4-H Bottle
Rockets
Monroe County
Grades 3-12
4-H Bottle Rocket Project
General Guidelines:
• All exhibits will consist of one bottle rocket made from a 2-liter, plastic soda bottle.
Plans for the construction of a bottle rocket are included in this manual. The basic plans
may be altered by the member.
• This project will be exhibited by grade level.
Level 1: Grades 3 – 6
Level 2: Grades 7 – 8
Level 3: Grades 9 - 12
• 4-H members will be judged according to their grade in school
• Bottle rockets will be judged based upon creativity of the rocket and basic design. The
basic design may be altered in any way
• Painting and decals are optional
• Rocket base is optional. It may be used to enhance your rocket
• It will be up to the discretion of the judge whether a champion will be selected in each
division.
A completed bottle rocket consists of
• A 2-liter plastic bottle
• Nose cone (can be modified from enclosed design)
• 3-4 fins
• ½ cup sand/gravel (in Ziploc bag) OR modeling clay
Your completed bottle rocket must be ready for flying
Your name does not need to appear on the rocket. However you will need to have a place for
the entry tag to be placed for county fair.
Rocket Shoot-Off
4-H members will be given the opportunity to launch their rocket. Rocket launching is NOT
required but your rocket is required to be made to launch.
The Aerospace Leaders schedule a rocket shoot off annually after the fair, typically in
September. Your rocket for the rocket shoot off does not have to be your exhibited rocket,
however, you may use your exhibited rocket if you wish. Rocket launchers are provided for the
shoot off. Watch for your invitation in the mail.
Background:
A water rocket is a chamber, usually a 2-liter soft drink bottle, partially filled with water. Air is
forced inside with a pump. When the rocket is released, the pressurized air forces water out the
nozzle (pour spout). The bottle launches itself in the opposite direction. The bottle usually has a
nose cone for streamlining and fins for stability. Water rockets are easily capable of 100-meterhigh flights, but advanced hobbyists have combined bottles and staged bottles for flights over
300 meters high.
Water bottle rockets are ideal for teaching Newton’s laws of motion. The launch of the rocket
easily demonstrates Newton’s third law. 4-Hers can see the water shooting out of the nozzle
(action) and see the rocket streak into the sky (reaction). 4-Hers can also experiment with
different pressure levels inside the chamber and different amounts of water. The rocket will not
fly very high if it is filled only with air. The air will quickly rush out during the launch, but its
mass is very low. Consequently, the thrust produced is also low (Newton’s second law). By
placing water in the bottle, the air has to force the water out first before it can leave the bottle.
The water increases the mass expelled by the rocket, thereby increasing the thrust.
Like all rockets, the flight performance of water bottle rockets is strongly influenced by the
rocket’s design and the care taken in its construction. Beveling the leading and trailing edges of
fins allows them to slice through the air more cleanly. Straight-mounted fins produce little
friction or drag with the air. A small amount of ballast weight inside the nose cone helps
balance the rocket. This moves the center of mass of the rocket forward while still leaving a
large fin surface area at the rear. In flight, the rocket design acts like a weather vane, with the
nose cone pointed up and the fins down.
Description:
Using plastic, 2-liter, soft drink bottles, cardboard or Styrofoam food
trays, tape, and glue, 4-Hers will design and construct a simple
rocket. A simple assembly stand can assist when you are gluing the
fins on the rocket and mounting the nose cone. A small lump of
modeling clay or plastic bag with sand/gravel is inserted into the
nose cone to enhance the rocket’s stability in flight. The rocket is
launched with a special launcher.
Materials Needed:
2-liter soft drink bottle
Masking tape or duct tape
Low-temperature glue gun
Glue
4 ounces of modeling clay or sand or gravel
Fin and Nose Cone Material Ideas Are:
Corrugated cardboard, Foamcore, balsa wood, Styrofoam,
manila folder, cardstock, a second soda bottle, etc.
Other:
Grocery sacks
Thin fabric scraps
String
Sandpaper or emery boards
Art supplies
Duct tape
Bottle Rocket Design Tips:
Don't use a water bottle; soda
bottles are built to withstand
greater pressure. Take off the
wrapper. It's very important that
you do not cut the plastic of the
bottle at any time during
construction so be careful when
taking off the wrapper.
It's important to use a Low Temp
glue and gun. A high temp glue
gun can melt the bottle. You
may find that even a low temp
glue gun will warp the plastic of
the bottle but don't worry, it won't
weaken the plastic.
Management:
Collect a 2-liter soft drink bottle, save the cap too. Rinse the bottle and remove the label. There
will be some glue adhesive remaining on the bottle.
Goo remover can be used to clean it off, but it tends to smear the surface.
Optional but helpful:
Construct assemble stands out of small blocks of wood.
Attach a bottle cap to the middle of each board with a
small screw and a washer through the cap. When
constructing the rocket, screw the bottle neck into the cap
on the board and it will hold the rocket upright for gluing.
The block will also be convenient for storing the rocket
when it is not being worked on.
Make mounting stands by screwing the plastic bottle
caps to a board. Use a washer for added strength.
