Vortex generators reduce wind resistance and aerodynamic drag to improve fuel economy
By David Hubbard
Specially designed for large heavy-duty commercial vehicles, Airtabs™ are unique vortex generators that control airflow over a moving coach. They reduce wind resistance and aerodynamic drag to improve fuel economy.
The air rushing to fill the vacuum left by a moving vehicle creates drag and turbulence. This causes the engine to burn more fuel to produce the necessary power to overcome the resistance.
Wishbone-shaped Airtabs™ attach easily at the rear of the coach to create two tight vortices. These vortices combine to reduce suction and drag at the rear of vehicles traveling at speeds above 35 mph.
Airtabs™ improve vehicle stability and safety by altering the airflow patterns at the vehicle’s rear. The large random swirls at the rear of the bus are replaced by dozens of small, vigorous, “stream-wise” counter-rotating vortexes that trail several feet behind the vehicle.
Airtabs™ put to the test
Already proven to be effective in the trucking industry, Airtab, LLC, asked BUSRide to test the product on motorcoaches. BUSRide selected five motorcoach companies that represented a variety of climates and geographic conditions. Airtab, LLC, supplied each motorcoach company with Airtab® vortex generators to install, test and evaluate during the summer.
BUSRide asked the participating operators to keep a careful record of mileage and fuel efficiency both before and after the product trial, and to report any noticeable changes or improvements.
The drivers participated in evaluating vehicle stability and handling of the coach in actual service on the open road. Maintenance techs weighed in on the overall cleanliness of the rear of the coach, particularly from splash and spray during trips in adverse weather.
The results are in
All Aboard America!
Mesa, AZ
All Aboard America! installed and tested three coaches with AirtabsTM, for product trials on the same line-haul run from its Midland, TX, location.
The coaches ran from May through June for evaluation prior to installation. Two coaches ran July through August with AirtabsTM, while one continued without the product.
BEFORE Airtabs™ fuel mileage:
Coach 478: 6.30 miles per gallon
Coach 454: 6.35 miles per gallon
Coach 474: 7.11 miles per gallon
WITH Airtabs™ fuel mileage:
Coach 478: 6.54 (a 2.8-percent improvement in fuel mileage.)
Coach 454: 6.53 (a 3.7-percent improvement in fuel mileage.)
Coach 474: 6.87 (Continuing without AirtabsTM, Coach 474 showed a 3.5-percent decrease in fuel mileage over the first period.)
One driver reported noticing improved stability and better handling with the AirtabsTM through gusty West Texas cross winds.
Cyr Northstar Tours Lines
Old Town, ME
Cyr Northwest reported a “neutral experience” after a 10-day before and 10-day after trial period, comparing fuel data with and without the Airtabs™.
For the most controlled conditions, Cyr installed Airtabs™ on one coach that runs the same line-run route daily from Bangor, ME, north to Caribou, ME, with the same three drivers doing the testing at highway speeds.
BEFORE Airtabs™: 6.9 mpg
WITH Airtabs™: 6.5 mpg (a 6.2-percent decrease in
fuel mileage.)
Cyr notes that none of the three drivers reported noticeable change in the handling of the coach, and none was aware of the coach feeling any differently. The wash bay personnel did not notice anything different in the way of a cleaner appearance to the rear of the coach. They did say, however, that the washer brushes did not damage the Airtabs™.
Pacific Coachways Charter Services, Inc.
Garden Grove, CA
With Airtabs™ installed on one MCI J4500 coach, Pacific Coachways sent it out with the same driver on several extended trips as far away as Yellowstone, WY.
Comparing fuel records from previous trips without Airtabs™, the company reported the same fuel consumption for both before and after installing the product.
BEFORE Airtabs™: 5.82 mpg
WITH Airtabs™: 5.82 mpg (0.0-percent gain in fuel mileage.)
Winn Transportation
Richmond, VA
Winn Transportation installed the AirtabsTM on a Prevost H3-45. As Winn does not run regular scheduled service, the company tested its AirtabsTM on coach charters with one senior driver to various destinations.
BEFORE Airtabs™: 4.56 miles per gallon
WITH Airtabs™: 4.86 miles per gallon (a 6.2-percent improvement in fuel mileage.)
Winn notes the short test period, along with conditions like differences in idle time, traffic, accident delays, and speed limits. In his time with the coach, the driver did not notice any difference in handling or less sway in the coach.
The company says it will continue to monitor fuel mileage with the AirtabsTM over a longer period and offer its findings.
Arrow Stage Lines
Omaha, NE
Arrow Stage Lines installed AirtabsTM on four coaches at its Denver, CO, facility. The company provided 6-1/2 months of data before having AirtabsTM along with data from 3-1/2 months of testing.
MILEAGE and FUEL CONSUMPTION RESULTS
BEFORE Airtabs™:
Coach 508: 7.34 miles per gallon
Coach 509: 7.26 miles per gallon
Coach 510: 6.99 miles per gallon
Coach 511: 7.35 mpg
WITH Airtabs™:
Coach 508: 7.46 miles per gallon
(a 1.6-percent improvement in fuel mileage.)
Coach 509: 7.55 miles per gallon
(a 3.8-percent improvement in fuel mileage.)
Coach 510: 7.06 miles per gallon
(a 1.0-percent improvement in fuel mileage.)
Coach 511: 7.85 mpg (a 6.4-percent improvement in fuel mileage.)
Arrow Stage says its driver reported nothing different as to the handling of the coaches.
Tour West America
Phoenix, AZ
Tour West America installed AirtabsTM on a 2013 MCI J4500. Prior to the product trial, the company reported fuel mileage for one-month. The company tested the AirtabsTM on coach for approximately two months.
BEFORE Airtabs™: 5.79 miles per gallon
WITH Airtabs™: 6.13 miles per gallon
(a 5.5 percent improvement in fuel mileage.)
Of the three drivers who drove the bus before and after, one reported the rear of the bus staying cleaner throughout his trips. Another stated that the rear end of the bus felt a little more stabilized.
The company intends to install Airtabs™ on a 2003 Prevost H3-45 and test the product for an extended period.
With the Airtabs™, the seven coaches showing improved fuel economy averaged a 3.51 percent increase in mileage. Based on a $3.85 per gallon diesel fuel price as of November, this represents a savings of 13.5 cents per gallon.
Airtab®, LLC, represents the Airtab® product in Canada and the USA. AirtabsTM are a product of Aeroserve Technologies LTD located in Carp, ON, Canada. Airtab® is a registered trademark of Aeroserve Technologies Ltd. US and Canadian Patents.