The Physics of Flight Outreach Program Lesson Plan
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The Physics of Flight Class Description- In this class, students will explore the forces involved in flight through several demonstrations and experiments. They will work to design their own gliders in groups and participate in the design process. Total class time: 90 minutes Class Outcomes- -Students will be able to identify and explain the four basic principles of flight: Weight, drag, lift, and thrust. -Students will be able to describe the Bernoulli Effect and its role in generating lift. -Students will understand the basics of the design process, and will use that process to create a basic paper glider. Materials List- The kit to teach this class should include: -Drinking Straws -Balloons (standard latex) -String -Ping-Pong balls or empty soda cans -Copy paper -Paper clips -Scotch (Clear) Tape -Masking Tape or Chalk
The Physics of Flight Pre-Class Preparation and Set-Up Before teaching this class, try out the activities and demonstrations yourself, so that you know what to expect for timing and findings when you do them with students. Gather materials, and print out paper airplane instructions and templates from the end of this lesson plan. Do an internet search, and print some pictures of different flyers to use at the beginning of class (airplanes, gliders, helicopters, kites, birds, bugs, etc.) Or, if you will have access to a computer and projector with your students, put together a quick slideshow of pictures. Depending on your classroom space and set-up, you may want to set up the airfoil floor diagram (from the Lift! section) before class starts. Set up chairs and tables to provide group work space. Introduction (5 minutes) Who has watched something fly before? Whether it was a plane or helicopter, a bird or a bug, we ve all seen something fly. Has anyone ever imagined themselves flying? Humans have always been fascinated by flight, and although we may not be able to fly as perfectly as a bird, we have developed ways to get airborne. Have students take a look at pictures of different flyers (either printed out before class, or on a projector.) What things do they have in common? How are they different? How do they compare to flyers we find in nature? Today we will be Aerospace Engineers! We will be looking at airplanes and gliders, and the forces involved in flight. There are four forces that act on an airplane as it flies, and they are: Thrust, lift, drag, and weight. (Draw a simple diagram on the board to illustrate these concepts.) Weight of course is the force of gravity acting on the mass of the plane. Drag is the force of the air pushing back on the plane as it moves forwards. The other two forces (lift and thrust) are what we are going to explore next.
The Physics of Flight Lift! (20 minutes) It seems almost impossible that something as large and heavy as an airplane can stay up in the air, or even get off the ground in the first place. The secret to this is LIFT. We re going to do a couple of little experiments to see how this works. Divide your students into groups of 3 or 4, and give each group two ping-pong balls, two pieces of string (each about 1 foot long), some tape, and a drinking straw. Have the students tape a ping-pong ball to each piece of string, and then dangle the two balls about 2 or 3 cm apart from each other. Attach the ends of the string to something solid, like a table (the ping-pong balls need to be dangling in open air- it will not work if they are up next to a wall.) Tell the students that they are going to use the straw to blow air between the ping-pong balls. Ask each group to record- what do they think will happen? Most will probably say that the ping-pong balls will be blown away from each other. Have the students try the experiment. What happened? The ping-pong balls should have moved closer to each other, maybe they even hit each other! Why? What s going on here? (This same experiment can be done using two soda or juice cans instead of ping-pong balls, if these are more available. Just lay the cans on a flat surface and use the straw to blow between them. The cans should roll together in the same way the pingpong balls come together.) If the ping-pong balls do not come towards each other, they are probably hanging too far apart. Have students reposition them closer together. Bring the class together for an explanation: We just witnessed something called the Bernoulli Effect taking place. Fast moving air creates low-pressure. The faster air moves, the lower the air pressure will be. When you blow between the two ping-pong balls (or cans) you create a pocket of low pressure between them. The higher pressure on the outside presses in on the ping-pong balls, and they come together. (Consider using a diagram, like the one on the right, to illustrate this to your students.)
The Physics of Flight Lift! (continued ) This Bernoulli Effect is used to keep airplanes up in the air, and we re going to do another demonstration to see how this works. Using masking tape on the floor, or chalk if you are outside on pavement, outline the cross-section of an airplane wing (which is called an airfoil.) It should be curved on the top, and flat on the bottom. Now, create airflow lines that come towards the airfoil, and then separate to go above and below the airfoil, then come back together after they have passed the wing. You can make the upper curve on the airfoil a little dramatic so that students can clearly see how this works. Once the picture is complete, make sure students understand what they are looking at, and which side of the airfoil is the top of the wing. To demonstrate how this works, your students will represent the air. In pairs, they should walk towards the airfoil at a slow pace. Have one pair of students demonstrate. Once they reach the airfoil, they get separated, and some of our air must go above the airfoil, and some below. Now, because there is no offset of the air, these two particles must reach the back of the airfoil at the same time. What does the air going over the airfoil (along the curve) need to do in order for this to happen? It needs to move faster. Have a few pairs walk through the demonstration so everyone sees. Now, if the air on top of the wing is moving faster, what does that mean? (Think about the last experiment we did...) It means that there is lower pressure above the wing! The slower moving air below the wing will be at a higher pressure, and will push the wing up. We call this force LIFT and it keeps our airplanes up! The Bernoulli Effect strikes again!
