How Far Will It Fly? Build & Test Paper Planes with Different Drag

Introduction

Paper airplanes are fun and easy to make. Just fold a piece of paper into a simple plane and send it soaring into the sky with a flick of your wrist. Watching it float and glide in the air gives you a very satisfying and happy feeling.

But what allows the paper plane to glide through the air? And why does a paper plane finally land? To find out, we will talk about the science behind flying a paper plane and the different forces that get a paper plane to fly and land. These same forces apply to real airplanes, too. A force is something that pushes or pulls on something else. When you throw a paper plane in the air, you are giving the plane a push to move forward. That push is a type of force called thrust. While the plane is flying forward, air is moving over and under the wings and is providing a force called lift to the plane. If the paper plane has enough thrust and the wings are properly designed, the plane will have a nice long flight.

But there is more than lack of thrust and poor wing design that gets a paper plane to come back to Earth. As a paper plane moves through the air, the air pushes against the plane, slowing it down. This force is called drag. To think about drag, imagine you are in a moving car and you put your hand outside of the window. The force of the air pushing your hand back as you move forward is drag. Finally, the weight of the paper plane affects its flight and brings it to a landing. Weight is the force of Earth's gravity acting on the paper plane. Figure 1 below shows how all four of these forces, thrust, lift, drag, and weight, act upon a paper plane.

Figure 1. When a paper plane is flying, the four forces of thrust, lift, drag, and weight are acting upon the plane, affecting how well its journey through the air goes.

Well, what do you think? Would you like to start experimenting with these forces? In this aerodynamics science project, you will make a basic paper plane and then slightly alter its shape to increase how much drag is acting on it. You will investigate how far the basic paper plane flies and compare that to how far it flies when the drag is increased. How will adding drag affect your plane's flight? You can answer this question with just a flick of your wrist.

Terms and Concepts

• Force
• Thrust
• Lift
• Drag
• Weight
• Gravity
• Data
• Vertical
• Accurate
• Wind Tunnel
• Computer Simulation
• Turbulence
• Streamlines

Questions

• What is drag and how does it affect airplane flight?
• How do you think you could change how much drag a paper plane has?
• What provides thrust to a real airplane?

Materials and Equipment

• Paper (3 sheets)
• Metric ruler
• Masking tape (1 roll). Alternatively, if you are testing this project outside, you can use sticks or rocks.
• Tape measure
• Scissors
• Lab notebook
• Optional: Computer on which to run wind tunnel simulation software

Experimental Procedure

Flying the Planes

1. Go to the Amazing Paper Airplanes webpage with folding instructions for the basic dart design:
   1. Lee, K. (2012, July 25). Basic Dart: Folding Instructions. Amazing Paper Airplanes. Retrieved February 13, 2013, fromhttp://www.amazingpaperairplanes.com/Basic_Dart.html
2. Fold a piece of paper into the basic dart paper plane following the instructions.
   1. Figure 1 in the Background tab shows an example of a paper plane made using the basic dart paper airplane design.
   2. Make sure that you fold carefully and that your folds are as sharp as possible.
   3. In step 6 of the folding instructions, skip the optional step of bending up the tailing edge of the wings.
3. Repeat step 2 two more times so that you have a total of three paper planes. They should all look identical.
4. Make a data table in your lab notebook, like Table 1 below, where you can record the data you get from your experiment.

Paper Plane	Flight 1	Flight 2	Flight 3	Flight 4	Flight 5	Average
Plane 1
Plane 1 with Added Drag
Plane 2
Plane 2 with Added Drag
Plane 3
Plane 3 with Added Drag

Table 1. In your lab notebook, create a data table like this one. For each flight, write down how far the paper plane travels (in centimeters [cm] or meters [m]).

5. Go to a large area to fly your paper plane. Make sure that there is no foot or car traffic at the area. A long hallway or your school gym is a good location. If you are flying your plane outside, like in a baseball field or on a basketball court, do your experiment on a day when there is no wind.
6. Tear off a 5-foot-long piece of masking tape and tape it to the ground in front of you, going from left to right. This will be the starting line from which you will fly the paper planes. If you are doing this science project outside, you could use a line of sticks or rocks to mark the starting point.
7. Practice throwing or launching the paper planes. You will want to launch the planes in exactly the same way every time. Hold the planes at exactly the same spot on the plane every time you launch a plane.
8. Once you have finished practicing, it is time to start the experiment. Place your toe on the starting line you prepared earlier and then throw one of your planes.
9. Use the tape measure to measure how far (in centimeters or meters) the paper plane flew from the starting line. Record this distance in the data table in your lab notebook.
   1. This will be "Flight 1" for "Plane 1."
   2. Science is done in metric units (e.g., centimeters and meters) so your data should be written as such. If your tape measure does not have metric units, you can convert inches or feet to centimeters or meters using this website:
      1. Science Made Simple, Inc. (n.d.). Length conversion using online length converter by Science Made Simple. Retrieved February 13, 2013, from http://www.sciencemadesimple.com/length_conversion.php
10. Repeat steps 8-9 four more times using the same plane, trying to throw the plane as similarly as possible. Doing these repeats will help ensure that your data is accurate and reproducible.
    1. Before you fly the plane, make sure that it is in good condition and that the folds and points are still sharp.
    2. Record the distances in the data table in your lab notebook all in the same row as "Plane 1," as "Flight 2," Flight 3," "Flight 4," or "Flight 5."
11. Once you have flown plane 1 five times, change the plane to increase its drag.
    1. Look at the back of the plane, where the wings meet the ridge in the middle.
    2. Using scissors, cut slits that are 2.5 cm long right where either wing meets the middle ridge.
    3. Fold up the 2.5 cm cut section on both wings so that these sections are at about a 90 degree angle from the rest of the wing, as shown in Figure 2 below.
    4. How do you think this increases the plane's drag?

