Bottle Rocket help

Bottle Rocket
Instructor Info
 Mark Wylie & Grant Wylie
 thencwylies@aol.com
Process
 Read and understand the rules
 Research
 Design
 Build
 Test
 Analyze
 Start over
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
 What goes up must come down SAFELY
Important Rules
 Rockets will use 2 liter soda bottles
 Launched at 75 psi
 Best single rocket time will win
 Ties resolved by the flight time of the second rocket
What makes it work?
1. Water is poured into the pressure chamber
2. Air is then pumped into the bottle.
3. When the rocket is released, the air forces
the water out of the bottle.
4. Newton’s Third Law of Motion kicks in
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
Fins
 Fins keep the rocket stable in flight
 There must be at least 3
 Fins must be ridged
Fin Shapes
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
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.
Recovery Systems
 A recovery system is something that slows the rockets
decent.
 The two most popular at the parachute and the backslider HOWEVER ONLY A BACK-SLIDER BACK-SLIDER IS
ALLOWED IN THIS YEARS RULES
Recovery Systems
 Active – parachute, balloon, helicopter
 Passive – backslider
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.
Center of Pressure
Example Backslider
Examples
Resources
 http://dogrocket.home.mindspring.com/WaterRockets/
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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