Dr. John Foltz
College of Agriculture and Life Sciences
University of Idaho
PO Box 442336
Moscow, Id 83844-2336
March 17, 2016
RE: Idaho APPS Final Design Report
Dear Dr. Foltz,
Attached is the final design report for the Idaho APPS project.
We have outlined the future work that will need to be done in order to comply with the requirements of
the Health and Safety office. As discussed in the last meeting, a professional engineering or someone in
the field of ballistics or explosives should inspect the cannon before it is used. This will also help
determine if we have overlooked any safety risks. Appendix 2 shows the DFMEA we briefly discussed in
the meeting. This outlines potential failures and could be used as a tool for whomever inspects the
cannon.
Appendix 4 shows the math model used to predict launch criteria. This can be used as a tool for learning
at the corn maze. It is also discussed in the Math Model section of the report.
Please feel free to contact me over the coming months if you have questions. As I said before, I’d be
happy to help, but I may be unavailable at times. If that is the case, I will be sure to contact you once I
am available again.
Our team thanks you the opportunity to be involved in such a fun project. We all learned a lot and look
forward to seeing how our project is accepted by users at the Clearwater Corn Maze this year.
Sincerely,
Kara Peer
Team leader, Idaho APPS
peer3026@vandals.uidaho.edu
208-691-9105 (text or call)
1
Idaho APPS Final Design Report
(Advanced Pumpkin Propulsion System)
Josh Bouma
Kara Peer
Ramzi Sadeddinsarama
Andrew Schmohr
Shelby Smith
Submitted:
March 17, 2016
a
Executive Summary
Idaho APPS (Advances Pumpkin Propulsion System) is a team of seniors working together to build a
pumpkin cannon for Dr. John Foltz, the Associate Dean of the College of Agriculture and Life Sciences.
The cannon will be used as an additional attraction at the Clearwater Corn Maze held in Lewiston, Idaho
each fall. The cannon will be used by the general public to shoot pumpkins that range from five to eight
inches in diameter at a target approximately 150 yards away. The pumpkins will explode once they hit
the plywood target and spectators will be able to check their aiming accuracy.
The cannon is designed to use compressed air as its propellant. The cannon will be loaded from the
open end of the barrel by a designated operator. The trigger mechanism is a level action butterfly valve.
To increase recovery time between launches, the cannon will be rigged with one air tank and one
accumulator tank. The cannon will also feature horizontal and vertical aiming capabilities to give the
participant the full experience of shooting a cannon.
Safety protocols are being implemented in the design to ensure both the participant and the employee
overseeing the launch site are at no risk. A safety manual will accommodate the final product as well as
detailed instructions on how to operate the cannon.
b
Contents
Background ................................................................................................................................................... 1
Problem Definition ........................................................................................................................................ 1
Client Needs .............................................................................................................................................. 1
Specifications ............................................................................................................................................ 2
Concepts Considered and Design Selection .................................................................................................. 2
Propulsion System..................................................................................................................................... 2
Rail Gun ................................................................................................................................................. 2
Compression Spring System .................................................................................................................. 3
Extension Spring System ....................................................................................................................... 3
Compressed Air System ........................................................................................................................ 4
Propulsion System Selection ................................................................................................................. 5
Aiming ....................................................................................................................................................... 5
Health and Safety Criteria ......................................................................................................................... 6
Math Model .............................................................................................................................................. 6
Prototype Testing...................................................................................................................................... 8
Final Design ............................................................................................................................................. 10
Design Evaluation........................................................................................................................................ 10
Budget ..................................................................................................................................................... 10
Full Scale Test Results ............................................................................................................................. 11
Future Work ................................................................................................................................................ 11
Appendices..................................................................................................................................................... i
Appendix 1.
SolidWorks Drawings ......................................................................................................... i
Appendix 2.
DFMEA............................................................................................................................... ii
Appendix 3.
Launch Protocol and Procedure ....................................................................................... vi
Appendix 4.
