By Ryan Lee Price

 aerodynamic car in wind tunnel
Aerodynamics was great for racecars, airplanes and boats, but through the 1910s and 20s, car design was still function over form. Production car designers drew the square-shaped car built on a carriage chassis with foot boards, sunshades on the exterior of the windshields, detached headlights and rear lights perched on the fenders.
In the 1930s, automobiles began to resemble carefully designed pieces of art. Cars appeared with smooth rounded edges, graceful arching fenders, exterior lighting built into the bodywork. The radiator grille and shell were raked back slightly, which made cars look like they were going fast when they were standing still. The front office learned quickly: speed sells.
1934 Chrysler Airflow
Streamlined designs became eye catching. Chrysler in particular captured the techniques of aerodynamics and streamlining in its 1934 Airflow model. The Airflow, although a big step in aerodynamics in America, was poorly received and dropped soon thereafter. But revolutionary body styling still spread. Moving passengers forward allowed “fastback” lines, with grilled radiators and skirted fenders. Cars like the 1936 Lincoln Zephyr set styling patterns for years, though most of these designs only gave the appearance of drag reduction; few examples provided significant results.
Auto Union DKW F9
In Europe, Auto Union (the predecessor to Audi) made considerable progress in the mechanical aspects of their cars, but its engineers were seeking new methods of styling and materials selection to increase efficiency and speed. Using Paul Jaray’s patents, optimum aerodynamic properties were first calculated by theoretical methods, then tested in the wind tunnel. Using these methods, the production version of the DKW F9 achieved an astonishing drag coefficient of 0.42, a dramatic improvement over the F8’s 0.58.
Though the years, countless factors have shaped the way cars are designed, from increased safety regulations to the price of oil. In most of the passenger vehicles we see on the road today, aerodynamics plays a comparatively minor role in the overall design of the vehicle. John H. Lienhard, a professor of mechanical engineering and history at the University of Houston and author of “The Engines of Our Ingenuity” adds, “It took time for engineers to see that they had to smooth the bottom of an automobile as much as the top. It took time to see that sharp corners on the front of a car were terrible drag-inducers. Only in the last generation did 18-wheelers sprout those strange-but-effective, drag-reducing cowls over their cabs.” We have come to associate an appealing car design if it emulates the lines of a racecar, and no other aspect of a car’s profile better illustrates this than the distance between the wheel arch and the top of the fender. The perception of speed increases as that distance decreases.
Throughout the 1950s, a typical prototype sports racing car was small, lightweight, front-engined, and wrapped in a nicely designed aerodynamic shell. Due to relatively inefficient engines, racecar designers made cars look aerodynamic so that they cut through the wind, making up for horsepower deficits. But racecars of the era were prone to too much positive lift, causing them to launch into the air even if slightly provoked at high speeds.
1956 Porsche Type 550
In 1956, engineer Michael May thought that by constructing an airfoil, flipping it over so that it produced a negative force towards the ground, and mounting it onto his Porsche Type 550, he could utilize this down force to improve traction, grip, and handling. But race organizers kept his rear wing design off the track because the wing “restricted the view of the drivers behind him.”
It wasn’t until the 1960s that auto makers noticed that if they reduce the slope of the back of the car to 20 degrees or less, the air flow will follow the roofline and drop off the back of the car, greatly reducing drag. It was called a Fastback design, and an excellent example is the Porsche 935/78, better known as the “MobyDick.” The Fastback design isn’t without its flaws, especially in lift. Because it has a very large surface area in contact with air flow it suffers from a low pressure on top of the car. Usually, wings are used to combat this problem. It seems that good drag and good lift are mutually exclusive, you can't have both of them in equal amounts at the same time.
2E Can Am Chaparral
In 1962, Ferrari engineers discovered by adding an airfoil to the rear end of their Ferrari 246SP endurance racer they were able to direct the majority of the air flow away from the rear of the car, thereby reducing drag and lift. This technology trickled down the following year to the 250GTO road car, which incorporated a small duck tail rear wing. In 1966, Jim Hall mounted a wing onto his 2E Can Am Chaparral, competing well in the Can Am championship and further proving the concept. By 1968 wings started to show up on many Formula One cars, firmly establishing downforce airflow design.
In 1969 Porsche introduced the 917 to international sports car racing, a car with a reliable, low horsepower engine paired with sleek, low-drag bodywork. The combination worked well, but they couldn’t get the championships the factory wanted. They switched to a higher-horsepower engine, but the car was then plagued with aerodynamic instability problems (drivers soon named the car “The Ulcer”). Through wind tunnel testing, the front and rear bodywork was restyled and the car soon dominated the Sports Car World Championship in 1970 and 1971.
However, the wing did not get popular with the public until Porsche launched its 911 RS 2.7 in 1972, whose big duck tail reduced lift by 75 percent at high speed. A trademark of the 911, the “Whale Tail” appeared the following year on the RS 3.0 and it completely eliminated lift at the rear tires. It seemed that form had finally caught up with function in car design.
Stay tuned for Part 3 of “A History of the Invisible Wall: Aerodynamics in a Nutshell”

Not only is Ryan Lee Price a freelance writer specializing in automotive journalism and a former long-time magazine editor, he is part of the technical editorial team that provides content for most all of the ChiltonPRO and ChiltonDIY products. He currently resides in Corona, California, with his wife Kara and their two children.