A Classroom Study of the Lift of An Airplane

Introduction

An airplane has four primary forces acting on it: lift, drag, weight, and thrust. In this experiment, the lift is being examined. The lift of the airplane is the aerodynamic force that elevates it into the air and holds it there. For an explanation on how wings create lift, see Forces on an Aircraft.

Purpose

The purpose of this experiment is to discover the properties of lift.

Materials

• bicycle pedals 1/2" thread
• 1/2" brass (water piping) tee
• 3/8" diameter wooden dowel
• 3"x36"x1/16" balsa wood
• clamp
• fan
• manila folder
• paper tubes
• glue
• razor blade
• binder clip
• paper clips
• Ping-Pong ball
• string
• protractor

Alternatives:

• other type of bearing for bicycle pedal
• text books or other weight for clamp
• quart-sized milk cartons for paper tubes
• modeling clay for binder clip and paper clips
• pitot tube for Ping-Pong ball, string and protractor

Procedure

I. Set up the Wings (estimated time: 15 min.)

1. Cut the 3/8" diameter dowel to 26" inches
2. Cut out different sized wings of similar shape from 1/16" balsa wood using a razor blade (we chose four sizes of 30°, 60°, 90° triangles)
3. Cut a manila folder into a rectangle 8" x the length of your wing. Cut as many rectangles as you have sets of wings
4. Roll each piece of folder into a cylinder that fits snugly around the dowel
5. Glue each group of similar sized wings spaced evenly onto their respective cylinders
6. click here for pictures

II. The Flow Straightener (estimated time: 30 min.)

1. Roll pieces of 8"x11" paper into cylinder with a 1" or 2" diameter and 11" high
2. Glue all the cylinders together to cover the front of your fan
3. Another way to make a flow straightener is to glue together cut-open milk cartons

III. Setup (estimated time: 10 min.)

1. Slide the dowel through the brass T, so the T is roughly in the middle of the dowel
2. Use tape or rubberbands to secure the dowel in place
3. Screw the brass T with the dowel onto the bike pedal
4. Clamp bike pedal onto a table so the dowel swings freely
5. Place the fan in front of the dowel making sure that you don't obstruct the swing of the dowel
6. Clip a binder clip onto the front end of the dowel
7. Mark an angle for your dowel to fly at. A good angle would be anywhere less than 15 degrees from horizontal
8. click here for more pictures

IV. Run the Experiment (estimated time: 20 min.)

1. Use a method to measure the speed of the wind at each fan speed (click here to find out how we did it with a Ping-Pong ball)
2. Place the largest tail onto the end of the dowel
3. Hang enough paper clips onto the binder clip so that the dowel is balanced
4. Take off all the paper clips
5. Turn fan on highest setting
6. Start hanging paper clips off of the binder clip until the dowel flies at your specified angle
7. Record how many paper clips you used
8. Lower fan speed and repeat step 6 until you are out of fan speeds
9. Change the size of the tail pieces and repeat steps 3 through 7 until you have used all of your wings
10. click here for video clips

V. Analyzing the Data (estimated time: 20 min.)

1. Calculate the force of lift by setting the sum of every torque to zero (use our formula)
2. Plot the lift for each wind speed against the wing sizes
3. Plot the lift for each wing size against the wind speed

click here for data tables

Analysis

1. What do you notice about the relationship between the lift force and the wing size?

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2. What do you notice about the relationship between the lift force and the wind speed?

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3. Which wind speed and which wing size produced the most accurate results? The least accurate? Why do you think this is?

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4. What could have affected your results?

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5. How could you improve the experiment (setup, materials, data collection)?

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