The Effect of Drag on Various Wing Designs

Researched by Justin B. 
2003-04

PURPOSE

The purpose of this experiment was to determine which aerodynamic wing design created the least amount of drag.

I became interested in this idea because my dad works as a drafter at Smiths Aerospace and ever since he began working there, I’ve been fascinated with his work. 

The information gained from this experiment would help aerodynamic engineers create a plane that doesn’t need such a long runway to take off.

HYPOTHESIS

My hypothesis was that the wing designed with the Fighter Jet Airfoil would create the least drag. 

I based my hypothesis on a virtual wing design tester at http://www.pbs.org/wgbh/nova/wright/airborne.html.  It demonstrated that this design had the least drag. 

EXPERIMENT DESIGN

The constants in this study were
* The temperature of the wind tunnel
* The speed of the wind in the wind tunnel
* The day each wing design was tested
* The length of time each wing design was tested
* The time left in the wind tunnel
* Type of material used to create the wing designs
* The angle of attack (0 degrees)

The manipulated variable was the different wing designs tested in the wind tunnel. There were 4 different wing designs being tested. 

The responding variable was the amount of drag acting on the wing designs. 

To measure the responding variable I determined the amount of force that the wing designs pull on a spring scale. 

MATERIALS
 
 

QUANTITY ITEM DESCRIPTION
1 Wing suspender
1  Spring scale
1 Leaf Blower
4  6’’ pieces of balsa wood
1  Crafting knife 
1  Piece of sandpaper

2		 Right triangles from a 2’x2’ square, cut from .75” plywood
12 8-32 hex nuts
16 6x 1.5 screws
28 6x.75 screws
1 Clear packing tape
1 Electric tape
1 Low friction cart
1 Small pulley
1 100gram spring scale
1 Stopwatch

PROCEDURES

1. First, cut four 6’’ strips of balsa wood.
2. Sand these strips until you’ve created a High-lift airfoil, a Symmetrical airfoil, a Fighter jet airfoil, and a light airplane airfoil. (See appendix for sanding instructions.)
3. Set up your wind tunnel like so:
4. Suspend the spring scale above the hole in the top of the wind tunnel.
5. Tie two paper clips to the ends of your string.
6. Lead one of the paper clips through the pulley and through the hole on the top of the wind tunnel.
7. Attach the paper clip that went through the hole to the suspended spring scale.
8. Next, test the High-lift Airfoil in the wind tunnel for drag like so:
9. Suspend the High-lift Airfoil on the wing suspender and place it in the wind tunnel.
10. Attach the paper clip that’s in the wind tunnel to the wing suspender.
11. Next, turn on the wind tunnel you are using.
12. Leave the wing in the wind tunnel for one minute.
13. On the one minute mark, check the spring scale 
14. Record the number displayed on the spring scale.
15. Next, repeat steps 5-14 with the Fighter Jet airfoil.
16. Repeat steps 5-14 with the Symmetrical airfoil.
17. Finally, repeat steps 5-14 with the Light Airplane airfoil. 

RESULTS

The original purpose of this experiment was to determine which aerodynamic wing design created the least amount of drag.

The results of my experiment were the High Lift Airfoil and Symmetrical Airfoil had an average drag of 6.0 grams which was slightly lower than the Fighter Jet (6.7 grams) and the Light Airplane Airfoil (6.3 grams)

See the table and graph below.

CONCLUSION

My hypothesis was the wing designed with the Fighter Jet Airfoil would create the least drag. 

The results indicate that this hypothesis should be rejected because the Fighter Jet Airfoil had a drag average of 6.7, whereas both the High Lift Airfoil and Symmetrical Airfoil had drag averages of 6.0 grams. 

Because of the results of this experiment, I wonder if the drag produced by the wing designs would vary at a higher altitude because of less air density? 

If I were to conduct this project again I would create a wind tunnel that would produce 2-3 times more wind. I would use a better device to measure the force more accurately. I would create a wind tunnel that didn’t produce any eddies or gusts. I would do more trials on each wing. Better airfoil designs would also give me more accurate results.


