Pneumatic Catapult Games Using What You Know to Make the Throw. Pressure x Volume = Energy. = g

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1 Pneumatic Catapult Games Using What You Know to Make the Throw Pressure x Volume = Energy θ Mega Pascal s KE PE Range = Release Velocity g 2 1

2 Pneumatic Catapult Games Using What You Know to Make the Throw Description Engineering games provide purposeful engagement and fun for teachers and students. Teachers and students who participate in engineering games discover, demonstrate and share what they know and are able to do. Designing, building, testing and playing are dynamic parts of any engineering education program. Engineering games couple science, technology, engineering and math skills with performance assessment and purpose. Pneumatic Catapults: Compressed Air Powered Games Games are Engineering Immersion Activities. Participating teachers and students demonstrate science, technology, engineering and math skills by participating in a culminating activity involving the design, testing, construction and operation of a working pneumatic catapult. Terms and Concepts Precision Accuracy Percent Error Repeatability Algorithm Trajectory Materials/Equipment/Supplies/Software (Suggestions Only) Masking tape or plastic tape 8 ½ x 11 white paper sheets 8 ½ x 11 carbon paper sheets Calculator Spread Sheet Software 30 (10m) Tape Measure SolidWorks Software Completed Pneumatic Module Projectiles (Wood or hard plastic) Technology Standards Addressed in This Lesson Develop troubleshooting, research, invention, innovation and experimentation to solve problems relating to catapult targeting and performance. Objectives Students and teachers who participate in this lesson will: 1. Use geometry and trigonometry to develop a game scoring methodology. 2. Construct a pneumatic catapult capable of hurling a spherical (wood/plastic) projectile a minimum of Accurately and precisely target pneumatic catapults 4. Construct and implement modifications to a pneumatic catapult in order to improve the performance of the mechanism. 5. Organize and manage the production of a pneumatic catapult game. 6. Invent and implement a pneumatic catapult game designed and engineered by the student s 2

3 Pneumatic Catapult: One Game Idea Description Pneumatic Catapults is a targeting game. The objective is to post the highest score for 5 hurls or throws at the center of a target pad. Scoring is based on distance, accuracy and precision. Darts is the model for this game. The pneumatic catapult playing field requires a large open space with hard flat floors, high ceilings and little wind. The foyer, theater, stage, gymnasium and school cafeteria often provide ideal spaces that can accommodate several simultaneous game sessions. Minimum interior space requirements Length ( 8-9 meters ) Width ( 3-5 meters ) Ceiling hgt ( 3-4 meters ) The Scoring Pad The scoring pad is formed from sandwiched layer of carbon paper placed between two layers of white paper. The carbon paper creates a mark, where the projectile lands. This makes scoring a definitive process. The scoring pad or target is assembled using 8 pieces of white 8 ½ x 11 letter size paper sheets and 4 pieces of 8 ½ x 11 carbon paper sheets. Tape the white paper sheets together in groups of four as shown below. This will make form two scoring pads measuring 17 x 22. Note: Tape only one side of the paper sheets and always lay the taped side down (towards the floor). Assemble the 4 carbon paper sheets in a similar manner. Be careful to tape the sheets on the NON- CARBON side. The assembled carbon paper sheet is sandwiched in between the white scoring pads with the taped side up and the carbon or printing side down. 22 White Paper Target Side Up Taped Side Down Carbon Paper Taped Side Up Carbon or Printing side down 17 Down 3

4 The Target Each of the (2) white paper target layers should have identical target circles drawn on their top face. The intersection of the corners of the four papers should be the target center. The totally trebuchet target is formed using a series of 3 concentric circles having diameters of 16 (40cm), 8 (20cm) and 4 (10cm) respectively. 4 8 (20cm) 16 (40cm) Scoring Values The scoring values for the target circles are based on their relative areas. Area of a 16 circle = Approximately 201 in 2 (1297cm 2 ) Area of a 8 circle = Approximately 50.2 in 2 (324cm 2 ) Area of a 4 circle = Approximately 12.6 in 2 (81cm 2 ) The Scoring Algorithm The scoring algorithm for the Totally Trebuchet Game is based on the relationship between the diameter of a circle and the area of the circle. When the diameter of circle is halved, the area of the circle is reduced by 4 times. Conversely, when the diameter is doubled the area is increased by a factor of 4. This is evident in the relationship between the diameters and areas of the target circles listed above. Note: The larger, 16 diameter circle contains the same area as 16 of the smaller 6 diameter circles. The assumption is that the smaller circle is 16 times less likely to be hit. (In actuality it is 15 times harder due to overlapping areas). This relationship between the diameter and area of a circle forms the geometric foundation for an important science principle: The Inverse Square Law. Take the time to look it up and discover how it can be applied to the solution of a variety of energy and radiation problems. 4

