Kammback

Kammback (pronounced cam-bak)

A motif in automotive styling (originally dictated by wind tunnel findings during research into aerodynamic properties) in which rear of the car slopes downwards before being abruptly cut off to terminate in a vertical or near-vertical surface.  The things are known also as the Kamm tail (K-tail).

1950s (the actual design first appearing in 1938): The construct was Kamm + back.  The surname Kamm (related to Kamp) was of Germanic or Jewish (Ashkenazic) origin and translates literally from the German as “comb”.  The German comb was from the Middle High German kamb, kambe, kam & kamme and the Yiddish kam (comb).  Genealogists conclude Kamm was probably an metonymic occupational surname for someone who either made or sold combs, a common tool used for grooming or for textile work such as carding or combing wool.  There’s also the possibility the name of some Kamm clans could have been of topographic origin because in German, Kamm can also mean “ridge” or “crest” of a hill, mountain or some other elevation; it could thus have referred to someone who lived near such a geographical feature.  Less likely is that some arose from nicknames based on physical features or personal characteristics with Kamm used to describe someone with hair resembling a comb or someone with a sharp or distinctive personality.  The surname emerged in the Middle Ages, a time when hereditary family names were becoming more common in German-speaking regions and in addition to the presence in Germany, exists at various scale in areas with a historic patter of German migration (notably the north-eastern US and South Australia.

Back was from the Middle English bak, from the Old English bæc, from the Proto-West Germanic bak, from the Proto-Germanic bakam & baką which may be related to the primitive Indo-European beg- (to bend).  In other European languages there was also the Middle Low German bak (back), from the Old Saxon bak, the West Frisian bekling (chair back), the Old High German bah and the Swedish and Norwegian bak; there are no documented connections outside the Germanic and in other modern Germanic languages the cognates mostly have been ousted in this sense by words akin to Modern English ridge such as Danish ryg and the German Rücken.  At one time, many Indo-European languages may have distinguished the horizontal back of an animal or geographic formation such as a mountain range from the upright back of a human while in some cases a modern word for "back" may come from a word related to “spine” such as the Italian schiena or Russian spina or “shoulder”, the examples including the Spanish espalda & Polish plecy.

Tail was from the Middle English tail, tayl & teil (hindmost part of an animal), from the Old English tægl & tægel (tail), from the Proto-Germanic taglaz & taglą (hair, fibre; hair of a tail) (source also of the Old High German zagal, the German Zagel (tail), the dialectal German Zagel (penis), the Old Norse tagl (horse's tail) and the Gothic tagl (hair), from the primitive Indo-European doklos, from a suffixed form of the roots dok & dek- (something long and thin (referring to such things as fringe, lock of hair, horsetail & to tear, fray, shred)), source also of the Old Irish dual (lock of hair) and the Sanskrit dasah (fringe, wick).  It was cognate with the Scots tail (tail), the Dutch teil (tail, haulm, blade), the Low German Tagel (twisted scourge, whip of thongs and ropes; end of a rope), the dialectal Danish tavl (hair of the tail), the Swedish tagel (hair of the tail, horsehair), the Norwegian tagl (tail), the Icelandic tagl (tail, horsetail, ponytail), and the Gothic tagl (hair). In some senses, development appears to have been by a generalization of the usual opposition between head and tail.  The Oxford English Dictionary (OED) suggest the primary sense, at least among the Germanic tongues, seems to have been "hairy tail," or just "tuft of hair," but already in Old English the word was applied to the hairless "tails" of worms, bees etc.  The alternative suggestion is that the notion common to all is that of the "long, slender shape."  It served as an adjective from the 1670s.  A long obsolete Old English word for tail was steort.  Kammback is a noun; the noun plural is kammbacks.  No lexicographer seems to have listed Kammbackesque, Kammbacklike or Kammbackish as standard adjectives but, given the extent of the deviances from Professor Kamm's original which are still labelled as “Kammbacks”, they might be useful forms.  Who wouldn't want to be able to use terms like the comparative “more Kammbackish” and the superlative “most Kammbackish”?

