Category: Forces

How do you control a plane?

6/5/2014

I: Roll, Pitch, and Yaw
Roll, pitch, and yaw are the three types of motion on a plane. A change in any one of the three types of motion affects the other two.

Roll is the rotation of the wings around the body of the plane.
Pitch is the rotation of the nose and tail of the plane in a up/down direction.
Yaw is the rotation of the wings in a left/right direction on the same plane.

Check out the interactive image of the ailerons, elevator, and rudder of a plane here:
http://science.howstuffworks.com/transport/flight/modern/airplanes4.htm

III: Camber
The camber of an airfoil is the characteristic curve of its upper or lower surface (see below). The camber determines the airfoil's thickness. But, more importantly, the camber determines the amount of lift that a wing produces as air flows around it. A high-speed, low-lift airfoil has very little camber. A low-speed, high-lift airfoil, like that on the Cessna 150, has a very pronounced (curved) camber.

You may also encounter the terms upper camber and lower camber. Upper camber refers to the curve of the upper surface of the airfoil, while lower camber refers to the curve of the lower surface of the airfoil. In the great majority of airfoils, upper and lower cambers differ from one another.

Roll is the rotation around the front-to-back axis.

Pitch is the rotation around the side-to-side axis.

Yaw is the rotation of the wings around the vertical axis.

II: Controlling Roll, Pitch, and Yaw
The ailerons, elevator, and rudder control the movement of a plane. These are called the "control surfaces" because they are surfaces that control the movement of a plane!

The Ailerons Control Roll: On the outer rear edge of each wing, the two ailerons move in opposite directions, up and down, decreasing lift on one wing while increasing it on the other. This causes the airplane to roll to the left or right. To turn the airplane, the pilot uses the ailerons to tilt the wings in the desired direction.
The Elevator Controls Pitch: On the horizontal tail surface, the elevator tilts up or down, decreasing or increasing lift on the tail. This tilts the nose of the airplane up and down.
The Rudder Controls Yaw: On the vertical tail fin, the rudder swivels from side to side, pushing the tail in a left or right direction. A pilot usually uses the rudder along with the ailerons to turn the airplane.

Assignment
Read the blog post above, watch the videos, and explore the interactive websites (links). Then answer the questions below. Make sure to write the question and answer in complete sentences to receive full credit. There is an extra credit opportunity below!
Due Monday, June 9, 2014

Part I & II
1. What type of plane motion (roll, pitch, or yaw) occurs when a plane takes off and lands?
2. What type of plane motion (roll, pitch, or yaw) occurs when a plane makes a left or right turn in the air?
3. Where are the ailerons of a plane located?
4. What is the function of the ailerons?
5. Where is the elevator of the plane located?
6. What is the function of the elevator (on a plane)?
7. Where are the rudders of a plane located?
8. What is the function of the rudders?

Part III
1. What is camber?
2. What is the difference between upper camber and lower camber?
3. A high-speed, low-lift airfoil has very __________________ camber.
4. A low-speed, high-lift airfoil, like that on the Cessna 150, has a very ________________ camber.
5. Sketch the upper and lower camber line of an airfoil.

Part IV: Explore the website on wing design and answer the questions that follow:
http://www.pbs.org/wgbh/nova/space/lift-drag.html
1. What two forces combine to create lift?
2. An airfoil also creates lift by __________________ or redirecting airflow.
3. The amount of drag depends on an object's _________________ and _____________.
4. What will have more drag: a) monster truck; b) sports car
5. A __________________ surface causes more drag than a smooth, polished one.
6. A fighter jet has low lift and low drag. What about its wing shape gives it these properties?
7. How does the airfoil of the crop duster compare to the wing of the fighter jet?

Extra Credit:
Click on the link below to find the best lift to drag ratio (L/D) for different planes by adjusting their angle of attack and air speed. Then answer the questions below.
http://howthingsfly.si.edu/activities/how-wings-work
1. Why do you think a higher lift to drag ratio (L/D) is a major goal in wing design?
2. In order to achieve the best lift to drag ratio (L/D) for the Bleriot airfoil, what is the angle of attack and airspeed needed?
3. In order to achieve the best lift to drag ratio (L/D) for the DC-3 airfoil, what is the angle of attack and airspeed needed?
4. In order to achieve the best lift to drag ratio (L/D) for the 757 airfoil, what is the angle of attack and airspeed needed?

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What makes something fly?

6/2/2014

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The Four Forces of Flight

There are four forces that act upon an object to make it fly:

Lift = upward pull
Weight = downward force of gravity
Drag = force opposite to the direction of motion (friction)
Thrust = force that moves an object forward

When the forces of flight are balanced, an object can fly in a level direction. An object can go up (take-off!) if the forces of lift and thrust are more than weight and drag . An object can go down (land!) if the forces of weight and drag are greater than lift and thrust.

Take Off = Lift + Thrust > Weight + Drag

Landing = Lift + Thrust < Weight + Drag

How do objects DEFY gravity?
In other words, how can we create the lift needed to overcome weight (the force of gravity)?
Lift can overcome weight in two ways:

1) By creating differences in air pressure.
2) By pushing air downward.

But what does this even mean?!?!?! There there. I'll explain.

1) Create lift by creating differences in air pressure

The shape of a wing is called airfoil. The airfoil is what enables a plane to create lift.
The curved shape of a wing (airfoil) makes air above the wing move faster than the air below the wing.
Fast moving air has lower pressure than slow moving air, so the higher pressure air pushes the plane upward toward the low pressure area, generating lift. This is known as Bernoulli's Principle.

Bernoulli's Principle: As the speed of a moving gas or liquid increases, the pressure within the gas or liquid decreases

Daniel Bernoulli was the Swiss mathematician who first described the phenomenon that as the movement of a fluid increases, the pressure decreases.

2) Create lift by pushing air downward

A wing is shaped to force air downward, which causes an equal and opposite reaction from the air, forcing the wing upward. This is an example of Newton's 3rd Law of Motion.
When a bird flaps its wings, it is pushing air downward to pull itself upward.

Newton's 3rd Law of Motion: For every action, there is an equal and opposite reaction.

Isaac Newton was one of the greatest scientists and mathematicians who ever lived. He defined the "Laws of Motion" that describe the relationship between a body and the forces acting upon it.

So now we have Lift. Where do we get Thrust?
That's a much easier explanation. We get thrust from engines (like a car), propellers, and rockets!

Still confused? Watch the Bill Nye + BrainPop videos on flight (videos + links below)!

BrainPop: Flight
Username - ms881
Password - ms88rocks

Assignment
Answer the questions below in complete sentences, using the blog post, videos, and class notes to help you. WRITE the question and answer.
Due: Friday, June 6, 2014

1. What are the four forces of flight?
2. How does a plane balance the forces of flight in order to land safely? (hint: some forces must overcome others)
3. What is an airfoil?
4. Sketch an airfoil.
5. What is Bernoulli's principle?
6. How does Bernoulli's principle relate to flight?
7. What is another example of Bernoulli's principle in the real world? (hint: there is a poster in Ms. Shon's classroom with examples)
8. What is Newton's 3rd Law?
9. How does Newton's 3rd Law of motion relate to flight?
10. What is another example of Newton's 3rd Law of motion in the real world?

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How do you control a plane?

What makes something fly?

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