Development and Optimization of a
Soft-Projectile Launcher Utilizing
Mechanical Energy
Aaron Wagner
Mike Knoop
University of Missouri, MAE Capstone 4980, Fall 2011
Defining the Problem
Consumers modify blasters
to increase power
Increasing power decreases performance
Goal of this capstone group
1. Verify if adding rotation to darts improves
flight characteristics
2. Develop and optimize a design to maximize
performance
Defining Performance
a) Distance
b) Shot Grouping
c) Consistency of (a) and (b)
Increased Effective Range
Safety
Cost
Weight
Durability of System
Absolute Importance
Relative Importance
Current Competitors
Technical Difficulty
Target Value
Units
9
9
9
9
6
9
9
9
1
1
39
11
5
5
a
$
45
13
1
3
RPM
45
13
2
3
7.7*
m
45
13
2
4
b
cm
39
11
5
5
9
3
45
13
5
5
27
8
4
5
69
19
2
4
40
m/s
3
4
4
3
3
354
5
4
4
3
3
Notes
a
Less than $200
b
22.6±12.3
*
This value is expected to change once adjustments are made to account for
improvements resulting from the copper breach.
Improvement Ratio
Customer
Importance
Current Competitors
Muzzle Velocity
Mass of System
Non Custom Parts
Weight of soft
projectile
Shot Grouping
Distance Traveled
RPM of Soft
Projectile
Cost of Manufacture
Quality Function Deployment
1.7
1
1
1
1
Design Strategy: Iteration
Designing the Initial Prototype
Design inspiration
Design Strategy: Mock Launcher
Initial Prototype Concept
Direction
of Motion
Selecting a Flywheel Rotational Velocity
Measuring muzzle velocity of existing
soft-projectile launcher
Calculating a necessary rotational
velocity
𝑉𝑡 = 𝜔 ∙ 𝑟
Vt = 30 m/s
r = 3.81 cm.
𝜔 = 7500 RPM
Construction and Development
Failure Mode Effects Analysis
"A successful FMEA activity helps a team to
identify potential failure modes based on past
experience "
Initial Prototype Build
Direction
of Motion
Second Prototype Build
Direction
of Motion
Highspeed of Jamming
http://www.youtube.com/watch?v=c_Mi0Bm
miFc&list=PL0FF1657C0B08FAB8
Third Prototype Build
Direction
of Motion
Highspeed of Fishtailing
http://www.youtube.com/watch?v=BSyDEoXlY
4c&list=PL0FF1657C0B08FAB8
Highspeed of Single-Prong Barrel Close-up
http://www.youtube.com/watch?v=87Y0A6IMJ
M8&list=PL0FF1657C0B08FAB8
Barrel Iteration
Highspeed of Double-Prong Barrel Close-up
http://www.youtube.com/watch?v=f1uctE_u4
qk&list=PL0FF1657C0B08FAB8
Final Prototype Build
Direction
of Motion
Testing and Optimization
Parameters to Optimize
Flywheel rotation angle
Flywheel gap distance
Foam darts with high rotational
velocities are less-able to self-correct!
1250 RPM
High tip-off
Actually self-corrects
5000 RPM
Little apparent tip-off
Actually fishtails
1250 RPM Barrel Close-up
http://www.youtube.com/watch?v=9cDyEDYO
w7E&list=PL0FF1657C0B08FAB8
5000 RPM Barrel Close-up
http://www.youtube.com/watch?v=wBaZM7owLc&list=PL0FF1657C0B08FAB8
Selecting a Flywheel Rotational Velocity
Selecting a Flywheel Gap Distance
Distance Traveled (ft)
50.0
40.0
30.0
20.0
10.0
0.0
0.50
0.46
0.42
0.38
0.33
Distance Between Wheels (in)
0.29
Does Rotational Velocity Help?
Distance
+4.6 ft. (14%)
6
4
2
0
Distance (ft)
Neutral
Angled
50
47.5
45
Standard Deviation
25
27.5
30
32.5
35
37.5
40
42.5
Number of Occurences
Yes
-2.3 ft. (40%)
Future Work
• Precision machining
• Foam dart wear
• Integrating into an existing SPL
Final Thoughts
• Iteration is very important
• Pick a project which motivates you
• Relevance, Market Size
Acknowledgments
Humans vs. Zombies Mizzou for project funding
Brian Graybill for teaching us SolidWorks
Dr. El Giz-awy for Capstone guidance
Richard Oberto for fixing the highspeed camera!
Questions and Feedback
(or should we just test fire of our final design?)