Math Model ................................................................................................................... viii
c
Background
Dr. John Foltz (Associate Dean of the College of Agriculture and Life Sciences) has funded a senior
capstone design team to design and fabricate a pumpkin cannon to be used as an additional attraction
to the Clearwater Corn Maze held each fall in Lewiston, ID. Idaho APPS (Advanced Pumpkin Propulsion
System), the student design team, was formed to accomplish this task. Dr. Foltz would like to have the
pumpkin cannon as an attraction at the corn maze for the general public to shoot pumpkins at a target
for a small fee.
2011
Clearwater
Corn Maze
Proposed
cannon
launch site
Building pumpkin cannons and Pumpkin Chunkin’ contests are growing in popularity. Most pumpkin
cannons are only used by the people who built them; however, this pumpkin cannon will be different in
that the public will have an opportunity to shoot the pumpkin as well. Also, this cannon will not be
designed for distance; rather it will be used for accuracy in hitting targets. In years to come, Dr. Foltz
would like use this project as a spring board for a Pumpkin Chunkin’ contest that the Clearwater Corn
Maze will host. Idaho APPS will design the first cannon as a trial run to judge interest in such contests.
Problem Definition
The problem definition was the development and design of a pumpkin cannon for use at the Clearwater
Corn Maze. Most pumpkin cannons are built by trial and error. As a Senior Capstone Design Project,
this cannon will be built from an engineering standpoint. The Idaho APPS team expects to design and
engineer this cannon using their combined knowledge from their engineering coursework.
Client Needs
The following client needs are listed below:



Safety is top priority
Project a 5-8 inch diameter pumpkin 100 to 200 yards
Aiming capability, with some sort of sight on the barrel
1







Mobile (on 2 or 3 wheels), with a hitch to be able to connect to a tractor or car for moving
Sufficient velocity to smash the pumpkin with an impressive explosion
Operator and bystanders do not need to wear hearing protection
Short or no recovery time for the system (1-3 minutes)
Lowest construction cost possible
Estimated life of the product should be 5-8 years or longer
Aesthetically pleasing
Specifications
Specifications were developed from the above client needs and are presented below in Table 1.
Table 1 Specifications
Specifications
Size
Safety
Features
Qualitative
Wheels to handle terrain
Small enough to store in extra shop/shed space
Barrel large enough for 8 inch diameter
pumpkins
User friendly
No hearing protection needed
Tamper proof overnight
Launch far enough to break pumpkin but short
enough to see it break
“Coolness” Factor (aesthetics)
Short recovery time between launches
Long design life
Horizontal Aiming
Vertical Aiming
Quantitative
8 inch diameter or larger
6 ft by 15 ft footprint
8 inch inner diameter barrel
No age limit
Less than 125 dB when firing
Apply lock in under 1 minute
Range 100 – 150 yards
At least 8 on a scale up to 10 by Dr. Foltz
Less than 1 minute
5 to 8 years (40,000 uses)
15 degrees off center both directions
75 degrees up from horizontal
Concepts Considered and Design Selection
Propulsion System
Rail Gun
One of the first ideas for propulsion was to use the concept a rail gun. A magnetic plate would be
accelerated along the inside of the barrel by a series of electro-magnets pulling the plate towards the
open end of the barrel. The pumpkin would sit on the magnetic plate and would be launched from the
barrel with the plate came to rest at the end of the barrel. One advantage to this design is it would be
very quiet to launch. However, the disadvantages are that it would require a lot of electricity and it
would be expensive to build and program.
2
Compression Spring System
There were two ideas for spring propulsion systems. The first one was a compression spring system.
Error! Reference source not found. below shows a sketch of the set up. There would be two (or more)
springs connected to the back of the barrel and to a plate inside the barrel. A cable would be attached
to the middle of the plate and exit through the back of the barrel where it would be attached to a cable
winch. The pumpkin would rest against the plate inside the barrel. To launch the pumpkin, the cable
winch would crank back the plate and compress the springs. Once the plate is far enough back, a catch
would hold it in place and the cable would be released from the plate. A mechanical trigger would
release the catch on the plate and the springs would decompress, pushing the plate and the pumpkin
forward. When the springs reached their free length (fully decompressed length), the plate would stop
and the pumpkin would be launched out the end of the barrel.