The Physics of Flight Thrust! (10 minutes) Now, in order to get this lift, we need to have some relative air movement. This may come from wind, but most aircraft need THRUST to get the air moving around the wings. This next demonstration will show us how thrust moves an aircraft. Get students back into their groups once again. Give each group a drinking straw, a balloon, a long piece of string (at least 2 meters) and some tape. One student should blow up the balloon, but don t tie it! Have the student hold it closed (or use a paper clip to prevent air from escaping.) Another student should tape the drinking straw to the balloon so that it is lined up from top to bottom with the balloon. Then, have the students put the string through the straw. Have two students each take an end of the string, and hold it tight, horizontally. Now, slide the balloon to the end of the string and you re set for take-off! Before they let go, have students make predictions. What will happen to our airplane (the balloon)? Why? When groups have made their predictions, they can release their balloon and let it fly! If nothing is obstructing its path, the balloon should zoom down the length of the string to the other end. So what is happening here? We are seeing Newton s Third Law of Motion: For every action there is an equal and opposite reaction. As air is forced out the end of the balloon, it exerts an equal and opposite force, which pushes the balloon down the string. This activity most closely demonstrates jet propulsion, but there are other forms of propulsion that can be used. Can you think of any? Make sure students have their straw and balloon oriented the correct way, or the demonstration will not work. If you have time, you can also use this activity to explain more about drag: Drag is the force from the air in front of the balloon as it makes it s way down the string. The air has mass, and wants to stay at rest. As the balloon pushes on the air in front of it, the air pushes back, which creates drag and slows the balloon down.
The Physics of Flight The Glider Challenge (40 minutes) Not all aircraft use continual thrust. Some aircraft have an initial thrust and/or use gravity to create relative airflow and generate lift. These aircraft are called gliders. We are going to create our own gliders out of paper! In the appendix you will find instructions and templates from www.funpaperairplanes.com. (These are commonly called paper airplanes, although they are really gliders because they do not use thrust once released from your hand.) Each group can choose a design, and follow the instructions to create a glider. Then, give them some initial thrust (throw them) and let them fly! Now that everyone has their basic glider, we are going to try to make them better. Help the students to brainstorm things that might make their gliders go farther or travel more accurately. Things to try: Add weights to your glider- Using paperclips on the glider may help it balance and produce more steady flight. Try putting weight in different places and see what happens. Create fins or tips- The vertical fins or tips can help guide airflow and keep your glider more stable. Adjust the length of the glider, wing angle, width, etc. Cut flaps in the wings or tail of your glider- They will act similarly to fins or tips. Try a different glider design- follow the instructions, or create your own! Before they go to try these things out, ask your students- How will you be able to tell if your current glider is better or worse than the last one you tried? Help students develop criteria (distance, accuracy, repeatability, speed, etc.) that they can record in notebooks or on paper that will help them judge their gliders. Give students plenty of time to adjust their gliders, and try out new things. Have students start with the basic designs first, then after the initial build, they can try the more complicated designs. If you have internet access, students can search for other designs to use too. If students have trouble getting creative with their glider, have them take a look back at the pictures from the beginning of class, and ask them to think about the types of things they see on real airplanes, or on birds (for instance, a tail.) Is there any way they can replicate that element with paper and tape?
The Physics of Flight Conclusion (15 minutes) At the end of class, gather your students back together to discuss what they did, and the process they went through to design their gliders. Ask some questions to get conversation started: What was your best design? What elements did it have that made it work? Did your group experiment with adding weight, fins, or flaps? What difference did these things make? Did placement of these things make a difference? No matter how great your glider was, eventually it would fall back to earth. Why are airplanes able to stay airborne so much longer than gliders? How do you think the process you went through compares to what real engineers would do when designing a glider? What would be the same? What would be different? While it may become more complicated for engineers, the design process that they use has the same components as the process that you used in class today. Aerospace Engineers are the people who design aircraft in real life- What do you think might be some exciting parts of that job, and what might be some challenges?
