Portfolio of all extracurricular projects I have participated in from September 2015 to January 2017.

1. 29509 Anthony Road - Valley Center, CA 92082 – (760) 520-3141 – flyboyjosh@att.net
JOSHUA FIRTH-SCHAEFER
Undergraduate - Physics
During my time at Cal Poly San Luis Obispo, I have been engaged in several projects of varying levels of difficulty,
importance, and complexity. These undertakings have been completed through my involvement with the university club,
Cal Poly Space Systems; they have served to fuse my growing knowledge with my passion for building rockets.
The following is a summary of the various projects I worked on since Fall 2015; note the increasing importance and
intricacy of the projects as time goes on. The knowledge I accumulated enabled me to tackle increasingly complicated
endeavors requiring more research and skill.
2015 – 2016 Academic year
Yearlong Construction of a rocket to take place in the 2016 IREC competition at Green River, Utah.
Rocket Title: Uncle SAM.
Propulsion: Student-built hybrid motor; 400lb thrust and 230 second ISP.
This was a monumental undertaking that took over two-dozen students spread across multiple subsystems to complete.
Unfortunately, due to a leaking pyro-valve, our rocket didn’t launch during the competition. However, the valve was
repaired and launched in September 2016 at the FAR facility in Mojave, CA. The rocket lifted off our launch rail
beautifully, but due to the nitrous oxide being warmed by hot desert conditions, our mass flow was lower than expected,
resulting in lower thrust. The rocket eventually broke up in flight; however, despite slamming into the ground at terminal
velocity, our hybrid motor combustion chamber survived. What follows are my contributions to building Uncle SAM.

2. 29509 Anthony Road - Valley Center, CA 92082 – (760) 520-3141 – flyboyjosh@att.net
Test Rocket 2
Our second test rocket was 6” in diameter, and was meant to test full-diameter components including electronics, the
recovery system, and possibly our active control system. However, this rocket never flew. The separator mechanism (for
splitting the rocket in half to deploy the parachute) failed during testing, the parachutes and guidance system weren’t
ready, and we were already working on a variant of our competition rocket that would use a commercial solid instead of
our hybrid motor. However, we used what we learned from manufacturing this rocket to build our third and final test
rocket; this was also the first time that I was responsible for fabricating primary composite structures for a rocket, and
the first time I assembled a complete SolidWorks model for a rocket.
Once again, I was tasked with manufacturing the engine mount and sanding the carbon body tube. I was also responsible
for manufacturing the fins using dimensions from Open Rocket (a free amateur rocket-designing software), as well as
finding a means to develop a rocket that can have its engine mount, including other components, removed, repaired, or
replaced
The CAD model I developed was
mostly used to demonstrate to the
club that I was capable of utilizing
the software, as well as to present
my engine mount design to the
Test Rocket sub-system lead. The
nose cone and separator were
designed by other club members.
My design was praised and refined
by club officers, and I later worked
on assembling the engine mount,
and fabricating the body tubes.
During the construction phase, I
designed and built the assembly of
the engine mount. Using both my
ideas for the new modular mount,
as well as the insightful
suggestions of senior members, I
cut and machined the fins, the fin
mounts, and placed barbed inserts
into the centering rings. Others cut
out the centering rings and
secured the fin mounts to the
motor mount. I also assisted in
manufacturing the composite body
tubes, and conducted all the
finishing work.
After spending until midnight in the
machine shop finishing the rocket,
we spent much time admiring our
creation. Although this rocket
didn’t fly, we were so proud of our
construction and ideas that our
final test rocket incorporated much
of the design features used on this
one. At the time, this was one of
the greatest projects I had been a
part of, though more was to come.

3. 29509 Anthony Road - Valley Center, CA 92082 – (760) 520-3141 – flyboyjosh@att.net
Aside from my usual duties of
assembling and fabricating
relatively simple components, I
was given my first task on a mill.
Six holes needed to be drilled and
counter-sunk in order to bolt on
our separator ring. I was shown
how to set up an operate the mill
as well as the rotary chuck, and
was then left alone to complete the
task. Minor milling tasks assigned
to me would become routine after
this point.
Test Fires
One of the more exciting jobs to be
done at Cal Poly Space Systems is
test fires. Our campus has a
propulsion laboratory where we can
test our motors without traveling to
Mojave. We conducted a total of
four test fires; I participated in three.
For all the tests in which I was
present, I participated in a specific
role beyond assisting in setting up
test equipment. For the first test fire,
I was a range safety officer,
whereby I ensured the testing range
was clear of people or vehicles. For
the third and fourth tests, I was
operating the control box, which
meant I was responsible for
activating nitrous and nitrogen
valves, and the engine when the
order was given. For all tests, clear
and specific test procedures were
handed out to essential personnel
and were followed to the letter.
Test Rocket 3: Valley Forge
Our third and final test rocket was built to test the entire competition rocket above the engine; this meant that the same
recovery system, control system, electronics, payload, and body would be used on Uncle SAM. The only difference was
that we used a commercial solid rocket motor instead of our hybrid motor. Unlike our last two test rockets, not only did
this one fly, but we also recovered it. The only damage was a stripped bolt holding one of the fins, knocking it loose on
impact with the ground. Our drogue chute was also torn, but was intact enough to pull the main chute out of its housing.

