Cosmos in the Stacks turbofan

A interactive museum like exhibit of a turbofan for the Cal Poly Humboldt library in Spring of 2026.

The group, BMU(Beastmode United), consists of four first year engineering members: Henry Egami, Sean Hartzell, Aaron Rodriguez, and Tazewell Smith. All team members are taking ENGR205: Intro to Design, which is the class that this project is for. The project takes place over the Spring 2026 semester. The client that we are working with is the Cal Poly Humboldt Library, and the client representative is the Library Dean: Cyril Oberlander. The project that was assigned to BMU for this class is the Turbofan - Airplane Propulsion & Aircraft Engines, which will be displayed in the Hall of Simulation(Figure 1-1) in the Library.

Cal Poly Humboldt, located in Arcata, California, is a California state university. Previously known as Humboldt State University, Cal Poly Humboldt was officially turned into a Polytechnic university on January 22nd, 2022. The integration of CPH into the polytechnic system came with the shifting of the university’s focus to a more STEM centered campus. The push of STEM in CPH has resulted in a flourishing community of engineering students that work in collaboration with the school and other organizations for projects that help the campus and the area around it.

Due to many changes in technology, libraries have been undergoing changes in order to renovate and revolutionize how they can get people to come in and continue learning in different ways. The display of our project will hopefully create a more innovative and interactive environment for all library-goers. The Cal Poly Humboldt library consistently has visitors from all over and has been aiming to make additions to the library that can make it more appealing and attractive to the younger generations. The client representative has stressed the importance of these displays inspiring the future generations to pursue a higher education at university. The Cal Poly Humboldt Library has been a cornerstone in the university’s community as a place for people to study and learn. Dean Oberlander believes that a new addition of interactive displays could help continue to preserve the library’s legacy and solidify a strong community of learners in the library. The creation of this display will be in collaboration and thorough communication with Dean Oberlander and will be under the guidance of our Engineering 205 instructor, Lonny Grafman.

The objective of this project is to have a completed model of an airplane engine depicting airplane propulsion, which will be located in the Cal Poly Humboldt library Hall of Simulation. As a largely expanding section of the library, we hope to take part in creating new learning experiences in the space for children, students, and visitors to learn from and explore. To reach this goal, we had 12 weeks to complete this objective through extensive brainstorming, experimentation, prototyping, and then finalizing a completed model. Our final product has two turbofan displays with one being 3-D printed pulled apart Turbofan segents, and a fully built Lego turbofan model. By looking into the model, the viewers will be able to view the mechanics of an turbofan engine, seeing the process of air intake, compression chambers, the combustion chamber, and exhaust. Explaining these concepts will include a plaque explaining the occurring processes, along with interactive battery-powered lights for visual aid, highlighting the segments of the engine. Along with our satisfaction with the results, we have had to consider the wishes of the library dean, who wants a device that is exceptional for learning/teaching while keeping it relatively low maintenance for at least a decade.

Criteria	Constraints	Weight (1-10)
Cost	Must be under $550	10
Accessibility, Interactivity, Educational Value	Accessible for all, provides information, can be interacted with for at least 3 minutes	10
Durability	Can last 5-10 years with minimal maintenance	9
Aesthetic	Must look up to par with other displays in the Hall of Simulation at the Cal Poly Humboldt library	8
Sound	Must be below 50 decibels	7
Safety	Must be safe enough for children to use	5

The prototyping process that we used was integral in the testing for form and function of the ideas that we brainstormed. Throughout the whole prototyping process, we made sure to bring in our physical prototypes to meetings with our client in order to ensure that our design was evolving in the way that the client saw the project progressing. In order to cut back on costs, many prototypes were created with scrap wood, cardboard, duct tape, staples, and some later prototypes were created in Fusion360 as 3D models.

The first prototype that we created was a cardboard box that had a general form of what the project would be and what components that it would include. This prototype was created with scrap cardboard and was held together with duct tape. Additionally, this prototype had some rough cardboard cutouts of how the turbofan pulled-apart view would look and a piece that showed the Lego Turbofan view. Next, a cardboard frame was created to outline the plexiglass case. Finally, a cardboard gear system and gearbox were created with a handle to start testing gears for functionality. This entire prototype was created in a single 3 hour class period.

