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Water Bottle Rocketry
A Basic and Refresher Workshop
for Engineering Design
Purpose & Objectives of this
• Encourage and promote the integration of STEM
standards and concepts into the building and designing
processes of the Water Bottle Rocket
Let’s Focus On
• Explain Guidelines of the competition
• Help you teach your students:
Problems solving skills
How to budget their time
Cooperative behavior
Engineering and design concepts
What is a Water Bottle Rocket?
A water rocket is a type of
model rocket using water (and
pressurized air) to produce the
thrust needed to lift-off. The
pressure vessel (the engine of
the rocket) is usually a used
plastic soft drink bottle. The
water is forced out by a
pressurized gas, typically
compressed air, that produces
thrust and lifts the rocket.
Why use Water Bottle Rockets to
Teach STEM Concepts
attention getter
• Great application & display of scientific concepts
• Teaches students to communicate scientific ideas
(both orally and written)
• Easy way to teach Newton’s laws
Why use Water Bottle Rockets to
Teach STEM Concepts?
• Effective means to foster student collaboration
• Provides opportunity to use scientific tools and
• Awesome way to utilize mathematics to help
achieve goals and outcomes
STEM [ideas] of Water Bottle Rocketry
Technology Engineering Mathematics
Newton’s 3 Laws
Design Processes
Manipulating variables
to Maximize Hang time
Thrust vs. Drag
Material choice
Lift vs. Gravity
Tradeoff Concepts
Square root
Unit conversion
Scientific Inquiry
Center of Mass
Build Techniques
Center of Pressure Wind Resistance
Order of Operation
How are the Rockets Judged ?
• An overall winner will be judged upon the
following criteria (based on 100%).
- Hang Time of Rocket
- Technical Paper
- Patch Design
- Technical Drawing
NOTE: Elementary School is only Judged on:
- Hang Time of Rocket
- Patch Design
Final Hangtime Score Calculation
Hangtime – the time from when the rocket
(pressure chamber) leaves the launce pad until
the time it reaches the ground or strikes an
Max Hangtime – maximum hang time
recorded during the competition
Final Score = Team hangtime X 100
max hangtime
Safety First
The next 4 Slides and 13 bullet points will cover
Water Bottle Rocketry Safety. Why? I’m glad you
asked…! Because water bottle rockets can be
dangerous and can hurt someone if not handled
Fact: A water bottle rocket pressurized
to 60 psi leaves the launcher at 70 MPH…!
Safety Safety Safety…!!!
• Water bottle Rockets and Water Rocket
Launchers are NOT toys; thorough understanding
of their function is required prior to conducting
ANY launch activities
• Extreme caution should be used at ALL times
during launch activities
• Trained Adult supervision is required at ALL
times; Absolutely NO Exceptions
Safety Safety Safety…!!!
• Students and adults should wear safety
goggles/glasses during all launch activities
• NEVER stand directly in front of the launcher at
ANY Time
• NEVER approach a rocket that is under
• No running, horseplay, etc. around launch area
during launch activities. Be attentive at all times.
Safety Safety Safety…!!!
• Use ONLY large open fields for launch…250m
(~825 feet) or MORE of down range distance is
• Rope-off or “clearly mark” launch area
• Always conduct a trial launch at low air
pressure (i.e. 35-40psi) to get an idea of how
far your rockets will travel with respect to a
given launch area
Safety Safety Safety…!!!
• All rockets should be thoroughly inspected
prior to launch
• Do NOT over=pressurize rockets. 80psi MAX
• Always use a CLEAR audible countdown
before EACH launch (5! 4! 3! 2! 1!)
Basic Water Rocketry Concepts
• What is a Rocket?
– A chamber enclosing a gas under pressure
• A basic example is an inflated balloon
– The rubber wall compresses the air inside. Air quickly
escapes from the small opening at one end and the
balloon files in the opposite direction
Newton’s Three Laws
Water Bottle Rockets are governed by
Newton’s Three Laws
1) Objects at rest will remain at rest and objects in
motion will remain in motion in a straight line
unless acted upon by an unbalalnced force.
