`AerodynamicsCarole Janda                   O. A. Thorp Scholastic Academy                               6024 W. Warwick Ave.                               Chicago IL 60634                               312-534-3640Objectives:     Demonstrate skill in hypothesis formulation, identification and control of variables, data collection, organization and interpretation of data.     Discover and understand the basic principles of aerodynamics, includingthe roles and identity of natural forces involved.     Discover how the force of GRAVITY is overcome by the curved shape of an airplane wing and air pressure.     Discover why air pressure is lower moving across a curved surface vs.a straight surface, creating LIFT. (Bernoulli's Principle).     Discover why an airplane will stall if there is too much air pressureunder the wing.     Discover how THRUST force is used to overcome DRAG force, caused by friction.Materials needed:     paper - ditto, 2 sheets per person              markers or crayons           - 2cm. x 8cm., 1 per person               small box fan           - newsprint for graph, 1 per team         cool air vaporizer           - cups, 2 per person                      scissors           - clips, 5 per team                       cellophane tape     launcher, wood, with rubber band and thumb tack     floodlightStrategy:     Without any verbal explanation, the teacher will fly a paper airplane four times, measureing and recording the data on chalkboard after each flight. (The first flight will have 0 paper clips; the second, 1 paper clip; the third, 3 paper clips; and the fourth, 5 paper clips.)  The teacher will make a graph showing the distance of each flight then ask three questions,  "What did you see?"  "What was happening?"  "What does the chart show?"  The students will be able to read the graph; identify the source of the data; and then label it to show "Average horizontal distance".      The students will be encouraged to hypothesize the reason some airplanes flew straight, others either went to the right or to the left.  (Added weight, and uneven folds of the airplane.)The students will be grouped into teams of not more than four.Activity 1: The students will make identical airplanes from one sheet of ditto paper.  Step 1, fold paper in half, the long side.  Step 2, turn paper over, like an open book (spine up).  Step 3, fold upper corners toward center fold.  Step 4, fold down set of corners toward bottom of paper.  Step 5, repeat Step 3.  Step 6, fold back along original fold.  Place folded portion on bottom.  Step 7, bring one wing portion down to fold, starting at the nose carefully fold down to make a wing, repeat for second wing.  (It is important that the creases are even and sharp.)  The students will be given an opportunity to test their planes for air worthiness.  Following this test flight, they will then make another airplane.  Each team member will test their planes to determine the MOST air worthy plane to be used in the next activity. Activity 2: Teams will repeat the teacher's demonstration, using only ONE plane.  However, they will fly three trials of each, and record the distance on a data sheet.  Using the data, a graph of the "Average distance of each flight,"  will be made.  The students will explain their graphs and compare them to the other graphs.  (The added weight affects the distance because of GRAVITY, and the placement of the clips on the keel of the plane, = center of gravity) Activity 3: Each student will hold the end of a 2cm x 8cm piece of paper to their mouth and blow over the top of the paper.  (The end of paper rises.)  Now blow underneath, what happens?  Measure 3cm from the short end of the paper and fold, tape the ends.  Drape the untaped end between the forefingers of each hand, now blow over the top.  What happens?  Blow hard across the flat side.   What happens? Activity 4:  Pass out 2 paper cups to each student and a pair of scissors per team.  Students should hold the cups about 5cm (2") from their mouth and blow between the rims of the two cups.  (The inner cup will pop out.)  Cut out the bottom of one of the cups, place it on the bottom of the other cup, and  blow again.  The cup will no longer pop out.  (Air pressure is lost through the bottom of the cup.) Activity 5:  Using a box fan, blow vapor from vaporizer over a wing model to show how air travels over the curved and straight surfaces of an airplane wing. Students will discuss what they saw.  Repeat the demonstration.  Raise the front edge of the wing and repeat the vapor (air) flow demonstration.  Discuss and repeat.  For the third demonstration, raise the front edge so that the vapor hits the bottom of the wing.  Ask students what would happen if this was an airplane?  (Plane would stall and fall).  Using an overhead projector transparency with the three wing positions, ask a student to show the path of air using arrows.  Is this similar or different from the paper cup? Activity 6:  Introduce Bernoulli's Principle.  It takes more energy to move over a curved surface, less pressure causes LIFT FORCE.  Gas, steam, water, and other liquids are similar to air. Activity 7:  Using a model glider placed on a table or desk, ask students to hypothesize why the plane isn't moving.  Push it, why isn't it lifting.  What is holding it down?  (GRAVITY)  Ask students to explain how Bernoulli's discovery applied to counteract the FORCE OF GRAVITY.  Have a student hold a sheet of paper in his outstretched hand, then have him run with it.  The paper will LIFT.  Ask the students to explain how this is applied to the glider. Activity 8:  If the glider is pushed it will move and then stop.  Ask students to explain how friction causes the glider to stop.  This is called DRAG FORCE. How does an airplane overcome DRAG?  What causes an airplane to move?  A propeller or jet engine creates THRUST FORCE.  When a plane speeds up, THRUST is greater than DRAG.  THRUST is the force that pushes an airplane forward through the air.      Aerodynamics is the study of air as it moves around objects.  Discuss other areas where Bernoulli Principle is applied.  (Automobiles, boats, trains have smooth surfaces, reducing friction, this is called "streamlining").  Engineers designing skyscrapers, suspension bridges, automobile carburetors, pumps, and water driven turbines, all use aerodynamics. Performance Assessment:     Make a diagram of air currents, using arrows to show the direction of the air above and below an airplane wing.  Indicate the FORCES involved, and where more air pressure, and less air pressure is present.      Make a diagram of an airplane.  Show the direction of the four main FORCES that affect flight.  Pair the forces.  Describe the balance of forces. Rubric:     5 points - Identification of less air pressure over the curved surface of the wing, and more air pressure under the wing.  The direction of the forces of GRAVITY, LIFT, THRUST, AND DRAG, are correctly drawn.  GRAVITY vs. LIFT, and THRUST vs. DRAG are paired.  A correct description of how LIFT and THRUST balance GRAVITY and DRAG as opposing forces.                                    4 points - Indicates an understanding, but has not described how the forces are balanced, or has not identified the air pressure.     3 points - Has not indicated the correct direction of the forces of GRAVITY, LIFT, THRUST, and DRAG, but has described how the forces are balanced.      2 points - Has not identified the air pressure.     1 points - Has not written anything, has only drawn arrows.REFERENCES:Model Science Supplement for Magnet Schools and Magnet Programs K-6.  Chicago:Board of Education,  1991, pp.270-275.SuperScience Red, v.4, n.6.  New York: Scholastic, March, 1992.Urquhart, David.  The Airplane and How it Works.  New York: Henry Z. Walck, 1971 World Book Encyclopedia, v.1.  Chicago: Field Enterprises, 1973.`