The second prototype that we created was a sleeker and reimagined cardboard prototype of the base that would hold the pulled-apart view, the LEGO display, and all of the internal components. The main purpose of this prototype was to create a scaled version of our project that we could show to our client to ensure that the size of the project would be to their liking. Additionally, there is a cardboard piece extending from the base upward, which was used to show the total height of the project, including the plexiglass case. Overall, this prototype was very effective in finding the form and general size of our final project.

The third prototype that we created was a wooden skeleton of the base of the project that was used to find the exact measurements of the base. We would then be using these measurements to create a plan for creating the exact cuts that we would need for our final project. This prototype was made with scrap wood and staples. The primary function of the third prototype was also for the form.

Our fourth prototype was a “final rough draft” of what our project would look like. This prototype was created in Fusion 360 and has all of the components of our final project in it. This prototype was the design that had the most impact on our project because it contains both form and function elements. This prototype displays all of the buttons, the information plates, the area where the pulled apart view will be, the rotating disk for the lego display, and the crank that is used to rotate the LEGO display. This is the most detailed prototype that the team has created, and it has been serving as a guide for what our final product aspires to be.

This is the final design product for our completed Turbofan display. It includes many elements that make it educational, interactive, and look nice. The displays base is fully made of wood with plywood being used for the base plate, top plate, front and back plate. Locally sourced redwood was used for the walls of the base creating a sturdy structure. On top is a plexiglass case that encapsulates our two different Turbofan displays. the first one is a pulled apart Turbofan split into four segments and in front we have a fully built Lego Turbofan, each with it's own interactive elements. Then on the front plate of our display we have a dense informational on the Turbofan, beginning with a general overview of the Turbofan and then moving into the specific inner workings. Additionally to the side there is shorter descriptions corresponding to a specific Turbofan piece of the pulled apart model.

Wooden Base

The display case is built entirely on top of a wooden base, which is made out of three-quarter-inch plywood sheets and redwood two-by-eights . The specifics of this wooden base will be discussed in more depth, layer by layer. First, our display is all built on top of a (24in x 26in) piece of .75in thick plywood. On top of this sheet fits the frame of our wooden base with 1.25in thick redwood walls on the left and right side measuring to (25.5in x 7.75in). Each one of these redwood pieces has a 45-degree angle on the front that creates space for the front-facing panel, and they are screwed into the base plate. The top plywood plate is (24in x 17.75in) and is screwed into the redwood walls. This plate supports the Turbofan displays and the plexiglass case. The front-facing panel is also made of the .75in thick plywood and is (24in x 11in~) with a 45-degree angle on the top and bottom, allowing for a flush connection to the 45-degree cut redwood walls and top plate. This front plate also includes a laser-engraved metal plaque that displays dense information about the Turbofan. Adjacent to this are four buttons that correspond to the lights beneath the 3-D Printed Turbofan Segments, which will be covered below. On the right side of our wooden base, there is a wooden crank that connects to the spinning plate for the Lego Turbofan, which will be discussed further below. Lastly, the entire wooden base is stained with something for a nice, high quality finish.

Plexiglass Case

On top of the top wooden plate, there is a thin wooden frame that holds the plexiglass case square to the display. This plexiglass case is a rectangular case that encapsulates the Turbofan displays. The case's dimensions are (24in x 16.75in x 18in). The case is made of five clear sheets of plexiglass that are stuck together with polyvinyl acetate adhesive along the edges, creating a sturdy connection. While the plexiglass case is not fully connected to the wooden base, the .5in wooden frame holds the plexiglass in a way that only allows for its removal by forcibly lifting the case from the base of the display.

