Method One

method1 By using 6 inch tufts of yarn taped to the hood. Tape the strings 8 inches apart across the hood and in rows 8 inches apart. Stagger the rows so that the tufts do not interfere with each other. If a row of tufts is laying flat and moving "with the wind", there is flow and the Airtabs will work, If the tuft is "lifeless" or even pointing forward, there is flow separation at that point and the Airtabs will not perform in that position. Experiment moving the rows until you have narrowed down the row with the most vigorous airflow before separation. Airtabs will work at this spot. Do not place tufts in front of any air intake.

 

 

Method Two

method2 By using dust or oat husks sprinkled on the hood, you can see where the dust/husks remain while driving at speed. This would indicate where flow separation occurs and you would want to place the airtabs just forward of this point (in relatively undisturbed airflow) for maximum effect.

 By using dust or oat husks sprinkled on the hood, you can see where the dust/husks remain while driving at speed. This would indicate where flow separation occurs and you would want to place the airtabs just forward of this point (in relatively undisturbed airflow) for maximum effect.

 Exactly what benefit will present itself to the many different vehicle geometries are left to your experimentation. The fact that the airflow can be altered around your vehicle should be used for your benefit.

 

Aerodynamics of Bug Defectors

bug-deflector "Even bug deflectors or shields have an aerodynamic penalty of up to 5 percent," says International's Weber. That translates to a 2 percent to 3 percent drop in fuel efficiency. "It's on the leading edge of the hood. All the airflow is trying to get around the hood, and by adding a bug shield, you've increased the area." Rising fuel costs are causing truckers like Rips to consider more aerodynamic models, some truck makers say. "It's really changing the way owner-operators approach buying a truck," says Bob Weber, an engineer with International Truck and Engine Corp. "The thing at the top of their minds is fuel price."

Entire article located here...

Example of Airtab® placement on hood of vehicle.

August, 2006 Mr. Paul Ste.Marie from Calgary, Alberta Canada writes the following.

Animal Transport

Livestock trailers

Enclosed is my info on the results of the positioning of Airtabs™ on this truck and trailer. Please double click on each box in the table below to see the pictures. I am supplying this info on over two years of positioning the Airtabs firstly on the trailer and gradually to the truck. The final info is based on 16,000 miles of pulling in all kinds of weather and with the Airtabs positioned as they are shown.

Subject:

Vehicle

  •  2003 Dodge 3500 Dually
  • 6 speed Standard Cummins Diesel
  • 35 HP Predator Chip
  • Stage II Air intake
  • Cleaned up exhaust
  • Aux larger Fuel pump
  • 3.73 rear axle

Trailer :

  • Wilson 30 ft triple axle, 8.5 ft wide
  • Stock trailer, built to order with options using heavy aluminum.

We've increased our fuel mileage by about 9mpg on a full load, from 11-12 MPG to 20-21 mpg. We pull fast, heavy and long most of the time. With the Airtabs as installed, wind noise is reduced and the trailer stability is phenomenal. Evidence the Airtabs are working is most noted in rainy weather, in cross winds and meeting larger semi-trailers on two lane highways. The unloaded truck will get 25 mpg but with Airtabs fitted as per our pictures, we are getting 32-34 mpg. The Airtabs on the top rear of the cab eliminate 80% of the bugs on the front of the trailer. If you watch the bugs, they tell you where the air is going. The Airtabs on the hood of the truck keeps the windshield cleaner and reduces wind noise with the windows open.

There are 67 Airtabs on the truck and 95 on the trailer; A small investment for this kind of fuel economy and stability, not to mention the extra horsepower. It seems with Airtabs we aren't bucking wind, but directing it. This outfit gets a lot of curious looks but these results prove the Airtabs usefulness.

(Airtab would point out. The savings on a 1,000-mile trip fully loaded would be approximately 35 gallons of fuel. At $3.00 per gallon, that's $105 per 1,000 miles.)