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• Camber: A measure of the curvature of the airfoil 

  • The camber of the upper surface is more pronounced than the camber of the lower surface (usually somewhat flat).

• Leading Edge: Forward-facing end that is rounded

  Trailing-Edge: Rear-facing end that is narrow and tapered towards the rear

• Chord Line: Reference line drawn from the centre of the leading edge straight through the wing till the trailing edge.

  • This reference line is used to find the magnitude of the upper or lower camber at any point along the wing (by measuring the distance between the chord line and the upper and lower surfaces of the wing).

• Mean Camber Line: Another reference line drawn from the leading edge to the trailing edge.

  • However, unlike the chord line, this line is equidistant at all points along the wing from the upper and lower surfaces. 

• Airfoils are designed in such a way that the shape takes advantage of the air’s response to certain physical laws. Hence, two actions from the air are developed as the wing passes through. A positive or high pressure lifting action from the air mass below the wing, and a negative pressure lifting action from low pressure above the wing. 

  Teardrop wing profile results in the speed and pressure changes of the air passing over the top and under the bottom to be the same.

Camber in Design

The airfoil should be designed to maximize laminar flow to avoid pressure drag (as pressure drag is caused by a turbulent wake). For low traveling airfoils like a solar car, cambering the body is aerodynamically advantageous. NACA 66 airfoils are recommended for a basis for flat airfoils, but other optimized airfoils designs can be referenced for different car shapes. We may need to develop our own model to apply camber to a bullet design, as it’s shape varies about an axis.

The point of max thickness is the ideal position for a protrusion like a driver canopy. The positioning of the driver will influence airfoil design.

Top View Shape

The key design tradeoff in the shape from a top view of the car is the solar array area versus aerodynamic performance. The shape with the most favourable aerodynamic performance is a truncated airfoil. It features more pronounced curvature around the nose and a tapered end. The shape is not ideal for arranging rectangular panelling, and is harder to manufacture.

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The other shape is a rounded nose design. This design features a rectanglular shape with a rounded nose to direct airflow around the edge. It is easier to arrange solar panels on and manufacture. This can be advnatageous as extra power can help overcome the poorly optimized aerodynamic performance.

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Note on Fairings

Fairings that are completely rigid can be designed to mount onto a curve surface, but fairings that move are better mounted on flat surfaces and it can be worth it to flatten surfaces to get ease of manufacturability even at the cost of aerodynamics.