3D Printed Turbofan Segment

The 3D printed Turbofan segments are located in the back of the display area . Each 3d printed Turbofan section is held up by an acrylic dowel (3/16in x 12in) that will have lights illuminating the dowel from below. We tested sanding the dowels to varying degrees and found that the more the acrylic is sanded, the better the dowels illuminated from the LEDs. Additionally, the pieces of the pulled-apart view consist of the four main stages of the Turbofan’s inner core. The first stage that we included is the air intake, which includes the fan along with a pointed cone at the end, which increases the aerodynamics of the fan and guides the air. The second stage that we printed is the air compression stage, which includes a spool that holds 5 smaller fans that wrap around the spool. The third stage is the combustion chamber, which contains the mixer, the chamber, and more spinning fans wrapping around the chamber. Finally, the fourth stage that is printed is the exhaust stage, which includes the exhaust nozzle where the byproducts of combustion are shot out to create thrust. Our team believes that these four stages are the most important pieces that will give the best insight into the inner workings of the Turbofan and help create a base of knowledge in the viewers that can be built off of with the other resources in the library stacks.

Lego Turbofan

The Lego Turbofan is located in the close right corner of the display, and is a fully built Lego Turbofan model with dimensions of (10.6in x 6.3in x 11in). This model will be situated on top of a circular plate with a diameter of 10in. This disc is connected to the interactive wooden crank on the right side of the display, allowing for the disc to rotate a full 360-degrees with people's interaction. This is done by having the crank connected to an internal gearbox. This gearbox is 3-D printed, creating a working base to hold two bevel gears inside that convert the rotation of the crank to the spin of the disc at a ratio of 1:1

This section will describe how to build, maintain, and use the Turbofan jet engine display. Multiple subsections are provided to describe the details of all of the main parts of the display.

Base

Step 1: gather wood and cut it into these pieces

• Base Plate - 24in x 26in
• Top Plate - 24in x 17.75in
• Front Plate - 24in x 12in with 45-degree cuts on both sides
• Back Plate -  24in x 8.125in
• Redwood Walls (2x) - 25.5in x 7.75in with a 45-degree cut on the front
• Plexiglass Wood Lining Pieces - 24in x 0.5in (2x), and 16.75in x 0.5in (2x)
• Redwood Handles (2x) - 17.75in x 2.5in
• Redwood stage - 22.5in x 6in with 45-degree cuts on both sides
• Plywood rotating stage - Perfect circle with a diameter of 6in

Step 2: Cut holes in the front panel, right side, top plate, and stage

• Holes for Buttons - Diameter of 1.15
• Holes for Acrylic Rods - Diameter of 0.1875in
• Hole for Crank - Diameter of 1in
• Hole for Rotating Disk - Diameter of 1.5in

Step 3: plane wood - 80 grit -240 grit

Step 4: attach the top, sides, bottom, front, stage, and back with wood screws, hinges, and pilot holes

Step 5: Flush face route all sides and edges

Step 6: Stain and finish

3D Printed Pull-Apart View

Step 7: Print Gearbox - 200% scale

Step 8: Print fan parts -100% scale

Step 9: Glue not rigid pieces

Step 10: Glue sections of the fan together

Step 11: Drill 1 hole in each section of the pulled apart Turbofan, with a diameter of 0.1875, and glue acrylic rods into them

Lego

Step 12: Build LEGO

Step 13: Spray with glue adhesive for protection and added durability

Step 14: Attach to the circular rotating stage

Step 15: Attach the rotating disk to the gearbox dowel with a screw

Electronics

Step 16: Get buttons, wires, a power supply, and LEDs

Step 17: Cut 16 feet of positive (Red) wire into 8 similarly sized, smaller wires

Step 18: Cut 16 feet of negative (Black) wire into 4 similarly sized smaller wires

Step 19: Solder two positive wires to each button, creating an open circuit (4x)

Step 20: Solder the 12-volt LEDs positive wire to one of the positive wires from the button (4x)

Step 21: Use heatsync to cover the soldered/ stripped area (4x)

Step 22:Solder the negative (black) wire to the LED negative (4x)

Step 23: Put lights into designated holes for display (4x)

Step 24: Split the 12-volt power source into the positive and negative wires.

