# US 8,770,650 B1 · Variable geometry aerodynamic fairing for reducing base drag of tractor trailers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,650 B1 - Document ID: US8770650B1 - Status: Granted - Kind: B1 - Application number: 12/661,076 - Filed: 2010-03-10 - Granted: 2014-07-08 - Earliest claimed: 2010-03-10 - Applicants: Jon Andrew Brosseau - Inventors: Jon Andrew Brosseau - Web page: https://patentgrep.com/patent/US8770650B1 ## CPC - B62D 35/001: {For commercial vehicles or tractor-trailer combinations, e.g. caravans} - B62D 37/02: by aerodynamic means - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) ## Abstract A variable geometry aerodynamic fairing is described for reduction of the base drag of a tractor trailer traveling at highway speed. The base drag reduction is provided by a set of two adjustable rectangular fairings which can be opened from a flat configuration when folded one against each side door, into a set of curved airfoil shaped fairings extending into the boundary layer adjacent to the trailer sides and cambered such as to turn a portion of the mainstream side air flow into the base wake region of the trailer. The cambered fairings thus reduce the strength of the standing base wake vortices and hence, the resultant negative base pressures (drag) formed in the trailer wake region. A direct application of this device would be to improve the fuel economy of a large portion of the U.S. trucking fleet during highway transit, while still providing rapid fairing retraction into a thin, flat stowed position against the trailer doors for unloading at destination. ## Claims ### Claim 1 A system, comprising: a variable geometry aerodynamic shaped thin rectangular fairing, wherein the fairing is attached vertically to each side of rear doors of a last of at least one tractor pulled trailer, wherein when the fairing is extended from a stowed position, the fairing intercepts a portion of a boundary layer flow adjacent to each side of the trailer in a manner in which a controlled portion of the boundary layer flow as well as a portion of a the mainstream side air flow is directly turned and injected into a rearward turbulent base flow region of the trailer. ### Claim 2 (depends on 1) The system as recited in claim 1, wherein the fairing is adapted for extending from a stowed position to form a cambered airfoil at a fixed angle of attack to a trailer side flow field in such a manner as to efficiently turn a portion of a main side flow field around a top surface of the airfoil without inducing flow separation, back into a rearward turbulent base region of asymmetric vortices, to reduce a base region vortices' strength and trailer base drag. ### Claim 3 (depends on 1) The system as recited in claim 1, further comprising mechanical linkages and pinned restraints attached to an inside of the fairing which are adapted for inducing into the fairing, when the linkages are deployed, variable camber shapes which are configurable for the trailer travelling at different highway speeds. ### Claim 4 (depends on 1) The system as recited in claim 1, wherein a mechanically hinged mounting between a leading edge of the fairing and two or more rear door hinge pins provides a rotating taming motion to the fairing allowing for a shape of the fairing to be adjusted using a camber, an adjustable overhang of the fairing leading edge into a trailer side wall boundary layer, and rapid retraction of the fairing into a flat folded position. ### Claim 5 (depends on 1) The fairing as recited in claim 1, wherein the fairing is structurally characterized in that a shaped curvature of the fairing is designed to turn air flows in a manner to induce a pressure rise within a base low pressure region, wherein the base low pressure region is located in a wake region of the trailer. ### Claim 6 (depends on 1) The system as recited In claim 1, where the fairing is attached to the rear door with by means of door hinge pins that support the rear, door and the system further comprising, for each rear door: two or more gas springs with expanding ends, which are attached near the middle of the fairing with rod pin pivots and by a pivoting mounting end attached to a connecting frame, camber arms which are connected to an internal shaft mounted through the connected frame, such that when rotated in an arc various degrees of camber can be produced, a cable reel which is attached to the connecting frame which reels two or more wires which are attached to the mount end of the gas springs, where the system is designed to allow the gas springs to extend the fairing outward into the airflow during travel and the cable reel to compress the gas springs for a flat fairing stowage. ### Claim 7 A method for reducing base drag in a tractor trailer, the method comprising: intercepting a portion of a boundary layer flow adjacent to each side of the trailer in a manner in which a controlled portion of the boundary layer flow as well as a portion of a mainstream side air flow is directly turned and injected into a rearward turbulent base flow region of the trailer.