Alistair Duff, for technical assistance Mr. Andrew Crockett, for strain gauge assistance
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- 2.2 DESIGN IMPROVEMENT
2. THE WING MIRROR2.1 HISTORYThe shape and aesthetics of wing mirrors has evolved throughout the years of automotive design. In the early periods of automotive development the wing mirror was typically a flat, bluff body shape and was one of many components on a vehicle to be exposed to the free stream along with others such as headlights and wheel fairings. As the aerodynamics of motor vehicles became better understood the shape of most wing mirrors were adapted to be more streamlined. However, the majority of car designs still feature the wing mirror exposed to the free stream whilst other components such as the headlights and wheel fairings have been sunk into the body work to reduce drag. 2.2 DESIGN IMPROVEMENTA select number of car manufacturers are addressing the issue of wing mirror drag by replacing them with small mounted cameras. Images taken by these cameras are then relayed on small screens on the inside of the car door. This setup may improve the vehicle’s performance with regards to acceleration and top speed. However, the beneficial effects on fuel economy may be questionable due to the extra fuel consumption required for the operation of both the camera and screen. This setup may be more effective when applied to hybrid cars such as the Toyota 1/X concept car which omits wing mirrors from its design; as seen in Figure 2. 
Figure 2 - Toyota 1/X (omitted wing mirrors) It may also prove effective in future applications if the use of hydrogen fuel cell power plants are utilised in the automotive industry. At present, the best practise for automotive design remains to be the improvement and optimization of the wing mirror design. Some methods exercised in automotive design with the aim of improving wing mirror performance are: Streamlining the mirror shape, resulting in lowered pressure drag by minimizing flow stagnation on the leading faces and lowering the amount of recirculation downstream of the mirror. Some designs tend to resemble a cross section similar to a typical aerofoil, however, care must be taken to limit the lift force created as this can create vortex shedding downstream of the mirror and thus increase drag, when considering:  …E1
Reducing the wing mirror frontal area, which should reduce the drag , given that:  … E2
This should work in efforts to reduce the pressure drag. However, using a small mirror can have a negative effect on the cars performance with regards to safety due to reduced visibility for the driver. Smoothing the surfaces of the mirror housing to minimise any possible skin friction drag created, although the contribution of skin friction drag towards the total overall drag is a great deal smaller than that of pressure drag. To smooth out any small gaps or exposed features that may encourage localised stagnation and increase pressure drag: such as joints in the housing and areas around the hinges between the mirror housing and the mounting Download 3.93 Mb. Share with your friends:
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