Take Off With Paper Airplanes

This lesson teaches the engineering method for testing wherein one variable is changed while the others are held constant. Students compare the performance of a single paper airplane design while changing the shape, size and position of flaps on the airplane. Students also learn about control surfaces on the tail and wings of an airplane.

Designing the control system in an aircraft is more complicated than the control system for most other methods of transportation because not only can airplanes move left and right (yaw), but they can also pitch and roll. To master these added dimensions, engineers build ailerons, rudders and elevators to provide adequate airplane steering. Engineers build small-size models of the airplanes with these control surfaces, and place them in a wind tunnel to test the capabilities of their design. variable constant airplanes aerodynamics design model paper airplane After this lesson, students should be able to: Design a model of an airplane. Modify the airplane to attempt to improve its flight. Become familiar with parts of a paper airplane and how they relate to parts on a real airplane. Explain why testing of models is an important step in the design-build process. Who has designed and flown a paper airplane? How did it do? Did it go far or do tricks? How can we make our paper airplanes better? What does "better" mean? (Encourage discussions that involve making planes fly further, faster, with better control, etc.) Draw a picture of an airplane on the board or make an overhead of Figure 1. Review the different parts of the airplane: wings, aileron, tail, rudder, elevator, fin, flaps, fuselage, and cockpit. (Note: Lesson 6 of the Airplanes Unit details the different parts of the airplane.) We refer to the moveable parts of the plane's wing or tail as control surfaces (parts of the plane that the pilot can control from the cockpit). These parts of the airplane are going to be important to us today as we deign and modify our own paper airplanes to make them go farther. Engineers are trained to design a model and test that model to make it better, sometimes over and over again. One important part of this process is keeping track of each design change and its effect on the airplane. Does the airplane go farther when one part of the wings is changed? Or does it fly farther when one part of the tail is modified without the wing modification? Engineers who design airplanes test their models using a powerful wind tunnel and then carefully record and analyze their results. The wind tunnel allows them to determine if they have designed an airplane that will fly in different conditions and at different speeds. The wind tunnel also allows them to distinguish how small modifications to the plane can change the way it flies. Today, we are going to use a simple paper airplane design, which we will modify and then record how well it flies. Then, we will change certain parts on our planes and record our observations of how each change affects the plane's flight ability. Wing construction is basically the same for all types of aircraft. Early inventors tried a variety of materials for airplane wing construction. Most modern aircraft have all metal wings, but many older aircraft had wood and fabric wings. Most wing structures have two spars, the front spar and the rear spar. The front spar is found near the leading edge while the rear spar is about two-thirds the distance to the trailing edge. Depending on the design of the flight loads, some of the all-metal wings have as many as five spars. The ribs are the parts of a wing that support the covering and provide the airfoil shape. These ribs are called forming ribs, and their primary purpose is to provide shape. Some may have an additional purpose of bearing flight stress, and these are called compression ribs. Figure 2 below shows the structure of the wing. The front, fixed section of the horizontal tail is called the horizontal stabilizer and is used to prevent the airplane from pitching up or down. The rear section is called the elevator and is usually hinged to the horizontal stabilizer. The elevator is a movable airfoil that controls the up-and-down motion of the aircraft's nose. Refer to Figure 1 for a diagram of the control and stability surfaces on an aircraft. The vertical tail structure is divided into the vertical stabilizer and the rudder. The front section is called the vertical stabilizer and is used to prevent the aircraft from yawing back and forth. The principle behind its operation is much like the principle of a deep keel (the timber at the very bottom of a boat's hull to which the frame is attached) on a sailboat which helps the boat from rolling side to side. In light, in a single-engine aircraft, it also serves to offset the tendency of the aircraft to roll in the opposite direction in which the propeller is rotating. The rear section of the vertical structure is the rudder. It is a movable airfoil that is used to turn the