2) Force equals mass times acceleration
3) For every action there’s an equal and opposite
Newton’s First Law
The Law of Inertia
At Rest: Forces are balanced. The
force of gravity pushing down on the
rocket equals the force of the launch
pad pushing up.
In Motion: Thrust from the rocket
unbalances the forces causing a
downward thrust and an upward
reaction on the rocket
Newton’s Second Law
The Law of Proportionality
• Force equals mass times acceleration.
– Pressure inside the rocket exits the throat of the
bottle and produces force (thrust). Mass
represents the total mass of the rocket, including
its fuel.
• The mass of the Rocket changes during flight as the
fuel is used and expelled. The rockets weights less and
• Thrust continues until the engines stops firing
Newton’s Third Law
The Law of Interaction
• For every action there’s an equal and
opposite reaction (Action and Reaction)
Action: The rocket pushes gas out of the
engine (downward thrust)
Reaction: The gas pushes up on the rocket
Note: The action (thrust) has to be greater
that the weight of the rocket in order
for the reaction (liftoff) to occur.
Inertia is the tendency of an object to resist any
change in motion and is associated with the mass
of an object
Center of Mass (CM)
The Center of Mass is the exact point about which
all of the mass of an object is perfectly balanced.
• All matter, regardless of size, mass, or
shape has a center of mass.
• Around this point is where an unstable
rocket tumbles.
– Spinning and tumbling takes place
around one or more of three axes: roll,
pitch, and yaw
– Any movement in the pitch and yaw axes
directions can cause the rocket to go off
Center of Pressure (CP)
The Center of Pressure (CP) is the location
where the ‘pressure forces’ acting on a
rocket are balanced. The CP exists only
when air is flowing past the moving rocket.
(Based on surface area)
• Flowing air pushing against the rocket, can
cause it to roll and sway around the most stable
point (CG/CM).
• It is important that the CP of the rocket is
located toward the tail and the CM is located
toward the nose.
• DRAG = Air Resistance
• Air Resistance causes friction which slows
down the Rocket. Friction always works in the
opposite direction of the Rocket’s motion.
NOTE: Even when a rocket is descending, drag
counteracts the rocket’s motion!)
Now let’s launch into the
Rules and Guidelines
Objective of Competition
To launch a rocket propelled by water and air
and reach a maximum height. The launch angle
which can be adjusted from approximately 90
degrees, will be kept the SAME for all rockets
launching during a particular competition. Each
rocket will be launched using 12 ounces of water
and at 70 psi of air pressure.
Rules & Guidelines
Each team of 3 is required to submit:
Elementary School
- completed entry form
- patch design
Middle & High School
- completed entry form
- technical paper
- patch design
Note: Check with your State/Regional
Host for submission deadline
On the day of competition, but, prior to launch an
actual operating rocket with its corresponding
technical drawing must be submitted in order to
– At this time each entry must pass a visual inspection
and height requirement. ONE chance will be given to
correct rocket (see R&G for details)
Rocket Identification Diagram
Let’s Build a Rocket…!!!
Construction and Operation Requirements
1. The pressure vessel must be ONE clear 2 liter
bottle (i.e. NO tinted bottles allowed for use as
pressure vessel). So Do Not…
2. Water and air pressure will be the sole source of
3. DO NOT USE: Metal, Glass, Hard Plastics,
Rocks or Spikes to construct the rocket.
* * *Use of these materials will automatically
disqualify the team from the competition.* * *
Let’s Build a Rocket…!!!
Construction and Operation Requirements
4. On the bottom of the
rocket, leave 7.5 cm from
the throat of the exit plane
clear of any coverings
(paint, markings,
drawings, etc.).
5. Maximum total height of
rocket is 76.0 cm.
Let’s Build a Rocket…!!!
Construction and Operation Requirements
6. Nose-cone tip must have a
minimum radius of 1.5 cm.
7. Fins may extend to throat
exit plane but NOT below
the bottle’s Exit Plane.