Step 25: Solder all 4 negative wires from LEDs to the negative side of the power source

Step 26:  Solder all positive wires from LEDs to the positive side of the power source

Step 27:Use heatsync on all exposed solders

Step 28: Use electrical tape to hold wires together

Step 29: Plug in a 12-volt power source

Plexiglass Case

Step 30: Get and cut these dimensions of plexiglass

• Front Panel - 23in x 18in
• Back Panel -  23in x 18in
• Side Panels (2x) - 16.25in x 18in
• Top Panel - 23in x 16.75in

Step 31: Dry fit the panels together, and use clamps to ensure they fit together correctly.

Step 32:  Attach all panels together using polyacetate adhesive

Step 33: Let each panel sit and dry before attaching the next

Gearbox

Step 34: Get STL files and print the gearbox halves, two collars, two shafts, and two gears, all at 200% scale

Step 35: Glue each shaft to a gear with Gorilla glue and let it dry

Step 36: Attach each collar to an attached gear and shaft system

Step 37: Fit both gears into one of the gearbox halves to make a 90-degree angle with the gears

Step 38: Place the remaining gearbox half on top of the other half to close the box

Step 39: Take ¾ bolts and place them in the holes of the box to seal the box shut. (Drill may be needed)

Step 40: Place the gearbox in the wooden base and elevate it with material to line up both of the shafts with their respective holes. (The short one should be facing up, and the long one should be facing sideways)

Step 41: Screw the wooden rotating disk into the top gear and attach it with glue to make it more stable, while allowing the rotating disk to have some space from the wooden base so that it may rotate

Step 42: Screw and glue the knob into the second gear, also allowing for some tolerance for it to spin

Description of costs, donations, the fact that this is just proposed, etc. For a simple cost table, see Help:Table examples#Cost Table and Template:Bill of materials for two nice formats.

Item	Amount	Cost per unit	Total
Redwood — 18 ft x 2 in x 8 in	1	USD 0.00	USD 0.00
Filament — Used for pulled apart view, and gearbox (came in two 1kg rolls)	1	USD 30.85	USD 30.85
Screws — Used to join the base	2	USD 9.98	USD 19.96
Hinges — 1 pack of 2 hinges used to create an opening to the back plate of the base	1	USD 11.99	USD 11.99
Plexiglass — 1944 sq inches - Used to create a protective case for displays	1	USD 211.60	USD 211.60
Plywood — 5 ft x 5 ft Used for the top, bottom, and front panel of the base	1	USD 60.30	USD 60.30
Building Blocks Turbofan — Used as a rotating display	1	USD 60.00	USD 60.00
Electronics (LEDs, buttons and power source) — 4 buttons, 4 LEDs, and 1 12 volt AC to DC power source. Used for the interactive elements of the display	1	USD 40.00	USD 40.00
Grand total			USD 434.7EUR 373.84 <br />GBP 317.33 <br />CAD 539.03 <br />MXN 9,063.50 <br />INR 32,537.30 <br />

This is our final design of our Turbofan display, to operate it is quite simple. at the back there is a panel that folds up where you must pull out the power cord and plug it into a wall outlet providing power to the display. The front of our display has four buttons each corresponding to a light beneath the plexiglass rods supporting a piece of the pulled apart Turbofan. once a button is pressed the corresponding LED should shine up the rod causing it to glow if the display is plugged in. The knob on the side of the display rotates the Lego Turbofans in a full 360-degree motion only requiring the person to actively spin the knob, this component requires no additional set up or power.

Maintenance cost is close to zero dollars. Using donated redwood, we not only saved money but also chose a reliable and durable wood that will last upwards of 30 years. 3D printing is a relatively inexpensive repair and would only cost around 15 dollars for a 1kg roll of PETG filament. Weekly maintenance costs by time would be anywhere from 2 to 3 minutes to clean the plexiglass. Yearly maintenance cost for the power source will be anywhere from 3-15 dollars depending on usage.

The project should require minimal maintenance.

Weekly

• Dust display
• Clean plexiglass

Monthly

• Check on power source
• Check wiring/LEDs
• Lubricate gears in gearbox

Yearly

• Ensure wires are in good condition
• Inspect 3D printed parts and LEGO display

Electronics

To test the electronics, the wiring was laid out and connected to the power source, a button, and an LED. The wires were twisted together to form a temporary bond, which allowed testing of the buttons. The buttons worked, though our original power supply was damaged during testing. It meets the criteria through the aesthetic, along with the sound. The buttons are not very loud, and all of the wiring is hidden underneath the top plate of the wooden base.