The Physics of Flight References- Paper Airplane Instructions and Templates from: http://www.funpaperairplanes.com/plane_downloads.html
Classic Dart This plane is the classic schoolyard dart. It has short, compact wings and will fly straight as an arrow. It generally needs some up elevator along the back wing edges to fly properly. Orient the template with the UP arrow at the top of the page. Then, flip the paper over onto its backside, so that you cannot see any of the fold lines. Pull the top right corner down toward you until fold line 1 is visible and crease along the dotted line. Repeat with the top left corner. Fold the top point down toward you until fold line 2 is visible and crease along the dotted line. 9
Fold the top left and top right corners down and toward you and crease along fold lines 3. Fold the tip up and over the two diagonal folds along fold line 4 to secure them in place. Flip the plane over and fold the right side over onto the left side as shown along fold line 5 so that the outside edges of the wings line up. Also make sure the diagonal folds do not become untucked from the tip you folded up in the previous step. Fold the wings down along fold lines 6 and the winglets up along fold lines 7. Add wing dihedral by tilting the wings up slightly away from the fuselage. The wings will have a slight V shape when viewed from the front. Cut two slits, one inch apart, along the back edge of each wing to make elevator adjustments. Start out by trying some up-elevator. You are ready to fly! 10
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Arrow This plane is easy to fold and flies straight and smooth. Add a small amount of up elevator for long level flights. Orient the template with the UP arrow at the top of the page. Then, flip the paper over onto its backside, so that you cannot see any of the fold lines. Pull the top right corner down toward you until fold line 1 is visible and crease along the dotted line. Repeat with the top left corner. 3
Fold the right side over again and crease along fold line 2. Repeat with the left side. Fold the tip down toward you and crease along fold line 3. Now, flip the paper over. Then, fold the left side over onto the right side and crease along fold line 4 so that the outside edges of the wings line up. Elevator Fold the wings down along fold lines 5. Partially open the folds you just created so that the wings stick out straight. Cut two slits, one inch apart, along the back edge of each wing for elevator adjustments. Add wing dihedral by tilting the wings up slightly away from the fuselage. The wings will have a slight V shape when viewed from the front. Read the Introduction for more information about dihedral. Now you are ready to fly! 4
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Condor This plane produces tremendous lift at low speed, giving it a very low glide slope. It is an excellent indoor flier and will coast across the room on slow, smooth glides. Orient the template so that the UP arrow is at the top of the page. Then flip the paper over so that none of the fold lines are showing. Fold the top left corner down toward you until fold line 1 becomes visible. Crease along the dotted line and repeat with the top right corner. Fold the nose down until fold line 2 becomes visible and crease along the dotted line. 12
Fold the outside wing edges in and crease along fold lines 3. Fold the right half of the plane over the left half and crease along fold line 4 so that the outside edges of the wings line up. Fold the wings down along fold lines 5 and the winglets up along fold lines 6. Add wing dihedral by tilting the wings up slightly away from the fuselage. The wings will have a slight V shape when viewed from the front. Add elevator slits along the back edge of the wings to adjust the flight if necessary. You are ready to fly! 13
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Raptor This plane is an excellent outdoor glider. Launch straight up and it will glide down in big lazy circles. Adjust the elevator on the back edge of the wing to perfect the flight characteristics. Orient the template so that the UP arrow is at the top of the page. Then flip the paper over so that none of the fold lines are showing. Fold the top right and top left corners in until fold lines 1 appear and crease along the dotted line. Fold the nose down toward you and crease along fold line 2. 29
Fold the nose down toward you again and crease along fold line 3. Fold the top edge down toward you again and crease along fold line 4. Flip the plane over and fold the right half over the left half along fold line 5. Flip the wings down along fold lines 6 and the winglets up along fold lines 7. Cut slits along the back wing edge for the elevator adjustment. Add wing dihedral by tilting the wings up slightly away from the fuselage. The wings will have a slight V shape when viewed from the front. You are ready to fly! 30
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Bullet This plane flies as fast and as far as you can throw it, although it is not very stable during flight. It is a true dart and is very streamlined. The folds are very compact in this design, and accurate firm creases are critical. Orient the template so that the UP arrow is at the top of the page. Then flip the paper over so that none of the fold lines are showing. Fold the top left corner down toward you until fold line 1 becomes visible. Crease along the dotted line and repeat with the top right corner. Fold the left side over again and crease along fold line 2. Repeat with the right side. 21
Fold the left side over once again and crease along fold line 3. Repeat with the right side. Make sure that you are making firm, crisp creases along each fold line. Fold the tip of the nose down toward you along the fold line. Fold the right half of the plane over onto the left half along fold line 4 so that the outside edges of the wings line up. Again, make a firm crease along this fold. Fold the wings down along fold lines 5 and the winglets up along fold lines 6. Add wing dihedral by tilting the wings up slightly away from the fuselage. The wings will have a slight V shape when viewed from the front. You are ready to fly! 22
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