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The Shell Starship's customized carbon-fiber cab and full side skirts along the length of the trailer, Cummins X-15 Efficiency engine, Bridgestone’s low rolling resistance tires, and smart driving strategy all contribute to the result of 178.4 ton-mpg for freight ton efficiency (FTE)—a nearly 248% improvement over the North America average. (image: Jennifer Shuttleworth)

Starship road trip

Dubbed the Starship Initiative, the collaboration between Shell and AirFlow Truck Co. on the Starship Class 8 concept truck achieved 178.4 ton-mpg for freight ton efficiency (FTE) in a recent cross-country drive, a nearly 248% improvement over the North America average FTE of 72 ton-mpg for trucks.

The project culminated with the truck’s six-day 2300-mi (3700-km) coast-to-coast test drive that ended at its destination of Jacksonville, Fla., in late May 2018.

The Shell Starship project began about four years ago when several Shell employees had an idea for a hyper-aerodynamic fuel-efficient Class 8 truck. (See “Shell, AirFlow Truck debut hyper-fuel-efficient Class 8 concept truck” at https://www.sae.org/news/2018/03/shell-airflow-truck-debut-hyper-fuel-efficient-class-8-concept-truck.)

“If we brought many of the existing technologies together, how good could we be?” Bob Mainwaring, Technology & Innovation Manager, Shell Lubricants, said. “We thought that would be a really interesting thought experiment, if not real experiment,” he told Truck & Off-Highway Engineering at the Starship Initiative’s finale event in Jacksonville.

Chris Guerrero, Global Brand Manager, Heavy Duty Lubricants, explained that Shell also considered the concept as an opportunity to get a conversation started across the trucking industry. Was the original thought to produce a truck like this one? “No, I think the idea was more of the art of what is possible,” Guerrero said.

As it turns out, AirFlow owner Bob Sliwa had been thinking the same way.

Test-run results

At the Starship’s finale event, Carlos Maurer, President, Shell Lubricants Americas, told media gathered to hear the results of the test drive, “This is about the iterative process. We’ll continue to learn; we’ll continue to improve.” Maurer explained that he considered the results of the test run as just the baseline. “I think we will get much better as time goes by.”

The North American Council for Freight Efficiency (NACFE) recorded and validated the results of Starship’s run. Starship achieved the 178.4 ton-mpg for FTE, which is a more relevant statistic for judging the energy intensity associated with moving cargo from point A to point B since it combines the weight of cargo being moved with the amount of fuel consumed.

The Starship truck had a total average fuel economy of 8.94 mpg (17.27 km/gal), compared to the average U.S. fuel economy for transport trucks of 6.4 mpg (12.3 km/gal). The best fuel economy attained during the drive was 10.2 mpg (19.7 km/gal).

The final total truck and cargo weight was close to 73,000 lb (33,112 kg)—28% heavier than the average total gross vehicle weight of 57,000 lb (25,855 kg) for a U.S. on-highway Class 8 truck. The 39,900 lb (18,098 kg) payload had 77% more mass than the U.S. average payload of 22,500 lb (10,205 kg) and was comprised of clean reef material destined for a new offshore reef installation in Florida.

And, in terms of calculating estimated CO2, if all trucks in the U.S. (about 2 million) reached the overall fuel economy and FTE performance of Starship, they would emit an estimated 229 million fewer tons of CO2 into the atmosphere per year, according to Shell. A reduction of 229 million tons would correspond to a 60% reduction in CO2 emissions from the U.S. truck fleet. 

How they did it

To achieve these results with the Starship, Shell and AirFlow focused on aerodynamics, rolling resistance, engine efficiency, driveline efficiency and driving style.

The cross-country journey provided Shell with an opportunity to test Shell Rotella T6 Ultra 5W-30 Full Synthetic engine oil in a vehicle prior to its introduction to market. This low-viscosity API FA-4 engine oil is formulated to provide better fuel economy, improved high- and low-temperature performance compared to CJ-4 performance engine oils, and meets the requirements for many low-emissions engines.

Carefully thought-through aerodynamics started with the customized carbon-fiber cab, which Guerrero told TOHE they initially attempted to produce through 3D printing, but ultimately were unable to—the 3D printing technology isn’t there yet for the size needed, he said, another learning experience gained through this initiative. Carbon-fiber side skirts run the length of the trailer situated about 5 in (127 mm) from the ground.

