Aerodynamics and Design


As manufacturers squeeze all the fuel efficiency they can out of their designs, aerodynamics have been a huge concern –as well as looking sleek and advanced, an aerodynamic car cuts wind resistance for enhanced fuel efficiency. Modern designs are a pretty far cry from the boxy sedans of the 70s and 80s, but aerodynamics is hardly a new concern.

All the way back in 1923, Romanian engineer Aurel Persu ruminated on the ideal aerodynamic design; Persu decided that the ideal aerodynamic shape found in nature was a raindrop as it falls to the ground, with a super-low drag coefficient of 0.04. With that as a target, he began to draw up an aerodynamic sedan, with tall wheels mounted flush with the body inside fender wells, a steeply-raked front end, rear wheels spaced much more closely than the front, rounded contours and a rear end that tapered sharply. The Persu was designed with a drag coefficient of 0.22; for comparison’s sake, GM’s 90s-era EV1 had a drag coefficient of 3.95, the Hummer H2’s brick-like profile reaches 26.32, and the average drag number today is about 0.32.

The odd-looking design ended up looking a bit like a shoe, but Persu patented the car in 1924 and built a prototype in Germany , using a 1.4 liter 4-cylinder engine. Persu drove the car from Germany to Romania, racking up almost 75,000 miles; the car could achieve 50 mph, and while Ford and GM were both interested in the design, he never sold the patent to them. The Persu now sits in an automotive museum in Romania.

In the 30s, Chrysler engineer Carl Breer had some of the same curiosities as Persu as he studied the “V” flight pattern of geese, aircraft designs and the shapes of fish. Along with other Chrysler engineers, he borrowed Orville Wright’s wind tunnel to study drag and airflow patterns, building and testing at least 50 scale models. What they found was that the conventional two-box design of the day was terribly inefficient; their design ended up being the ’33 Chrysler Airflow. The Airflow looked unlike anything on the road, with a long hood and “waterfall” grille, a lower profile and sleeker lines. In addition, the Airflow featured all-steel unibody construction (even Ford and GM still used wood for frame members in the 30s) for an exceptionally robust car.

Unfortunately, the Airflow was an utter disaster sales-wise. Even by today’s standards, the car’s styling is oddball and not very attractive; it was offered with a six-cylinder and straight-eight engine, then restyled in 1937, but it was still not enough to attract buyers. The Airflow faded into obscurity, but not before its design influenced Toyota’s 1936 AA Model; some even contend that it influenced Ferdinand Porsche’s first-generation VW Beetle.