Submitted by: Tom Shepard
University of St. Thomas
[email protected]
Water Balloon Launcher Design Project
ENGR 150
Note to Instructors: Students rank their interest in building a compressed air cannon, catapult or trebuchet for
their design and are split into teams accordingly.
Objective: Design, build and test aremotely triggered water balloon launcher for distance, accuracy, and
consistency.
Key Dates:
– Design ready for initial testing: October 23rd
(device must successfully launch a water balloon towards target by end of lab on this date)
– Final testing: October 30th
– Final Report Due: November 6th
Design Rules:
1. Your launcher must have at least 3 layers of safety built in.
2. Your team must complete a safety report before building and testing.
3. Your launcher must be made from scratch. Individual components such as wheels, ball bearings, fasteners,
may all be purchased but the body must be built/shaped by the team.
4. Your launcher must be remotely launched from a distance of at least 8 ft.
5. UST will cover up to $100per project. Students may use free materials which will not count towards the
$100, but their cost must be included in the bill of materials.
6. Only the water balloons provided may be used, teams are responsible for filling them to the desired volume.
Final Testing:
1. At the final testing teams will have 10 minutes to launch a maximum of 10 balloons.
2. Teams may make adjustments during the 10 minutes.
3. Balloons will be measured based on where they first impact the ground.
4. Balloons which break during launch will be measured based on where the rubber first impacts the ground.
5. All parts of the launcher must remain behind the chosen launch line.
Performance criteria:
A team’s overall performance score will be the sum of all balloons which score points during the final testing.
Any design which is damaged so badly it is deemed unsafe to launch, will receive a performance score of 0 for
any remaining balloons.
The target has 3 scoring rings worth 1 pt., 3 pts., and 5 pts. Points are also determined by how far from the
target the launcher is placed. A launcher placed 50 ft. from the target will receive a distance score of 1 pt. while
a launcher placed 115 ft. from the target will receive a distance score of 5 pts. The total score for a balloon is:
target score x distance score. For example, a balloon which is launched from 70 ft. which lands in the 3 pt. ring
would earn a score of: 2 x 3 = 6 pts. The total performance score for a team will be calculated by summing up
the score for each balloon in the final test.
Performance score = sum of (target score x distance score) (for all balloons in final testing)
The performance grade for each team is determined by the overall final testing performance score from:
Performance Grade Total Performance Score
A
>30
B
25-30
C
20-24
D
15-19
F
<15
Grading:
25% - working initial design that meets constraints by initial testing deadline
25% - Performance grade
25% - final report
25% - group member assessment
** Points will be lost for failing to adhere to your safety report guidelines
Extra Credit:
5% - extra credit for team with highest (final test points)/(material cost)
2% - design looks professional
Final Report:
The final report must be typed, Times New Roman font size 12, normal 1” margins and 1.5 line spacing. It
should include the following sections while being concise, yet thorough. The audience for your report is a 1st
semester engineering student just learning about the engineering design process. The length should be roughly
6-10 pages. The final report is to be e-mailed to the instructor on the due date.
Cover page – team member names, date, lab day/time, photo/detailed sketch of final design (optional name of
final design)
Body – The main body of the paper should be broken into the different steps of the engineering design process.
Each section should define the specific step, discuss why it is important to include in an engineering design
problem, and detail what your team specifically did for that step and the results which were reached.
Though one frequently needs to jump backwards in the process in order to move forward, the different steps
are:
1.
2.
3.
4.
5.
6.
7.
Identify the need/problem and its constraints
Research the problem
Develop possible solutions
Select the best possible solution(s)
Construct & prototype
Test & evaluate the solution
Communicate the solution
a. final testing performance
b. energy efficiency
c. what worked well
d. what did not work well
e. major lessons learned during the project
f. bill of materials
8. Redesign (suggestions for future improvements)
References – Include all references which were cited in your report.