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Kammback
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A Kammback is a car body style that derives from the research of the German aerodynamicist Wunibald Kamm in the 1930s, this research itself deriving from that of another pioneer German aerodynamicist, Baron Reinhard Koenig-Fachsenfeld.
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Encyclopedia
A Kammback is a car body style that derives from the research of the German aerodynamicist Wunibald Kamm in the 1930s, this research itself deriving from that of another pioneer German aerodynamicist, Baron Reinhard Koenig-Fachsenfeld. "Kammback" is an American coinage. In Europe the design is generally known as a Kamm tail or K-tail.
History
Freiherr Reinhard Koenig-Fachsenfeld "developed a body style whose tail was cut off to form a flat rear surface" while working on an aerodynamic design for a bus, and he patented the idea.
The innovative tail treatment also minimized turbulence created by Paul Jaray's aerodynamic designs on certain 1935 passenger cars. In 1936, "further research by the FKFS--Forschungsinstitut fur Kraftfahrwesen und Fahrzeugmotoren Stuttgart (Stuttgart Research Institute for Automotive and Automobile Engine Technology), under the direction of Wunibald Kamm, proved that vehicles with the so-called K- or Kamm tail, following Koenig-Faschsenfeld’s lead, offered a good compromise between everyday utility (e.g. vehicle length and interior dimensions) and an attractive drag coefficient."
The earliest use of "Kamm" to describe an automobile body incorporating this design was the prototype 1940 'Kamm' Coupe based on a BMW 328 chassis.
Aerodynamics
While the realities of fluid dynamics dictate that a teardrop shape is the ideal aerodynamic form, Kamm found that by cutting off / flattening the streamlined end of the tear at an intermediate point, and bringing that edge down towards the ground, he could gain most of the benefit of the teardrop shape without incurring such a large material, structural, and size problem. The airflow, once given the suggestion of the beginning of a turbulence-eliminating streamlined teardrop tail, tended to flow in an approximation of that manner regardless of the fact that the entire tail wasn't there. This is called the Kamm effect.
There is controversy about the proportions of a true Kamm tail. According to the classic definition the tail should be cut off where it has tapered to approximately 50% of the car’s maximum cross section, which Kamm found represented a good compromise - by that point the turbulence typical of flat-back vehicles had been mostly eliminated at typical speeds. Thus a minivan is not a Kammback, and neither are numerous cars that have truncated tails.
Automakers’ use of the term “Kammback” has diminished as Kamm's principles have become more generally assimilated into modern car design.
Kammback examples
High-performance cars
The Kamm tail was used on many high-performance and competition cars, such as:
Mass-production cars
Kamm (and Kamm-like) tails can be seen on numerous mass-production cars, such as:
AMC and GM have publicized certain models with truncated tails as “Kammbacks” even though it is obvious to the eye that they do not meet the classic "50% cross-section" definition, i.e. the AMC AMX-GT and Pontiac Firebird-based "Type K" concept cars, a Chevrolet Vega station wagon, and a version of the AMC Eagle.
Hybrid mass-production cars
As the Kamm tail’s low drag helps improve fuel consumption, it features on subcompact hybrid cars designed for maximum economy, for example:
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