Months before the Formula SAE Michigan competition in May, teams were hashing out product development decisions. The end-game was presenting a racecar that had the right stuff for earning high points in the challenge’s vehicle design evaluation as well as the acceleration, skid pad, endurance, and autocross dynamic performance events.
The majority of teams participating in the 34th annual challenge at the Michigan International Speedway opted to power their racecars with a sport bike engine from Honda, Kawasaki, Yamaha, Suzuki or smaller engines from other manufacturers. Several of the veteran teams pinned their drivetrain to a steel spaceframe, or a monocoque—as was the case with England’s Oxford Brookes University racecar.
“When we first started in 1999, our car was an aluminum sandwich panel monocoque,” Luke Evans, Oxford Brookes University’s chassis group leader, told SAE Magazines.
During the next 11 years, the school’s team competed with various carbon-fiber monocoque and steel spaceframe cars. They returned to an aluminum monocoque racecar in 2011.
“We have the skins on the car cut separately and then form the panels afterward, and this allows us to place hard-points internally within the sandwich panel to distribute point loads,” Evans explained.
In preparing the car for this year’s competition, the chassis was extended further rearward.
“This reduced the number of tubes in the rear subframe, which because we do not laser-cut them—we fabricate by hand—it saved a lot of time. We also went with an external roll hoop, which is a lot lighter. It also helped reduce the time needed to manufacture the entire chassis,” said Evans.
One of the big chassis changes for the 2012 racecar was the thickness of the seatback (an angled section of the chassis that forms the seat’s angle) and the floor.
“We designed the thickness to the chassis’ needs. Last year when we used the same panel thickness all around, the torsional stiffness of the chassis was nearly twice what we actually needed. So we saved mass at the sacrifice of stiffness, but the stiffness is still adequate for what we need,” Evans said, noting that the overall chassis for 2012 shed 17.6 lb (8 kg) compared to the 2011 chassis.
Michigan State University’s (MSU) racecar also features a carbon-fiber monocoque, a change from last year’s 4130 steel spaceframe.
According to Benjamin Bosworth, MSU’s chassis team leader, “We were able to achieve twice the stiffness at the same chassis weight as last year. And, we’re also able to better package the powertrain, suspension, and other vehicle systems.”
The racecar’s carbon-fiber side pods feature integrated louvers, which serve both an aesthetic and a functional purpose.
“We have a 14-in by 10-in radiator to help keep the engine cool. The louvers—five on each side pod—help vent the hot air, and they help convey an aggressive look,” said Bosworth.
While a few teams opted for aerodynamic packages, the University of Kansas racecar is visually defined by its soaring carbon-fiber rear wing and a massive carbon-fiber wing on the nosecone.
“It’s almost the biggest front wing we could have under Formula SAE rules. We refer to it as the snowplow,” said Cameron Bryant, the team’s manufacturing leader.
The team’s racecar featured giant-sized wings at previous Formula SAE events, but “these are the biggest by far that we’ve ever had. We’re shooting for an overall 550 lb (2.45 kN) of downforce with these wings,” said Bryant.
Last year, the University of Kansas car had the engine inside the monocoque.
“The engine is stressed this year, so it is hanging off the back of the monocoque and taking all of the stress from the suspension. Going with this design approach makes the vehicle a lot lighter, and the engine is more easily accessed. Four bolts and the whole rear of the car comes off in 20 minutes,” said Bryant.
Gary Latham, a first-year Formula SAE design judge, said the collegiate team members made product development decisions based on the same set of criteria as professional motorsports engineers.
“A great deal of what gets into a racecar is dictated by the rules. But you also have to stay within a budget, so you have to be wise about where the money is spent,” said Latham, Design Department Director for Pratt & Miller, a New Hudson, MI, engineering firm that designs and develops racecars for the American Le Mans Series and the Grand-Am Series.
Latham said preparing a racecar for competition pushes engineers to stay focused.
“Everything is either limited by budget, by the available time frame, or by both factors. The race is going to happen whether you’re ready or not, so it’s better to take the approaches that you can manage to get done in time for the race,” said Latham.
To help get ready for their first appearance at a Formula SAE competition, the University of North Florida (UNF) team consulted with two veteran teams, the University of Florida and the University of South Florida.
“We’re pretty close-knit. We all talk and discuss different designs,” said Casey Foster, UNF’s team captain.
The UNF team took a very hands-on approach to designing and building a reliable racecar.
“We started off with blocks of foam, and we hand-cut the foam blocks down into the shape we wanted for the car’s body. Everything was hand-cut. We didn’t use CNC equipment to cut the molds. It was very time-consuming, but it’s a one-of-a-kind racecar. We even had an engineering student, who is also studying art, airbrush an osprey onto the hand-lathed fiberglass body,” Foster explained.
For Foster, Formula SAE is a “great learning opportunity, and it helps you grow as an engineer. This program is more in-depth than anything I’ve ever done. I had an internship for four years and even that was not as in-depth and as difficult as this has been.”
The top 10 overall winners were: Oregon State University (U.S.) 1st; Karlsruhe Institute of Technology (Germany) 2nd; Universitat Stuttgart (Germany) 3rd; Technical University of Munich (Germany) 4th; University of Michigan-Ann Arbor (U.S.) 5th; Graz University of Technology (Austria) 6th; Metropolia University of Applied Science (Finland) 7th; Ecole De Technologie Superieure (Canada) 8th; Friedrich Alexander University of Erlangen (Germany) 9th; and University of Wisconsin-Madison (U.S.) 10th.