FORMULA STUDENT ADFA SUSPENSION
One feature that caught the attention of many was the suspension design on the Australian Defence Force Academy at the University of South Wales (ADFA) car in Australia. ‘We’ve got a pretty unique suspension design with a beam axle at the front and the rear. The rear is a De Dion twist axle, so we’ve put a slot down the centre of the beam so that it’s kinematically compliant and can roll. We’ve also got a Watt’s linkage in the back, so it’s a really different concept to what other teams have,’ explained the team leader who came up with the concept. The benefits were already
evident. ‘The beam axle system cuts the number of chassis hard points by 60 or 70 per cent. On the front we’ve only got four pick-up points, whereas on the independent suspension car we’ve got eight just for the wishbones. When you start including the rocker and the damper, that gets even more. What it allowed us to do was to build the chassis with the minimum amount of jigs, so the manufacturing was quicker and easier. We also got rid of 16 spherical bearings on the car, again reducing costs. The whole idea is to give good
wheel attitude control. Of course, there are compromises, like unsprung mass, but we can actually touch our roll centre. It’s a physical thing, which makes it easier to tune the car.’ This brave design choice
was a result of the team being very resource constrained. ‘We had to design it using the top level systems engineering approach – looking at what aggregation of sub-optimum systems is going to give the best system for the team. The university were looking at cancelling the entry, because previously we were finishing the car three days before the competition. It was unreliable, heavy, overpriced and sapped all the resources. So these circumstances were what drove the design.’ The proof came in the
overall results, as ADFA Racing finished seventh in Australia having finished third in Acceleration and Fuel Economy. From that point, they decided to go further afield. ‘We thought while we’ve got something pretty different, why not take it overseas and see what everyone thinks?’ They finished in the top 20 on the Skidpad and the Design final at Silverstone.
Formula SAE BY KALEY ZUNDEL
FSAE CALIFORNIA With wins in Design, Acceleration, Endurance and Overall Dynamics and a 94.5 point lead over the second place finishers, École de Technologie Supérieure (ETS) clinched first place overall for the first time in the university’s history, in the process making it the first Canadian university to win the North American Formula SAE series.
The 2011 competition was
held at the Auto Club Speedway in Fontana, California for the sixth and final year and welcomed its highest attendance yet, with 61 teams registering. They represented Brazil, Canada, China, Japan, Mexico, UK, USA and Venezuela. All static events took place in the NASCAR garages and suites, while the dynamic events were staged and run on the infield course areas. Taking first place in Cost was the University of Alberta entry with an adjusted cost of $10,027 (£6120). That was just $578 (£353) higher than the team’s 2010 budget, which also captured it a first place finish. Alberta also won first place in Presentation. Announced for the Design semi- finals were seven universities: University of Oklahoma;
University of Washington; Oregon State University; Missouri University of Science and Technology; University of Bath; École de Technologie Supérieure and University of Wisconsin- Madison. Out of these seven semi-finalists, Oregon, Bath and ETS went forward to the Design finals and public review, where the performance on track and the knowledge of the students were thoroughly assessed. Design event captain, Mike O’Neil, eventually pronounced ETS the overall winner. The Dynamic events started with morning Acceleration and Skid Pad sessions, followed by the Autocross event in the afternoon. With 43 cars crossing the start line in Acceleration, it was ETS who crossed the finish line with the shortest elapsed time of just 3.916 seconds. Of the 41 cars that entered
the Skid Pad event, the University of Oklahoma posted the best time of 4.878 seconds to take first place, while in the afternoon, 47 cars crossed the starting line for Autocross. And with a wing designed on the car for the first time in the university’s history, Oregon State University’s entry seized first
A radical re-think of the use of resources led to the inclusion of a De Dion beam rear axle, greatly simplifying the rear suspension assembly and making manufacture quicker, easier and cheaper. It worked, too
62
www.racecar-engineering.com • September 2011
With wins in four separate categories and an astonishing 94.5 point lead, the École de Technologie Supérieure (ETS) was dominant
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