A conscious and ongoing effort to reduce drag in vehicular structures is seen in the prior art and the reduction of drag or resistance in vehicles is of increasing importance where fuel economy is an increasingly large consideration in automotive and vehicular design. Current application of aerodynamic concepts shows that many prior approaches to streamlining were of more optical and retinal satisfaction than the achievement of minimal drag. While this is true in automobiles, it is particularly true where trucks and trailers are considered because of the substantial surfaces involved and the enormous increase in reliance upon trucks and trailers for haulage and heavy transport. This is accentuated by the need for maximum cargo space and the use of relatively sharp corners and boxy appearance at the front of trucks and trailers.
Early efforts at minimization of drag were found in changing body styles; in bridging between tractor and trailer as in U.S. Pat. No. 3,945,677 to Ronald A. Servais, et al; in the modification of the front wall of trailers as in U.S. Pat. No. 3,415,566 to W. H. Kerrigan; and in the spaced foils or shields as seen in U.S. Pat. No. 2,964,352 of J. Werner. More lately, the direction taken by persons seeking to minimize drag in such vehicles is exemplified by the use of corner plates having gradual and concave arcuate rise from a plane transverse to the principal direction of vehicle travel and then reversing in an arc closing on the corner and in parallel side contact with the vehicle body. This work is seen in the recent U.S. Pat. Nos. 3,934,922 and 4,057,280 to Paul B. MacCready, Jr. and Peter B. S. Lissaman.
By contrast, the present invention provides a distinctly different approach to reduction of drag by the utilization of a drag attenuating corner cover similar to a subsonic airfoil comprising an elongate strip having a surface which abruptly arises from a transverse front surface or plane; the strip then wraps around the corner in a convex or bulbous arch and returns or reverses direction outboard of the flank plane of the vehicle body and tapers generally back toward the flank plane of the vehicle body in one or more undulations or ripples formed by alternate concavities and convexities until the surface fairs into contact against the flank plane of the body well rearward of the projected intersection of the front and flank planes. "Front" as used here has reference to the surface first engaging air or wind flow and which surface is generally perpendicular to the airflow. "Flank" as used here means the surface plane as, for example, side and top of a vehicle which is generally parallel to the airflow in moving vehicles. The undulating or ripple surface commencing with a discontinuity outboard of the flank plane and diminishing rearwardly to closure against the flank plane discourages and delays boundary layer separation as the air flows across the flank plane thereby reducing aerodynamic drag.
Alternatively the elongate stip may wrap the corner in a convex or bulbous arch lying below the flank plane of the vehicle body and extending rearward asymptoticly joining the flank plane at its leading edge.
Accordingly, the principal object is to provide a wholly new edge surface useful in reducing drag in vehicles.
Another object is to provide an edge surface which may be added onto or which may cover existing corner or edge contours and which is economical to form and install as either an original or an "after market" add-on construction.
Another object is to apply aerodynamic boundary layer concepts for attached flow in solving the problems of resistance or drag in vehicles at the corners thereof in a manner compatible with present day vehicle construction.
Another object is to provide a device for enshrouding any forward facing corner that is itself too sharp to maintain attached flow and may be applied to any corner which faces into the oncoming airstream.
Another object is to provide an "add-on" device which exhibits attached flow around a previously separated flow corner.
Still other objects, including applicability to various flow facing surfaces and corners, will be better appreciated as the description proceeds.