An aerodynamic “Starship” tractor-trailer rig crushed industry averages when it hauled 39,900 pounds of cargo across the lower U.S. last month.
Using largely off-the shelf components, the giant truck achieved nearly 2.5 times the average for freight hauling efficiency.
That was even after organizers of the Starship project acknowledged this week that several key components either weren’t working or hadn’t been installed in time for the 2,300-mile, 6-day trip from San Diego, Calif., to Jacksonville, Fla.
The trip, which avoided most of the nation’s mountainous terrain, was run without the electrically assisted drive axle that had been planned, and with a key air-flow diverter disabled.
The Class 8 rig nevertheless achieved an average fuel economy of 8.94 mpg and a freight-ton efficiency level of 178.4 tons per gallon of fuel. The industry averages for Class 8 long-haul trucks is 6.4 mpg and 72 tons per gallon.
There have been many aerodynamic truck projects – mostly one-off demonstrations – and aero kits for trailers have been in the market for years.
The Starship Initiative, a project of Shell Oil’s lubricants division and independent trucker and truck aero specialist Bob Sliwa’s AirFlow Truck Co., was designed to put existing technologies together and subject them to real world conditions, Dan Arcy, Shell’s global technology manager, told Trucks.com.
“Not everything went as planned, but by showing what can be done now, we open the conversation about what can happen in the future,” Arcy said.
An independent third party, the North American Council for Freight Efficiency, verified the trip results, at an event Tuesday in Jacksonville.
The results “are very impressive and will be good for spreading awareness of what aerodynamic improvements can do without using a lot of expensive stuff,” said Antti Lindstrom, a trucking industry analyst with IHS Markit.
Truckers – independents and fleet operators – can adopt for their own trucks most of what was done to create the Starship truck, Sliwa said during an interview in Jacksonville at the end of the cross-country run.
“The beauty is they don’t have to have the money to do it all at once,” Lindstrom said. “This truck uses components that can be added one at a time, as finances permit.”
“You start with wide wheels and tires, for instance, and with [fuel] savings from that you add trailer skirts next month, and cab fairings after that, until you’re achieving the efficiency you need,” he said.
Neither Sliwa nor Shell executives would discuss component costs, but the most expensive piece likely was the custom cab, hand-built by Sliwa in his shop in Connecticut.
The bullet-nosed design uses foam-backed carbon fiber and the entire one-piece body and sleeper unit weighs a mere 300 pounds, he said. A steel roll cage, added for safety, weighs 366 pounds. A standard sleeper body can easily weigh a ton or more.
Despite the truck’s lighter weight and the nearly 13.5-foot height of the flat-sided trailer with its ground-hugging skirts, the Starship wasn’t bothered by wind or buffeting from passing trucks, Sliwa said.
But Sliwa said he sketched the Starship years before either of those companies unveiled their trucks. It flowed from a bullet-shaped truck Sliwa built and tested in 2012, he said.
That shape “is probably the best for a Class 8 truck,” Lindstrom said, adding that a top Daimler Truck executive told him several years ago that shapes taken from bullet trains likely were best for trucks but that Daimler would take it slow in adopting non-traditional designs because of truck buyers’ resistance to change.
Resistance appears to be weakening, though.
When Sliwa made his first fuel economy run in a streamlined truck in 1983, “95 percent of the drivers who talked to me at stops were against it,” he said.
During his 2012 “bullet truck” run, negative reaction to the truck’s swept-back design was about 50 percent.
For the Starship trip, which was planned with publicized stops in New Mexico, Texas and Mississippi, “it turned around and about 95 percent of the comments were positive,” Sliwa said.
“A lot of drivers wanted to know if the truck was autonomous, or electric, and were happy” when told it was a standard diesel, he said.
A 6-cylinder, 400-horsepower Cummins X15 diesel engine mated to an Eaton 18-speed transmission powers the custom-bodied International ProStar chassis. The system provides 1,850 pound-feet of torque.
The boat-tail trailer with ground-hugging side skirts is topped by a 5,000-watt solar power array that provides electricity for the 48-volt climate system and the 12-volt accessories.
Sliwa said he spent about 8,000 hours over three years designing and building the custom carbon-fiber cab and other aerodynamic fittings for the tractor and trailer. That includes the massive curved glass windshield that had to be installed in two pieces. He worked with Shell and several parts and component suppliers including Bridgestone Tire, automotive plastics specialist Röchling Automotive and startup hybrid axle developer Hyliion.
Bridgestone and its Bandag retread brand supplied the tires. They are new Bridgestones on the front “steered” wheels and Bandags on the driven and trailer wheels. That’s “because retreads provide some of the lowest rolling resistance on the road,” said Erica Walsh, commercial tire sales director for Bridgestone America.
Röchling designed the truck’s active grille shutter system, which closes the grille opening to provide improved aerodynamics when under-hood airflow isn’t needed.
Hyliion’s electric axle, initially intended for the trailer to help provide uphill push, never made it onto the truck but is slated to be used in the updated version, said Thomas Healy, Hyliion’s chief executive.
When Shell contacted Hyliion about participating, the company had just switched its focus from electric powered trailer axles to developing electric axles for the tractor, Healy told Trucks.com. Although development of an axle for the Starship was launched, the component couldn’t be readied in time, he said.
Although Shell executives wouldn’t acknowledge plans to conduct a second Starship run, they talked freely during Tuesday’s event about making improvements that were identified during the initial drive, including installing the Hyliion axle and repairing the cab-to-trailer air gap deflectors that failed to operate.
An updated truck also likely would get a more aerodynamic grille with a smaller opening, modifications to the aerodynamic skirts for the tractor and trailer – they leave only about 6 inches of ground clearance and were damaged by road debris and a trailer tire blowout – and possibly even a full belly pan for the trailer to further reduce drag, Arcy said.
Beyond promoting its products by helping the truck roll, with lubricants and diesel fuel, Shell’s role in the Starship Initiative is rooted in the company’s belief that the time has come to “elevate the conversation” about bringing advanced and alternative technologies into trucking, said Megan Pino, global manager for the Shell Rotella heavy duty lubricants brand.
“We are an energy company, and energy’s role in global CO2 emissions is a big issue,” she said.
Shell has to figure out its role during a time when people are trying to reduce use of fossil fuels.