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.

 The first plane to be designed with the intent to evade radar was the Horten Ho 229 in 1943 (Horst).  In the nineteenth century, James Clerk Maxwell, a Scottish physicist, created mathematical formulas to determine how electromagnetic radiation would scatter after hitting a specific geometric shape (“Stealth Technology”). Throughout the 50s and 60s, scientists and mathematicians continued to try and develop formulas and models of how electromagnetic waves reflect off surfaces (“Stealth Technology”).  By the 1970s, the United States needed stealth technology, for their planes were continually being shot down (Science Buddies). Denys Overholser, a computer scientist, and Bill Schroeder, a mathematician, created a computer simulation using the equations by Petr Ufimtsev (Science Buddies). This simulation showed how electromagnetic waves reflect off both two-dimensional and three-dimensional shapes (Science Buddies). This program allowed scientists to accurately predict what a radar signature would look like before the plane is built (Science Buddies). Using the program, the United States was able to design a plane that could evade 99% of electromagnetic waves (Science Buddies). Overtime, stealth technology developed even further. Stealth technology is a variety of technologies and design features that decreases the distance a vehicle can be detected by either radar, infrared, or sonar (Science Buddies). Scientists are constantly working on and improving stealth technology . Planes, specifically, use stealth technology to avoid detection by radar. Radar is a system used, in this instance, for detecting the presence, speed, and location of planes (Woodford). This system works by sending out radio waves (similar to light waves but are longer and have lower frequencies) in a direction (Woodford). If a plane is hit by such waves, it reflects the waves back towards the radar where a sensor will pick it up (Science Buddies). The plane will then show up as a blip on the radar display. To make an aircraft stealthier, scientists can reduce the aircraft’s radar cross-section, the measure of how detectable an aircraft is on radar(Science Buddies). In order to reduce radar cross-section, there are two methods commonly used by stealth planes: absorption and deflection (Horst). Absorption works by covering the plane in radar absorbing coating (Suk). These coatings have electric and magnetic properties that absorb the microwaves radar sends out (Suk). However, these coating designs are difficult to plan out as there are constraints retaining to the volume and weight that is allowable for the coating (Suk). The coatings also need to be cleaned and retreated after each flight in atmosphere controlled laboratories (“Stealth Warplanes”). Deflection works by using many angles on a plane to deflect radio waves (Horst). Radio waves bouncing off a plane are similar to light bouncing off a mirror (Harris). If they hit a tilted surface, it will reflect upwards rather than straightforward, like it would hitting a vertical, flat surface (Harris). The waves will hit the plane and bounce off in all directions (Horst). Round shapes on a plane have the chance of facing the radar when radio waves bounce off of them and do not scatter the waves in as many directions (Herring). Flat surfaces tend to only be presented directly above or below the radar, allowing the plane to fly undetected near radars (Horst). Faceted designs work best for stealth planes as the multiple surfaces efficiently reflect the radio waves away in directions that are not back towards the radar (Winarto). However, using faceted designs leads to aircraft being aerodynamically unstable (Science Buddies). Flight computers can be used to solve this problem efficiently and with low risk, allowing airplanes such as these to be able to stay airborne (Science Buddies). (5) Using deflection as my chosen method of stealth technology, I will be using an LED flashlight, light meter, and paper to act as the radar and plane. An LED flashlight produces an electromagnetic wave, visible light (Science Buddies).This electromagnetic wave will represent the radio waves produced by radar. To represent the radar’s receiver, a light meter will be used to receive the reflected light. A light meter reads the intensity of the brightness of light that can be seen with the human eye (Lister, Brownyn). It measures in lux, a measurement of illuminance. A single lux equals one lumen of light spread across one square meter (Lister, Brownyn). In this experiment, it will read the light reflected back by the test shape. The test shapes will be sheets of white printer paper. White paper, like all objects, reflect light (Saini). White objects in particular, do not absorb any visible colors of light, allowing it to act more as a deflection technology than absorption technology (Saini). Each test shape will represent a type of airplane.

 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.

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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).

All in all, stealth technology is a variety of designs and technologies that are used when designing stealth planes. These planes have a faceted design created by using a computer simulation to find the best shape to deflect radio waves. Evading radar, a system that detects the position of planes by sending out radio signals, is done mainly be reducing radar cross-section. One method of reducing radar cross-section is by building planes that deflect the radio waves. The more faceted the plane, the stealthier the plane is. My project focuses on which 3-d shape made out of paper is the stealthiest. This is tested by measuring how much light each shape reflects. A flashlight is shone on the shape and a light meter measures the light reflected. These represent the radar. The shapes (cylinder, crumpled cylinder, V-shape, and W-shape) represent the varying shapes and designs of stealth planes. 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.

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.
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• 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/.
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• “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.
• Winarto, Hadi. “Aerodynamic Implications of the Requirement for a Stealthy Aircraft.” Academia.edu, 2007, www.academia.edu/7670867/Aerodynamic_Implications_of_the_Requirement_for_a_Stealthy_Aircraft.
• Woodford, Chris. “How Radar Works: Uses of Radar.” Explain That Stuff, 24 Aug. 2018, www.explainthatstuff.com/radar.html.