Bottle Rocket Instructor Info  Mark Wylie & Grant Wylie  [email protected] 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/      - 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