The New Chassis

After refining the new steel tube chassis design we fired up our Miller DialArc TIG welder and started practicing. Seeing as there is only one member of our team, Scott, that had any experience TIG welding we decided that might be a real hang up. So Josh S. and Brett both sat down and spent two days TIG welding. By April 29th these were our results!

After speaking with several people it was determined that we needed about three months to create a steel tube frame, this is not acceptable since the competition in about 5 weeks... We decided that the new chassis must be completed by May 14 if we are to have any chance. So we are giving ourselves 2 weeks to complete a chassis when neither past Formula SAE or Mini Baja teams were able to complete a chassis in anything less then 3 months. Some may call that impossible....

We call it a Challenge!!

April 30th the construction of the steel tube frame starts.


Here is Brett cutting the first tube!


Here is Brett demonstrating our tube coping machine (aka Lathe)

So are you making bets among your friends, coworkers or family members if we make it?

Disaster....

There are some great challenges that need to be overcome when doing a carbon fiber chassis for a Formula SAE car. First is money, with the help of Rick McMillen at IndustriTech that was not a problem. Second is time, with the help of Rocky Mountain Composites we were able to create a buck in a quarter of the time of prior years. Third is luck, fate, destiny... What ever you want to call it. For a carbon chassis to come out correctly there are so many events that need to take place flawlessly.

Our chassis fate was the simple fact that when it was placed into its final cure it was set on the oven floor... This simple problem caused the film adhesive and carbon plies around our hard points to never reach their gel temperature and never fully cure. If the chassis was placed on some stands where airflow could have reached both sides of the part then this post would probably not exist. However, that is speculation and also irrelevant at this point.

The beautiful carbon chassis that delaminated during mold separation. The chassis is standing on the rear bulkhead and you can see the bottom side and also the up sweep of the nose.

So at about 3:00pm on April 21... Plan A failed.

By 3:15 pm on April 21... Plan B was in effect.

After about 15 minutes of disbelief, just staring at the chassis in complete silence, the team decided on a new path. The time and resources are not available to try and create a new chassis. So it was decided to create a steel tube frame chassis that would incorporate as much of the original design as possible. So we got to work.

By 7:00pm that same night a preliminary chassis was designed and the structural integrity was evaluated.

By the next day the chassis was refined from an initial weight of 84 lb down to a respectable weight of 65 lb and an expected torsional stiffness is 4,400 ft lb/degree. The result looked something like this!

Carbon Fiber Layup

After finishing the molds for the nose, chassis and body we then needed to layup the carbon fiber in the molds. This is one of the harder parts of the build. When laying up the fiberglass you can freely dart (cut a line in the fabric to avoid creases) and patch as the final fabric appearance is not important. With the carbon, however, the final appearance is important so careful thought has to be put into the sequence of plies and also it is important to avoid darts and patches if at all possible. So this process can be likened to wrapping a football with paper... without wrinkles! Time consuming and at times... very frustrating!

Here is the nose after the carbon had been layed up. The nose consisted of three panels. One panel that covered the bottom, front and top and two other panels that covered each side.

Here is Kent making patterns for the chassis.

Josh S. and Brett laying up the chassis.

Here is the outside skin for the chassis. you can see the 45 degree fiber orientation in this photo. The chassis consists of two plies, aluminum honeycomb core and then two more plies. There are reinforcements throughout for items such as suspension mounting points, seat belts, engine mounts, etc...

Here is Brett and Tyler showing their approval of the freshly bagged chassis.

Here is a impressive piece. Tyler and Josh S. layed a single sheet of carbon down the middle of body mold! It is impressive because of the complex curvature around the driver opening.