Figure 1 Compression Spring Sketch
The major advantage to this system is there would be no electricity required to launch the pumpkin.
Since the launch site is at the corn maze, it may be difficult and expensive to get electricity to the
cannon and a spring system would negate this inconvenience. Another advantage is the low cost. This
system would not only be inexpensive to build, it would have little to no operating and maintenance
costs. However, there are disadvantages as well. Mainly, as the springs decompress to their free length,
they lose acceleration. This would cause the pumpkin to actually slow down as it reached the end of the
barrel. If the springs were strong enough to give the pumpkin the initial velocity it needed before the
springs were completely at their free length, this problem could be avoided. However, this would
require a lot of prototyping and testing.
Extension Spring System
The second spring system considered was similar to a slingshot. Figure 2 below shows a sketch of this
system. This design would use multiple extension springs connected to the back of the barrel and to
cables (shown in red) on either side. The cables would then each wrap around a pulley and attach to a
basket in the middle of the barrel. The pumpkin would rest in the basket. To launch the pumpkin, the
basket would be pulled back and hook on a catch outside the rear of the barrel. The springs inside
would be stretched as the cable pulled them forward toward the pulleys. A trigger would release the
catch and the springs would pull the cable back, launching the basket and pumpkin forward, and the
pumpkin would be launched out the end of the barrel.
3
Figure 2 Extension Spring Sketch
By using extension springs and making them shorter with a higher spring constant, this would minimize
the de-acceleration problem with the compression spring concept. It would still be an issue, but
extension springs set up in this way have a more constant acceleration. This system still has the
advantage of low cost as the other spring system did. However, there would still be a lot of prototyping
and testing required for everything to work properly. Another disadvantage to both spring systems is
they required more physical strength to launch and they take time. It could take longer than the
required one minute to pull the pumpkin back into place.
Compressed Air System
The final concept considered was a compressed air system. This is how most existing pumpkin cannons
are designed to launch pumpkins. Figure 3 below shows a sketch of this system. The compressed air
system would have two air tanks on either side of the barrel. The tanks would be filled with an air
compressor to the required air pressure. The tanks will be sized such that only one tank will be needed
to launch a pumpkin. This way, there is a faster recovery time between launches. Each tank would have
a ball valve to control the expulsion of the air from each tank separately. Inside the cannon would be a
sabot for the pumpkin to rest against. The sabot would create enough of a seal to keep the barrel
pressurized as the pumpkin is launched. To launch the pumpkin, a solenoid switch will actuate one ball
valve, releasing the air in the tank quickly into the barrel. The air would then push the sabot along the
barrel and launch the pumpkin. The compressor would turn on and begin filling the first tank while the
second tank would be ready to go for another launch.
Tank 1
Compressor
Ball Valves
Tank 2
4
Figure 3 Compressed Air Sketch
One of the main advantages to this system is the force behind the pumpkin coming from evenly
distributed air pressure should increase consistency and accuracy. There would not be any deacceleration problems like the spring systems experienced. Another advantage is that it would not
require as much prototyping and testing. A disadvantage of this system is that it will be more expensive,
both to build and to operate. There will need to be electricity available at the site in order to
continuously run the air compressor, which will be an additional cost each year.
Propulsion System Selection
A decision matrix was constructed to compare each propulsion system and rate them in different
categories. Table 2 below shows the decision matrix with the final values. There were three categories
chosen to rate each propulsion system: ease of use, cost, and ease of design/manufacturing. Each
category was given a weight based on how important that category was to the overall design. Each
propulsion system was rated on a scale of one to ten for each of the three categories, one being the
lowest score and ten the highest. The ratings were chosen by all five group members, and then
averaged to get the numbers in the table. Each number was then multiplied by the appropriate weight
and totaled at the bottom of the column. The propulsion system with the highest score was the
compressed air system and was the system selected to move forward with.
