A system for reducing slipstream drag for high-performance motor cars

Abstract: A system for reducing slipstream drag for high performance motor cars comprising lateral apertures (2) provided near the rear end (4) of the car body (1) and means (6) for generating air flow through the apertures. The means may comprise front air intakes (6) for cooling the motor-car engine and the air flow through the side apertures (2) may be directed tangentially of the motor car body.

Description: The subject of the present invention is a system for reducing drag for high-performance motor vehicles, particularly racing cars. In particular, the invention relates to a system for reducing slipstreams drag by actively controlling the boundary layer flow in the regions of the motor vehicle body near its rail, in order to assure improved performance as well as greater freedom in the styling of the rear part of the car body. The system according to the invention comprises at least a lateral aperture provided near the rear end of the car body and means for generating an air flow through said aperture. US-A-2 037 942 discloses a motor vehicle of the type indicated above, comprising a substantially annular aperture near the rear end of the body, whereby it allows to discharge a uniform air flow from the aperture in order to reduce the resistance of the body. The present invention is characterised by the features set forth in the characterising portion of the annexed claim. This enables effective active control of the boundary layer flow to be achieved and also keeps the flow lines close to the sides of the car near its tail at high speeds, preventing the separation of the flow from the car body and thus reducing the slipstream drag with the result that the drag coefficient is decreased. The invention will now be described in detail with reference to the appended drawings, provided purely by way of non-limiting example, in which: Figure 1 is a partially-sectioned, schematic plan view of a racing car with a system for reducing slipstream drag according to the invention, and Figure 2 shows the detail indicated by the arrow II of Figure 1, on an enlarged scale. With reference to Figures 1 and 2, the body of a high-performance motor car, in particular a racing car is indicated 1 and is provided, in accordance with the invention, with lateral apertures 2 in the sides 3 of the body 1 near its rear end or tail 4. The two apertures 2 communicate through respective ducts 5 with two front air intakes 6 for admitting air for cooling the car's engine. The cooling air flow which enters the intakes 6 when the car is moving, emerges from the apertures 2 in the rear regions of the sides 3. As shown in greater detail in Figure 2, the arrangement of the apertures 2 is such that the emerging air flows pass tangentially over these regions of the sides 3 so as actively to control of the boundary layer flow, re-establishing a condition of substantially laminar flow against the surface of the body 1 and preventing the flow from separating from the surface of the body 1. This limits the width of the turbulent slipstream in the tail region 4 with the end result that the slipstream drag is reduced. In the embodiment described above, use is made of the dynamic pressure produced by means of the cooling air intakes 6 to blow the air through the lateral apertures 2. The system according to the invention enables the drag coefficient to be reduced by virtue of the reduced slipstream drag while at the same time providing ample freedom for the styling of the rear part of the car body 1.

Claims: A system for reducing slipstream drag for high-performance motor cars, comprising at least a lateral aperture (2) provided near the rear end (4) of the car body (1) and means (6,) for generating an air flow through said aperture (2), characterised in that the means (6) for generating the air flow comprise a pair of symmetrical convergent elongated ducts (5), each of said ducts (5) extending substantially longitudinally inside the body (1) along a respective side (3) of the body (1), between a respective front air intake (6) fed with air only by means of the ram effect, for admitting air for cooling the car engine, and an aperture (2) arranged to direct the air flow only tangentially of the respective side (3) of the car body (1).

Inventors: CORNACCHIA FELICE, DI GIUSTO NEVIO, CORNACCHIA, FELICE, DI GIUSTO, NEVIO
Applicants: FIAT AUTO SPA, FIAT AUTO S.P.A.
Application year: 1990
Main classification: B62D35
IPC codes: B62D35