Design Constraints: Where to Begin?

November 9, 2016

In a previous post, we talked about how Aerodynamics decide the shape of the car body. Since that shape is essential, the other components are system are designed from there.

Shell has specific rules on the car weight, length, width and height. None of the parts can be on the outside of the car, at all.

  1. h) None of the body dimensions above must be achieved by design singularities such as ‘stuck-on’ appendages or cut-outs

(Shell Eco-marathon 2016 Global Rules)

The frame, brakes, electrical, and steering must fit inside the car body (the pod), while allowing space for the driver. Their combined weight must add up to no more than the weight maximum of the rules. This includes a minimum driver weight of 140 kg. Since less weight mean less energy, all teams want their driver very close to that number. It’s another tough challenge, but knowing what percent of the weight the driver will take up allows us to consider the other components weights with respect to it.

The driver also has to be able to see! That’s not so easy to adjust for. Keeping the streamlined shape while adding in the cars various systems makes it a tight fit inside. The driver can’t sit up straight, they must be reclined, conforming to the width and height of the rules.

There’s no door to get in or out. Prototype teams design the pod to split in half along the horizontal. It’s the best method for fabricating and eliminating cracks along the side of the body (which can aversely affect aerodynamics.) 

Here’s a visual of how the driver and components are organized in prototype cars:

École Polytechnique, Montréal

École Polytechnique, Montréal