Table 2 Decision Matrix
Ease of Use
Cost
Ease of Design/Manufacturing
Total
Item
Weight
50
30
20
100
Compressed Air
8.8
6
8
780
Compression
Springs
6.2
7
6
640
Extension Springs
7.6
8
6.1
742
After prototype testing was completed and the full scale cannon went into production, there were some
logistical issues with using two compressed air tanks. With the limited budget, it was difficult to safely
mount two tanks to the frame. Also, as the horizontal and vertical aiming decisions came together, it
was determined that the accumulator tank which would hold the air had to rise and lower with the
cannon barrel. This would be very difficult with two barrels. It was decided that one accumulator tank
would be used and an air compressor large enough to decrease the time to refill the accumulator should
be purchased.
Aiming
The cannon is required to have vertical and horizontal aiming capabilities. There were a few ideas for
the horizontal aiming, but all with the same basic concept. This concept was that the cannon had to
swivel at its base. One idea was to mount the cannon to a frame shaped like football goal post. Then,
the base of the goal post would go through an opening below it and sit on roller bearings. The roller
bearings would allow the goal post to rotate side to side. This concept was upgrades when one of the
5
team members found a swivel plate. The swivel plate had a plate on the top and bottom of some
bearings and accomplished exactly what was intended by the design described above.
There were a few concepts considered for vertical aiming. One idea was to have a rack and pinion
attached to the base of the cannon. The rack would be attached to the base and the pinion would be
attached to the bottom of the barrel. When the pinion gear is turned, it would move along the rack,
raising or lowering the barrel. A similar concept for the vertical aiming was to use a scissor style jack.
This would be attached to the barrel of the cannon about half way up the barrel. When the jack screw is
turned, it would raise the barrel of the cannon. One problem with this system is the sleeve the jack is
attached to the barrel with will have to shift slightly as the barrel is raised and lowered. The scissor jack
would be the cheapest solution and therefore it was chosen for the vertical aiming. The final vertical
aiming design included two posts anchored to the base of barrel that could be cranked up and down. A
cradle connecting the two posts would support the barrel. The curvature of the cradle allows the cannon
to slide as needed for horizontal aiming. The aiming system is illustrated in Appendix 2.
Health and Safety Criteria
Since the cannon will be used by the general public, with the supervision of the client’s employees, the
cannon needs to be easy to use and safe to operate. The Environmental Health and Safety office met
with the team on numerous occasions to ensure their requirements were met. To make the cannon as
safe as possible for the user, it is required that a designated operator be in charge of going through the
launch procedure. The user is still responsible for triggering the system. A few key operations and safety
guidelines are outlined below.
1. The cannon and all its components should be inspected prior to each season according to the
guidelines in the safety manual.
2. The cannon is to be front loaded by a designated operator, not the user.
3. To shoot the cannon, the operator must follow a few rules and guidelines. The launch protocol
and procedure is provided in Appendix 3.
4. The launch protocol can be dramatized to improve the theatrics, but all the steps of the
procedure must be followed.
While the corn maze is closed, the air compressor will be disconnected and all hose connections will be
removed to prevent anyone from tampering with the cannon or using it unsupervised.
Math Model
A math model was produced to mathematically determine what is going on during propulsion. This was
used in conjunction with the prototype testing to get some ideas of how to size many of the
components on the cannon. It was also used as a tool for predicting the exit velocity, the distance the
projectile will go, and other flight parameters.
In our design, the pumpkin is propelled by work done from the expansion compressed air in the storage
tank under isentropic process. Isentropic processes assume constant entropy from the initiation until
completion of the process.
6
Work done by expanding compressed air
= Initial energy of compressed air – Final energy of compressed air – Atmospheric
𝑾 = 𝑷𝟏 ∗ 𝑽𝒌𝟏 ∗
(𝑽𝟏 + 𝑨𝒔 ∗ 𝑳𝒔 )−𝒌+𝟏 𝑷𝟏 ∗ 𝑽𝟏
−
− 𝑷𝒂𝒕𝒎 ∗ 𝑨𝒔 ∗ 𝑳𝒔
−𝒌 + 𝟏
−𝒌 + 𝟏
P1: Initial pressure of compressed air, before opening the valve (Pa)
V1: Initial volume of compressed air, volume of storage tank (m^3)
As: cross sectional area of shooting barrel (m^2)
Ls: Length of shooting barrel
k: isentropic process constant, (1.4)
Patm: Atmospheric pressure (101,325 Pa)
Now, from work we can calculate the initial velocity of the pumpkin – the velocity at the end of the
shooting barrel as soon as it exit’s.
