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An Introduction to Water Rocketry Mrs. Hlinka UMS Science

Important Rules Must use a standard 2 liter soda bottle No glues, metal or wood allowed Measured on time in the air Time stops when the first piece of your rocket hits the ground

Parts of a Basic Water Rocket

Parts of Rocket (cont.) Nose Cone- For aerodynamic effect Ballast (not always necessary) but adds mass to rocket for increased stability. Fins- for stability Pressure vessel- source of rocket propulsion. ** Must be airtight!

When preparing your 2-liter bottle do not use the following items: Hot/Boiling water Knives/Razors Sandpaper Chemical Adhesives * These things may compromise the structural integrity of the bottle. Remember it is pressurized with air!

What Do I Need? One 2-Liter bottle (or more bottles if you want to make a tall rocket) Materials for Fins Materials for Nose Cone Materials for Parachute Tape

The Rocket Body One bottle is all that is needed for a basic rocket. If you want to make a taller rocket cut the bottom portion off another two liter bottle.

Rocket Body: Ballast If you want to add some ballast to your rocket you can use items such as: sand, foam peanuts, modeling clay, newspaper, etc.

Rocket Body (cont.)  Push bottom half of two liter bottle upside down into top half – to keep ballast in place.  Use small pieces of tape to secure bottom piece inside bottle.

Rocket Body (cont.) Place two liter bottle (pressure vessel) into top half. Try to make bottles straight. Use little pieces of tape to secure bottles. This is not necessary if you are using a single bottle.

How Do I Attach Fins & Nose Cone? The packing tape with strings is my favorite. It holds really well and makes it easier to repair your rocket quickly! Duct tape is also excellent!!

Fins are the guidance system for your rocket. Square/Trapezoidal: Fins yield MORE stability, but create MORE drag. Triangular/ Epsilon: Fins introduce LESS drag, but yield LESS stability.

Materials for Fins Milk or Juice bottle Foam trays Unused election signs (work great & are water proof) Cardboard Corrugated Plastic Plastic Folders Poster board

Fin Templates (or design your own!)

Fins Use a template, a marker and draw fin patterns on the material you have chosen to use.

Fins (cont.) Cut fins out.

Measure for Fins Measure your rocket to make sure the fins are equally placed around bottle.

Fins (cont.)  Attach fins to rocket using tape.  Use either 3 or 4 fins.  More than four adds unnecessary weight.

Materials for Nose Cone You can use many materials to make a nose cone. To create a rounded tip you can use an egg carton or a plastic egg shell. Small Nerf footballs, foam noodles, foam balls, etc. all work well & allow the rocket to make a soft landing!

Nose Cone Materials

Nose Cone  Roll your material (plastic file folders work great) into a cone.  Use tape to hold material in place.  Place plastic egg shell on the cone as tip. Use tape to fasten tip to cone.

Nose Cone (cont.) Fasten nose cone to the body with tape.

FLOUNDER NOSE CONE The first type illustrated here is called "The Flounder". It is the easiest to make but lacks flight stability. The cone is made from poster board or tag board. You can make the cone by simply cutting a large circle out of the poster board (about a 6 inch radius). Cut a line from the outer edge of the circle to the center on the radius. Overlap the cut edges and turn the circle while holding one edge stationary until you get the desired cone shape. Secure the cone with staples or tape. Attach to the bottle with tape or similar adhesive.

As I mentioned before "The Flounder" lacks flight stability, this can be fixed to a degree by pressing a small lump ( a few ounces) of clay to the inside of the nose cone. This will add mass to the cone and keep your rocket from flipping end over end while in flight. This new and improved rocket could be called "The Bullet". You can also put a golf ball or tennis ball in the nose cone for top weight.

“Bertha” Nose Cone The "Bertha Series" nose cones are easy to make as well but require a little attention to detail. The "Bertha" nose cones are made by cutting the bottom off a spare bottle and attaching the top portion onto the pressure chamber. One strip of tape should be enough to hold the cone on. (Note: Never cut the pressure chamber) Using this method you can even make your "Bertha" rocket two or three nose cones tall! (we call that a "Big Bertha") Within the top nose cone you can add a small lump of clay to increase the mass. Pay attention to keep all the cones in a straight line. A curvy rocket will not be safe coming off the launcher.

“Space Needle” Nose Cone The "Space Needle" style of nose cone can be made from a spare bottle, empty paper towel roll, and a tennis ball or racket ball. This type of nose cone adds a great deal of inertial mass to the rocket and makes it really stable. Simply, attach the towel roll to the top of a single Bertha nose cone and then fix the tennis ball to the top of the roll. Take your time building this set up because you want the entire assembly to be straight as an arrow. Cut tabs in an index card and glue or tape the card to the tube. This will hold the tube upright. Then glue or tape the tabs onto the nose cone top.

Recovery Systems A recovery system is something that slows the rockets decent. The two most popular at the parachute and the back-slider

Parachute Parachutes work best but are harder to get to work consistently The size needs to match the rocket. It should have 8 to 10 strings Fold it like an accordion and then wrap extra string around it to keep it folded

Making a Parachute Cut Here

Making a Parachute

Backslider/no parachute 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.

Example Backslider

Decorating Your Rocket  You may decorate with stickers, paint, wrapping paper, etc.  The bottom of your rocket though must remain clear of any obstructions.  Fins cannot extend past bottom half so that the rocket will fit on the launcher.

How Do I Launch My Rocket?

Launch Pad

Tips Lengthening the rocket adds stability Experiment with different fin shapes Try different body shapes Try to make the body smooth (no kinks with tape). Do not use any glues, masking or scotch tape, wood or metal on your rocket. BE AS CREATIVE AS YOU WANT !! HAVE FUN!!