Wooden Base

We tested the wooden base by making a skeleton of the base. This gave us a visual for the real size of the project. After we made our final base, we each tested the sturdiness by applying pressure and made sure that each of the team members could hold and move the base. The base is durable, and with stain and finish, the base will not deteriorate for over 5 years at a minimum.

3D parts

The 3D parts were tested by having multiple prints of the STL files attempted. Our first prints had the parts at a scaling of 50%. This allowed us to get an estimate for how large we can make our prints. We also chose yellow and green filament for our 3D parts, to stick true to the colors of Cal Poly Humboldt. This fits with the aesthetics criteria and also aligns with what our client wanted.

Hand Crank

The hand crank was tested in Fusion. The gears were found as a free STL file, and the crank itself was created using scrap wood from the Swetman Makerspace. To test it, it was put together outside of the box and then spun a few times by the team members.

Plexiglass Case

The plexiglass case was ordered in specific sizes of two 18-inch by 18-inch pieces and three 18-inch by 24-inch pieces. The plexiglass was tested by holding all 5 pieces near each other, forming the rough shape of the case. The plexiglass was tested through assembly and putting the case on top of the display. It holds well and provides the needed function.

Through out the project we learned many lessons relating to the creative design process of engineering projects. We started the project by defining and identifying the problem that our Hall of Simulation needed an upgrade, and by communicating with the client we started to understand the ways in which we could successfully take part in upgrading the space. Then we got to practice the brainstorming process, which was an opportunity to show us how no ideas are bad ones and how important it is to just allow everyone to openly flow and shoot out ideas because its the best way to get to the good ideas or bridge to an even better one. importantly to it was great practice showing us how to create a safe space were us engineers can openly let ideas be formulated in the moment with the support of others to iterate on these ideas compared to feeling discouraged to share incomplete solutions. Then the lessons learned through the prototyping, iteration, and testing stages of the design process were hugely important in our understanding of how projects are created starting with nothing but passion, and how key simply having a passionate team is for projects overs extended periods of time. Additionally as first year engineers this gave us an introduction to important skills like woodworking, wiring electronics, and CAD/3-D printing.

As our Engineering 205 course and project are coming to and end, iterations to the project will be limited, but there are things that could be improved upon and iterated by others in the future. The structural aspects of the display are good, and we don't see needing to much changing but there are slight changes that could be made to our interactive Turbofans. The Lego Turbofans crank could be improved, the gear box and spinning works good, but if the gear box was metal instead of 3-D printed it would be smoother. The pulled apart Turbofan we are very proud of, but one of our brainstorm ideas was to also have a light system showing airflow through the Turbofan. This idea was to ambitious this time to implement, but we all still believe would look awesome, and encapsulate the concept of airflow through the system in a way that would be easy to follow and be very informative.

For any troubleshooting related to the project, refer to the table below where we have solutions to any possible problems we could foresee.

Problem	Suggestion
Dirt or grime	Use cleaning wipes to clean overall project and plexiglass. Also consider vacuuming display.
Lights aren't turning on	Make sure display is plugged in, if not, open back panel and take out plug, and plug it into nearest wall outlet. If it is plugged in, have someone qualified to glance at wiring connections, and/or unscrew pulled apart Turbofan base and check if the LEDs are burned out.
Lego Turbofan isn't spinning	Check if external knob is spinning, if not, check inside of the display for some sort of blockage. if issue isn't easily solved you will then have to remove the entire gearbox by detaching the knob, and circular plate the Lego sits on, and then rip the gearbox from its wooden based, undo the bolts, and look inside the gearbox for the issue.
3-D prints need replacing	in the slim chance the pulled apart model or the gearbox become damaged, refer to the Turbofan deliverables file, where all of the used files for printing can be found.

Introduce team and semester in the following format:

• Lonny Grafman
• Emilio Velis
• Henry Egami
• Sean Hartzell
• Aaron Rodriguez
• Tazwell Smith