Aerodynamic trailer apparatus with optimized small skirt

An apparatus for a trailer that has a longitudinal direction, a lateral direction, and a height direction, comprising:

• a trailer skirt configured for attachment to the trailer, wherein the trailer skirt has an outer surface that has an outer surface length, wherein a majority of the outer surface length is oriented at an angle from 3 degrees to 7 degrees to the longitudinal direction such that the majority of the outer surface length extends inboard in the lateral direction upon extension forward in the longitudinal direction;
• wherein the trailer skirt has an overall length in the longitudinal direction and an overall height in the height direction that has an overall length/overall height ratio that is 6 or less;
• wherein the trailer has a trailer length in the longitudinal direction that is at least 35 feet, wherein the trailer has a longitudinal midpoint that is located in the longitudinal direction, and wherein a majority of the outer surface length is located rearward of the longitudinal midpoint in the longitudinal direction;
• a rib cover that is carried by the trailer, wherein the rib cover is located higher than a bottom edge of the trailer skirt in the height direction, wherein the rib cover is wedge shaped and located outboard from the trailer skirt in the lateral direction;
• wherein the trailer has a plurality of cross-members that extend in the lateral direction and are spaced from one another in the longitudinal direction, wherein the rib cover covers increasingly larger portions of successive cross-members upon extension of the rib cover forward in the longitudinal direction.