Or put in other terms, the drag coefficient on an LCV is only marginally more than half of the sum of the drag on the two vehicles it replaces when wind angles are at zero degrees.
Where applicable, any barriers to entry within the Canadian trucking community were explained to separate those technologies which could likely be used to those that would likely never gain widespread acceptance due to operational barriers For heavy vehicles such as tractor-trailer combinations and buses, pressure drag is the dominant component due to the large surfaces facing the main flow direction and due to the large wake resulting from the bluntness of the back end of such vehicles.
Although friction drag occurs along the external surfaces of heavy vehicles, particularly along the sides and top of buses and trailers, its contribution to overall drag is small (10% or less) and is not a strong candidate for drag-reduction technologies.
Ideally, a study could be conducted whereby a variety of gap fillers, side skirts and boat tails are sequentially added to the LCV in order to determine if the effects of these devices on LCVs is similar to their effect on conventional vehicles.
Canadian Motor Vehicule Safety Standards (CMVSS) compliant mirrors are responsible for approximately 2% of the overall drag on a conventional tractor and trailer.
And if so, what configuration would be best suited to optimize drag reduction between the two trailers of an LCV.
This study could be performed at both gaps to quantify the incremental effect of add on devices, compared to the large reductions that are achieved via the removal of one of the tractors.
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There are still opportunities for incremental decreases on LCV drag.