Virginia Science Olympiad:

1
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
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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!

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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

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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

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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

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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

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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.
• Newtons 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.

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Parts of the Rocket and Forces
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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

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Fin Shapes
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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

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Launcher

• Commercial Bottle Rocket Launcher about 200
• http//shop.pitsco.com/store/detail.aspx?KeyWords
  rocketlaunchersearchtype0sport3by20c0t0
  l0ID1179
• Build one MUCH more affordable
• http//faculty.kfupm.edu.sa/AE/aymanma/images/How
  20to20make20a20soda-bottle20rocket20launcher.
  pdf

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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?article276
  cg.cp.cla
• http//www.scioly.org/wiki/Main_Page SO student
  center
• http//en.wikipedia.org/wiki/Water_rocket General
  -good

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Towers

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

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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

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Towers - basics
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Towers - basics

• 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

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Towers - scoring

• The score is pure efficiency
• Efficiency (mass held)2
  bridge mass
• Bridges that dont meet specs are tested but
  moved to tier 2
• Bridges that are untestable are in tier 3 and
  ranked by mass

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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