Virginia Science Olympiad:Bottle rocket and towers

Bottle Rocket: Adapted from the NC presentation by Mark & Grant WylieTowers : Courtesy Leah Puhlick, Langley HS coach

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!

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

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

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 GLASSESNothing 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

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 psiBest single rocket time will winTies resolved by the flight time of the

second rocket

How does it work…

Water is poured into the pressure chamberAir is then pumped into the bottle.When the rocket is released, the air forces

the water out of the bottle.Newton’s 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.

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

Fin Shapes

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

Launcher

Commercial Bottle Rocket Launcher: about $200

http://shop.pitsco.com/store/detail.aspx?KeyWords=rocket+launcher&searchtype=0&sport=3&by=20&c=0&t=0&l=0&ID=1179

Build one – MUCH more affordablehttp://faculty.kfupm.edu.sa/AE/aymanma/

images/How%20to%20make%20a%20soda-bottle%20rocket%20launcher.pdf

Resourceshttp://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

Towers

Students design a tower with best efficiency

up to 15 kg of mass will be tested

impounded

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

Towers - basics

Towers - basics

Other things to note:Must be wood and glue (no bamboo,

laminates, etc.)No maximum wood sizeMust support 5x5x2 cm block w/ ¼ “

threaded rod 50 cm above test baseChain must hang within 2.5 cm of

center of test base when bucket attached

Towers - scoring

The score is pure efficiency:Efficiency = (mass held)2 bridge mass

Bridges that don’t meet specs are tested but moved to tier 2

Bridges that are untestable are in tier 3 and ranked by mass

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 sparinglyHave students draw plans, cover with

clear packing tape and work on top of plan

Keep everything symmetrical, level, square