Work from compressed air = Kinetic Energy
w = (m * v^2)/2
v = SQRT (2*w/m)
v = initial velocity of pumpkin (m/s)
w: Work from compressed air (Joules)
m: mass of pumpkin (kg)
From the initial velocity of the pumpkin, we are able to use the projectile motion equations to predict
the horizontal distance of travel for the pumpkin. The following equations consider the air drag, as it
works against the motion of the pumpkin decreasing the distance of travel.
For the horizontal travel,
Sx: Horizontal distance (m)
m: Pumpkin’s mass (kg)
Vxo: Horizontal initial velocity (m/s) = v * cos (θ)
Θ: Launching angle
t: time of travel (s)
k: Drag constant = pumpkin’s mass (kg)*gravitational acceleration (m^2/s) / terminal velocity (m/s)
Terminal velocity = SQRT (2*pumpkin’s mass*g / Cd(drag coefficient)*air density*pumpkins area)
For the vertical distance,
7
Sy: Vertical distance (m)
Vyo: Vertical initial velocity (m/s) = v * sin (θ)
From the above equations, a spread sheet on excel is produced and different time increments are
inserted in both equations, the horizontal distance is when the vertical distance goes to zero.
20 psig - angle 20
VERTICAL DISTANCE (M)
80
70
60
50
40
30
20 psig angle 20
20
10
0
0
50
100
150
200
HORIZONTAL DISTANCE (M)
Figure 4 Plot of flight path produced from math model.
Prototype Testing
After the math model was constructed we began prototyping. We built two
prototypes out of 2 inch schedule 40 PVC. Both prototypes had 2 foot long
barrels and a ball valve acting as the trigger. The difference between the two
prototypes was the accumulator lengths, one was made with a 1 foot
accumulator the other had a 2 foot accumulator. This doubled the volume
that the second accumulator had. The prototype shown here was the one
with the shorter accumulator length. A golf ball was used as our projectile,
this was useful because they are all the same size and weight. A foam sabot
was placed behind the golf ball to prevent further pressure losses from air
escaping around the projectile.
8
To test the prototypes we found a park with a safe launch point to fire the projectile. We then tested
both prototypes at two different pressures, 20 and 30 psi. After the accumulator was charged we held
the launch angle at a constant 45 degrees and fired. The distances were measured using a measuring
wheel and recorded for statistical analysis. Some factors that were out of our control and assumed as
constant during testing includes, wind speed and direction, air temperatures, and the speed the valve
was turned. These variables may have affected our data in. We shot each prototype 20 times at each
pressure (20&30 psi).
Figure 5 Graph of results from prototype testing
Table 3 Statistical analysis of results from prototype testing
Pressure (psi)
Math model
Prediction (ft)
Mean (ft)
Median (ft)
Std. Deviation
Variance
Short Accumulator (1ft)
20
30
107
145
Long Accumulator (2ft)
20
30
144
282
113.7
113.5
4.46
19.91
149.8
150
3.56
12.69
151.25
152
6.13
37.57
9
286.15
286.5
8.48
71.92
Final Design
The final cannon was built with a schedule 80 PVC holding tank and fittings. The barrel itself is schedule
40 PVC due to supply limitations and the fact that it takes lower average pressures than the holding
tank. It’s still rated for operating pressures over triple the pressure we use to launch pumpkins. The
barrel is connected over the holding tank by two elbows and an 8 inch lockable flanged butterfly valve
forming a C-shaped design as shown in the picture below.