The active grille shutter on the truck, supplied by Röchling Automotive, can help improve the mpg or FTE. “Although the shape itself of Starship was extremely aerodynamic and had a lower coefficient of drag compared to many vehicles on the road today, this was where we saw an opportunity to still improve and worked with Bob [Sliwa] to come up with a solution,” said Ryan Forman, Product Manager, Aerodynamics and Engine Encapsulation Systems.

Purely funded by Röchling, the company developed, tested and did some programming as well as the fitting in the truck, so they could offer AirFlow the best performance benefit. “It made sense to add it if we could actually give him [Sliwa] a tangible benefit versus having a technology that’s just contributing extra weight,” Forman explained.

The shutter system is positioned behind the Starship’s grille. When air is needed to cool the cooling pack, the vane can be opened, but it can be closed when air is not needed to redirect the air around the vehicle. In a cold-temperature climate, the shutters and vanes can be closed to help improve engine warm-up time—for example, incorporating this product on a traditional vehicle with an internal-combustion engine reportedly can help to reduce engine warm-up time by 50%.

Another aerodynamic contribution is the Starship’s boat tail, which helps streamline the truck and reduce drag. Elongated side panels maintain airflow with the long side skirts that reduce rear-end drag.

A late addition to Starship was a recently DOT-approved full-video-only camera monitoring system, adding to the streamlined design by replacing traditional side-view mirrors. The MirrorEye, made by designer and manufacturer Stoneridge, provides a nearly 180-degree view on each side of the truck. Sliwa explained the switch, made just prior to hitting the road, took a couple of days to get acclimated to.

“It’s astronomical the difference of how clear the visual acuity of these monitors and cameras are at nighttime,” he said.

A 400-hp (298-kW) Cummins X-15 Efficiency engine, Bridgestone’s low rolling resistance tires, and a smart driving strategy also contributed to the FTE result.

More to come

The project did not end when the truck arrived in Jacksonville. Both Shell and Sliwa talked about improvements and additional efficiencies that are possible in the next phase of Starship. “I’m excited to tweak it,” Sliwa said, which includes performing more testing. He explained that the truck left his shop in Connecticut in February for various commitments, trade shows and the cross-country test drive, with no formal testing.

“If I was to choose one thing to do now it would be to hone all of that interaction [between technologies] to make that work [optimally],” Shell’s Mainwaring said. “What’s the best strategy to really refine it.”

Hyliion’s founder and CEO Thomas Healy also looks forward to Starship’s next phase of development and incorporating his company’s hybrid-electric technology on the truck. “We have been involved, but at a distance at this point,” Healy told TOHE.

Hyliion plans to get Starship to its new headquarters in Austin, Texas, to install its intelligent electric drive axle technology on the truck, which due to the many trade-show commitments and the cross-country trek wasn’t able to happen as of the finale event. The company’s core competency is on the software side, leveraging partners for technology like the electric motor and batteries, Healy noted.

At Hyliion, engineers will remove the rear axle of the tractor and replace it with the company’s patented fully electric drive axle. “On the right side of the frame rails we mount a battery pack, in the middle of the frame rail there’s a cooling system and then it’s also combined with a control system that actually brings all of the technology together,” Healy explained.

When the vehicle accelerates, or it hits an uphill, the electric axle kicks in and helps drive the vehicle forward, taking some of the load off the diesel engine so it doesn’t have to consume as much fuel. Then, when the truck is slowing down or going downhill, “we kick in the electric motor to capture energy, which slows the vehicle down and it also recharges the batteries back up,” he said.

Using this technology, which also incorporates predictive terrain mapping, Healy said some fleets are able to achieve an up to 25% fuel-economy savings based on the routes they’re driving.

Another possible future enhancement to Starship is a cab-to-trailer active gap sealer, which deploys flaps attached to the back of the cab that touch the trailer. It seals that space between the two for improved aerodynamics. The gap sealer will fold up at speeds under 35 mph (56 km/h). According to a Shell representative, the technology did not work as intended for this first iteration, so was not used on the cross-country test drive.

With future testing and technology implementation on the docket, stay tuned for more from the Starship Initiative.
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