PTC Awards Entry
2005 Sooner Racing Team Formula SAE Vehicle
Trey Wheeler, David Oubre, Marcus Evans, Chris Allbee, Andy Horner, Matt Brown, James Clement, Tim Charlton,
University of Oklahoma
Education, College and University
PTC Creo Parametric
Our design entry is a complete Pro/ENGINEER CAD model of the Sooner Racing Team’s (SRT) 2005 Formula Society of Automotive Engineers (FSAE) racecar. FSAE is an international student engineering competition held annually in Detroit. This model will give the SRT a competitive edge in all aspects of competition. This is the first such model ever created by the SRT. Vehicle development and manufacturing were improved greatly with the aid of the completed solid model. The model includes every component of the vehicle including fasteners, hoses, and wiring. Mass properties are accurate for every part with the exception of purchased items such as the engine, dampers, and tires. These parts were modeled as accurately as possible and assigned a theoretical density based on the volume of the CAD part and the weight of the actual part.
The SRT’s previous car took approximately seven months to manufacture while the current car took only three and a half. This was accomplished through better organization and scheduling. Vehicle weight was reduced over the previous design by 10%. The previous car weighed 515 lbs while the new one only weighs 465 lbs. Vehicle cost was also reduced with the aid of the CAD model. The previous car cost $22,000 to manufacture while this year’s model has a predicted final cost of $17,000. Since the body and engine system are incomplete, the total cost can only be estimated. Pro/ENGINEER’s direct impact on the FSAE competition for the SRT would be a big advantage for the Design Event. The SRT’s goal is to make it semi-finals in design, and the solid model would help greatly in meeting this goal.
Since this vehicle is designed for a student engineering competition, innovation is what drives the overall design. Of course, fundamentals are very important to cover, but innovation is what scores extra points. Major innovations in the design include center lock nut wheels, tripod joints integrated into the outboard spindles, inboard suspension packaging, a brake bias monitoring and adjustment system, and a well packaged cockpit. A center lock nut wheel was implemented into the previous design and modified to make it better for the current vehicle. This required the use of a live spindle rotating within the upright. To reduce the extra unsprung mass caused with this design, the rear tripod joints were integrated into the spindle. Previously, a tripod housing had to be bolted to the backside of the spindle for the half-shaft to drive the rear wheels. Working inboard from the half-shaft, the differential assembly had a significant weight reduction over previous designs to reduce rotating mass. Figure 1: Front outboard assembly Figure 2: bias adjustment system In 2004, the SRT took home the first place trophy for brake system design. The main innovative feature for this system is the use of a brake bias (front to rear) monitoring and adjustment system. Pressure transducers were installed in the lines so that line pressure could be monitored in the cockpit. A small electric motor was connected to a threaded brake bias bar so that the driver could adjust the bias with the push of a button. Other innovations to this system are a hat/ rotor assembly that is lighter and more durable thanks to shape optimization in Pro/MECHANICA. Figure 3: Cockpit with driver interface and seat Ergonomics had never been considered much during design of the SRT’s previous vehicles. For the 2005 car, several wooden mock-ups were made before frame modeling began. Once cockpit clearances had been resolved, a seat was designed to hold the driver comfortably and seal the cockpit from the outside elements on the sides and bottom. The mold for the seat was CNC milled out of medium density fiberboard (MDF) to ensure mold quality. Carbon fiber was chosen as the seat material because of its high strength to weight ratio.