The Come Up Jessie fauconier


Purpose: Design, build, and test a tennis ball air-cannon that would be able to accurately hit targets set out on the football field.

Requirements: Using an Arduino code firing system to control the release of the ball, have adjustable pressure, elevation abilities, and Z-axis rotation for the cannon.

Design Period

initial DESIGNING THE Barrel support FOR THE CANNON

This is the design process and product of barrel support. We only printed out the front face in an effort to prevent wasted materials. The remaining faces of the box were printed out towards the end, but we assembled the 2D models from Onshape by interlocking the corresponding teeth on the box.

Before we could start building a cannon, the first step was to have a barrel support that would be able to hold the cannon securely and prevent any minor skews, shakes, or changes of position when it came to fire (1 degree change in position could result in missing the target by a few feet! A good support system was critical).

These pictures were the use of Mr. Twilley's information about inputing our dimensions into an online box maker and then cut it out via Onshape. (Onshape is a design tool that is used to sketch, adjust, and virtually assemble projects where the engineer is free to create all the pieces/parts they would print out on a 2D space, in order to create their 3D model)

Before this, I had never used Onshape before, but I got acquainted with the system with the help of my group members, independent notes, and practice.

Trials & Errors of the box's Holes

Finding measurements for the openings on our barrel support.

Since measurements in the engineering world are never actually what is given (a 4-foot board is, in reality, more like 3.8 feet), so we needed to create openings in our barrel support that would grasp our cannon firmly. Since we had no cannon of our own, we took measurements of Mr. Twilley's previously built air cannon from different orientations and took the average of this recorded data. Then we adjusted our Onshape design accordingly.

Deciding on the ideal dimensions of the holes for the barrels. The opening should be firm enough to hold the cannon securely--without possibility of shifts, wobbles, etc. when fired.

Using Onshape and the class laser, we began the trials of holes whose diameters we were testing on the barrel. The purpose was to find the precise and ideal opening size for the barrels of the cannon--Onshape designs allowed for more significant figures in the dimensions of the parts than were obtainable by the limits of human capability and measuring tools used.

The various holes on the bottom picture actually only differed by at most 5 thousandths of an inch! However, they had drastic physical differences. For example, the final diameter of the holes was 2.363 inches, but a 2.365 inch hole would be loose enough to freely spin around the barrel. Our 2.363" was the ideal measurement because it allowed for us to move the face of the box to our desired length, but was firm enough to prevent any wobbling, turning, or shifting once the cannon's barrels were through.

Scrapped connecting piece of barrel support

Initially, our box design was going to be more complex and structurally sturdier: we were going to build two smaller boxes and have this (bottom right) connector that would hold them together. We ended up scrapping the idea in favor of the classic box structure because of following concepts for the base that would require attaching to as much surface area of the box as possible.
Building the Cannon

preparing and Assembling the Cannon pieces

Cutting the provided PVC pipes
Priming the joints of the cannon

For the reaction between the primer and cement to be immediate and permanent, we applied primer to both the "female" (the inner portions of a connecting piece) and the "male" (the outward-facing surfaces) parts of the connecting joints of the cannon.

Holding the primed and glued bonds between pieces in plae

These are pictures of us quickly putting the glued and primed pieces in their proper positions, and holding them firmly so that the joining could set, which was at least 30 seconds (but we held it for 45-60 seconds to make sure the bond was permanent since the reaction tends to move the materials from where you placed them--creating a "pushing back out" motion that would be detrimental if the seals between pieces were skewed).

Attaching the valve opening

Finally, here we are creating the opening and applying to it special glue that would allow the filling of air into the cannon (from a pump). This would also be where we attach the given gauge to get a reading of the pressure of the air inside the cannon. This special glue was meant to solidify, so we had to make sure the inside opening of the bike valve was not cut off or blocked, and generously applied the glue to the outside and up onto the valve to eliminate any chance of air escaping.

