Bottle Rockets - B 2016-17 CeAnn Chalker ceann@chalker.org Bro. Nigel Pratt bronigel@kellenberg.org Jim Woodland

Disclaimer This presentation was prepared using draft rules. There may be some changes in the final copy of the rules. The rules which will be in your Coaches Manual and Student Manuals will be the official rules.

What is Bottle Rockets? Teams - design, construct & launch water rockets to stay aloft for greatest amount of time while carrying a raw chicken egg that survives impact

Event Parameters 2 Rockets are prebuilt by team members Only 1 launch per rocket No sharing rocket parts Eye Protection #5 must be worn One warning given

Event Supervisor Provides Launcher Water Two Marked Grade A Large Chicken Eggs per team (plus extras for breakage)

Construction – Pressure Vessel The Rocket’s Pressure Vessel must be made out of a single 1-liter or smaller plastic carbonated beverage bottle Label must be presented if removed Inside diameter of nozzle of approximately 2.2 cm

Construction – Structural Integrity Structural integrity of pressure vessel may not be altered. For example: Physical damage Thermal damage Chemical damage Safety check will be done

Construction – Attachments Yes! Only TAPE may be used to attach items to the Pressure Vessel. NO GLUES of any type may be used on the Pressure Vessel. Glue may be used in other parts of the rocket

Construction – Nose Cone Nose of the rocket must be rounded or blunt at the tip. The nose must be designed such that when a standard 2 liter bottle cap (~3.1 cm diameter x 1.25 cm tall) is placed on top of the nose, no portion of the nose touches the inside top of the bottle cap (see Figure 1).

Construction – Bottle Opening All parts must be 5 cm above the level of the bottle’s opening nothing may break this plane no tethering allowed

Construction – Inserting the Egg The Egg must be easily removed Nothing may be adhered to the egg (e.g. glue or tape)

Construction – Design Restrictions Rockets during launch or flight must not- Become separated Change shape Deploy any type of recovery system No parachutes!

Construction – Safety Restrictions No metal may be used anywhere on the rocket. No commercial model rocket parts. No explosives, gases (except air), electronic devices, elastic, throwing, remote, chemical or pyrotechnics allowed.

Competition – Basic Details Walk in or sign up event Wear Safety Goggles Students will add Egg, any amount of water, set on launcher, launch, and retrieve their rockets. 10 minutes to launch 1 or 2 rockets (only 1 launch per rocket)

Competition – Loading the Egg Teams are allowed to inspect and select the 2 eggs to launch If a team breaks an egg before launch they may request another egg Replacement eggs as of now will not receive a time penalty, this may change in the rules Teams load their egg into the rocket Reminder – nothing may adhere to the egg

Competition – Launching Rockets launched using Launcher provided by supervisor Only water/air pressure will be used for energy to the rockets Maximum of 60 psi for launching Once rocket is pressurized, no one may touch or approach the rocket

Competition – Timing Timing begins when the rocket separates from the launcher. Timing ends when any part of the rocket: touches the ground or rests on an obstruction or goes out of sight Rockets launched before time expires will be scored

Competition – Retrieval & Egg Examination Teams will immediately retrieve each rocket Remove the eggs in the presence of the Event Supervisor for inspection Egg survival is defined as an egg leaving no wet spot on a paper towel

Scoring Combined greatest time aloft of both rockets recorded to the nearest hundredth of a second. If only 1 rocket is launched, the team receives the time for only that one launch. Will be scored in either Tier 2 or Tier 3 based upon survival of the egg

Scoring – Tiers Tier 2: Tier 1: Tier 3: Launches with 2 surviving eggs Launches with no surviving eggs

Violations Construction Violation – Competition Violation - A Rocket with a Construction Violation will not be launched. Competition Violation - A Rocket with a Competition Violation will not be scored even if it has a time. If a Team has one Legal Rocket, that Rocket will be ranked in the appropriate Tier depending upon the survival of the egg. Note – With 1 rocket the best they can place would be in Tier 2. If Both Rockets have violations the team will not be ranked and receive only Participation Points

Tie Breaker Tie Breaker The better score of each tied team’s best rocket.

So, How DO you become a Rocket Scientist?

Research READ this Year’s SO Rules First! Search the Internet for: “backslider” “backglider” “water rockets” as opposed to “bottle rockets”

The Bottle – MASS is Key! ALWAYS remember: Keep MASS at a minimum!!! F=ma Get a variety of CARBONATED 1 liter or smaller bottles from DIFFERENT companies. You’ll be surprised at the variation of masses Use non-carbonated bottle parts for your extension, nose cones, egg holder, etc. these tend to be thinner and lighter weight Trim away ANY excess parts that are buried in the rocket and will not affect it in any way Do not cut or damage the pressure vessel!

The Bottle – More ways to reduce MASS Remove the labels (keep them – know which label goes with what rocket) Clean off the ALL the glue, but don’t scratch the rocket Build CLEANLY! The smoother the sides of the rocket, the better Use as little tape/glue as you can – both for mass and aerodynamic clean builds

The Fins – Don’t forget MASS Use 3 Vertical Fins evenly spaced suggestion: thin styrene sheets, thinner bottles, card stock, balsa or bass wood They do not have to be large!!! Remember the 5 cm “No Fin Zone!” Cut out a piece of non-carb bottle that matches the curve of your pressure chamber. Glue the fin to the piece and then tape it to the pressure chamber!

The EGG… and It’s Holder (MASS again!) What material for the holder? bubble wrap, plastic egg suspended, foam with egg cutout, air cushions, balloons, etc… Location? “….must be easily removed” Practice with plastic eggs (with masses between 57 – 60 g) for correct stability of the rocket. Transitioning to real eggs, use zip lock bags to facilitate clean up.

Rocket Stability is Vital! Center of Gravity (CG) Center of Pressure (CP)

Center of Gravity (CG) Determine the CG by balancing the rocket on a pole, dowel or pencil. CG should be at least 1 rocket diameter higher than the CP!!

Center of Pressure (CP) “2D” test to determine CP: a simple mechanical way to determine the approximate CP for the rocket. Make a two dimensional tracing of the shape of the entire rocket on a piece of cardboard and cut out the shape. Use a pole to determine where it balances. The point at which the rocket is balanced is approximately the center of pressure. It is extremely important the CP is closer to the tail than the CG. If they are reversed or in the same place, the rocket will be unstable in flight

Adjustments and Size Ways to change CG and CP positions: size of fins location of masses (Putty could be added to the inside of the nose cone, etc.) Total Rocket Length: depends on mass and stability Which depends upon design and materials Research and Experiment with various designs and materials

Bottle Rockets in a Blizzard! Have Snow Shovel, Will Launch!

Chasing Down a Rocket Oh What Fun in the Ohio Snow!

Blue Skies are Deceptive! Launching in Frigid, Single Digit Temperatures!

(Search: “water rocket” not “bottle rocket”) Good Websites (Search: “water rocket” not “bottle rocket”) http://www.h2orocket.com/ http://www.waterrocketmanual.com/index.htm http://polyplex.org/rockets/simulation/ http://polyplex.org/rockets/ http://txsnapper.eezway.org/waterrocketguy/backslider.html http://www.aircommandrockets.com/ (Cool videos of extreme bottle rockets) And many others!! Good Luck…and Happy Launching!