Urbee to Be First 3-D Printed Car

DN Staff

December 20, 2010

5 Min Read
Urbee to Be First 3-D Printed Car

KOR EcoLogic's hybridvehicle stands out from the pack for reasons other than its futuristictear-drop shape or promise to get up to 200 mpg on a hybrid electric/gasolineengine. The Urbee blazes new ground in that it's the first automobile prototypewith a body produced solely using a 3-D printer.

Unlike other alternative energy vehicles under development,the Urbee is being architected from the ground up to be as efficient aspossible and to run on renewable energy, including electricity, solar, hydro orwind power. Key to the design goals of the two-passenger Urbee - which is beingpositioned as urban vehicle for short trips, not long hauls - is the ability tobe charged from an accessible conventional energy source, whether it's astandard home outlet, a home solar array or a windmill. It will also run on aslittle as 1 percent of energy per mile travelled.

"Our vision is that you should be able to capture enoughenergy from the footprint of the garage you parked in to run the vehicle," saysBlaine McFarlane, mechanical engineer at KOR EcoLogic. With that in mind, theKOR EcoLogic team envisioned the Urbee relying on a power source the size of acity lot, for example, whether that source was solar panels on the roof of ahouse or the equivalent of a small ethanol field, he explains. "It doesn't makesense that you need a solar collection system the size of a Wal-Mart buildingto run your vehicle," McFarlane says. "To us, it's a matter of scale."

A group of engineers, led by Jim Kor, started the projectmore than 13 years ago, more as a part-time exercise and relying primarily onspreadsheets and computer simulations to explore their design goals. As marketdemand for alternative energy vehicles began to heat up, the team regrouped anddecided it was time to put serious development muscle into the Urbee project.

Rather than employing expensive materials or complexmanufacturing processes, the Urbee design focused on seven key principles inorder to maximize the distance that can be traveled per unit of energyconsumed. They are: weight, coefficient of aerodynamic drag (Cd), rollingresistance (Crr), frontal area, maximum speed and maximum acceleration. "Wedidn't start with what people would like to have - we started with what thephysics would allow," McFarlane says. Based on those core design points, theUrbee team made trade-offs. For example, the car's design won't allow for zero to60 mph in 5 sec, but McFarlane contends that that's not how most people drive,particularly within city limits.

In addition to its teardrop design, the Urbee calls forhigh-pressure tires to reduce rolling resistance and also incorporates a small 7hp engine for backup. Unlike many of the emerging electric/hybrid vehicles, theUrbee eschews lithium-ion batteries for lead acid batteries - a choice McFarlanesays fits with the Urbee's design principles around simplicity and ease ofservice.

Technology Building Blocks
Autodesk's InventorCAD software and other digital prototyping tools are the starting point for thedesign process. Urbee received the Autodesk digital prototyping suite for anominal fee as part of its participation in the company's Clean-Tech Partnerprogram. Inventor is used to model and create the drive train and framecomponents in addition to sheet metal design of the simpler shapes. For complexshapes like body parts, the Urbee team employed Autodesk Alias and AutodeskShowcase was used for the photorealistic rendering aspects of the vehicledesign.

Initially, two industrial designers carved a 60-percentscale version of the Urbee out of clay and the model was cut in half and 3-Dscanned to get the surfaces into the computer. That model was scaled to full size,and Autodesk Alias was tapped to split the vehicle model into body panels andglass and to incorporate edge profiles to determine the joints between panels,McFarlane says. An aerodynamic study was then conducted on the full-scale 3-Dmodel, and once the team was confident with the shape and aerodynamic drag, itwas ready to build a physical prototype.

It's at this stage that technology really steals the show.Rather than using conventional forming technologies to create a prototype, KOREcoLogic, in partnership with Stratasys,decided to produce the body panels for the prototype using Stratasys' fuseddeposition modeling (FDM) 3-D printing process, which creates plastic parts byapplying thermoplastics in layers from the bottom up. With this method, theUrbee team eliminates having to create any tooling or machining, and approach improvesflexibility when a design change is required, McFarlane says.

Initially, the KOR EcoLogic team 3-D printed a one-sixthscale model of the Urbee to confirm design points, an exercise that took abouttwo-and-a-half to three days using two Stratasys machines. The group is in themidst of 3-D printing a full-scale model, and the team is evaluating the use of3-D printing for other parts of the car, including air ducts, headlights andinterior components. Currently, there is no official time frame for the Urbeeto go into production.

"With traditional prototyping processes, we'd still bemaking patterns," McFarlane says. "Sending off files and getting them printedrather than doing handwork frees up all kinds of time for designers to work onother things. It's basically cut close to a year off of our prototypeschedule."

For more information on KOR EcoLogic's Urbee and to watch avideo, go to http://www.urbee.net/home/.

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