Good finish leads to great start
The Kettering Formula SAE team is gearing up for the 2005 season with a lighter vehicle that they hope will drive them into the top 10 at the Silverdome in May.
A good finish at the 2004 Formula SAE competition is the foundation this year's team is building on at Kettering University. "We are coming off the best finish ever for our program," said Andrew Nabb of Cambridge, Md., and chief engineer for the team, "and the momentum and experience we have retained for this year should push us even further."
The Formula SAE competition, sponsored by the Society of Automotive Engineers (SAE), will be May 19 through 22 at the Silverdome in Pontiac, Mich. SAE is an international organization focused on sharing information and exchanging ideas for advancing the engineering of mobility systems.
Formula SAE and Formula Student are small racing car design and build project competitions for engineering students. The formula race car project is part of the students' academic studies at Kettering. The car itself is a single-seat autocross race car, open wheel, open cockpit vehicle powered by a four-stroke engine (up to 610 cc).
> This year the Kettering team is working on making their vehicle lighter and more stiff. "We're trying to cut the overall weight by 25 pounds to 460 pounds," said Seth Lerner, of Rochester, N.Y. and engine team leader for the Kettering team. "We've made the suspension system out of titanium, which has the same strength as steel at half the weight."
> Lightening the overall weight has also turned into the team's biggest engineering challenge. While the titanium they are using for many parts including the control arms, drive shafts uprights and spindles is lighter than steel, it cannot be welded in open air.
"Titanium has to be welded in an inert chamber," said Nabb. Oxygen reacts with titanium weakening it and making it brittle. To weld the parts they need for their vehicle, the Formula team created a chamberthat "looks like a big baby incubator," said Nabb, "wefill the chamber with argon gas, an inert gas, which allows us to successfully weld the titanium."
Not only is titanium tricky to weld, it's also expensive. "We have saved some money by using scrap from parts left over from airplane production," Nabb said. "Seth has found a way to manage the engine budget to make engine production cheaper, opening up funds for the titanium."
A lighter vehicle doesn't guarantee better performance, so the team is also exploring design changes including a stressed engine frame, where the engine is bolted to the front and back of the frame making it part of the frame. This technique reduces the weight of the chassis because it eliminates the weight of uprights formerly supporting the engine. It also increases overall vehicle rigidity lowering bending when the car is turning. A stiffer frame makes the handling more predictable and makes chassis tuning more precise, said Nabb.
In addition to structural changes the team will incorporate what they call "high tech electrical stuff," or more precisely, an electronic automatic shifter that will make the car much easier to drive, a planned launch control that will limit wheel spinning when starting from standing still and traction control.
Internal modifications are also aimed at improving performance. "The engine this year will incorporate many internal modifications aimed at increasing our average power," said Nabb.
Because teams must use a stock engine with a restrictor that limits the top end power to around 80 horsepower, the key to better performance is midrange power. This means the engine must run smoothly and make power over a wider range of RPMs (speed) than the stock 100 hp engine does.
"We are using custom ground cams, higher compression pistons and an extrude-honed head to alter the engine to make more all around power," Nabb said. "We arealso trying to reduce the interia of the engine, by using the lightened crank, aluminum clutch springs and the lightened rear sprocket. Less inertia means less power is used to accelerate the engine, so the car accelerates faster," added Lerner.
To accomplish all the improvements the team has had to juggle the available funds. One cost saving measure was to switch the engine management system to a low cost unit. "The ECU, or electrical control unit, is a computer that runs the fuel ignition and spark timing," said Lerner, "we went from a unit that costs $4,000 to one that costs $700." Big savings when every penny counts. The group is still seeking sponsors to help defray the cost of machining engine parts. "It's beyond our capabilities to machine parts in-house," said Lerner.
While their eyes are on the Silverdome in May, the team would also like to take their vehicle to an international SAE student competition this year. "We have a good chance at winning an international competition," said Nabb. The group would like to find sponsors so they can compete in Great Britain in the summer.
For more information about the Kettering Formula SAE team, contact Nabb at firstname.lastname@example.org.
Written by Dawn Hibbard