Bottle Rockets!

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 forthe 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 chamber2. Air is then pumped into the bottle.3. When the rocket is released, the air forcesthe 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 orpolyurethane 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 toequilibrium• This means if the rocket begins to veer, it will straightenback up on its own.• To be stable, the center of mass must be closer to the topof 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 getstraight.

Recovery Systems• A recovery system is something that slows the rocketsdecent.• The two most popular at the parachute and the backsliderHOWEVER ONLY A BACK-SLIDER BACK-SLIDER ISALLOWED IN THIS YEARS RULES

Recovery Systems•Active – parachute, balloon, helicopter•Passive – backslider

Backslider• Backslider is made by making the center of gravityclose to the center of pressure• This prevents the rocket from turning over at apogeeand instead floating down on its side.• Fins on this type of rocket should be larger to helpslow 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.htmconstruction and discussion• http://txsnapper.eezway.org/powerdeployment/Robert Youens - Coneybackslidergreat info• 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