The cannon rests on a six wheeled base originally designed for a tractor pull competition. It is held on by
a collar that connects to a rod allowing the cannon to swing up and down. The rod runs through a rear
support shaped like a football goal post that is mounted on top of a steel turn-table. The turn-table bolts
to the frame and allows horizontal sway for aiming. The front end of the cannon rests on another goal
post style support that can be jacked up and down for vertical aiming and allows a certain safe degree of
horizontal aiming. On the front of the base is a flip down wheeled trailer jack to allow the cannon to be
rolled around a location.
The system can be charged by any compressor, but the one included with the cannon has a regulator
that allows the operator to set the pressure before attaching it to the holding tank and simply allowing
the compressor to fill the holding tank to the right pressure. There is a quick connect attachment on the
holding tank for charging the cannon. There is also a pressure relieve safety valve tapped into the
holding tank at the standard 125 psi. Near the valve at the back end of the cannon a pressure gauge is
mounted so the operator can always see if the system is charged and to what pressure it has been
charged before actuating the valve.
Design Evaluation
Budget
The final budget is shown in Table 4.
Table 4 Preliminary Budget
Item
Cost
Base and Wheels
Barrel – 10 “ SCH 80 PVC
Scissor Jack (vertical aiming)
Steel Plate (horizontal aiming)
Valves, Elbows, Wye
Compressor
Air Tanks
Fasteners and Miscellaneous
Subtotal
Total
* These items have yet to be purchased.
10
$ 594
$ 600
$ 50
$ 75
$ 270
$ 300
$ 170
$ 200
$ 2,259
$ 2,485
The total budget fro this project was $2500, this amount was to include prototyping and all other project
expenses. We wanted to keep the expenses of the project as low as possible that is why we chose the
materials and procedures that we did. The total amount spent on prototyping was around $65, keeping
the prototype cost low allowed us to have money for other aspects of the cannon design. The actual
cannon cost $1400 for the parts that were needed, a large portion of this was spent on the air
compressor that was needed to fill the accumulator tank. Things that still need to be considered in the
budget are Kevlar sleeves for the accumulator and barrel. All future work should be able to be
completed within the current budget.
Full Scale Test Results
After designing all the components of the cannon, a Design Failure Mode Effects and Analysis chart was
developed to determine potential failure modes. The chart, show in Appendix 2, lists an item or part,
then a possible failure mode. For example, the frame is a part and a failure mode would be bolts coming
loose. Then it lists the effects of the failure. In this case, the cannon could fall apart. This is rated on a
severity scale from one to ten where one has no effect and ten is hazardous and makes operation
unsafe to the operator and involved non-compliance with government regulations. Then next column
indicates the potential cause of the failure followed by an occurrence rating. This is again on a scale of
one to ten where one is unlikely and ten is extremely likely. Following the occurrence rating is the
current design controls. This column indicates what is currently being done to help minimize or
eliminate the failure mentioned. The following column is a detection rating on a scale of one to ten.
This indicates how likely the current design control is going to detect a failure. The column titled RPN
multiplies the 3 rating numbers together to get an idea of how crucial the potential failure mode is. The
final column shows a recommended action for preventing the failure. In most cases, reading the safety
manual is the best way to prevent failure.
Future Work
With the cannon completely constructed and tested, the bulk of the future work for this project will be
dedicated to licensing procedures and meeting special Health and Safety requirements. It takes a
considerable amount of time to complete that process. This will require the project to be passed on to
another team. The cannon can be used for demonstrations but in order to be used as an attraction at
the Clearwater Corn Maze more safety requirements must be met. Certain safety protocols will be
examined closely. The University of Idaho Environmental Health and Safety office will need to sign off
the final design. They will also help ensure an adequate safety and operation manual has been written
to accompany the cannon when it is passed on to the client.
The most important current change that needs to be completed is the addition of a Kevlar sleeve around
all the PVC components. While they are all rated well above operating pressures and have burst
pressures 10 to 20 times our maximum operating pressure, the possibility of them bursting must be
accounted for. A Kevlar sleeve would be relatively cheap and easy to install while adding both strength
by reinforcing the PVC as well as a layer that would contain any fragments if there ever was a burst. It
would allow the pressure to escape, but not the potentially dangerous shrapnel.
