Airplane Design and Flight Fascination with Flight Objective: 1. You will be able to define the basic terms related to airplane flight. 2. You will test fly your airplane and make adjustments to improve its flight. Related Careers: Aircraft Instrument Repairer Aircraft Designer Aircraft Engineer Aircraft Electronics Specialist Aircraft Mechanic Pilot US Military Key Words and Definitions: 1. Duration - Measured to a hundredth of a second. Time starts when the model leaves the launcher s hand and end when it first touches the ground. 2. Distance - Measured from where the model is launched to where it lands. Length of the model is not included. 3. Aerobatics - Total number of loops, dips, circle etc. each judged on a scale of 1 to 10. 4. Aesthetics - Best looking and most creative design. Must meet minimum flying requirement. 5. Duration and Distance - After measuring the time and distance as mentioned above, add the values together. Seconds plus feet. Procedure: During this activity you will design and build 3 paper airplanes, all of which have to be colorfully decorated. Your objective is to build each plane so that it can fly a minimum of 15 feet. Rules: The models must be made entirely of paper (of any type or weight). The models must not exceed a maximum of 2 feet squared. The models must be launch manually by the participant. All models must reach the minimum requirement for flight (15 feet). 1
Related Information: Since the earliest recorded history, man has strived to conquer the air, defy gravity, and fly like the birds. These dreams go back as far as the great mythological characters of the Greeks. The ancient Greeks told the story of an inventor named Daedalus and his son Claus, both of whom flew with wings of feathers and wax. Lcarus flew too close to the sun, the wax melted, and as a result he fell into the sea and drowned. Leonardo de Vinci drew designs of flying machines in the 1400 s and the Montgolfier brothers succeeded in flying a manned hot air balloon for over five miles in 1783. Many others experimented and built models to further the idea of flying, but it was the Wright Brothers that flew the first airplane. On December 17, 1903, Orville Wright became the first person to fly an engine-driven, heavier-than-air machine. Since the time of the Wright Brothers historical flight, the world has seen much advancement in the field of aviation. Today aircraft play a vital role in society s transportation, commerce, industry, and national security. We have supersonic jet passenger planes, radar evading air force jets, and space shuttles orbiting the earth. What will tomorrow bring in the way of aviation? Will you play a part? The Parts of an Airplane The typical airplane has five basic parts; the fuselage (body), wing, tail assembly, landing gear, and engine. All these parts, except the engine, make up the plane s airframe. 2
The fuselage is the main body of the airplane. It carries the pilot and crew, the passengers, and the cargo. It is cylindrical and tapers towards the nose and more toward the tail. The engine of most single-engine planes is in the front of the fuselage. Some jet planes have one or all of their engines at the rear of the fuselage. At the front is the cockpit, which contains the controls and instruments used by pilot in flying the airplane. The main part of the fuselage of an airliner contains the cabin, where the passengers sit. In the large planes, such as a Boeing 747, the cabin has separated decks (floors) for the passengers. The wings of an airplane extend outward from each side of the fuselage. A wing has a nearly flat bottom and a curved top. It is this shape that gives an airplane its lifting power. Air passing over the curved top moves faster than air passing under the flat bottom. This creates a difference in pressure, so the wing is pushed up from beneath. The faster the wing is passing through the air, the greater the lifting effect will be. An airplane wing has a root, tip, leading edge, and trailing edge. The root is the part of the wing attached to the fuselage. The tip is the end of the wing farthest form the fuselage. The leading edge is the curved front edge of the wing. The top of the wing thickens from the leading edge and then slopes back to the knife like trailing edge. All airplanes wings have two basic controls flaps and ailerons. These controls are hinged sections of the wings along the trailing edge. Both wings have a flap and an aileron. The flaps are nearest the wing roots. A pilot lowers the flaps to increase lift at low speeds. The ailerons are nearest the wing tips. The can be moved up or down to help control a plane s lateral stability (balance from side to side). They are also used to make a plane bank (tip to the right or left for a turn.) Wings come in various shapes depending on the purpose of the airplane. Airplanes that fly near or above the speed of sound have swept-back (V-shaped) or delta (triangular) wings. See illustration at the right. 3
