Tuesday, November 9, 2010

Some Real Engineering

So, I've been pretty busy the last few weeks, notably with another checkpoint on my now-70-page (!) portfolio for Intro to Flight. So I haven't had much time to write. However, I've been thinking about the title of this blog (Engineer in Progress) and thought I might talk some about the actual engineering that I have, you know, in progress.

Most of the actual hands-on stuff I'm doing is outside of class, on the UD Aerodesign Team, where I'm part of "Team X," which is a group of veteran members who are working on sizing the plane and laying out its overall configuration -- sort of a combination steering committee and senior design group. So far we've mostly been working on laying down our basic configuration and sizing our competition plane from the constraint diagram we've constructed from the AIAA "Design, Build, Fly!" competition rules and our own testing. (A few weeks back, we got to test hand-launch speeds in an Air Force motion-capture facility, which was a really fun afternoon, and got us some great data for the team.) It has been a challenging process, involving a lot of learning very rapidly. When we touch on this material in Intro to Flight, I often discover a great deal of more in-depth material that I simply never had the chance to learn as Team X dealt with it. The payoff has been that I feel like my abilities as an aeronautical engineer are actually being tested, not just developed, by the class. Team X’s job is not yet done, and the job of the Aerodesign Team won’t be done until the plane flies at competition in April in Tuscon, Arizona, but I am very much enjoying the feeling of being closer to where the action is than I felt I was last year.

Additionally, I'm in charge of the Connections Group, which is coordinating all the connections between the parts of the plane (see diagram below) as well as the process of assembling the plane. This is important because the competition requires that the plane fit into the dimensions of a standard carry-on suitcase (total of 45 dimensional inches) while also carrying some payload. To do that, we simply need more wing area than could fit into the box with no assembly. Last year, our team had two failed flight attempts due to issues with assembly -- one due to the results of a poor design of wiring runs in the wing that pulled out during the five-minute timed assembly and couldn't be fixed, and the other due to a disconnect along an inaccessible internal connection inside the tail boom that was not detected until the elevator failed to respond on the runway. This was largely because there had been no consideration at all of assembly and checkout procedures before we arrived at competition and neither was there much thought given to structural or electrical connections prior to their construction. (Several key decisions were made in the wind tunnel by a single now-departed member on the day that they were implemented with no further review.)

The Connection Group was formed this year specifically to make sure that this whole issue of attachments and the assembly method was fully examined at the design stage rather than the construction or operational stages. The general idea is to examine all of the connections between components that will be detached in the box and ensure that designs are fully worked out, including both structural and electrical (that is, servo wiring) considerations. Right now we're looking at five different type of connections, which are shown on the diagram below.

Connection Location Diagram Showing Five Types of Connections

Of these, the tail connections are giving the most trouble. The landing gear design is mostly modifying last year's connections to be able to be assembled more quickly and the wing design is mostly an improved form of the final design of the wing connection used last year with the issues that impeded assembly at competition reworked or eliminated.  The tail boom connections are proving more troublesome because they are subjected to bending moments in both pitch and roll, as well as twisting moments along the axis of the boom and possible axial normal forces. We're dealing with these well at the tail's connection to the fuselage. We've developed three or so conceptual designs that should be flexible enough so that one will work however the boom and tail end up being sized. The outboard connection is proving more troublesome; so far, it requires a lot more weight and complexity than the fuselage connection to the tail. I've been exploring whether this outboard connection can be eliminated while keeping the macro design of the plane within the competition constraints, but I've so far been having little luck.

This whole connections issue has been interesting for me because I was part of the assembly crew last year. Thus, I am not only involved with the design of this section this year and am seeing how decisions and assumptions made at that overall conceptual effort can effect individual systems, but I also have hands-on experience with operations of the part of the plane I'm designing. Thus, I can understand how that experience can vary depending on the quality of the design work. On the whole, I feel like I'm understanding the process more, and feeling even more like an engineer-in-progress instead of just an engineering student.

On a closing note about connections, I thought I'd link to James Burke's series Connections (the first video of which can be found on the web here). This is an amazing television series about the interconnectedness of life, and how developments and principles originally researched for one use can end up having huge effects when used in different ways combined with other things in entirely different disciplines. Every episodes starts with one element, and moves along a chain to an endpoint you wouldn't have guessed at the start. While this is interesting, the real stand-out moment came when I understood that these connection chains branch and interconnect, and how the spread of new thoughts and ideas across large and vibrant societies can spark huge numbers of cross-fertilized ideas that never could have been conceived by a smaller or more restricted group. It's fascinating food for thought, especially for an engineer, and an argument for that old notion of the "Renaissance man." Who knows when a working knowledge of, say, gardening, painting, or music could lead to seeing a new solution to an old problem or seeing a new problem that can be solved with an old solution? That broad knowledge can come in handy. Of course, I could be telling myself this only to justify in my mind all those hours I spent on the Brebeuf Jesuit Brain Game team. Who knows?

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