LoneStar combines form and function

  • 31-Mar-2008 07:36 EDT
Black LoneStar on Bridge.jpg
"Our engineering team, which has diverse backgrounds in the automotive, aerospace and trucking industries, felt confident that we could develop this truck without spending months in prototyping," said Tom Braughman, vice president and general manager of Navistar Heavy Truck Vehicle Center.

Quick, say the first things that come to mind when describing the front-end of a Class 8 commercial truck. Most likely your blunt assessment cited one or more of these descriptors: Flat grille. Smooth hood. Square nose.

“You can forget about that now,” proclaimed Dave Allendorph, Chief Designer for Navistar’s Truck Group after the International LoneStar made its world debut at the 2008 Chicago Auto Show. “It’s not boring, it’s not plain vanilla,” Allendorph said about the Class 8 truck whose shapely chrome grille and sloped hood is reminiscent of International Truck’s late 1930s D-Series pickup truck.

The arrival of the LoneStar is Navistar’s bid to mesh a customized look with an aerodynamic design. “On LoneStar, we shaped and minimized the aerodynamic drag of components traditionally associated with classic trucks, like the externally mounted air cleaners. That’s something we haven’t done in the past,” said Ron Schoon, Chief Engineer for Aerodynamics at Navistar’s Truck Group, parent company of the International Truck and Engine Corp.

LoneStar’s one-piece, vacuum-formed aluminum front bumper—a claimed first for the industry—provides high style, and it was purposely “shaped to smoothly transition the approaching air around the front tires and onto the sides of the truck,” said Schoon. In addition to the bumper, grille, and air cleaners, LoneStar’s frame rails, front axle position, fenders, chassis skirts, cab interior, and its wheel design are unique.

International’s ProStar, which launched in 2007 and is considered the most aerodynamic, fuel-efficient Class 8 truck on the market, provided LoneStar with its basic cab structure as well as the structural interior parts that are forward of the B-pillar. LoneStar, like many other Class 7 and Class 8 International products, offers the Caterpillar C15 and the Cummins ISX engines as well as manual and automatic transmission choices from Eaton and ArvinMeritor.

LoneStar’s product development was put on the fast track and unfolded without a physical prototype, shaving 12 months from the company’s usual start-to-finish timetable. “Our process was 36 months overall, including the fuzzy planning/customer needs front-end work,” said Mark Wohlford, Senior Program Manager, Heavy Product Center at the International Truck Development and Technology Center in Fort Wayne, IN. The clay approval to full production timetable is 26 months, including design, tooling, testing, and manufacturing ramp-up.

The iterative steps to arrive at LoneStar’s aerodynamic profile involved CFD analysis, using CAD data from the clay model as well as testing a 1/8-scale model in the wind tunnel. A full-scale wind-tunnel test was done “using a mule, which was a vehicle mocked up with full hood, grille, bumper, air cleaners, and chassis skirts representing the A-surface of our intended design. We did ‘what if’ trials at each step, identified improvements, and put the improvements in for the next step,” said Wohlford.

Added Schoon, “We also conducted evaluations of competitive vehicles in the full-scale wind tunnel.”

LoneStar’s interior is atypical, as was the approach taken to arrive at the sleeper cab’s design. “We mocked up functioning bucks made out of Styrofoam, cardboard, and other materials to simulate an actual sleeper cab. We let truck drivers/customers interact with them for a while and provide feedback to the designers and engineers,” said Wohlford.

The sleeper cab, which can be separated from the driver’s cab area by optional real wood flooring, includes a crescent-shaped couch, a pull-down 42-in (1067-mm) wide bed with standard innerspring mattress or optional memory foam mattress, a Monsoon audio system, fold-out tables, an optional refrigerator, and airplane-styled overhead cabinets.

LoneStar will be offered with 42 factory-installed accessories encompassing 23 exterior parts and 19 interior items. The non-sleeper cab version is expected to start at $115,000, while the high-end sleeper cab model is expected to be priced between $135,000-$140,000.

Production of the LoneStar is slated to start in August 2008 at Navistar’s plant in Chatham, Ontario, Canada.
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