TAIL ASSEMBLY The tail assembly is the rear part of the airplane. It helps guide the plane and keeps it balanced in flight. Most tail assemblies consist of a vertical fin and rudder and a horizontal stabilizer and elevator. The fin stands upright and does not move. It keeps the rear of the plane from swinging to the left or right. The rudder is hinged to the rear edge of the fin and can be moved from side to side. It helps control the plane during a turn. The stabilizer is like a small wing in the tail. It prevents the tail from bobbing up and down and keeps the plane flying in a steady horizontal direction. The elevator is hinged to the rear edge of the stabilizer. A pilot moves the elevator up or down to raise or lowers the plane s nose. Today, many have what is called a stabilator, which is a single solid unit that moves on the ground of water. The landing gear also supports the weight of a plane on the ground of water. The landing gear consists of the wheels or floats upon which an airplane moves on the ground or water. The landing gear also supports the weight of a plane on the ground or water. Power of Flight An airplane s engine is the heart of the airplane. It produces the power that makes the plane fly airplanes use three typed of engines; gasoline, jet, and rocket. Gasoline engines or piston engines are the most widely used. Most small and some large airplanes have gasoline engines. These planes also have one or more propellers. The engine turns the propeller, which moves the plane through the air. Gasoline engines are the heaviest and least powerful of airplane engines, therefore they are used for shorter distances carrying smaller loads. Jet engines enable airplanes to travel long distances at high speeds. Commercial airlines use jet-powered airplanes to transport thousands of passengers to various destinations each day. Jet transportation is the most economical for long distance travel. Rocket engines are used for experimental planes and for takeoff assistance with heavy loads or short runways. 4
How Do Airplanes Fly? Flight is impossible without the use of some energy. For example, a hot air balloon needs energy to fuel the flame that heats the air to make it rise. The energy of the wind, or of rising hot air, is needed to allow fixedwing aircraft to gain altitude. To understand how an airplane flies we must understand the forces that are acting on the airplane, whether it is a model you have built or a commercial airliner. Lift - - The natural force that pushes a plane upward against the force of gravity. It is created by the movement of a plane s wings through the air. Thrust - - The force that opposes drag and moves the plane forward. It is created by a plane s propeller or jet engines. Gravity - - The weight of the airplane is acted upon by gravity, which pulls the plane down toward the earth. Drag - - The displacement of the air by the plane itself, and the friction of the plane s surface against the air create drag, which tends to hold the airplane back. It is easy to see how most of these forces work. For example, the more streamlined the airplane is, the less drag we will have. The lighter the weight of the airplane, the less effect gravity will have. We can see how the engine and propeller must overcome the force of drag. But how can the force of lift overcome the force of gravity? When the wings of an airplane are pulled through the air by the engine or propeller, they create lift. This lift is actually a bulge in the air, which occurs when the air travels more rapidly over the top of the wing, creating a low-pressure area. A high-pressure area is created below the wing. Bernoulli s Principle tells us that the air pressure will decrease as the speed of the air increases. The cross- sectional shape of the wing is called an airfoil. There are many different airfoils that create lift. The shape of the airfoil will also affect the drag. So far we have learned the basic parts of an airplane and how to keep an aircraft up in the air, and moving forward. Next, we must consider how to control the aircraft so that it is stable in its forward flight, and capable of making controlled banks, turns, and circles. The control surfaces of an aircraft allow this type of controlled movement. 5
Stability Vertical and horizontal control surfaces are important to the stability of the aircraft. These surfaces at the tail of the aircraft act like the feather of an arrow to keep the nose pointing in the direction of travel, and to keep the wings at the correct angle of attack. Both the rudder and the stabilizer on an aircraft help to increase the stability. Another factor that increases the stability is the dihedral of the wings. Dihedral is the angle at which the wings are inclined upwards when the aircraft is viewed straight on. A horizontal line (dashed line) is included in these illustrations to help see the dihedral angle of these three variations. Center of Gravity The center of gravity is the point where the yaw, pitch, and roll axis intersect. On most airplanes, the center of gravity is slightly forward to achieve the most stability in normal, level flight. If the center of gravity is to far to the rear, the airplane will stall in flight. To correct this, add weight to the nose. If the center of gravity is too far forward, the airplane will nose dive. To correct this, add weigh to the tail. Because airplanes are often in a position where up and down are meaningless terms, there are three special terms used to describe an airplane s movements. Yaw is the movements to the left or right. Pitch is the movement up or down. Roll is the banking motion from left to right. The tail is made up of two parts. One part, the vertical stabilizer or fin, is not moveable. The other part, the rudder can be pivoted left or right to move the nose of the airplane left or right along the yaw axis. 6
The elevator is the moveable surface on the horizontal stabilizer. The elevator can be pivoted up or down to move the nose of the airplane up or down along the pitch axis. The aileron is the moveable surface on the wing of an airplane. It can be pivoted up or down to control the bank of the airplane along the roll axis. The two ailerons, left and right, will work together, moving in opposite directions to achieve banks and rolls. Transportation Evaluation Fascination with Flight Evaluation Directions: Write the correct answer to the question on your answer sheet. Airplane Design and Flight 1. What are the five basic parts of an airplane? 2. The cross-sectional shape of a wing is called an: 3. All airplane wings have two basic controls called: 4. List the four forces that act upon an airplane: Name the parts of this airplane: 5. 6. 7. 8. 9. 10. 11. 12. 7