5 Scoring The score for each throw is calculated by multiplying the point score by the range. The total score is the sum of five consecutive throws. The range is established by a calibration throw. (Note: A properly constructed GEARS pneumatic catapult should be capable of hurling the 1 wood ball a minimum distance of 20.) This is an initial throw made by a competing pneumatic catapult that has been secured to the floor in any of several ways. These include tape, or by securing the model trebuchet to a stiff weighted platform. The calibration throw is used to establish the location and distance between the target center and the trebuchet. Once made, the calibration throw determines the playing field set up, and no further adjustments are allowed. The target center is secured in place directly over the landing point of the calibration throw. The target should be secured in such a way that it is not easily moved out of place, but allows for the top sheets to be rolled back to reveal the point score after each throw. This can be accomplished with tape or weights. Following the calibration throw, the team makes 5 consecutive throws and records the point score for each throw. Scoring is marked by a dark blue circle formed on the bottom target paper by the contact of the projectile against the carbon paper. It is important that the target sheets be carefully aligned and secured together with staples or tape along one edge. Each time a throw is made the top target sheets can be rolled back to reveal the mark made by the contact of the projectile and the carbon paper. Any scoring mark that touches a target circle is considered to be INSIDE that circle area. Circle each mark after every throw and label it with the team number and date. Using different colored pens makes it easier to differentiate between teams or series of trials. In this way a single target can be used many times. Record the scores and range on the scoring sheet provided at the end of this text. The team with the greatest total score value for 5 consecutive throws, wins. Playing the Game The pneumatic catapult games begin after the GEARS pneumatic modules have been constructed, tested and improved through the addition of throwing arms, projectile holders or any adjustments and other modifications approved through discussion between the participating players. Note: It is advisable to allow a maximum of only 0.7mPa or100psi of reservoir pressure and no more than 0.35mPa or 50psi of system (working) pressure. Increasing the working pressure is not a particularly insightful improvement and only serves to stress the components. The engineering objective of this activity is to extract the maximum performance within a given set of parameters. 5

6 Example Game Procedure The procedures described below are the responsibility of the playing teams. The instructor should serve only to observe and answer direct questions. 1. The completed pneumatic catapult is secured to the playing field floor in one of several ways: Taped to the floor ( Not the best) or secured to a weighted deck made from stiff materials like tag board or plywood (Suggested). It is important to take precautions to insure that the pneumatic catapult does not move inadvertently during the throw. How this is accomplished depends on the engineering efforts of the playing team and their motivation to succeed. 2. Make a calibration throw and mark exactly where the projectile landed. Measure the distance from an agreed upon point on the pneumatic catapult assembly, to the landing point of the calibration throw. The purpose of the calibration throw is to establish the target center and the scoring range of the pneumatic catapult. 3. Tape the target to the floor with the center of the target directly over the marked landing point of the calibration throw. 4. Make a series of 5 consecutive hurls without moving the pneumatic catapult or the target. 5. Record the point value of each throw on the score sheet provided at the end of this chapter. Each time the projectile lands on the target a carbon contact point is marked on the bottom sheet. Circle this point and mark the team number and date next to it. This will allow the participating teams to use the targets through multiple trials. In addition, the top and bottom layers can be reversed. This provides two sets of targets and serves to protect the more valuable carbon paper. Note: The carbon paper can be used for many trials, and even through several seasons of play. 6. Compute the score for each throw. This is accomplished by multiplying the point score of each throw, by the measured distance of the calibration throw. 7. Sum the five scores. The team with the highest total wins. Creating New Challenges Some of the creative enjoyment of participating in engineering challenges comes from creating them. Students should be encouraged and allowed to develop additional trebuchet challenges in which they can exercise the joy of being creative. The GEARS pneumatic module and parts can be used alone or combined with other Found components and new ideas in order to create any number of engineering challenges. Regardless of which games and challenges are developed, it will be necessary to provide documentation. The production of the game rules, description and objectives is a valuable exercise in engineering creativity and communication. Students should be encouraged to create games and document them. This will help build a library of games for an engineering program of activities. It is not enough to think up a new game. It is necessary to risk playing it, work the bugs out of it, and document it. Creating engineering challenges that have multiple solutions arrived at through the exercise of creative thinking and the application of math, science and engineering knowledge is a worthy accomplishment. Inventing engineering games employs high order thinking skills and playing them helps to develop these skills. 6

7 Pneumatic Catapult Games Score Sheet Team Number: *Trial Date Team Members: Throw Points Scored Calibration Range **Computed Score Notes: Corrections, adjustments etc Grand Total *Performance gains are achieved through multiple trials and experimentation **Computed Score = Points Scored x Pneumatic Catapult to Target Center Distance Note: Show all scoring calculations on the back of this page. 7

8 Pneumatic catapult Games Assessment Rubric This rubric is offered as an example. Teachers and students are encouraged to create assessment tools that reflect their needs and expectations. Required Skill or Competency Meets or Exceeds this Requirement Meets Some of this Requirement Meets little or None of this Requirement Participates in the pneumatic catapult game by making five competitive throws and recording the results on the assigned score sheet. Score 4-5 pts Score 2-3 pts Score 0-1 pts Participates in the creation and construction of a target pad. Modifies, improves, tests and records results in an effort to create a competitive pneumatic catapult Creates a pneumatic catapult capable of throwing a projectile 20 feet or more. Demonstrates leadership skills by consistently helping to manage and produce the pneumatic catapult games. Invents a new pneumatic module challenge and produces the scoring sheet and rules. Competitive placement in the pneumatic catapult games. (Highest point value for 1 st place) Maintains accurate and organized records of class notes, trial tests, CAD drawings and pneumatic catapult construction and modifications created during this activity. 8