Water Bottle Rocketry A Basic and Refresher Workshop for Engineering Design Purpose & Objectives of this Session • Encourage and promote the integration of STEM standards and concepts into the building and designing processes of the Water Bottle Rocket Let’s Focus On • Explain Guidelines of the competition • Help you teach your students: – – – – Problems solving skills How to budget their time Cooperative behavior Engineering and design concepts What is a Water Bottle Rocket? A water rocket is a type of model rocket using water (and pressurized air) to produce the thrust needed to lift-off. The pressure vessel (the engine of the rocket) is usually a used plastic soft drink bottle. The water is forced out by a pressurized gas, typically compressed air, that produces thrust and lifts the rocket. Why use Water Bottle Rockets to Teach STEM Concepts • Its EXTREMELY FUN and an AWESOME attention getter • Great application & display of scientific concepts • Teaches students to communicate scientific ideas (both orally and written) • Easy way to teach Newton’s laws Why use Water Bottle Rockets to Teach STEM Concepts? • Effective means to foster student collaboration • Provides opportunity to use scientific tools and instruments • Awesome way to utilize mathematics to help achieve goals and outcomes STEM [ideas] of Water Bottle Rocketry Science Technology Engineering Mathematics Newton’s 3 Laws Flight Design Processes Manipulating variables to Maximize Hang time Inertia Research Assembly Fractions Thrust vs. Drag Material choice Testing Exponents Lift vs. Gravity Tradeoff Concepts Troubleshooting Square root Area Ballast Redesign Unit conversion Scientific Inquiry Center of Mass Build Techniques Measurements Aerodynamics Center of Pressure Wind Resistance Force(s) Order of Operation Equations/Formulas How are the Rockets Judged ? • An overall winner will be judged upon the following criteria (based on 100%). - Hang Time of Rocket - Technical Paper - Patch Design - Technical Drawing 45% 25% 15% 15% NOTE: Elementary School is only Judged on: - Hang Time of Rocket 70% - Patch Design 30% Final Hangtime Score Calculation Hangtime – the time from when the rocket (pressure chamber) leaves the launce pad until the time it reaches the ground or strikes an object Max Hangtime – maximum hang time recorded during the competition Final Score = Team hangtime X 100 max hangtime Safety First The next 4 Slides and 13 bullet points will cover Water Bottle Rocketry Safety. Why? I’m glad you asked…! Because water bottle rockets can be dangerous and can hurt someone if not handled properly. Fact: A water bottle rocket pressurized to 60 psi leaves the launcher at 70 MPH…! Safety Safety Safety…!!! • Water bottle Rockets and Water Rocket Launchers are NOT toys; thorough understanding of their function is required prior to conducting ANY launch activities • Extreme caution should be used at ALL times during launch activities • Trained Adult supervision is required at ALL times; Absolutely NO Exceptions Safety Safety Safety…!!! • Students and adults should wear safety goggles/glasses during all launch activities • NEVER stand directly in front of the launcher at ANY Time • NEVER approach a rocket that is under pressure • No running, horseplay, etc. around launch area during launch activities. Be attentive at all times. Safety Safety Safety…!!! • Use ONLY large open fields for launch…250m (~825 feet) or MORE of down range distance is preferred • Rope-off or “clearly mark” launch area • Always conduct a trial launch at low air pressure (i.e. 35-40psi) to get an idea of how far your rockets will travel with respect to a given launch area Safety Safety Safety…!!! • All rockets should be thoroughly inspected prior to launch • Do NOT over=pressurize rockets. 80psi MAX • Always use a CLEAR audible countdown before EACH launch (5! 4! 3! 2! 1!) Basic Water Rocketry Concepts • What is a Rocket? – A chamber enclosing a gas under pressure • A basic example is an inflated balloon – The rubber wall compresses the air inside. Air quickly escapes from the small opening at one end and the balloon files in the opposite direction Newton’s Three Laws Water Bottle Rockets are governed by Newton’s Three Laws 1) Objects at rest will remain at rest and objects in motion will remain in motion in a straight line unless acted upon by an unbalalnced force. 