Figure 2. To increase the paper plane's drag, first cut slits 2.5 cm long where the wing meets the ridge at the back of the plane, and then fold these cut sections up. Each wing should now have a 2.5 cm long section at the end of the wing that is folded up, at about a 90 degree angle from the rest of the wing, as shown in these pictures taken from different angles.

12. Using plane 1 with added drag, repeat steps 8-10.
    1. Record the distances the plane flies in your data table in the row titled "Plane 1 with Added Drag."
    2. In your lab notebook, record any observations about how this plane appears to fly compared to how plane 1 flew before you added drag.
13. Repeat steps 8-12 using one of the other two planes you made (in step 2).
    1. Record the distances the plane flies in the row titled "Plane 2" and then "Plane 2 with Added Drag" once you repeat step 14.
    2. In your lab notebook, record any observations you make.
14. Repeat steps 8-12 using the last of the three planes you made (in step 2). (This plane should not have been flown previously.)
    1. Record the distances the plane flies in the row titled "Plane 3" and then "Plane 3 with Added Drag" once you repeat step 14.
    2. In your lab notebook, record any observations you make.

Analyzing Your Data

1. Using the data you collected in the data table in your lab notebook, calculate the average distance that each plane traveled, with and without added drag. Record your results in the column labeled "Average" in the data table.
   1. For example, if plane 1 traveled 4.60, 4.14, 5.00, 5.33, and 3.86 meters on flight 1, 2, 3, 4, and 5, respectively, to figure out its average distance you would first add these five distances together (which gives you 22.93 m) and then divide this number by five, which gives you an average distance of 4.59 meters.
2. Use the data from your data table to create a bar graph.
   1. You can plot your data by hand or you can plot your data online at Create A Graph.
   2. Label the x-axis (the horizontal axis) "Paper Plane" and label the y-axis (the vertical axis) "Average Flight Distance." You will have six bars, one for each of the planes without added drag, and one for each of the planes with added drag. Make each bar go up to the average distance that plane traveled.
3. What does your graph tell you? How did adding drag to your paper planes affect how far they flew?
   1. Can you explain your results in terms of how forces allow a plane to fly? Hint: Re-read the Introduction in the Background tab.

Optional: Use a Wind Tunnel Simulator

It was pretty easy, fast, and inexpensive for you to test different versions of a basic paper airplane with added drag. But what about engineers who have to design and test real airplanes that cost millions of dollars? It would be much too expensive to build and test each different version of the plane. Engineers use wind tunnels to test smaller models of planes, which is much faster and cheaper. To allow even quicker testing, they can use computer simulations of different plane designs, then they do not have to build a physical model at all, and can do all the testing on a computer.

In this project, you can use simple, free wind tunnel simulation software called Flow Design to compare different versions of your paper airplane. Flow Design simulates the flow of air around a three-dimensional object (illustrated by the colored lines in Figure 3, below) and calculates the drag force on that object. Flow Design will help you visualize how the air flow changes around the plane, and how the drag force increases, when you add flaps to the plane, as described in step 11, above.

Figure 3. These screenshots of the Flow Design software show simulation of airflow around two different paper airplane models. The plane on the top does not have flaps on the back, so the airflow is very smooth. The plane on the bottom has flaps that make the airflow much rougher (this is known as turbulence).

To get started using Flow Design to analyze different paper airplanes, follow these steps:

1. Follow the directions at autodesk.com/education/free-software/flow-design to download and install Flow Design on your computer. This requires creating a free Autodesk.com account.
   1. Remember to check the system requirements at http://www.autodesk.com/store/flow-design/system-requirements to make sure your computer can run FlowDesign.
2. Download the 3D design file for the regular paper airplane and save it on your computer.
3. Download the 3D design file for the paper airplane with flaps and save it on your computer.
4. Read the instructions and watch the videos at http://help.autodesk.com/view/ADSKFD/ENU/ to learn how to use Flow Design. Spend some time getting familiar with the software before you continue.
   1. Note: you will need to follow instructions for the "standalone" version of Flow Design. Flow Design is also available as a plugin for other Autodesk programs called Inventor and Revit, which have different interfaces.
5. One at a time, open the "regular paper airplane" and "paper airplane with flaps" files in Flow Design.
   1. View the streamlines, or lines representing air flow around the models. How do they differ for the two different models?
   2. Flow Design also calculates the drag force on each model. Is the drag force bigger for one of the designs?

If you really want to be creative, and design and test your own paper airplane models, you can use Computer-aided design (CAD) software to design any type of paper airplane that you can dream up, and then test it in Flow Design. If you want to try designing your own paper airplanes in CAD, refer to the Science Buddies abbreviated project idea Design and 3D-Print Your Own Robot! to get you started.

Variations

• Does size matter? Make planes of different sizes but keep the design and the type of paper you use the same. Do bigger planes fly further?
• Do more complicated planes fly further? In order words, does the number of folds that you use to make a paper plane affect the distance that it flies? Try this out using the same size and type of paper.
• Does the type of paper you use affect how far the paper plane flies? Try making paper planes out of different types of paper, such as printer paper, construction paper, and newspaper. Make all of the planes using the same design and fly them as similarly as you can. Does one type of paper seem to work best for making paper planes? Does one type work the worst? You may need to do several trials to see a trend.
• Some people like to add paperclips to their paper planes to make them fly better. But where should the paper clips be placed for the best flight? Try adding paperclips to the back, the front, the middle, or the wings. You can add one paper clip or several, but try to be consistent with how many you use. Take notes in your lab notebook so you know what you tested. Does adding paperclips somewhere make the paper plane's flight better, worse, or have no effect at all?