4. 29509 Anthony Road - Valley Center, CA 92082 – (760) 520-3141 – flyboyjosh@att.net
As usual, I was responsible for
fabricating and assembling the engine
mount. However, this time, I learned how
to use a rotary table to cut out the
centering rings and the notches for the
carbon fiber fin mounts.
Unlike other projects, I found myself
mostly responsible for integration and
assembly rather than fabrication; I drilled
and tapped holes into our new separator
rings, and later attached them to the
rocket. Components from other sub
systems, including the electronics,
recovery system, and control system
needed to be integrated into the rocket
according to CAD models.
We launched our third test rocket at the Friends of Amateur Rocketry
facility in Mojave. I was responsible for assembly and transport.
Uncle SAM Components
Among the numerous components I had
to fabricate and assemble for our
competition rocket, the most significant
was the construction of aluminum feet that
would secure carbon fiber rods to the
combustion chamber and nitrous oxide
tank. By now, I was known for enjoying
working in the machine shop, so this job
was immediately offered to
me. This was thus far the third
lathe job I did, as well as the
most complicated. I used more
tools for this one task than in
any other project. Given the
relative intricacy of this task
compared to others, this was
the most satisfying and
rewarding I had done thus far.
For this academic year, we are perusing the same goal as last year: participation in the IREC competition. We are
building a new and more powerful hybrid motor, and are using lessons learned last year to not only build a higher quality
rocket, but also to develop new procedures and techniques to prevent problems we had last year. As a devoted member,
I have been assigned as a Dedicated Manufacturer; I will be responsible for designing and machining components for
2016 – 2017 Academic Year

5. 29509 Anthony Road - Valley Center, CA 92082 – (760) 520-3141 – flyboyjosh@att.net
sub-system leads. I will be participating in design reviews, and projects of greater responsibility as the year progresses.
Additionally, my recent employment as a machine shop technician has expanded my knowledge and skills as a machinist
such that I am capable of performing all machining work that doesn’t need to be done on a CNC.
Nitrous Oxide Test Tank
My first project of the year has been the development and construction of a nitrous oxide tank capable of holding 18
pounds of nitrous at 800 psi. The idea of this tank is to have a sturdy container to protect our nitrous oxide in the unlikely
event of a catastrophic combustion chamber failure; we don’t want a ruptured oxidizer tank releasing decomposing
nitrous. Thus, beyond the pressure and oxidizer mass requirements, I was told that the tank needed a factor of safety of
at least 5 at 815 psi, and be rated to 2500 psi. Once the tank is completed it will undergo hydrostatic testing.
As one might
imagine, this isn’t
just a machining
project, it has also
been a significant
research project.
Not only have I
exceeded all of my
prior capabilities in
SolidWorks and
Excel, I have also
created my first
practical MatLab
code in order to
model the
performance of the
test tank under specific conditions. Additionally, I have
created multiple iterations of this Mat Lab code as new
and superior nitrous oxide data is found and
incorporated. This
project has
demonstrated my
ability to tackle
significant projects on
my own with
autonomy, little
instruction, and
necessary research.
As soon as I was able, I ordered my material and began
work on the tank. Pictured just above is an aluminum
cylinder that will become two end-caps for the tank. This
project has involved nearly fifty hours of work on a
manual lathe and mill, and has served as a rewarding
challenge and learning experience.
Pictured above is one of the end-plates that fits to the
very top and bottom of the tank. Being eight inches in
diameter, it couldn’t fit onto our lathe chucks, so I had to
face it on a mill.
Once completed, the tank
weighed a little over 60
pounds, just four pounds
more than what my MatLab
code predicted. The excess
threaded rod was later
removed with an angle
grinder, and appropriate
plumbing will be attached. It
is able to hold between 12
and 18 pounds of nitrous
oxide at temperatures
ranging from 20 degrees to
70 degrees Fahrenheit.