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For
the real tests check out what out customers are saying click
here..
To read the results
of the BTAC / IRTE TECHNICAL TRIALS at MIRA click here
Some
of the variables that affect fuel economy when you do testing:
Speed
The speed that is used will affect the fuel economy. Constant speed,
controlled electronically will ensure that any changes in truck configuration
will be notable. Thats why we did some tests on a special test
track, and some on a straight highway, but all with trucks that were
limited to a maximum speed.
Since Airtabs reduce drag, one of the possible benefits is that for
the same amount of horsepower, the truck can go faster. The problem
is that if you go faster, you wont see any improvement in fuel
economy, just an improvement in time. Unless your trucks are governed
to run at a constant speed, look carefully at the tachometer logs to
make sure the speeds are the same!
Wind
At 60 mph (100 km per hour), wind resistance is about half the total
drag on the truck. At 70 mph, its two thirds of the total drag.
The rolling resistance doesn't change much with road speed, but the
wind resistance changes dramatically.
So if youre doing 60 mph road speed into a 20 knot headwind, then
you've got 80 mph of wind resistance. Turn around and make the wind
a tailwind, and you are driving into a 40 mph of wind resistance.
Rain
or water on the road
Water standing on the road affects fuel economy. If you think of the
effort necessary to pump that water out from under your trucks
wheels, that energy has to come from somewhere- and that somewhere is
your engine. A truck rolling down the highway can pump as much as a
ton of water per hour, and that can affect fuel economy by up to 6%.(thats
why we did the tests on a dry test track, and for the over the road
tests, compared long-term results for several months)
Load
Different loads take different amounts of power to move. Heavier loads
will mean more rolling resistance, and poorer fuel economy. (Thats
why the same loads were used on the trucks on the test track, and for
the over the road tests, we knew the trailers were carrying the same
loads on all the runs.)
Tire
Pressure
The wrong tire pressure will affect the fuel consumption. (For the test
track, the tire pressures werent changed between runs, and for
the over-the-road tests, the results were averaged over several weeks)
Drivers
Perhaps the largest difference that can be found in fuel economy tests
is the driver. Late braking, or heavy acceleration will waste fuel.
(For the test track, the drivers were kept the same, their runs were
monitored to be the same to the nearest second, and for the over-the-road
tests, the same drivers were driving the same trucks before and after
Airtabs were fitted)
Traffic
Stop and go traffic or lots of speed changes will affect fuel economy.
Obviously, there should be no other traffic on the test track!,
Drafting
Running close behind another truck can improve the fuel economy of the
rear truck, and make the fuel economy of the lead truck worse. On the
test track, the trucks stayed at least 500 yards apart, and for the
over the road tests, the drivers did not draft at any time.
What
We Did
The first place the Airtabs were tested was in long distance runs
with a fleet in the USA. For this test, the tractors only were fitted
with Airtabs . This 3 month trial was long enough to remove any
minor variations, and showed a consistent 3% fuel savings.
The next test was done in England at a test track, where two heavily
loaded trucks were fitted with a partial set of Airtabs (less
than half the normal kit) only on the tractor. The tests were extremely
accurate - to give you some idea of how accurate, the fuel temperature
was measured as well as the volume and weight. The average speed for
these tests was only 47 mph, but even with a partial fit and this slow
speed, an average of 2% fuel was saved when Airtabs were fitted.
A full set of Airtabs only on the tractor at 60 mph average speed
would save at least 3%.
The most recent set of tests were done on a company running consistent
loads between two points that are some 250 miles apart. Airtabs
were fitted to the tractor and the back of the trailer. The same drivers
are used all the time, and the company has been keeping very accurate
records for many years.
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