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Operators put Airtabs to the test
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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 AirtabsTM 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” counterrotating vortexes that trail several feet behind the vehicle. AirtabsTM 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. 12
BUSRIDE | DECEMBER . 2013
BEFORE AIRTABSTM fuel mileage: Coach 478: 6.30 miles per gallon Coach 454: 6.35 miles per gallon Coach 474: 7.11 miles per gallon WITH AIRTABSTM 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 AirtabsTM. For the most controlled conditions, Cyr installed AirtabsTM 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 AIRTABSTM: 6.9 mpg WITH AIRTABSTM: 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 AirtabsTM. Pacific Coachways Charter Services, Inc. Garden Grove, CA With AirtabsTM 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 AirtabsTM, the company reported the same fuel consumption for both before and after installing the product. busride.com