Fleet Management News & Business Info | Commercial Carrier Journal
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28 commercial carrier journal | august 2017 Great gains Savings on weight and aerodynamics give International's Super Truck high yields on efficiency BY JASON CANNON T he only thing more eye-popping than the aesthetics of Navistar's CatalIST Super Truck project is its $7 million price tag, but that's only a small part of the $40 million spent on the joint project with the U.S. Department of Energy. DOE's goal for its Super Truck projects with truck makers is to boost freight efficiency, a combination of equipment weight reduction and improved fuel efficiency, by 50 percent. Navistar says its CatalIST obliterated that target with a 104 percent improvement. "Freight efficiency is literally how much freight X miles per gallon at 65,000 pounds GVW," says Navistar's chief engineer of advanced vehicle technolo- gies, Dean Oppermann, a man who'd be listed as CatalIST's father if the truck had a birth certificate. Shedding weight To reduce the rig's weight, Oppermann and his team shaved 2,000 pounds off the trailer, but added 1,500 pounds back through aerodynamic devices such as slotted skirts, a boat tail, gap treatment and 48-volt solar panels. Aluminum land- ing gear and lightweight axles helped shed pounds, as did the thinner DuraPlate walls on the Wabash trailer. Working with an LT tractor, the team pulled out 2,300 pounds. e skirts and hood are carbon-fiber, and the wedge- shape cab is a carbon-fiber skin over a steel structure. e windows and wind- shield are polycarbonate, which is lighter and stronger than glass. Super-single tires and aluminum tanks round out most of the 2,800 pounds deleted from CatalIST, improving freight efficiency 8 percent. Aerodynamic design In designing the trailer, Oppermann add- ed a boat tail that extends well below the underride guard and acts as an extension of the skirts at the rear of the truck. A full-width reinforced carbon-fiber bogie treatment acts like a boat's hull under the trailer, separating the airflow coming into the trailer axles. CatalIST's segmented Wabash trailer skirts flare inward as they reach the end of the trailer. e reduced aerodynamic benefit resulting from the slotted skirt, Oppermann says, is offset by the skirts being lighter and having other advan- tages, such as having segments that can be replaced individually when damaged. At full height, the skirts ride well above curb level, so they're not easily deformed. e trailer's aerodynamic improvements reduced drag by more than 30 percent. CatalIST completely shed its mirrors, which slashed aerodynamic drag and wind noise and improved side visibili- ty. Mirrors were replaced with exterior cameras and interior pillar-mounted monitors. Oppermann says most drivers who've tested the truck say it takes them about 20 miles to fully adapt to using the monitors. I got the hang of it in less than that. e wraparound windshield design provides excellent visibility of traffic. e polycarbonate windshield also allowed designers to keep airflow attached to the truck longer as it comes over the A-pillar. During my drive around Chicagoland, when rain droplets hit the windshield, they barely moved. e ones that did were forced le or right by air crossing the windshield rather than straight up, as expected. A side effect of keeping the air close to the truck around the A-pillar is addi- tional noise reduction. With the truck at freeway speed, there was no noticeable change in tone when I rolled down the window. I didn't even have to raise my voice to account for wind noise, because there was none. Another distinct feature: An air-over- leaf suspension drops the front of the truck and rear of the trailer for an airfoil shape – picture the cross-section of an airplane wing – across the top of the combination when it hits 50 mph. "On the expressway, you're not expect- ing to see curbs or bumps, so having it as low as possible is a good thing," Op- permann says, "On the expressway, when it's most important, you have basically a leaf-spring feel – a little bit firmer – that our customers like." When the truck drops to 35 mph, the The performance of International's CatalIST more than doubled the goal of boosting freight efficiency by 50 percent.