This is Part 5 of a series written by guest writer Ricky Nietubicz on his experience on the Formula SAE team at the University of Delaware. FSAE is a competition where students design, build, and compete with small formula-style racing cars. Ricky was President of his FSAE club, and his team went to the Nationals in Detroit during the 2006-2007 season.

By this point you have a team in some sort of organized format, a usable shop, now you’re ready to get crackin’ on the car. The key to the car is the design, and thinking ahead. As usual, it sounds simple, but in practice it gets more complicated. Decisions need to be made at different stages, and designing a car from scratch is no picnic.

The first goal is, simply, to not have to design a car from scratch. Ideally you can evolve from your team’s previous car or cars. If your team lacks previous cars, or if they weren’t well thought-out enough to be a good platform for evolution, or you just want to try something different, that’s fine too. Whatever you do, there is one simple rule of thumb that will make everything easier- write everything down as you do it. This will help with the design report- you won’t be sitting there, 6 months later, wondering why the heck you did something a certain way, and you won’t have to do the design report all at once, it’ll just happen as it happens. This will also make evolutionary design infinitely simpler in future years.

First things first, you have to do some early design decisions. The big mama is whether you want to do a steel frame or a monocoque. Each has its advantages. Having seen the arguments both ways, I’d say a monocoque is the way to go, mostly from a rigidity standpoint. The inherent problem with an open car is tying the front and rear of the car together, the same problem us Miata guys have. You can’t cage an FSAE car in, due to the rules and the requirement that you be able to exit the car in 3 seconds or so. The end result is that it’s hard to tie the front to the rear, and you get chassis flex. There are ways to design a steel frame around this, but a monocoque takes a lot of the design problems out of it, as it has a continuous u-shape through this area. The steel frame, however, is easier to do with resources on hand (all you need is a pile of chromoly tube and a TIG machine) and therefore can be done more rapidly. Each has plusses and minuses, I suggest you think this through and write down your findings (at some point you or someone on the team may want to change from a steel frame to monocoque or vice versa, it helps to have the pros and cons of each written down so you don’t constantly rehash the same argument year after year). New information will come up and should be addressed, but don’t waste time making the same points over and over.

The next major design decision that should be made is the engine. Pros and cons of different engines will be covered later, but for this area, you just need to think about packaging. A one or two cylinder engine fits differently than a 4-cylinder, and your design needs to reflect that. The idea is to have the smallest car you can have that fits what you need it to.

Think about where you’re going to put the fuel tank and what size it will be. Then figure out what you’re doing for suspension and where the pickup points will be, as this will dictate where your frame must be strong. Don’t forget the rules that apply to frame design, there are minimum dimensions.

Don’t be afraid to look at other teams for inspiration. Sure, teams aren’t exactly going to walk you through their design process, it’s a competition, after all. But they will have photos on websites, and from these you can look at their designs and see what they’re doing. While at competition, take your own pictures, lots of them, of as many cars as you can. When the results are posted, look at which of these teams did well on the design report, and figure they’re likely doing something right that you should look to for inspiration.

Model and test. Remember, it’s an engineering competition first and foremost. You’ll want to be able to show why you did things a certain way. This is necessary for the competition but also a real benefit when you’re working on future cars. The last thing you want to do is get the car built, have somebody lean on the rear roll hoop and watch the chassis flex, precipitating a real-world test of torsional rigidity that reveals a figure comparable to a wet noodle, when it is far past the point to do anything about it.

Again, save everything. Even the designs that are horrible, awful and incredibly stupid ideas. Ideally, you can keep these files electronically as well as in hard copies, so that you can refer back to them when designing future cars and parts. Also, ideally, you’ll keep, along with these files, explanations of why you did things that way, why you thought it would work, and why it did or didn’t work.

Design is all in the process, the very long and time-consuming process. This is where the engineers on the team must come to the forefront, as they are the ones with some understanding of the mechanics involved. There are a great many books available that focus on race car suspension design, and, well, thank heavens for SolidWorks, and those who can operate it.