|
by Steve Conover on
January 29, 2006
Introduction
On January 28, 2006 we loaded up the large and small potato gun,
2 bags of potatoes, 13 Pykrete rounds, and
embarked on our third system test for our
potato launcher.
Primary objective were:
- Gather additional data
- Test new Pykrete rounds
- Demonstrate to friends and family.
I'd like to mention our guests because we had a great turnout. I
was really happy that so many people showed up: have Kevin,
Andy, Corey, Dennis, and Stephanie. They were extremely
helpful and it was great to have some company.
Shot of all our visitors (left) and
a shot of Adam and me with the launcher (right)
General Information
Each launch usually represents about a month of development time.
However, the only new element to the launch was the Pykrete rounds.
This is because we have been working on the primary fire
mechanism--a large component of the launcher which is not yet
finished.
However, we felt like our 3 main goals were good enough and, to
be honest, we also just wanted to get out and shoot some stuff
around.
Launch Data
We shot a bag of potatoes into the lake, but all our measured
shots were done with Pykrete. The results are as follows:
Angle: 11o
Total Shots: 11
Launcher: Small / Bazooka
Data:
|
# |
PSI |
Distance
(ft) |
Velocity
(ft/s) |
|
1 |
60 |
270 |
151 |
|
2 |
60 |
295 |
157 |
|
3 |
60 |
265 |
149 |
|
4 |
60 |
290 |
156 |
|
5 |
40 |
250 |
145 |
|
6 |
40 |
250 |
130 |
|
7 |
40 |
200 |
145 |
|
8 |
40 |
250 |
130 |
|
9 |
40 |
220 |
145 |
|
10 |
75 |
300 |
136 |
|
11 |
65 |
300 |
159 |
Table of Results (above)
Scatter plot of distance and pressure, with
logarithmic trend line in red (above)
Comments:
- As expected, the Pykrete rounds
would flip end over end during flight.
- Also, they did not launch any
further than the small potato rounds.
- The Pykrete quickly became deformed
and was fairly mushy after 4 hours of launching.
- Cracks and anomalies in the Pykrete
caused most of the rounds to break during launch or at landing.
At the very least all rounds lost the bit of excess water on the
end of the round.
Long Shot
We made a long shot with the large gun at 45o, and
were quite pleased with the results.
After a lot of searching, Corey found the place of impact about
600 feet downrange (way to go Corey!), and the actual Pykrete round
was found another 10 or 20 feet past that.
This was the longest recovered shot we have ever made.
Interestingly, our calculations indicate that the smaller launcher
would be able to reach these same distances if we were to raise it
up to 45 degrees.
What Next?
Our next launch will see a lot of changes.
We will soon be testing a new primary firing mechanism. Instead
of pulling the lever by hand, we have already been working on having
a piston slam the valve open. Also, we are researching using a
"sprinkler valve" instead of the butterfly valve we are using now.
We will also be adding a rifled barrel to prevent the Pykrete
from flipping during launch. We would also like to do some
experiments on pure synthetic rounds that will be more durable and
possibly have fins.
Be sure to keep track of things here on this website because
there will be a lot of neat additions in the next few weeks!
More Photos
Get Involved
If you are interesting in our project and would like to get
involved, there are several ways that you can help us out.
- Send Suggestions: We would love to hear from
you about what you think we are doing right and we are doing
wrong. If you think of a better way to do something or an
experiment that would be nice to try with the launcher please
let us know.
- Meet with Us: We meet in Madison every Saturday
afternoon (~12:30) to build and test components. There are
a ton of modules and tasks to work on. If you think you
can make a good contribution then let us know.
- Help fund our work: If you like what you see at a
launch or on this web site then you should think about making a
donation. We don't mind putting our own money into the project,
but some things that we want to do are just to expensive. You
donation would mean a lot to us, and you'll be funding
both a great project and the education of a number of engineers
in Huntsville, AL! See below for more info.
Donations
As you can tell, we are always working very hard to make this
project the best that it can be. If you like what you see and want
to help us continue our work, please click the button below and make
a donation via PayPal's secure payment system. Thank you!
|
