36-24-36

Modern human beings, especially the fairer gender has always been fascinated by the magic number 36-24-36. This has not been the case always. Body shapes have always evolved over a period which currently rests at what is popularly called “size zero”

The evolution of the design of automobiles has also followed a similar trend. To understand this evolution let me introduce you to the concept of Drag faced by car when it moves.

When you put your palm outside, as the car moves you feel a force on your hand. This force pushes your hand in a direction opposite to the movement. If you tilt your hand a little the force reduces. This force is called Drag.

 

This force is a function of,

a) Speed of car

b) Co-efficient of drag (commonly denoted as Cd) which depends on the shape of the car

c) Speed of car.

The lower the co-efficient, the lower the drag. The least Co-efficient is for Tear Drop designs and maximum for Boxy designs.

The more the force, the more load on the engine as the car tries to go faster and hence more fuel is consumed. This force becomes more pronounced as the cars travel faster.

The boxy shaped automobile such as the Austin 7, was popular initially and this worked well as they travelled only at limited speeds. Fuel consumption was also not much of a concern in those days.

 

As the speed of cars increased and prices of fuel increased, people began to focus on the Drag Force and thereby on the design. There was also a time when the aerospace technology collaborated with the automobile design resulting in more streamline shapes. Classic cars made by Tatra in the 30’s and 40’s are example of this.