2) Force equals mass times acceleration 3) For every action there’s an equal and opposite reaction Newton’s First Law The Law of Inertia At Rest: Forces are balanced. The force of gravity pushing down on the rocket equals the force of the launch pad pushing up. In Motion: Thrust from the rocket unbalances the forces causing a downward thrust and an upward reaction on the rocket Newton’s Second Law The Law of Proportionality • Force equals mass times acceleration. – Pressure inside the rocket exits the throat of the bottle and produces force (thrust). Mass represents the total mass of the rocket, including its fuel. • The mass of the Rocket changes during flight as the fuel is used and expelled. The rockets weights less and accelerates. • Thrust continues until the engines stops firing Newton’s Third Law The Law of Interaction • For every action there’s an equal and opposite reaction (Action and Reaction) Action: The rocket pushes gas out of the engine (downward thrust) Reaction: The gas pushes up on the rocket Note: The action (thrust) has to be greater that the weight of the rocket in order for the reaction (liftoff) to occur. Inertia Inertia is the tendency of an object to resist any change in motion and is associated with the mass of an object Ballast Center of Mass (CM) The Center of Mass is the exact point about which all of the mass of an object is perfectly balanced. • All matter, regardless of size, mass, or shape has a center of mass. • Around this point is where an unstable rocket tumbles. – Spinning and tumbling takes place around one or more of three axes: roll, pitch, and yaw – Any movement in the pitch and yaw axes directions can cause the rocket to go off course Center of Pressure (CP) The Center of Pressure (CP) is the location where the ‘pressure forces’ acting on a rocket are balanced. The CP exists only when air is flowing past the moving rocket. (Based on surface area) • Flowing air pushing against the rocket, can cause it to roll and sway around the most stable point (CG/CM). • It is important that the CP of the rocket is located toward the tail and the CM is located toward the nose. Drag • DRAG = Air Resistance • Air Resistance causes friction which slows down the Rocket. Friction always works in the opposite direction of the Rocket’s motion. NOTE: Even when a rocket is descending, drag counteracts the rocket’s motion!) Now let’s launch into the Rules and Guidelines Objective of Competition To launch a rocket propelled by water and air and reach a maximum height. The launch angle which can be adjusted from approximately 90 degrees, will be kept the SAME for all rockets launching during a particular competition. Each rocket will be launched using 12 ounces of water and at 70 psi of air pressure. Rules & Guidelines Each team of 3 is required to submit: Elementary School - completed entry form - patch design Middle & High School - completed entry form - technical paper - patch design Note: Check with your State/Regional Host for submission deadline On the day of competition, but, prior to launch an actual operating rocket with its corresponding technical drawing must be submitted in order to compete – At this time each entry must pass a visual inspection and height requirement. ONE chance will be given to correct rocket (see R&G for details) Rocket Identification Diagram Let’s Build a Rocket…!!! Construction and Operation Requirements 1. The pressure vessel must be ONE clear 2 liter bottle (i.e. NO tinted bottles allowed for use as pressure vessel). So Do Not… 2. Water and air pressure will be the sole source of propellant. 3. DO NOT USE: Metal, Glass, Hard Plastics, Rocks or Spikes to construct the rocket. * * *Use of these materials will automatically disqualify the team from the competition.* * * Let’s Build a Rocket…!!! Construction and Operation Requirements 4. On the bottom of the rocket, leave 7.5 cm from the throat of the exit plane clear of any coverings (paint, markings, drawings, etc.). 