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Prelim Date: April22
Final Date: May 12
An Introduction toWater 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 yourrocket hits the ground
Parts of a Basic Water Rocket
Parts of Rocket (cont.)
•Nose Cone- Foraerodynamic effect
•Ballast (not alwaysnecessary) but addsmass to rocket forincreased stability.
•Fins- for stability
•Pressure vessel- sourceof rocket propulsion.** Must be airtight!
When preparing your 2-liter bottledo not use the following items:
Hot/Boiling waterKnives/Razors
SandpaperChemical Adhesives
*These things may compromise thestructural integrity of the bottle.
Remember it is pressurized with air!
What Do I Need?
•One 2-Liter bottle (ormore bottles if you wantto make a tall rocket)
•Materials for Fins
•Materials for Nose Cone
•Materials for Parachute
•Tape
The Rocket Body
One bottle is all thatis needed for a basicrocket.
If you want to makea taller rocket cutthe bottom portionoff another two literbottle.
Rocket Body: Ballast
If you want to add some ballast to yourrocket you can use items such as: sand, foampeanuts, modeling clay, newspaper, etc.
Rocket Body (cont.)
Push bottom halfof two liter bottleupside down intotop half – to keepballast in place.
Use small pieces oftape to securebottom piece insidebottle.
Rocket Body (cont.)
Place two liter bottle (pressure vessel) into top half. Tryto make bottles straight. Use little pieces of tape tosecure bottles. This is not necessary if you are using asingle bottle.
How Do I Attach Fins & Nose Cone?
The packing tape with strings is my favorite. It holds really welland 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 electionsigns (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 patternson the material you have chosen to use.
Fins (cont.)
Cut fins out.
Measure for Fins
Measure your rocket to make sure thefins are equally placed around bottle.
Fins (cont.)
Attach fins to rocketusing tape.
Use either 3 or 4 fins.
More than four addsunnecessary weight.
Materials for Nose Cone
•You can use manymaterials to make a nosecone.
•To create a rounded tipyou can use an egg cartonor a plastic egg shell.
•Small Nerf footballs, foamnoodles, foam balls, etc. allwork well & allow therocket to make a softlanding!
Nose Cone Materials
Nose Cone
Roll your material(plastic file folders workgreat) into a cone.
Use tape to holdmaterial in place.
Place plastic egg shell onthe cone as tip. Use tapeto fasten tip to cone.
Nose Cone (cont.)
Fasten nosecone to thebody withtape.
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 therockets decent.
The two most popular at the parachute and theback-slider
Parachute
Parachutes work best but are harder to get to workconsistently
The size needs to match the rocket.
It should have 8 to 10 strings
Fold it like an accordion and then wrap extra stringaround it to keep it folded
Making a Parachute
CutHere
Making a Parachute
Backslider/no parachute
Backslider is made by making the center ofgravity close to the center of pressure
This prevents the rocket from turning over atapogee and instead floating down on its side.
Fins on this type of rocket should be larger to helpslow it down.
Example Backslider
Decorating Your Rocket
You may decoratewith stickers, paint,wrapping paper, etc.
The bottom of yourrocket though mustremain clear of anyobstructions.
Fins cannot extendpast bottom half sothat the rocket will fiton 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 withtape).
•Do not use any glues, masking or scotch tape,wood or metal on your rocket.
•BE AS CREATIVE AS YOU WANT !!
•HAVE FUN!!