Corsa Research & Development

The year before I joined the Formula SAE team at Portland State University the previous years team had built their most successful car to date.  It was the first time they had finished the endurance event at competition and while their results overall were mediocre it was a big step forward from all the years before.   

One of the first events each year is the Dallesport Shootout put on by Oregon State University.  Schools often use the event to determine who is quick enough in the cars to be drivers that year as well as show off old cars from the previous year.

This is a photo of me testing out the car on the acceleration course.  My previous experience in autocross and in go karts made adapting to the formula car pretty easy.  

We learned from the old chassis that there were some immediate areas that could use improvement.  These included making it easier for the driver to get in and out in order to comply with the "5 second escape rule" and the rear sub-frame was changed from round tube to square to allow easier mounting of a new differential design.  

One of my first manufacturing projects was notching tubes to be used in the building of control arms for the new car.  While a pretty straightforward job, it was the first time I had used the hydraulic band saw and the mill and a big step forward for me.  

Pictured here is the new differential carrier (or half of it at least) in the process of being machined.  

One of the key aspects of Formula SAE is learning to design parts that can be easily manufactured.  I had yet to jump into design work at this point but learning to fabricate parts was a great way to learn what aspects were important in a design.  One of the biggest hurdles for students was simply designing parts that could be manufactured, let alone manufactured easily.

I started by learning to operate a manual mill to face and fly-cut material to specified dimensions.  I then learned the basics of operating CNC mills.  At Portland State we had a 2-axis mill so it became important to understand not just how to load and run programs but also how much material (AKA: Feeds and Speeds) could be removed per pass to keep the machine happy.  I also learned and became quite skilled at lathing parts.  

The completed differential carrier half.  The other half was symmetrical to this.  When assembled it both held the Taylor Race differential and served as the rear jacking point of the car.  There was no adjustment for chain tensioning built into this design, that would be done with another part.  

Since we used the same engines it made sense to reuse parts as often as possible such as this intake that was 3D Printed.  It was specifically designed to work with the car as well as comply with the rules that mandated the use of a 25 mm intake port.   

Some new ideas are tested such as this fan blade wheel center.  A pet project of one of the team leaders that year. Its intent was to improve brake cooling by actively creating airflow through the wheel and across the discs.  This idea went on to actual production of wheel centers at great expense but eventually the company that was creating them dropped the sponsorship and scrapped the idea altogether.

In retrospect the car could of actually used smaller brake discs and a much more efficient and simpler way to cool the discs, should cooling be needed, would of been through the use of simple ducts rather than expensive, difficult to machine parts.    

One of the biggest problems many cars experience is having the engine over heat from poor cooling system design.  We decided to use a much smaller radiator than the previous year so it was important to make sure it had adiquate airflow.  

We earned a 16th overall finish.  That was and continues to be by far the best finish in Portland States history.

Looking back at both cars we began to look at what we can improve for the next year.  When checking over the old car I noticed the spherical bearing in the control arm looked a bit odd and after playing with it a bit the ball popped out and went rolling across the floor.  As it turned out these bearing weren't designed for the loads that the control arms see, definetly something that needs to be fixed. 

Post competition I insisted we buy basic tools such as scales to measure the weight distribution and ensure the car was properly corner weighted.  This also helped us to bring the engineering of the car full circle going from design to building to testing to gathering data so that we could go back to design and improve the weak points and start the cycle all over again.  

We found the cars suspension setup was really in need of improvement as the rear wheels would lift in a corner  and with the Torsen type differential, the car would be unable to apply power and drive out of corners.