Let’s Build a Rocket…!!!
Construction and Operation Requirements
8. The maximum fin width
distance from the bottle is
10.0 cm (or 16.5 cm from
center of bottle axis).
***Note: No forward swept type
of fins are allowed to be used
on the rocket.
9. The use of parachutes is
NOT allowed.
Swept Fins
Let’s Build a Rocket…!!!
How to Build The Water Bottle Rocket
Cutting Tools
• 2-liter soda bottles
• Poster Board
• Adhesive – Caution: Hot glue
will weaken the pressure
vessel walls
• Scissors, utility knife,
hacksaw, etc.
– Clear packing tape
– Foam mounting tape
– Carpet tape
Decorations: (NO
• Markers, spray paint,
stickers, etc.
Materials for Fins
- Balsa/Bass wood
- Corrugated plastic
- Foam board
- Old credit/gift cards
Let’s Build a Rocket…!!!
How to Build The Water Bottle Rocket
Let’s Build a Rocket…!!!
How to Build The Water Bottle Rocket
Let’s Build a Rocket…!!!
Nose Cone Design and Construction
1. Cut a circle out of poster board/card stock
2. Cut a line along the radius
3. Rotate paper into a cone, adjust angle, then tape
Let’s Build a Rocket…!!!
Nose Cone Design and Construction
4. Trim base of cone until it
matches top of rocket
5. Cut nose cone tip off to allow
a 1.5cm minimal radius and
add a ball (or a plastic egg
6. Secure nose cone to water
Let’s Build a Rocket…!!!
Fin Design and Construction
Determine fin patter (analytic design or trial & error
Use recommended materials but okay to be creative
Do NOT use off limit materials
Use as many fins you feel necessary (remember more
fins = more mass/weight/drag)
Here are some fin
pattern examples
Let’s Build a Rocket…!!!
Patch Design
A patch is a creative display that reflects the
dedication and mission of the team.
– For the competition your symbolic picture must comply with the
following rules:
1. Each entry is to be prepared and submitted by the
SECME School Teams who will be participating in the
Water Rocket Design Competition.
2. Patch designs must be submitted on 13” X 13” poster
3. All entries must contain the team name and follow the
theme of this year’s SECME competition.
Let’s Build a Rocket…!!!
Patch Design
4. A short (less than 1-page) explanation of the symbols of
the patch must be included on the back of the patch (See
example on pg 45 of National Guidelines; Full version)
5. All teams participating in the Water Rocket Competition
must be prepared to display their patch prior to the launch
of their rocket.
6. Patches must be hand-made original work.
7. Only Ink pens, pencils, markers, or paint may be used.
* * * NOTE: Any Patch Design deemed inappropriate will be
pulled from the competition.
Let’s Build a Rocket…!!!
Patch Design
Evaluation Categories
(1 – 30 points)
a. Innovativeness of the design.
(1 – 30 points)
a. Uniqueness of the information depicted.
III. APPEARANCE (1 – 20 points)
a. Attractiveness/neatness of the presentation
(1 – 20 points)
a. Representation of the team’s name and SECME
(The highest possible score is 100)
Technical Report
White Paper
12-pt Type/Standard Font
Double-spaced Text
1” Borders
1. Cover Page:
2. Abstract
3. Table
4. Introduction
5. Design Background
6. Calculations
7. Conclusions/Recommendations
8. Acknowledgment
9. Appendix
NOTE: Please read the
official Rules and
Guidelines for specific
ALSO NOTE: Take EXTREME caution regarding plagiarism
Take Home Points
• Teachers should focus on STEM standards along with
the design and build of Water Bottle Rockets
• Teachers should ensure that students design, build, test,
troubleshoot and rebuild as much as necessary to
thoroughly grasp the STEM concepts regarding Water
Bottle Rocketry in order to be ready for both Regional
and National Competition
• Students should design and build their rockets to:
– Minimize drag (wind friction)
– Maximize stability
– Maximize rocket’s time aloft
• Remember… STEM, STEM, STEM…!!!