Creating the Base

Scrapped Designs for First Base

Sketches of an early concept that was never put into action

I think the flaw with these sketches were that they were not realistic for the materials we were given, the mechanics of how it would work, and the time we had to implement the ideas. With each explanation of "how would we do this?", a new problem would arise with "that doesn't make sense because...". Looking back, these ideas were complex but not impossible. With a larger window of time, we could have recreated the VEX robot gears that would allow the the pulling of the front of the cannon upwards, while the back of the cannon remained on ground level (best shown by the left picture). I believe these concepts were born when I came down to Mr. Twilley's other class and briefly collaborated with Charles. However, relaying the concept back to my team served to only find flaws in the theories.

Scrapped "Gravestone" Design

First feasible base design. Was soon scrapped because new inspiration arose.

The concept was--as shown in the top left picture--the vertical structure would have holes on its sides in which the cannon arms would fit. These holes would be wide enough to hold the cannon (maintain its position at the different intervals) while also being curved enough to allow small adjustments once the cannon was mounted in the correct elevation. The top right photo introduced an idea that did make it into the final product: the circular mount. This would allow full 360 degree rotation and was fondly referred to as "Ol' Reliable". In the same picture was also another structure, called "the square base", that saw the end which was the base that had a circular indent in it where Ol' Reliable would be able to swivel without loosing position. The rest of the images were also early brainstormings that were well intentioned but were more figurative than they were realistic. For example, the drawing in bottom left and the one directly above it were hopeful in that we would create wheels with spikes/teeth that would be able to control elevation (looking back, this idea was expanded and executed in other groups' designs), but it was not efficiently applicable to the box we had produced, nor was it a sturdy structure, nor did we really have the materials. The photo with the text, "goals" also had feasible options such as the "sliding feet" that was our recreation of a tripod--hoping to angle the feet so that they could slide along a created gutter that would have holes in which we could place a pin to manipulate the elevation of the entire structure--and also introduced undeveloped versions on the "triangles" that could hold the base structure at the bottom, as well as the concept of having the angle of elevation be determined by a rotating device.

Designing "Gravestone" Base

This was the Onshape design of the first version of the base structure, but apparently the cannon, "cannot print in 3D" (Mr. Twilley) which was a reference to the laser not being able to cut out the angled structure that combines the (grey) vertical component with the (light blue) circular structure. This structure concept was not scrapped, however, and instead was modified into the "triangle" that still served to anchor vertical components to horizontal structures in the final base. Looking back, the holes should have tapered at a downward angle--creating an ellipse rather than a circle--so that the cannon's back (the end of the cannon that is the U shape/not the 2 arms) would remain stationary on the floor, while the arms could comfortably angle upwards. Overall, other than the classic concepts (Ol Reliable and the square base and the soon to be conceived triangles), the vertical component of this design was scrapped--and probably for the better.

Inspiration for New Base Design

The 2 images of the tripod were the inspiration for the concepts of our version of the tripod in earlier mentioned brainstorming. The telescope, however, was a turning point in the project. This image spurred the crucial concept of the rotating "arc". This image was able to put into reality what our brainstorming was trying to manifest: a structure that could rotate giving the elevation angle full freedom, while still maintaining a firm grip on the cannon. From here, it would be up to us to figure out how to maximize contacted surface area to the box in order to increase stability, and to find a means of stopping the elevation at the desired angle. This arc concept gladly made it/was central to the finished product.

Sketches for "Arc" Base

Here we bring back the concepts of the tripod and wheels with teeth. Initially, after we established that the arc would hold onto the cannon from underneath (shown in top and bottom right), we had momentarily complicated the component that would control horizontal rotation: we would have yet another complex structure underneath the arc that would be controlled by the "tooth-wheels", but this idea was soon scrapped because we had not the time, materials, or sound structure that would be able to stop and hold the tooth-wheel in its position (effectively stopping the elevation).

Designs for Arc Base

With the help of Mr. Twilley's input, we were finally able to sketch a final design of the base that was soon cut and built into reality. In top left, we finished the box (we had stopped because of past ideas of different box designs and base constructs). Following from left to right in the pictures' order: Top 2nd was the creation of the circular base, the next pictures up to middle first was the establishment of the arc. This was a fun process to make because of the new discovered tool in Onshape that created holes in a circular fashion. The teeth that popped out from the arc served to be an issue later on. The orange and blue triangles in the middle row were the modified versions of the angled (3D) component that held the Gravestone and circular bases together. They were triangles because they were able to reach both up and out giving equal attention to holding vertical structures and covering enough of a horizontal distance to keep them upright. They also had a form that stretched straight down in order to reach through the holes in the circular base that are demonstrated in the bottom left photo. Thanks to Mr. Twilley's guidance, the arc transformed from the material-wasting, thick version in the middle row to the simpler and more elegant version of the arc in the bottom left. The issue that arose from this, however, was the need for a "top" which served as a lid that held the 2 arcs together and would be the portion that fits onto the box.

