Fluid Dynamics and Cars

Rumpler Tropfenwagen

Nerd alert: as in were going to talk physics but I promise it won’t get too complicated.

What actually accelerates a car? Well there is the driver and the tires and so on, but technically acceleration is any change in velocity, and velocity is speed in a single direction. So the steering wheel accelerates you around a corner and the brakes technically accelerate you to a stop.

The air around a car exerts force on it as well. To improve the speed and fuel economy of a car you will have to look at fluid dynamics. Dynamics is the science of mechanics where objects are pushed or pulled around by forces. Mechanics is the science of anything moving or in motion.

We don’t think of air as a fluid but every gas is essentially a fluid for the purpose of studying how it flows or is moved through. Newton’s second law says motion…okay, okay, we’ll knock it off. You get the picture.

When viewing the pictures in this post it helps to know two things:
1st that aerodynamic cars are more like concept cars–not practical for large scale production despite the hopes and dreams of the designers.
2nd that air is not only pushed out of the way in an efficient manor but the manor in which the air collapses behind a fast moving object can also create drag.

Are you still with us?

The History of Aerodynamic Designed Cars

Amazingly, the first car built with aerodynamics in mind appears to be in the 19th Century. Created by Camille Jenatzy (who was also known as the Red Devil) it reached 50mph, which though nothing special today, was the fastest a car had ever gone at the time. 

Camille Jenatzy – Jamias Contente

The vehicle which broke the record, La Jamias Contente, which translates as Never Content looks bizarre to modern eyes and was probably extremely out of the ordinary when it was manufactured too. It was a battery powered vehicle rather than using gas or diesel. The position of the driver was incredibly high.

Although the bodywork looks as if it were made from aluminum it is actually a light alloy called partinum, a compound of aluminum, tungsten and magnesium. Where this car succeeded an fluid dynamics it failed as car. Not good at steering so roundabouts were out of the question.

Remember the Rumpler Tropfenwagen? No. We don’t blame you. It’s a weird name for a car only remarkable in the context of earodynamic design. Named after its creator Edward Rumpler, who looked at the natural world for inspiration shaping the car like a water droplet. Even today many cars are droplet or bubble shaped. A drop shape isn’t the most aerodynamic of designs-else all racing cars would be shaped that way–it’s an excellent example of the use of aerodynamics in the vintage period.

Tatra 77

Another early car which used aerodynamics was the Tatra T77, created in 1946 by Paul Jaray. Paul Jaray was an engineer who also designed airships and seaplanes and one of the first people to use wind tunnels in car design. Although more conventional looking than the Jamais Contente it still used strong mechanical principles. The Tatra would pave the way for further Volkswagen (motor company) designs, though not a VW itself.

These days a wind tunnel seems a relic from another era. Now days, design is done through computer modelling. It is expensive to build and maintain a wind tunnel, and with computers you can tweak your car design to adapt to different aerodynamics in an instant, even changing design for a single component change to the car. However, we have these awesome computer models because designers gathered so much data from testing every kind of design they could dream up.

Nowadays it would be unthinkable to design a car for the public without looking at aerodynamics. Maximizing fuel economy and increasing the driving experience ads value to your vehicle just as much as “looking cool.”

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