11
In addition, the cannon still needs to have a sight installed. A rear peep hole should be installed through
which to look at a front crosshair sight mounted to the forward vertical barrel support. This would allow
the operator to see directionally where they will be shooting. The system will need to be sighted in and
correlated for different pressures, angles, and pumpkin weights.
The horizontal aiming is currently done by simply pushing the barrel one way or another at the front
support. A long leverage arm should be attached to the top swivel plate at the rear support so that the
operator can more easily get the force needed to rotate the cannon from the back. This would enable
quicker horizontal aiming adjustment and eliminate having to move from the back of the cannon
In order to ensure the cannon complies with all health and safety regulations, the apparatus must be
inspected by a professional engineer or someone with adequate knowledge in the field of ballistics or
explosives. It is suggested that an inspection occurs at the beginning of each season before the
accumulator tank is charged for the first time. It is also suggested that after an initial inspection as soon
as the cannon is complete, a safety manual should be written. Anyone who is to operate the cannon
should be familiar with the safety manual in order to remediate any problems that could arise during
operation.
12
Appendices
Appendix 1.
SolidWorks Drawings
i
Appendix 2.
DFMEA
DESIGN FAILURE MODE AND EFFECT ANALYSIS
(DFMEA)
Idaho APPS
Project
Year
2011-2012
Shelby, Ramzi, Josh, Andrew,
Kara
Team Members
ITEM AND FUNCTION
CURRENT DESIGN
CONTROLS
SEV
Base
Wheels
axle breaks
cannot roll
6
rough
terrain
1
Hitch
detaching
cannot tow
6
excess
force
1
bolts come
loose
cannon
visibly falls
apart
8
cyclic
loading/
vibration
bolts come
loose
cannon gets
loose from
frame and
goes un
noticed
10
cyclic
loading/
vibration
frame
frame
4
ii
check terrain
before installing
wheels
material type
and attachment
to base
sufficient
5
tighten all bolts
before
operation
5
tighten all bolts
before
operation
RECOMMENDED
ACTIONS
RPN
POTENTIAL
CAUSE(S) OF
FAILURE
9-May-12
DETECT
POTENTIAL
EFFECT(S) OF
FAILURE
OCCUR
POTENTIAL
FAILURE
MODE(S)
Revision Date
Revision
Number
1
6
1
6
1
1
40
Read safety
manual
frequently,
especially before
each season
50
Read safety
manual
frequently,
especially before
each season
Barrel
frame
breaking
barrel falls
through
9
excess
force
2
frame made
from steel
1
18
Sabot
degradation
failure to
launch
8
moisture,
excess
force
3
material type
1
24
stuck in
barrel
failure to
launch
bursting
no
accumulator
tank or
barrel
Barrel
bursting
harm to
operator/
audience
barrel
collar
around
barrel
becomes
loose
barrel
rotates
sideways
/becomes
loose
sabot
Barrel
Kevlar
sheath
epoxy
doesn't hold
shrapnel
could fly out
8
10
improper
loading
defects in
barrel
10
defects in
barrel
8
loose
connectes
at collar
9
barrel
bursts and
kevlar/
resin
doesn’t
hold
iii
1
use plunger to
load
1
Kevlar sheath to
prevent flying
shrapnel
1
Kevlar sheath to
prevent flying
shrapnel
5
tighten all bolts
before
operation
1
get expert
advise on
application
process
2
2
2
1
1
Read safety
manual
frequently,
especially before
each season
16
Read safety
manual
frequently,
especially before
each season
20
Read safety
manual
frequently,
especially before
each season
20
Read safety
manual
frequently,
especially before
each season
40
Read safety
manual
frequently,
especially before
each season
9
Read safety
manual
frequently,
especially before
each season
Vertical
aiming
Horizontal
aiming
lift plate on
upright
weld breaks
loose
barrel falls
7
weak welds
2
have welds
checked by
certified welder
jack
lift screw
threads
shear
barrels falls
back to
upright
supports
7
crank not
rated for
that weight
1
2 ton jack
1
7
swivel plate
internal
corrosion
horizontal
aiming
difficult
4
store cannon in
covered
location, protect
from weather
1
16
weld breaks
loose
