

produced• 1/2V^2 = The velocity of the air over and under the wing. If the

velocity is doubled, the lift is quadrupled, in other words, it’s squared.

• A = Area of the wing, the larger the area is, the more lift is produced.

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The Forces Acting Upon an Aircraft

Natural Forces• Drag – Drag is caused by the

air the aircraft is travelling through. The aircraft has to force it’s way through it as the air won’t simply move for the aircraft.

• Gravity – Earth’s gravity pulls everything around us down towards the Earth. Gravity is measured in “G’s” with 1 G being Earth’s regular gravity.

Artificial Forces• Thrust – This is what pulls or

pushes an aircraft through the air which in turn causes air to flow over the wings and create lift.

• Lift – Lift is what causes the aircraft to fly and break free of gravity’s hold.

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The Components of an Aircraft

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The Three Axes

The Lateral Axis The lateral axis is

expressed in pitch, the higher the pitch, the higher the nose is pointing. Pitch is controlled using the elevator.

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The Three Axes

The Vertical Axis The vertical axis is

expressed in yaw. Yaw describes which direction the nose is pointing, left or right. Yaw is controlled by the rudder.

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The Three Axes

The Longitudinal Axis The longitudinal axis is

expressed using roll. Roll describes the angle of the wings in relation to the ground. Roll is controlled using the ailerons.

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Chapter 2

To Fly By the Lifting Power of Rising Air

Glider Flight

Gliders utilize the columns of rising air (thermals) that are created by the Sun’s heat. As the air closer to the ground warms up, it begins rising up as warmer air is less dense than colder air. Once the air cools again, it begins dropping back down to Earth. This creates a convective circulation within our atmosphere. Gliders use this rising air to receive their power rather than using an engine.

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Glider Design

Gliders are naturally missing one major thing powered aircraft have: an engine. Also unlike most powered aircraft, most gliders have lift spoilers on top of their wings. These are used to increase the rate of descent by disrupting the flow of air over the wings, therein disrupting the production of lift.

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Chapter 3

Balloons – They Create Their Own Thermals

How Balloons Fly

Balloons achieve flight using the same principle that gliders use. The difference is that they create their own thermals. Because warmer air is more buoyant than cold air, the hot air in the balloons will rise. Other balloons use lighter-than-air gasses, such as hydrogen or helium to rise. Lighter-than-air gasses are just that, gasses that are lighter than air, and therefore, more buoyant.

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Components of a Balloon

When compared to a winged aircraft, balloons are very simple aircraft. The largest part of a balloon is always the envelope.

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History of Balloon Flight

The first balloon flight is one of the most important milestones in aviation history as it can be considered the first powered, manned flight. Hot air balloons like the one used during the first balloon flight do not rely solely upon their environment to fly, they create their own means to fly, which means the balloon flight was powered. The first balloon was performed by the Montgolfier brothers in France on November 21, 1783. It lasted 25 minutes and their balloon landed about 5 miles from where it was launched in Paris.

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Quiz

Question 1

What does Bernoulli’s

Principle state?

A) E=MC^2B) When an airplane’s

elevators are up, the nose goes down.

C) When a fluid’s speed is increased, it’s pressure decreases.

D) Temperature drops at an average rate of 3 1/2°F per 1,000ft of altitude

Question 2

Which type of movement moves around the vertical axis?

A) RollB) DiveC) PitchD) Yaw

Question 3

What mechanism enables glider pilots to overcome ‘Ground Effect?’

A) Tow HookB) SpoilersC) Altitude RadioD) Stabilator

Question 4

What is the average lapse rate for our atmosphere?

A) 10°K per 10ftB) 2°C per 48m^2C) 3 ½°F per 10,000ftD) 2°C per 1,000ft

Question 5

When was the first balloon flight conducted?

A) FranceB) ChinaC) AmericaD) German

Question 6

What is the principle

which states that something lighter than air will float on the air called?

A) Law of MotionB) Theory of RelativityC) BuoyancyD) Angle of Attack

Credits

• Created by Ryan Stanley• Based on “Aerospace Dimensions” Module 1

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