3, 2, 1, Blast Off!

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3, 2, 1, Blast Off!
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Process

• Read and understand the rules
• Research
• Design
• Build
• Test
• Analyze
• Fix

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Important Rules

• Build up to 2 rockets before the tournament
• Rockets will use 2 liter carbonated bottles
• MUST WEAR SAFETY GLASSES
• Nothing within 5 cm of the nozzle
• Launched at 75 psi
• Can use any recovery system
• Best single rocket time will win

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What makes 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

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Parts of the Rocket and Forces
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Pressure Chamber

• 2 Liter soda bottle
• Do not cut or scratch the pressure chamber.
• Can glue fins to pressure chamber with silicone
  or polyurethane glues.
• If pressure chamber is damaged it will not be
  launched

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Fins

• Fins keep the rocket stable in flight
• There must be at least 3
• Fins must be rigid
• Backswept fins work best

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Fin Shapes
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What does it mean to be stable?

• Stability the tendency of the rocket to return
  to equilibrium
• This means if the rocket begins to veer, it will
  straighten back up on its own.
• To be stable, the center of mass must be closer
  to the top of the rocket than the center of
  pressure

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Nose Cones

• Popular types
• Conical
• Blunted Conical
• Elliptical
• Spherical
• Nose cones reduce drag
• Conical are easy to make but can be difficult to
  get straight.

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Recovery Systems

• A recovery system is something that slows the
  rockets descent.
• The two most popular at the parachute and the
  back-slider

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Recovery Systems

• The velocity of a falling object can be shown as
  follows
• where v(t) is velocity, g is acceleration do to
  gravity, c is the coefficient of air resistance,
  t is time, and v(0) is initial velocity.
• C is much larger for a parachute than a
  backslider therefore, it will fall much more
  slowly

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Parachute

• Parachutes work best but are harder to get to
  work consistently
• The size needs to match the rocket.
• It should have 8 to 10 strings
• Fold it like an accordion and then wrap extra
  string around it to keep it folded

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Making a Parachute
Cut Here
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Making a Parachute
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Backslider

• Backslider is made by making the center of
  gravity close to the center of pressure
• This prevents the rocket from turning over at
  apogee and instead floating down on its side.
• Fins on this type of rocket should be larger to
  help slow it down.

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Example Backslider
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Examples