You're an aerospace engineer on a tight timeline to develop a component for a rocket engine. No sweat, you think - you know the concepts by heart, and the model looks appropriate in CAD. But you inspect the 3D-printed part that you've outsourced for manufacturing, and something is wrong. The impeller blade angle is off, and the diameter is larger than the design intent. The vendor won't get back to you. Suddenly you're over budget. Something is leaking. Running the pump test rig, you're not sure where that vibration is coming from.
Successfully navigating nightmares like this can make or break an engineer, but real-time problem-solving during assembly is something few undergraduates experience as part of their curriculum. Enter class 16.811 (Advanced Manufacturing for Aerospace Engineers), a new communication-intensive laboratory course that allows juniors and seniors to drive a full engineering cycle, gaining experience that mirrors the challenges they'll face as practicing engineers.
In just 13 weeks, students design, build, and test a laboratory-scale electric turbopump, the type of pump used in liquid rocket propulsion systems to deliver fuel and oxidizer to the combustion chamber under high pressure. Teams of two or three students work through the entire production process while balancing budgets, documenting, and testing.
The course was developed and taught by Zachary Cordero, Esther and Harold E. Edgerton Associate Professor, and Zoltán Spakovszky, the T. Wilson Professor in Aeronautics, along with a team of teaching assistants (TAs), technical instructors, and communication experts. It ran for the first time last fall, open to students who had completed Unified Engineering, the foundational Course 16 curriculum covering the four disciplines at the core of aerospace engineering. It generated so much interest upon its announcement that spots were allocated via lottery.
"Sometimes it's assumed that students will get hands-on experience through their extracurriculars, but they may not. Students in this class gain that experience through exposure to cutting-edge design and manufacturing tools, like metal 3D printing," says Cordero. "They don't just learn how to solve a problem set - they learn how to be an engineer."
Training for a rapidly evolving field
The course was born out of feedback from participants at an annual workshop that Cordero organizes each summer addressing materials challenges in reusable rocket engines. Attendees representing industry, government, and academic sectors consistently emphasized the need for the next generation of engineers to be familiar with advanced engineering concepts, in addition to having strong fundamentals. Experience with new computational design tools and processes like additive manufacturing is becoming essential for success in the aerospace industry. "Our mission is to train, inspire, and motivate the next generation of aerospace engineers. We have to listen to what our industry partners want from engineers and adapt our curriculum to meet those needs," says Cordero.
Spakovszky, Cordero, and the team built the course over two years of Independent Activities Period workshops, developing independent modules that teach concepts for constructing the turbopump. The first set of labs focuses on the impellers - the rotating bladed-disk component that draws fluid into the pump to pressurize it. The second lab breaks down the rotor system that supports the pump impeller, and the third covers integration of the rotor assembly into the casing and final testing.
Throughout the course, students receive instruction in technical communication and training on the full array of machine shop tools available in the Arthur and Linda Gelb Laboratory. Beyond learning the concepts and tools, the majority of the design and implementation is up to the students.
"They are pushed to learn how to learn on their own," says Spakovszky. "The key differentiator here is that there is no solution. In other classes, you have a problem, and the instructor has the solution. This is open ended, and every team has a different design." Project management is left up to each team, with instructors and TAs serving as resources, rather than leads. Each team works with vendors to help bring their designs to life. The students conducted their machinery analysis using the Agile Engineering Design System (AEDS) and Advanced Rotating Machine Dynamics (ARMD) software tools from Concepts NREC. Impellers were printed at the MIT SHED (Safety Health Environmental Discovery lab), with support from Tolga Durak, managing director of environment, health and safety, and by industry collaborators at Desktop Metal.
"A lot of the design questions we were working with don't have firm answers," says junior Danishell Destefano. "I learned a lot about how to read technical literature and compare design trade-offs to make my own decisions."
On the floor
"Making things is really hard," says Spakovszky. "In addition to manufacturing parts and components, the assembly of rotating machinery requires careful tolerancing of the part dimensions and precision manufacturing of the interfaces to meet design specification."
At the core of the curriculum is the manufacturing process itself, with its myriad components posing a unique challenge for students who may not have experienced the kind of rapid design cycle that is becoming more and more common in the field. The course uses concurrent engineering as a methodology to emphasize the close connections between fundamental concepts, functional requirements, design, materials, and manufacturing.
Student teams document their lab results in written reports and give regular progress presentations. Lecturer Jessie Stickgold-Sarah instructed the class on professional communication. At the end of the semester, students walk away with the ability to not only create new things, but communicate about their creations.
"I really enjoyed working with this group of students," says Stickgold-Sarah. "The main paper and presentations required students to express the reasoning using the design-build-test sequence, and to explain and justify their choices based on their technical understanding of core topics. They were incredibly hard-working and dedicated, and the papers and presentations they produced exceeded my expectations."
The course culminates in a final presentation, where teams showcase their findings and get feedback from their MIT instructors and industry representatives - potential future colleagues and employers.
Whether or not students go directly into a career in rocket or jet propulsion, the breadth of skills they learn in class has applications across disciplines. "The biggest skill I've gained is time and project management. To build a pump in a semester is a pretty tough timeline challenge, and learning how to manage my time and work with a team has been a great soft skill to learn," says Destafano.
The course drives home the reality that the manufacturing process can be just as important as the product. "I hope through this, they gain confidence to explore the unknown and deal with uncertainty in engineering systems," says Cordero. "In the real world, things are leaking. Things aren't as you initially anticipated or behaving as you thought they would behave. And the students had to react and respond. That's real life. It's kind of intuitive, kind of common sense, sure - but you can hone that skill, and develop confidence in that skill."