RESEARCH REPORT

Introduction

Studying lift and drag of wing design could help Aerodynamic engineers create an airplane with a wing design that would be so efficient, it would cost less to fly an airplane. People can benefit from this research because during the holidays, more people would want to travel in a faster plane and get where they want to go quicker than travel in a slow airplane for 3 or 4 hours.

Flight Forces

Drag is just one of the four forces of flight; there is also gravity, thrust, and lift acting on the plane as it flies. As a plane takes off, the wings are producing lift as the plane starts to take off but for lift to be produced there must be another force working, thrust. Gravity is also acting on the plane, gravity pulls the plane down toward the ground and just as lift is pushing the plane up and acting against gravity, drag comes into play. Drag is the force that tries to stop the forward motion of the plane.

Friction

“Friction is the resistance offered to the movement of one body past another body with which it is in contact. In certain situations friction is desired. Without friction the wheels of a locomotive could not ‘grip’ the rails nor could belts transmit power.” The Columbia Encyclopedia, Seventh Edition. 

Friction causes heat, erosion of rubbing surfaces, and possible damage to machinery. To avoid friction, lubrication is often used in machines. Roller or ball bearings are also used to minimize friction.

Friction decreases if the contacting surfaces are really smooth, as a greater force is needed to move the surfaces past each other. That is why airplane surfaces tend to be really slick and smooth.

Fluid friction occurs in the flow of liquids and gases, like air.  Air friction is affected by increased wind speed. The modern streamline design of airplanes and automobiles is intended to minimize fluid friction while retaining speed and protecting the structure.

Aeronautics History

On the 17th of December at Kitty Hawk, North Carolina, Orville Wright was preparing to make the flight of the century. The cold air of December didn’t stop the Wright brothers from testing their makeshift airplane. To the public’s astonishment, the plane made the flight and retuned safely. From that cold morning of December to the first man on the moon, aviation has grown to greater lengths than probably what even the Wright brothers had expected. 

Aerodynamic Engineers

Aerodynamic engineers specialize in the construction of things such as airplanes and missiles. Not only do they design these mechanical wonders, they have to develop and test them as well. There are astronautical engineers that specialize in the area of spacecraft design. Aeronautical engineers specialize in the area of aircraft design.

Summary

Engineers and scientists study the four forces of flight to make transportation easy and quick. From the Wright brother’s flight to future flights, scientists will probably continue to study flight. An efficient design with good lift and low drag is less costly to fly.
 
BIBLIOGRAPHY

“Aerodynamics.” The World Book Encyclopedia 1998.

“Aerospace engineers.” Wing Designs. February 4, 2004<http://www.pbs.org/wgbh/nova/wright/airborne.html> 

Arnett, Landin. “The Effect of Different Fuselage Shapes on Drag.” November 22, 2003<http://www.selah.k12.wa.us/SOAR/SciProj2003/LandinA.html>

Bureau of Labor Statistics, U.S. Department of Labor, Occupational Outlook Handbook, 2002-03 Edition, “Aerospace Engineers,” on the Internet at http://www.bls.gov/oco/ocos028.htm (visited February 19, 2004). 

“Friction,” The Columbia Encyclopedia, Seventh Edition. 2002.

Lift and Drag October 17, 2003 <http://home.hccnet.n1/m.holst/LiftDrag.html> 

“Principals of Aerodynamics” The World Book Encyclopedia. 2002. 

ACKNOWLEDGEMENTS
 

I would like to thank the following people for helping make my project possible:
* My mom for driving me to get the supplies I needed
* My dad for helping me create my wing designs
* Mr. Newkirk for helping me perfect my journal and report.
* Mrs. Helms for just helping me here and there
* Other Advanced science Students for helping me put this project together and helping me along the way
* Mr. Smith for constructing the wind tunnel I used.

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