Virginia Science Olympiad: Bottle rocket and towers Bottle Rocket: Adapted from the NC presentation by Mark & Grant Wylie Towers : Courtesy Leah Puhlick, Langley HS coach

Each device should be clearly labeled with the team name and number BASICS TO REMEMBER Each device should be clearly labeled with the team name and number Note: All building events with the exception of Bottle Rocket must be impounded Any student on the team may help build, impound, and/or compete with the device FOLLOW THE RULES!

SAFETY REGULATIONS Under each event description there is a section for “eye protection” followed by a number Descriptions of what these numbers refer to appear on the www.soinc.org under “events” For Bottle Rocket - # 5 or high impact goggles/spectacles must be worn – that is they must be rated ANSI Z87+ For Towers - #2 Safety Spectacles with Side Shields ANSI Z87

BOTTLE ROCKET Teams of 2 students design, build, and bring bottle rockets for maximum flight times Longest flight wins; 2nd flight is used as tie breaker Tier 2 - launch with rocket parts separating during launch or flight Tie 3 - construction and/or competition violations

Important Rules Build as many rockets as you like but have 2 ready for the tournament with no metal or commercial bits. Unaltered pressure chamber and safe nose. MUST WEAR SAFTRY GLASSES Nothing within 5 cm of the nozzle (Fins and other parts must be 5 cm or higher above the opening of the bottle) What goes up must come down SAFELY

More Rules… Rockets will use 2 liter soda bottles Labels may be removed from the bottle but MUST be presented at safety inspection Launched at 75 psi Best single rocket time will win Ties resolved by the flight time of the second rocket

How does it work… Water is poured into the pressure chamber Air is then pumped into the bottle. When the rocket is released, the air forces the water out of the bottle. Newton’s Third Law of Motion kicks in - for every action there is an equal and opposite reaction the rocket's action is to push down on the ground with the force of the pressurized air that is pumped in, and the reaction is that the ground pushes the rocket upwards with an equal force.

Parts of the Rocket and Forces

Pressure Chamber 2 Litter soda bottle Do not cut or scratch the pressure chamber. Can glue fins to pressure chamber with silicone or polyurethane glues or simply use strong packing tape. If pressure chamber is damaged it will not be launched

Fin Shapes

Recovery Systems A recovery system is something that slows the rockets decent. The two most popular at the parachute and the back-slider ONLY A BACK-SLIDER IS ALLOWED IN THIS YEARS RULES

Launcher Commercial Bottle Rocket Launcher: about $200 http://shop.pitsco.com/store/detail.aspx?KeyWords=rocket+launcher&searchtype=0&sport=3&by=20&c=0&t=0&l=0&ID=1179 Build one – MUCH more affordable http://faculty.kfupm.edu.sa/AE/aymanma/images/How%20to%20make%20a%20soda-bottle%20rocket%20launcher.pdf

Resources http://dogrocket.home.mindspring.com/WaterRockets/- center of gravity & center of pressure http://waterrocket.uh-lab.de/backglide.htm backslider construction and discussion http://txsnapper.eezway.org/powerdeployment/ great info Robert Youens -Coney http://www.info-central.org/index.php?article=276 cg.cp.cla http://www.scioly.org/wiki/Main_Page SO student center http://en.wikipedia.org/wiki/Water_rocket General - good

Students design a tower with best efficiency Towers Students design a tower with best efficiency up to 15 kg of mass will be tested impounded

Important measurements: Must be a min. of 50 cm above test base Towers - basics Important measurements: Must be a min. of 50 cm above test base Must span 20x20 cm opening on test base Must pass through 8 cm diameter hole 30 cm above test base

Towers - basics

Towers - basics Must be wood and glue (no bamboo, laminates, etc.) Other things to note: Must be wood and glue (no bamboo, laminates, etc.) No maximum wood size Must support 5x5x2 cm block w/ ¼ “ threaded rod 50 cm above test base Chain must hang within 2.5 cm of center of test base when bucket attached

The score is pure efficiency: Efficiency = (mass held)2 bridge mass Towers - scoring The score is pure efficiency: Efficiency = (mass held)2 bridge mass Bridges that don’t meet specs are tested but moved to tier 2 Bridges that are untestable are in tier 3 and ranked by mass

Towers - tips Balsa has best weight to strength ratio – order online for better pieces (http://www.modernss.com/ has good balsa, cutters, etc.) Glue adds the most weight – use sparingly Have students draw plans, cover with clear packing tape and work on top of plan Keep everything symmetrical, level, square