Fundamentals of FlightA Basic Introduction to Aerodynamics

By Warren Puckett; Physics Instructor & Pilot

The Four Forces of Flight

The four forces act on the airplane in flight and also work against each other.

The Four Forces of Flight

The four forces act on the airplane in flight and also work against each other.

Weight counteracts lift.

The earth’s gravity pulls down on objects and gives them weight.

What’s it take to create lift?Air and motion.

How do we explain lift?Newton’s Laws of Motion and Bernoulli’s Principal are used to explain lift.

Newton’s Second Law: force causes a change in velocity which in turn generates another force.

Newton’s Third Law: net flow of air is turned down resulting in an ‘equal and opposite’ upward force.

Newton’s Third Law states that for every action there is an equal and opposite reaction.

Venturi Tube Bernoulli's first practical

use of his theorem Where are venturi tubes

used today? Jet Engines

Hold two sheets of paper together, as shown here, and blow between them. No matter how hard you blow, you cannot push them more than a little bit apart!The moving air creates a low pressure area that sucks the papers together.

Bernoulli’s Theory in Action

Air speeds up in the constricted space between the car & truck creating a low-pressure area. Higher pressure on the other outside pushes them together.

What is a wing?A wing is really just

half a venturi tube.

A fluid (and air acts like a fluid) speeds up as it moves through a constricted space

Bernoulli’s Principle states that, as air speeds up, its pressure goes down.

Bernoulli's Principle: slower moving air below the wing creates greater pressure and pushes up.

Bernoulli’s Principle: Air moving over the wing moves faster than the air below. Faster-moving air above exerts less pressure on the wing than the slower-moving air below. The result is an upward push on the wing--lift!

http://www.grc/nasa.gov/WWW/Wright/airplane/shape.html

A wing creates lift due to a combination of Bernoulli’s Principal & Newton’s Third Law

Internal ribs define the wings shape

Wing Shape

Hang gliders use wing warping to control the wing.

Note how the wing tips are at different angles than the center.

The thick wing airfoil is used to produce a large amount of lift at a lower speed.

This US Navy Carrier Jet has a very small wing, how can it fly? Can you see the thin airfoil?

Why is the wing small? Because it flies FAST!

How can an airplane fly upside down?

http://www.grc.nasa.gov/WWW/Wright/airplane/incline.html

Pitch Around the Lateral Axis

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.

Elevator Controls Pitch

Roll Around Longitudinal Axis

Ailerons Control RollThe 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.

Yaw Around the vertical Axis

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.

Rudder Controls Yaw

Drag is the force of resistance an aircraft ‘feels’ as it moves through the air just like a boat makes a “wake” moving through water.

For an airplane to speed up while flying, thrust must be greater than drag.

For an airplane to take off, lift must be greater than weight.

Engines (either jet or propeller) typically provide the thrust for aircraft. When you fly a paper airplane, you generate the thrust.

AIRPLANE PARTS