## Test for 3-D Geometric Shape Reflection

Technology is constantly evolving. With its constant evolution brings the competition of creating even newer technology. Our military, and many others, have created planes able to evade enemy radar and fly undetected using stealth technology.  I plan to test which 3-D geometric shape reflects the least amount of light to determine which shape most efficiently evades radar.  I chose to test this topic because I wanted a unique problem that dealt with current issues and ideas. Stealth technology is constantly being worked on and comes in many shapes and forms. I chose to focus on radar stealth technology dealing with geometric shapes for an original experiment.

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My hypothesis for this experiment is as follows: If the W-shaped piece of paper is the best shape to evade radar, then the W-shaped paper will reflect the least amount of light picked up by the light meter.

To complete this experiment I will need to use a cardboard box approximately 24.14 x 43.20 x 36.80 cm, black construction paper, an LED flashlight with the on-off switch towards the end of the handle, a light meter, six sheets of white paper approximately 21.59 x 27.94 cm, a pencil, a ruler, tape, scissors, and a lab notebook. I estimate my experiment will take approximately one to two hours to complete. I will be following the following steps, based off of Science Buddies’ Stealthy Shapes science experiment, to complete my project.

To begin, the box in which the experiment will take place must be set up. To set up the box, first cover the entire inside of the cardboard box with black construction paper. This will limit the amount of reflection from surfaces that are not the shapes being tested. Next, tape the sensor part of the light meter to the inside of the box. Place the sensor so the base is resting on the floor of the box and placed in the middle of the side. Tape the back of the sensor to the wall to avoid the tape reflecting any light. Ensure the display part of the light meter lies outside of the box so it can be easily read. Then, cut a hole in the box that is able to hold the flashlight. The hole should be just big enough for the flashlight to fit through in order to reduce the amount of outside light. Place the flashlight with the on-off switch outside of the box and the LED light inside the box. It should be above and relatively close, about 1-3 cm, to the light meter. This will be the last step for setting up the box.

Next, create the 3-D shapes that will be tested. There will be four shapes: cylinder, crumpled cylinder, W-shape, and V-shape. First, make an open cylinder shape. Take one sheet of paper and overlap the two shortest sides to form a tube shape. Tape the inside of the newly formed cylinder so the sides form one crease. Next, create the crumbled cylinder.  Begin by crumpling a sheet of paper into a ball and uncrumpling it. Then follow the previous steps to make the crumpled paper into a cylinder. This will create the open crumpled cylinder. Next, create the W-shape. Fold a sheet of paper in fourths, across its width, so it has ridges that form a W shape. Repeat this step one more time with a separate sheet of paper. Then, create the V-shape. Fold a sheet of paper in half, across its width, so it has ridges that form a V shape. Repeat this step once more with a separate sheet of paper. These will be the six pieces of paper that will be tested.

Third, find a location to conduct the experiment. Set up the box in the location of your choosing. Place the rectangular cylinder in the center of the box with the crease facing away from the light sensor. This will act as your test shape. Draw a mark on the bottom of the box where the cylinder’s closest edge to the sensor lies. Use a pencil, for the mark may have to change. Close the box, ensuring that the flaps stay closed. Use books to hold down the flaps if they do not close. Turn on the light meter, then the flashlight. Read the light meter’s display to see how much light is being reflected back from hitting the cylinder. If the display reads less than 50 lx, turn off the flashlight and move the cylinder closer to the light sensor. Erase the previous mark and draw a new one. Repeat the previous steps. If the display reads over 50 lx, the experiment is ready to begin.

Fourth, it is time to test the shapes. Before the testing begins, keep in mind that an LED flashlight will be brightest when they are first turned on. As they stay on, they heat up to a steady-rate temperature, and at this point the light will not be as bright. To avoid this, turn off the flashlight after each trial. Now it’s time to test the shapes. Begin by placing the cylinder shape in the box. Make sure the cylinder’s edge lines up with the mark, the crease is facing away from the sensor, and the cylinder lines up with the flashlight. Once in place, close the box flaps and weigh them down if they do not stay. Turn on the light meter and then the flashlight. Record the measurement on the display immediately. Turn off the flashlight. Repeat for the other three shapes, each individually. For the W-shape and the V-shape you will want to pay attention to how you arrange them. The W-shape should be oriented so the two leading folds are facing the sensor. These folds will act as the leading edge and should be aligned with your mark. The V-shape’s single fold should face the sensor and will act as the leading edge. Complete 30 trials for each shape. Once complete, it will be time to analyze the data and make conclusions.

Last, interpret the data. Calculate the average illuminance for each shape using the 30 trials. Create a bar graph with the test shapes on the x-axis and the average illuminance on the y-axis. Compare the results. The shape with the least average illuminance will be the shape that is the stealthiest. The shape with the greatest average illuminance will be the least stealthiest. Conclude which shape was the stealthiest and how each shape relates to the profiles of stealth and commercial aircraft. Finally, accept or reject your hypothesis.

In my experiment, I will have multiple variables and controls. The dependent variable in an experiment is the variable whose value depends on another variable. In this experiment, the dependent variable will be the amount of light reflected back to the light meter. The independent variable is the who affects the dependent variable and is not affected by another variable. In this experiment, the independent variable will be the shape and the orientation of the paper. Control variables in a scientific experiment are variables or values that stay the same throughout the process. The control variables in this experiment include the type of paper used, the size of the paper, the amount of light coming from the LED flashlight, the type of flashlight, the type of light meter, the room or location that testing takes place, and the amount of outside light (if any).

Works Cited

Harris, Tom. “How Stealth Bombers Work.” HowStuffWorks Science, HowStuffWorks, 28 June 2018, science.howstuffworks.com/stealth-bomber4.htm.

Herring, Brian. “Radar and How to Evade It.” Physics Behind the F-22 Raptor, 17 Mar. 2007, ffden-2.phys.uaf.edu/212_spring2007.web.dir/brian_herring/Slide3.htm.

Horst, Adam Thomas. “How Does Stealth Technology Work.” Science in Our World Certainty and Controversy, 3 Dec. 2015, sites.psu.edu/siowfa15/2015/12/03/how-does-stealth-technology-work/.

Lister, John, and Bronwyn Harris. “What Is a Lux Meter?” WiseGEEK, Conjecture Corporation, 21 Sept. 2019, m.wisegeek.com/what-is-a-lux-meter.htm.

Saini, Sajan. “Why Doesn’t a Plain, White Piece of Paper Reflect Light, but a Mirror Does?” Mit Engineering, 21 Feb. 2012, engineering.mit.edu/engage/ask-an-engineer/why-doesnt-a-plain-white-piece-of-paper-reflect-light-but-a-mirror-does/.

Science Buddies Staff. “Stealthy Shapes: How to Make an Aircraft Invisible to Radar: Science Project.” Science Buddies, Science Buddies, 16 Jan. 2019, www.sciencebuddies.org/science-fair-projects/project-ideas/Phys_p075/physics/stealth-make-an-aircraft-invisible-to-radar#background.

“Stealth Technology.” Centennial of Flight: Born of Dreams, cybercemetery.unt.edu/archive/flight/20110713034254/http://www.centennialofflight.gov/essay/Evolution_of_Technology/Stealth_tech/Tech18.htm.

“Stealth Warplanes: They Can Run, But They Cant Hide.” The Thistle, 4 July 2000, www.mit.edu/~thistle/v12/2/stealth.html.

Suk, Han. “The Design of Broadband Radar Absorbing Surfaces.” Calhoun Home, Monterey, California. Naval Postgraduate School, 1 Sept. 1990, calhoun.nps.edu/handle/10945/30692.