“Aerodynamics is for people who can't build engines”, Enzo Ferrari said; “I build engines and attach wheels to them”.
Great engines without a doubt he did build, but other people were not much behind I terms of power and technology. To get ahead, they used brain, not brawn; they took advantage of the science of aerodynamics, which is still not fully understood; and experimentation continues.
“According to the laws of aerodynamics, the bumblebee can’t fly, but the bumblebee doesn’t know anything about the laws of aerodynamics, so it goes ahead and flies anyway”, said Igor Sikorsky of helicopter fame, which bear his name.
Aircraft were the first to make use of the science of streamlining to go faster with less power.
The auto industry has taken notice of the advances in the aircraft industry, and for a number of decades aerodynamics have become a vital element of automotive development to improve efficiency.
“The more air you have to push out of the way to reach or maintain a certain speed, the more energy you're using. And the more energy you use, the less efficient your journey will be”, one aerodynamicist explained.
To make a vehicle more streamlined, or aerodynamically efficient, the frontal area as well as the overall shape has an effect on how well the vehicle performs.
Colin Chapman of Lotus fame and Jim Hall’s Chaparral racers from General Motors brought aerodynamics to the forefront in the auto industry during the 1960s, although experiments date back as far as the 1930s.
A fascinating subject, involving science as much as art & style, still gives engineers and designers headaches and heartaches, especially as fuel-consumption decrease is of vital importance in this day and age of alternative transportation.
The aerodynamic efficiency is measured and expressed in Cd numbers to compare and evaluate shapes. This will become apparent when you get into details in the linked articles.
When powerful computers became available to industry, computational fluid dynamics (CFD) helped shape cars and trucks to lessen air resistance and reduce turbulence behind the vehicle — just as important as the shape at the front.
Much progress has been made with help from this new branch of science –CFD– but the proof is in the pudding, and that is tested and validated in a wind tunnel. The link takes you directly to the automotive part, but above that is much more information.
Most wind tunnels are of a size, which accepts scale models only. One of the most complex devices in automotive development, they are very expensive to construct and operate. An electric motor to drive the ‘wind generator’ fan has many thousands of horsepower in automotive wind tunnels – (measured in kilowatt in electric applications).
A recent NASA aircraft wind tunnel installation mentions 135.000 HP for its huge drive motor.
This writer had the privilege of a private tour of the world’s newest climatic wind-tunnel at the University of Ontario in the home-town of General Motors Canada. One of the most sophisticated and largest in North America, the unit can produce extreme heat, humidity, or cold, making snowstorms or driving rain, while testing vehicles for real life situations; as for its size, it can measure anything from a downhill ski racer in a tuck to a highway coach.
From the slide rule to CFD, the wind tunnel has the most influence on a vehicle’s shape; is it any surprise then that many, many cars are named after a wind? Chevy Tornado; Ford Zephyr; Maserati Ghibli, and most cars from that firm; Volkswagen Passat, Jetta, and many other cars by the company storming to new heights. And all those names are but a few.
“The Winds of Change.” “Shaped by the Wind.” That’s no hot air, as you can see in these pictures.