cannon
could
dislodge
from base
2
have welds
checked by
certified welder
bursting
no
accumulator
tank or
barrel
1
Kevlar sheath to
prevent flying
shrapnel
swivel plate
Accumulator
Tank
tank
air fitting
and
pressure
relief valve
air hose
leaking
tearing,
disconnect
pressure
doesn’t hold
air leakage
4
8
weathing
weak welds
10
defects in
barrel
7
hairline
fractures
around
fittings
7
weathering,
excess
pressure
iv
1
inspect before
each season
1
material type,
screw in
connection
1
14
1
2
2
1
Read safety
manual
frequently,
especially before
each season
16
Read safety
manual
frequently,
especially before
each season
20
Read safety
manual
frequently,
especially before
each season
14
Read safety
manual
frequently,
especially before
each season
7
Read safety
manual
frequently,
especially before
each season
butterfly
valve
cannon
disconnect
from
accumulator
tank
shrapnel
could fly out
10
bolts not
tight
enough
1
v
inspect before
each season
1
10
Read safety
manual
frequently,
especially before
each season
Appendix 3.
Launch Protocol and Procedure
Notes:


This is not the protocol for launching the final design. This is only for testing purposes to be
carried out by cannon designers with safety officials present at all times.
Two people must be present for all testing; one operator and one spotter
Warning:


Anyone within 20 feet of cannon should be wearing protective eyewear at all times.
Only operator and spotter can be within 10 feet of cannon during testing.
Phases:
I.
II.
Loading (To be done by operator)
a. Ensure the system is not charged
i. Check that the stopcock is closed
ii. With air pressure gauge, check accumulator tank for any pre-existing air
pressure
iii. Open bleeder valve to slowly release any pre-existing air pressure
iv. Check pressure gauge again to ensure it reads zero
v. Open launch valve to allow air to move freely between accumulator tank and
barrel
b. Lower barrel to proper loading height and stand to the side of the barrel opening
i. Never stand immediately in front of the barrel
c. Check barrel for obstacles or obstructions with plunger
i. Handle of plunger has marks to show how far in it is
d. From the side of the barrel, place sabot in the barrel
e. Insert pumpkin (or surrogate projectile)
f. Using plunger, push the pumpkin and sabot to the base of the barrel
g. Close bleeder valve
h. Close the launch valve
Charging the system
a. Spotter: Ensure all bystanders are wearing protective eye wear
i. Eye wear must be worn during the entire testing procedure
b. Spotter: Clear launch area to 180 degree line
c. Operator: Point barrel straight down launch area
i. Horizontal launch angle should be zero
ii. Vertical launch angle is maintained at 20 degrees
d. Operator: Ensure trigger valve on cannon is closed
e. Operator: Ensure bleeder valve is closed
f. Operator: Open stopcock
g. Operator: Pressurize accumulator tank to desired pressure
i. Begin at 10 psig and progress by increments of 5 or 10 psig
vi
III.
IV.
ii. Never pressurize above 100 psig
iii. Monitor accumulator tank pressure by use of pressure gauge on bleeder valve
Launching
a. Spotter: Visually check that the launching area is clear and call out “Clear launch area
and prepare for launch”
b. Operator: Visually check launch area and call “launch area clearing, ready to launch”
c. Operator: Release trigger
d. Both: Ensure sabot and projectile have cleared the barrel
e. Repeat phases I-III as needed
Shutdown/Lockout
a. Discharge the system
i. Close stopcock
ii. With air pressure gauge, check accumulator tank for any pre-existing air
pressure
iii. Open bleeder valve to slowly release any pre-existing air pressure
iv. Check pressure gauge again to ensure it reads zero
v. Open launch valve to allow air to move freely between accumulator tank and
barrel
b. Lower barrel to vertical angle of 0
c. Place end cap on barrel to prevent weather damage
d. Place lock on trigger mechanism
vii
Appendix 4.
Math Model
viii
ix