aircraft. Engineers have to be aware of the construction of the wings when testing their designs. When designing and testing planes, engineers make several test flights with different wings and wing designs. The rudder and tail are also important in the design of most airplanes, almost like the tail of a kite, in that these two components also greatly affect flight capability. The fuselage is the central body portion of an airplane which accommodates the crew and passengers or cargo. In general, the cockpit of aviation airplanes is usually the space in the fuselage for the pilot and the passengers. In some aircrafts, it is just the pilot's compartment. Located underneath the airplane, the landing gear support the plane while on the ground. Wings are the parts of airplanes that provide lift and support most — if not all — of the weight of the aircraft and its contents while in flight. A propeller is a rotating blade located on the front of the airplane. The engine turns the propeller, which subsequently pulls the airplane through the air. Flaps are the movable sections of an airplane's wings closest to the fuselage. They are moved in the same direction (down), enhancing the lift of the wing and enabling the airplane to fly more slowly while still creating enough lift to stay in the air. Ailerons are the outward movable sections of an airplane's wings which move in opposite directions (one up, one down). They are used in making turns. The rudder is the movable vertical section of the tail that controls lateral movement. The horizontal stabilizer is the horizontal surface attached to the aft part of the fuselage that is used to balance the airplane. The elevator is the movable horizontal section of the tail that causes the nose of the plane to move up and down. Better By Design At the end of the activity, ask students to discuss the engineering process of designing and testing. What are the steps? (Answer: Brainstorm, design, build a model, test, redesign, test again, redesign again, etc.) Review the parts of an airplane, as drawn/displayed on the board. What did we change on our airplanes to make them fly differently? What changes made some planes fly farther than other changes? (Encourage students to use vocabulary terms to describe the parts of their paper airplanes that they modified. Most students will have changed and tested the aileron, rudders, flaps, and/or elevators to make their planes fly further and with more control.) Brainstorming: Have students generate a number of possible ideas about airplane design. Encourage wild ideas and discourage criticism of any ideas. How can we make planes better? What does "better" mean? (Encourage discussions that involve making planes fly farther, faster, with better control, etc.) Question/Answer: Ask students questions and have them raise their hands to respond. Write answers on the board. For what reason do aerospace engineers use a wind tunnel? (Answer: To test their airplane designs to make them fly better.) What part of the airplane is the fuselage? (Answer: The central body portion of an airplane which accommodates the crew and passengers or cargo.) Do engineers always test a model of a design before they build the real thing? (Answer: Yes, engineers may test a model many times before getting the design exactly right.) What parts of an airplane might you change if your airplane is not flying as far as it can? (Answer: Any part. Accept all answers from a plane's parts that you pointed out on the diagram in the introduction. Remind students that they will only want to change one part at a time.) Engineering Report: Students write a short report to their "company" about their new paper airplane model. Include the following in their reports: The name of their model paper airplane. How far their paper airplane flies. What changes they made to their paper airplane to improve its performance. Why the company should consider building their airplane. A picture (drawing) of their airplane. Pass the Buck: In groups of four, have students brainstorm ideas to design the ultimate paper airplane. First, assign one student in the group to be the recorder. Then have someone toss out an idea. Next, another person in the group provides an idea that builds on the first. Go around the group in this fashion until all students have put in enough ideas to put together a design. When they are done, have them share their idea(s) with the class. (This can also be a fun exercise to do as an entire class!) How a Plane is controlled: Students can learn more about how airplanes are controlled. This extension sheet discusses control surfaces and helps students modify their paper airplanes to make them move up/down and left/right. Have students research airplanes on the Internet. They may want to begin with: http://www.grc.nasa.gov/WWW/K-12/airplane/ http://www.knowable.com/?dl=1 http://vestibule13.20m.com/ezine/northington.htm http://www.pbs.org/wgbh/nova/xplanes/airborne.html http://www-spof.gsfc.nasa.gov/stargaze/Sflight.htm