Getting that Perfect Fit

Many. Many. Issues. When one problem was fixed, another popped up like a daisy through a sidewalk: "how did that even get like that? That's not supposed to be like that" (us at many points during this stage). This process was after we cut out the parts in the Shop Bot, sanded them down to be smooth, and the time race was on! These specific pictures were taken after school (except for the top row which just showed the finished box and new wood we would be working with). Since the Shop Bot cuts corners in a "T-bone" fashion (meaning that the laser goes past the points of the square corner), and the fact that it was also partially damaged, Shri and I learned how to chisel away unwanted wood material in order to even down the corners, edges, slots, and openings (best evidence of this was photo 3 in row 3). My least favorite/particularly hard spots were INSIDE the openings that would hold the triangles into the circular and vertical bases. These proved difficult because they could not be sanded down like the other surfaces and edges, and required manual shaving down with various files. Also, shout out to Kris Burns for saving the day!! In the bottom right picture--after all the sanding, eroding and chiseling was done--Kris used a hammer and small pieces of wood to wedge the triangles into the openings, effectively closing the gaps they had and proving to be one of the most reliable/sturdiest portions of the structure. Those triangles are not going anywhere--not because of the wood glue, but because of Kris. Shri and I would have never thought to do that.
Finally, all parts have been assembled, placed, and glued. The bottom row is us using clamps overnight to keep the parts in perfect position and even tape was used to keep the glue from dripping away (it made a cool design when bottom left dried though!). Final touch ups were adding a bolt in the middle of the structure so that the circular base could spin, but would be spinning around an axis rather than in an indent in the square base (as thought it would in previous designs). Another addition was the use of a small metal rod that would serve to be a pin between the hole in the circular base and the openings in the square base. Ol Reliable received 2 of its own metal rods that allowed swivel motion as well as stopping action.
The first 2 rows are of the math and calculations involved in writing the lab for the experiment/trials and collected cannon data. We tried to incorporate physics and calculus and variables that we didn't have, so the application of what we learned in other classes were not applicable to this real world situation... Good to know.. Anyway, the last 2 rows are of our group shooting the cannon outside on the first day. Top Left showed our cannon at the ready, top right showed the cap popping off because we never really glued it down with primer and glue. After doing so, bottom left and right show Keon pumping in the air to get the pressure of the cannon up to the right PSI value, and me measuring the pressure with the gauge in order to make sure the proper angle and pressure was used to hit our targets.


When we were outside testing our air cannon in the Battle Ship game, our team placed 2nd with 25 points (acquired from hitting the square surrounding tarp and hitting the lid of the target).

The bottom picture is the organized data that we collected from our trials outside on both the football field and the tennis court (tennis court trials found in middle). The top picture is an excerpt screenshot from the final lab write up in which we analyzed the data we collected.

What I would change if I could redo this cannon would be to not include holes in the front portion of the arc (since they are increasingly approaching 0 degrees above the horizontal, thus being detrimental to our aiming). I would also take greater care in mapping out the designs of how the pieces will fit together once printed out in the 3D Space. For example, we ran into problems with assembling the interlocking pieces of the cannon. Therefore, I would analyze their original orientation in Onshape in greater detail before we cut. Finally, we would create our own elevation that would include the cutting of thick, vertical poles (cut by the same material as from the rods that stop and hold the cannon). These elevated stands would allow us to dig our cannon into the grass on the football filed, while also establishing a sturdy stand on which we could fire from.

Here is our final cannon. Very proud to have been a part of this group and to have created this structure that not only came out wonderfully--through its many changes, variations, and strifes--and into the manifestations of our combined efforts and time. We look forward to future challenges and to taking out battleships with our battle cannon!

~ Jessie Fauconier, 2017

Created By
Jessie Fauconier

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