Wunibald Kamm helped define modern-day aerodynamics
Modern vehicles with low Cd values owe a lot to an innovation developed in 1930's
- Published in Milestones.
The rear part of the streamlined car body is cut off and a flat rear face is formed
Other engineers continued to develop vehicles that tapered at the rear into a point or an edge
Kamm and Koenig-Fachsenfeld continued to work closely together, and the design principle they developed was simple. Koenig-Fachsenfeld’s patent stated that: “The car body gradually tapers into a streamlined shape of sufficient leanness to permit the airflow to cling to the rear part of the body, but the streamline does not end in a point or an edge but the rear part of a streamlined car body is cut off and a flat rear face is formed.”
The first concept vehicle, the Everling, built in 1938 and based on a Daimler 170 V chassis, was quickly followed by the K3, built with the help of Koenig-Fachsenfeld the same year but based on the BMW 328, and the K5 was built a year later in 1939.
Initial wind-tunnel tests highlighted astonishing drag coefficient figures for the time. The average score for a vehicle in the 1930s was 0.55Cd, but Kamm’s test cars reduced that figure to a theoretical 0.24Cd – although later when the K5 was taken into the wind tunnel that increased to 0.37Cd.
Other aerodynamicists of the time used some of Kamm’s principles in vehicles. But other engineers continued to develop vehicles that tapered at the rear into a point or an edge.
The Kamm-back was first used on high-performance vehicles like the Ferrari 250 GTO and BMW 328 Kamm-back, but soon the principle was transferred to mainstream vehicles too.
Cars as diverse as the Citroën GS, Honda CRX and Audi A2 have all benefited from Kamm’s aerodynamics work. And today Kamm’s work continues to help OEMs to improve efficiency, particularly in hybrid vehicles such as the Honda CR-Z.
