During the summer of 2023, I had the opportunity to intern for the Department of Defense as a Mechanical Engineering Intern, at Whiteman Airforce Base, in Missouri.
During my time there, I helped design a removable maintenance platform for the B-2 Spirit Stealth Bomber.
I gained a lot of experience with SOLIDWORKS, which I had rarely used before the internship, as well as finite element analysis.
I also expanded my communication and team-building skills by meeting with project stakeholders to establish product requirements and develop designs with my team.
Unfortunately, I cannot go into much detail about what I worked on, and how/ where/ why it is used, but what I can do is show the CAD designs we, as a team of 3, created throughout the design process, as well as talk about what I learned during my first experience working in a professional engineering setting.
Displayed Below are the designs for the maintenance platform that we researched, designed, and developed over the course of the 10-week internship.
I did most of the CAD for our team, which gave me a great opportunity to learn SOLIDWORKS in a professional setting. The only other CAD software I had used before the internship was OnShape, to 3D print a bulkhead and two avionic bay caps for the Lazarus Rocket. I was essentially learning on the fly, picking up modeling techniques from other interns and mentors.
Slotting Plastic Platform (Weeks 7-10)
Slotting Foam Platform (Weeks 7-8)
Two Piece Foam Wedge Platform (Weeks 7-10)
Soft Top Folding Platform w/ Extending Support Arm (Weeks 7-8)
HardTop Folding Platform w/ Extending Support Arm (Weeks 6-7)
1D Telescoping Platform (Weeks 4-6)
Telescoping and Folding Platform (Weeks 4-6)
2D Telescoping Platform (Weeks 1-4)
For each design, we created a design review, which listed the background, project statement, and design constraints, and explained the design in detail. Including CAD, drawings, FEA, and any additional calculations.
The FOS was calculated by dividing the material yield strength by the maximum stress observed during the simulation.
Any FEA we would do was set up in SOLIDWORKS, and was either done on assemblies using local interactions such as pin connections or welds, or just done on single parts. In the case of the image on the left, this hinge had three parts, a top hinge, a bottom hinge, and a pin.
As you can see, our designs changed quite a bit over the course of 10 weeks. This was due to the dynamic environment that our platform would be used in. The platform needed to be big enough and strong enough to support a human and tools, but small enough to fit in some really tight spaces.
During the first few weeks of the internship, we struggled to get a complete set of project requirements, as the environment in which our project would be used was restricted. We eventually got clearance and went to take field measurements, which helped us strictly define our project constraints. In addition, we spoke with project stakeholders and determined a list of requirements that they would need for the design.
It was at the time of communicating with stakeholders and defining project constraints that I learned the first thing that was different between working in industry and studying in school. I quickly learned that engineering is not only problem-solving and product design, but it also requires streamlined communication with stakeholders. Such communication is vital to defining your problem statement and constraints so you actually solve the problem that needs solving.
After designing a few more designs, we went to take field measurements again a few weeks later and found that our project environment changes quite dynamically, which led to even more complications in the design.
After a few design reviews, and a critical design review with stakeholders and mentors, we eventually settled on two designs. The Slotting Plastic Platform, and the Two Piece Foam Wedge Platform.
Slotting Plastic Platform
Two Piece Foam Wedge Platform
As a team, we decided to split up between the two designs. For the last three weeks, I designed the Slotting Plastic Platform, and my two other team members designed the Two Piece Foam Wedge Platform.
The idea of the Slotting Plastic Platform, is to have one large platform surface made up of a number of middle platforms, and a male and female end platform. The platform pieces are pulled together by elastic cordage that runs through the four middle tubes.
The slotting feature allows the platform to be as long as you want it to, but also contract to a very small profile so it can fit into really small spaces and maneuver around tight corners.
Exploded View
Folded Up
What makes the slotting platform able to be small yet strong, is the internal supporting structure that slots each platform piece together.
FEA was done on the support frame to determine product failure points. Material selection was a big factor, as an included constraint was for the platform to be as light as possible while still being strong.
FEA on the entire support frame using SOLIDWORKS
View of the support frame slotting
During the last week of my internship, we went through a design review and were making plans to order parts to build a prototype. I made sure to document my recommended fabrication process, as well as the CAD as much as possible, as I would not be there to help after I had left.
Female Platform Global Variables Map
Middle Platform Global Variables Map
Male Platform Global Variables Map
SOLIDWORKS Assembly Drawing for Male Platform
SOLIDWORKS Assembly Global Variables Document
The entire CAD assembly reads values from a text document titled "global variables". Any user can go and change the values, which changes the entire design in every part and assembly file.
I also created a map of each platform type, which depicts every global variable used on the part and what it changes. This makes it so much easier for someone to make a custom dimension change to the entire assembly. It's hard to see here on my website, but the entire map is included in a PDF file, and you can search any global variable name to see how it affects the assembly.
I also created drawings for each part and assembly, to follow during fabrication.
Overall, I am very grateful for being able to learn from and work alongside engineers at Stealthwerx and the 509th Bomb Wing, gaining invaluable experience that will undoubtedly open up future opportunities.
I gained my first experience operating in a professional environment, where I communicated with stakeholders, defined product constraints, presented design reviews, and collaborated with other engineers and mentors.
I also learned a lot about mechanical product design, got a lot of SOLIDWORKS experience, and improved my FEA knowledge.
The B-2 Spirit is an amazing aircraft, and I strive to become an engineer who helps design aircraft of that magnitude one day. My time working with the B-2 will inspire me for years to come.