5. Maximum total height of rocket is 76.0 cm. Let’s Build a Rocket…!!! Construction and Operation Requirements 6. Nose-cone tip must have a minimum radius of 1.5 cm. 7. Fins may extend to throat exit plane but NOT below the bottle’s Exit Plane. Let’s Build a Rocket…!!! Construction and Operation Requirements 8. The maximum fin width distance from the bottle is 10.0 cm (or 16.5 cm from center of bottle axis). ***Note: No forward swept type of fins are allowed to be used on the rocket. 9. The use of parachutes is NOT allowed. Forward Swept Fins Let’s Build a Rocket…!!! How to Build The Water Bottle Rocket Materials Cutting Tools • 2-liter soda bottles • Poster Board • Adhesive – Caution: Hot glue will weaken the pressure vessel walls • Scissors, utility knife, hacksaw, etc. Tape – Clear packing tape – Foam mounting tape – Carpet tape Decorations: (NO WATER PAINT) • Markers, spray paint, stickers, etc. Materials for Fins - Balsa/Bass wood - Corrugated plastic - Foam board - Old credit/gift cards Let’s Build a Rocket…!!! How to Build The Water Bottle Rocket STEPS: Let’s Build a Rocket…!!! How to Build The Water Bottle Rocket Let’s Build a Rocket…!!! Nose Cone Design and Construction 1. Cut a circle out of poster board/card stock 2. Cut a line along the radius + 3. Rotate paper into a cone, adjust angle, then tape Let’s Build a Rocket…!!! Nose Cone Design and Construction 4. Trim base of cone until it matches top of rocket 5. Cut nose cone tip off to allow a 1.5cm minimal radius and add a ball (or a plastic egg half) 6. Secure nose cone to water rocket Let’s Build a Rocket…!!! Fin Design and Construction • • • • Determine fin patter (analytic design or trial & error Use recommended materials but okay to be creative Do NOT use off limit materials Use as many fins you feel necessary (remember more fins = more mass/weight/drag) Here are some fin pattern examples Let’s Build a Rocket…!!! Patch Design A patch is a creative display that reflects the dedication and mission of the team. – For the competition your symbolic picture must comply with the following rules: 1. Each entry is to be prepared and submitted by the SECME School Teams who will be participating in the Water Rocket Design Competition. 2. Patch designs must be submitted on 13” X 13” poster board. 3. All entries must contain the team name and follow the theme of this year’s SECME competition. Let’s Build a Rocket…!!! Patch Design 4. A short (less than 1-page) explanation of the symbols of the patch must be included on the back of the patch (See example on pg 45 of National Guidelines; Full version) 5. All teams participating in the Water Rocket Competition must be prepared to display their patch prior to the launch of their rocket. 6. Patches must be hand-made original work. 7. Only Ink pens, pencils, markers, or paint may be used. * * * NOTE: Any Patch Design deemed inappropriate will be pulled from the competition. Let’s Build a Rocket…!!! Patch Design Evaluation Categories I. ORIGINALITY (1 – 30 points) a. Innovativeness of the design. II. CREATIVITY (1 – 30 points) a. Uniqueness of the information depicted. III. APPEARANCE (1 – 20 points) a. Attractiveness/neatness of the presentation IV. CONTENT (1 – 20 points) a. Representation of the team’s name and SECME theme. “SECME: STEMULATING MINDS” TOTAL (The highest possible score is 100) Technical Report GENERAL REQUIREMENTS: – – – – White Paper 12-pt Type/Standard Font Double-spaced Text 1” Borders 1. Cover Page: 2. Abstract 3. Table 4. Introduction 5. Design Background 6. Calculations 7. Conclusions/Recommendations 8. Acknowledgment 9. Appendix NOTE: Please read the official Rules and Guidelines for specific details ALSO NOTE: Take EXTREME caution regarding plagiarism Take Home Points • Teachers should focus on STEM standards along with the design and build of Water Bottle Rockets • Teachers should ensure that students design, build, test, troubleshoot and rebuild as much as necessary to thoroughly grasp the STEM concepts regarding Water Bottle Rocketry in order to be ready for both Regional and National Competition • Students should design and build their rockets to: – Minimize drag (wind friction) – Maximize stability – Maximize rocket’s time aloft • Remember… STEM, STEM, STEM…!!!