Procedure:
Wash/clean your 2-liter soda bottle. Collect materials such as Styrofoam food trays, poster
board, tape, sandpaper, art supplies, duct tape, heated lowtemperature glue guns, extra glue sticks, etc.
Assemble your mounting stand. It will assist you while constructing
your rocket.
Design your bottle rocket. You may draw the design or create it in your
head. You can decorate your rocket any way you would like. Use
sharpie markers, paper, paint, or any arts and crafts supplies – the
possibilities are endless. Just keep in mind that you want to keep your
decorating balanced so your rocket is capable of being launched.
Assemble your bottle rocket. There is no set rules about number,
shape and placement of fins and nose cone. The object of this project
is for you to design a bottle rocket that will launch AND fly! Decide how
many fins you would like. Four fins are easier than three, but if done correctly either way works
well. The fin shape is provided below. Trace the fin design out on corrugated cardboard,
Styrofoam, foamcore, balsa wood, or any light weight material. Using an exacto-type knife, cut
the desired number of fins out from the sheet. Make sure that the corrugated “ribbing” pf the
cardboard or the grain of the wood is running parallel to the leading or trailing edge of the fin. If
this is not done, the fin may rip apart in mid-flight.
1”
Fold Line
Corrugated cardboard
“ribbing” direction
4”
4”
Prepare Tail Fins for attachment:
• Corrugated cardboard: Once the tail fins have been cut, split open the
1” section of cardboard that extends beneath the triangular portion of
the fin. When opened, this portion should be at a right angle to the fin.
Next, take two bobby pins and bend them into a “T” shape. Make sure
the top of the “T” is at least 1½” wide. Insert the two bobby pins into
one of the fins so that the “T” portion of the bobby pin rests against the
extended portion of the fin. The bobby pins are used to stiffen the fins
during flight. Repeat this step for each fin.
• Lightly sand the fins so they become smooth if using balsa wood.
Now, it is time to mount the fins onto the rocket. Take a piece of paper
and wrap it around the lower portion of the bottle (near the opening end). Mark the
circumference of the bottle where the piece of paper overlaps its self. Remove the paper and
measure the distance to the mark that was just made. This will tell you the circumference of the
bottle. If you are planning 4 fins, divide the circumference by 4. Use this number to divide the
piece of paper into four equal sections and mark the sections. If you are planning for 3 fins, use
the same process, but this time divide the piece of paper into 3 sections. Wrap the piece of
paper around the bottle as before and secure it with a piece of tape. Take a felt marker and
transfer the section marks on the paper to the bottle. These marks designate where the fins are
to be placed. Make sure everything is perfectly even, or the rocket will not fly well. Next, take a
straight edge (ruler) and draw a line through the mark that was made so you will have a guideline for fin mounting.
Once completed, mount your fins with duct tape, rubber cement or glue to your bottle as
shown below. Carefully align the fins with the straight lines you have just drawn. If you are
attaching your fins with glue or rubber cement, press the fins down onto the bottle and use a
piece of tape on either side of the fins in order to keep them straight while the glue sets. It is
best if only one fin is done at a time and the fin is kept vertical until the glue has set. Make sure
all of the fins are perfectly aligned and straight. The bottom of your fins should be about 3”
away from the “open” end of your bottle.
Fins, Top View
Fins, Side View
The final step is to construct and attach a nose cone.
cut here
Sand/Gravel
OR
Modeling Clay
attach
to nose
The nose cone can be made from cardboard, cardstock, etc. You can
create your own design or use the pattern in this manual. Trace and cut
a nose cone from the material of your choice. Fold the nose cone so
that it will fit over the top of the bottle rocket.
You can also construct a nose cone from a second 2-liter soda bottle.
This can be done by cutting the top from the second 2-liter bottle (as
shown) and attaching it to the end of your rocket. Just be sure to cover
the hole where the threaded portion of the neck was removed.
Tape or attach the plastic bag of sand/gravel or modeling clay to the
bottom of the bottle before attaching your nose cone. The weight of
this will prevent turbulence when you launch your rocket.
Glue, Tape, or Cement the nose cone to the top of the rocket.
If you wish, a parachute can be added. Decorate
as you wish. The rocket is now finished. Make
sure all glue has dried completely and the fins are securely attached to
the rocket before it is flown.
Challenge: Think of a way for the nose cone to pop off in decent,
releasing a parachute or streamer. Remember: your rocket will be
accelerating back to earth at a velocity of 32 ft/second.
Ever wonder why a real rocket has a pointed nose cone?
It’s to provide stability as the rocket breaks the sound
barrier. However, the best nose cone design for a low
velocity model rocket is parabolic.
When the rocket has been completed, qualify the rocket
for flight by conducting string tests. Using several feet of
string, tie the rocket around the middle so that it balances.
Because of the nose cone weight, the balance point will be
towards the nose. When the rocket hangs level, a small
piece of tape should be temporarily fixed to the string and
bottle to keep the string from slipping. The rocket is then
twirled in a circle. If the rocket tumbles while circling, it is
not stable and needs more nose cone weight, bigger fins,
or a combination of both. If the rocket circles with the
nose always pointed forward, it is stable and ready for flight.
Nose Cone Pattern
4”
6”