How flow can you go?

By Paul Abelson, senior technical editor

In 1985, two trucking visionaries met for the first time. One was OOIDA’s executive vice president, Todd Spencer, who among other tasks wrote for this magazine. He saw a very unusual truck at a trade show and decided to do a cover story for a 1985 issue of Land Line.

The truck was modified from a 1980 Ford CL9000. The owner, modifier and visionary was Robert “Bob” Sliwa of Newington, CT. He was just old enough to have a chauffeur’s license, the forerunner to today’s CDL, when he bought the truck and became an owner-operator. Even though he drove for maximum fuel economy, the best he could average was 4.4 mpg.

Relying on his tinkering and a successful drag racing background, he started improving the truck.

From racing and his research, he knew that aerodynamics, driving technique and parasitic loads affect fuel economy. Truck aerodynamics were still in their infancy in 1983, when Bob built what must be the first-ever working aerodynamic truck. The Kenworth T600 was still several years away. Roof fairings had just come on the market, and trailer fairings were almost a quarter-century in the future, but Bob built tractor and trailer fairings onto his rig. The result was a cabover combination that eventually got to 10 mpg.

Bob soon left driving for other pursuits, but he never stopped dreaming about his aerodynamic truck, even when his work involved computer analytics and later operations management for a major logistics company. He even tried to get the CEO to adopt his ideas, but with no luck. Still, Bob kept his dream alive.

In 2008, while watching an episode of “American Chopper,” Bob realized he wasn’t getting any satisfaction working with software. It was time to return to his dream. With funding from the remainder of his 401K, he bought a 2003 Kenworth T2000 and started the modification process.

The original 1985 Land Line article helped the OOIDA member attract sponsorship. Some contributed parts and equipment, some funding. Jeremy Singley of East Middlebury VT, a noted industrial designer, helped design and fabricate the aerodynamic front of the AirFlow Truck.

“You can’t control something if you don’t measure it. I learned that from my time as an operations manager,” Bob said. “So I designed my own monitors for the Cummins engine using my background in computers.” His high-definition display not only reads engine and trip data, but also shows percent of available power being used.

The ISX produces 450 hp with Smart Torque generating 1650/1850 lb-ft of torque at only 1,100 rpm. Bob keeps the rpm low, usually between 1100 and 1250. The truck is geared to do 55 mph at 1,250. The Eaton-Fuller 13-speed overdrive transmission pulls through 3.55 to 1 drive axles. Bob uses 455/50 R 22.5 Michelin X-One Tires.

The truck’s aerodynamics play a major part in the outstanding fuel economy Bob achieves in real world service. Granted, he searches out lighter, high-cube loads that still yield good revenue. Hauling freight during the 876 mile trip from Newington, CT, to Louisville for MATS, he used fewer than 70 gallons, averaging better than 12.5 mpg. He cruises at the lowest rpm practical for conditions. Bob is off the throttle on as little as a 1 percent downgrade and lets gravity take him to as much as 70 mph.

Sliwa and Singley worked with FreightWing to develop a skirt that goes over drive and trailer wheels for maximum aerodynamic advantage. Even the tractor has steps removed and tanks fully enclosed. To make that work, they developed steps that extend when the tractor doors open and that retract when they close. An unintended benefit is added security in less-than-desirable neighborhoods. Criminals cannot jump up to access the truck.

In addition to the full skirting and sealing the tractor-trailer gap, Sliwa and Singley developed a 4-foot trailer extension like a “boat tail.” Net drag went from just under the 600 pounds typical with a conventional truck to only 330 pounds on the current AirFlow Truck. And with less drag on the vehicle, the 450-hp engine performs more like a 550-hp engine at cruising speed.

Besides aerodynamics, Bob concentrated on reducing all parasitic loads. Low amperage Truck-Lite LED headlights, developed for our military, are used to lessen the load on the alternator. A Dynasys APU was installed to eliminate idling. A Horton WindMaster Revolution high-efficiency fan is driven through a computer-controlled viscous coupling to reduce drag and eliminate shock loads.

The daytime air conditioner is electrically driven to eliminate drive belt drag. Even waterless coolant cuts demand on the cooling fan. The Meritor Tire Inflation System by PSI reduces rolling resistance. Citgo 5W-40 Syndurance oil reduces internal engine drag, and K&N intake air filters lessen air restriction.

While the results from the current truck are impressive, Bob’s next truck promises to be even better. It will be designed as a total vehicle, not as a modification to an existing truck. Computer simulations indicate that drag will be reduced a further 33 percent to only 220 pounds. That alone should yield another 10 to 15 percent improvement in fuel economy, bringing Bob close to his goal of a 15 mpg truck. The prototype of the next AirFlow Bullet Super Truck is due to be on the road in 2015. LL