Monday, February 12, 2007

Sunday, February 4, 2007

2006-07 Formula Team Fabrication Update

This year the chassis team consists of two senior Mechanical Engineering Technology majors, Todd Knallay and Ryan Reynolds. Todd has focused on the design and fabrication of the chassis frame and Ryan has focused on the pedal assembly and steering.

The chassis frame, while keeping the same basic geometry and increasing the rigidity from last year, is expected to weigh only 62 lbs, which is about 15-20 lbs less than previous LETU frame designs. The chassis was designed using a FEA software to optimize the design for low weight and high rigidity.

The pedal assembly has been changed from a floor mounted system to a top mounted assembly which results in a lighter assembly that is easier to adjust. The steering geometry was reworked to fit the slightly different suspension geometry and new kingpins.
Things are looking bright in the Machine Design Lab as the team is assembling the chassis.

Josh Stralow deposits a high quality weld using the Gas Tungsten Arc Welding process.

The late nights continue as the chromolly space frace begins to take shape.

Todd Knallay precision grinds a tube joint to perfection.

All of the main components are ordered and already starting to pour in. There is so much work to be done as the team prepares to build another car.

2006-07 LeTourneau Formula Final Design


The 2006-07 Formula SAE car is a solid design, optimized for weight, cost, manufacturability and packaging, keeping with the original goals of designing a high performance prototype race car. It uses a 4130 chromoly tube frame chassis which meets the torsional rigidity specifications necessary for optimal performance. The suspension geometry is a push-rod/bell crank system implemented in both the front and rear. A one-piece kingpin was designed to create a better and stronger system. Our engine will again be a Honda CBR 600 f4i inline four cylinder engine with a custom designed exhaust and intake. The power will be transferred to the Torsen T1 limited slip differential mounted directly to the engine via a set of sprockets and 428 chain, then from the differential to wheels through Taylor Racing axles and a set of C.V. joints. Our car’s estimated total weight, without the driver, is 497 pounds. This accounts for all purchased parts and includes estimated weights of every component.

This design has decreased manufacturing complexity by minimizing the number of re-designed parts. This can be mostly attributed to last year’s car, which made a huge step toward a great design. Also, the packaging has been carefully considered, brackets drawn, and fasteners modeled in order to minimize, if not eliminate, interference problems that commonly arise during fabrication. All of this planning has also allowed our team to keep the center of gravity as low as possible.

In order to minimize weight, stress analysis was performed on every major component. A general safety factor of 1.2 was used for the design of most components, while a larger safety factor was used for critical components such as the kingpins and a-arms due to their dynamic loading and to ensure they do not fail. The defined maximum loading used was a 3.5g bump acting on the tire, and a 3.5g lateral load. This would relate to a worst case scenario of full cornering at a maximum speed with a sharp impact, such as a large bump.

God has provided received donations accounting for approximately $9,080, and promises of $5,500. This figure does not include the promised donated machining, parts, supplies, and other miscellaneous services. This blessing of funds enables us to order some of the required purchased components before leaving for Christmas break in order to prevent delay in the spring semester.

The intent was to design and build a high performance, well packaged, low weight prototype race car and the result of this fall semester has placed us well on our way. We are excited about starting construction of our design and plan to produce a car which will place well at competition and can be continued to be used as a solid starting point for future teams. With God’s continued blessing and a team that continues to be committed, we are confident this can be accomplished.