Inside the Aerodynamic Design of a Record Breaking Car
Kyle Maxey posted on March 05, 2014 | 13825 views

In auto racing, aerodynamics is often the measure that separates winners from the rest of the pack. The Edison2 Very Light Car (VLC) has already won the automotive X prize.  Now the Edison2 team has their sights set on a land speed record. 

But first a little history.  Ever since people started setting land speed records, aerodynamics have played a key role in their automotive designs. In1899 Camille Jenatzy, fueled by a passion to change the electric carriage market, climbed aboard his torpedo shaped La Jamais Contente (roughly translated as "Never Satisfied"). Racing through the streets of Achères, Yvelines near Paris, Jenatzy's machine reached a land speed record of 105.8km/h (65.8mph) becoming the first car to clock in at over 100 km/h.

While La Jamais Contente's aluminum alloy body and dual direct drive motors were certainly sophisticated for their day, it wasn't long before Jenatzy's record was eclipsed. Since that time automotive engineers have kept pushing the frontiers of automobile performance, and that tradition continues with the Edison2 VLC.

Like Jenatzy's avante-garde auto, the Edison2 VLC uses a number of cutting edge technologies to reach its performance goals. We spoke with the Edison2 team to get an inside perspective on its advanced aerodynamics.

According to Brad Jaeger, Edison2's VP of Engineering, "the VLC is unlike most autos in that it wasn't modelled after another car.  Instead its aero design is more like an airplane's."

Starting with a nose that's as small as possible, the VLC was built to have a minimized frontal footprint. Featuring a highly tapered body, the auto resembles the streamlined design of a Cessna Citation. Similar to an airplane, the VLC also features its own type of wings that project outward from the car's slipstreamed body to hold the auto's wheels. Encased in fairings whose shape are the quintessential embodiment of aerodynamic design, the VLC's slim 19 inch tires carry not only the vehicle's weight, but its suspension system as well. This innovative feature is unique to the VL and lends the car's aerodynamic body greater stability while also reducing its weight.

Although the Edison2 team was confident in the VLC's shape, the team wanted to test their design, so they headed for GM wind tunnel facility in Warren, Michigan. Amongst active betting and excited expectations, Edison2's designer looked on as the wind tunnel's massive turbine revved to full speed. With wind howling over the VLC's sleek surface it was becoming apparent that Edison's engineers had a winner. When the test had finished and the results were returned, the Edison2 VLC was named the most aerodynamic car ever tested at the GM facility – its drag coefficient was a mere .160.

While the VLC's aerodynamics are outstanding, there is more to the design than just slicing through the air.  The design also has to be efficient at translating the car's power to the track through the use of downforce. Just like an airplane, cars create lift as they accelerate. And while most cars aren't in danger of taking off, even a tiny bit of lift can reduce the grip between a vehicle's tires and the track. That minor inefficiency can reduce a car's top speed, which is something the Edison2 team can't afford when challenging for a land speed record.

In the case of the VLC, finding the right balance of downforce was vitally important given the fact that the designers had sacrificed engine size in favor of light weight. The wings connecting the auto's wheels to its body were designed to provide enough downforce to maximize the potential of its 40HP engine. In fact, using only 6HP the VLC can reach as speed of 60mph (96.5 km/h).

Throughout the process of developing the VLC's aerodynamic frame, Siemens' Solid Edge monthly subscription software has given Edison2 the ability to incorporate the expertise of designers and engineers on an as-needed basis. This flexibility has allowed the project to iterate and finalize their design quickly, saving both time and money.

The shape of the VLC defines the car's performance and aesthetic. If, as planned, the Edison2 one day enters the consumer market, that will be a record-breaking moment of another kind. The world's most aerodynamic passenger car would be an accolade that would surely impress Mr. Jentatzy.  

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Disclaimer: Siemens has sponsored promotion of their design software solutions on ENGINEERING.com. They have no editorial input to this post - all opinions are mine.

Kyle Maxey

Images Courtesy of Edison2

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