Some notable Kammbacks

The Kammback (also known as the Kamm tail) was named after German engineer & aerodynamicist Professor Wunibald Kamm (1893–1966) who during the 1930s pioneered the shape, his work assisted greatly by some chicanery within the Nazi military-industrial complex which enabled the FKFA (Forschungsinstituts für Kraftfahrwesen und Fahrzeugmotoren Stuttgart (Research Institute of Automotive Engineering and Vehicle Engines Stuttgart) institute he established in 1930s to secure funding to construct a full-sized wind tunnel equipped with a two-part steel treadmill in the floor and an 8.8 metre (350 inch) diameter axial fan, able to drive air at up to 400 km/h (250 mph).  What the two concentric floor turntables allowed was that as well as enabling turbulence to be studied from the side on the running steel belt, slip angles were also possible.   At the time, it was the most modern structure of its kind on the planet, the very existence of which was owed to the priority afforded by the Nazis to re-armament, especially the development of modern airframes, most of the money eventually coming from the Reichs-Luftfahrt-Ministerium (RLM, the State Air Ministry).

A classic Kammback on a 1970 Fiat 850 Coupé (1965-1973), one of the last of the generation of post-war mainstream rear-engined cars built in Western Europe.

While Professor’s Kamm’s work on automobile shapes continued, increasingly the facility became focused on military contracts, contributing to an extraordinary range of novel aircraft designs, some revolutionary and most of which would never reach production.  All of this ceased in July 1944 when the facility was severely damaged in air-raids by Royal Air Force (RAF) Bomber Command, a costly campaign in which one mission incurred a loss-ration of 20% and it wasn’t until the late 1940s that reconstruction began after it was acquired by Daimler-Benz AG which enlarged and modernized the machinery, the early fruits including the 300 SL (the W194, first gullwing coupé) which won the 1952 Le Mans 24 hour race and the W196R “streamliner” Grand Prix race cars which created such a sensation in 1954.  Although he wasn’t part of “Operation Paperclip” (the US project which secured (by various means including the military “smuggling” them into the country despite many being wanted by those investigating war crimes and crimes against humanity) Professor Kann was acknowledged as one of the world’s leading authorities on turbulence and between 1947-1953 was part of the team working at Wright-Patterson Air Force Base in Dayton, Ohio.  Some of what was undertaken then remains classified but it can be assumed it was all related to military projects and what would later become the space program.

The Kammback which really wasn't: 1976 Chevrolet Vega Kammback.

One often misunderstood aspect of the Kamm tail is that the aerodynamic benefits are realized only if the flat, vertical surface created was no more than about 50% of the total area of the vehicle (as viewed directly from the back).  That’s why even designs which don’t conform to the requirements are often casually referred to as “Kammbacks” and in the US, Chevrolet were cynically opportunistic when the Vega range (1970-1977) included what was nothing more than a two-door station wagon (estate), it was named “Vega Kammback”.  Actually, even the existence of the thing in the US was unusual because at that stage, General Motors (GM) really “didn’t like” small station wagons but many critics did agree the Kammback was the best looking of the Vega’s body-styles.

2023 Ford Mustang coupe (left) and convertible (right).  Three of the Mean Girls (2004) ensemble (Karen Smith (Amanda Seyfried (b 1985)), Gretchen Wieners (Lacey Chabert (b 1982)) & Cady Heron (Lindsay Lohan (b 1986)) in 2023 filmed a commercial for Pepsi Corporation, one of the props a 2023 Ford Mustang convertible.  So ubiquitous has the Kammback become that its now unnoticed (except in its absence), one quirk being that when convertibles are created from such a base, many of the aerodynamic advantages are lost, one reason why (all else being equal which is rarely the case) a convertible will tend to have slightly inferior performance and slightly higher fuel consumption.

The knowledge gained from aero-engine development during World War I (1914-1918) meant even the mainstream engines of the 1920s were developing much more power so the speeds of cars were rising.  Some intrepid types also took advantage of the number of huge, powerful aero-engines being sold cheaply as “war surplus”, installing them is powerboats and racing cars, resulting in some fast machines and not a few fatalities.  However, it became clear the law of diminishing returns applied as speeds rose because while an increase of 100 horsepower might make possible an increase in top speed from 100 to 120 mph, another 100 hp might yield only another 10 mph; wind resistance increasing too much for the power to overcome.  Thus the interest in aerodynamics, then usually called “streamlining” something which, coincidently, produced some memorable art deco designs buy the engineers were interested in higher speeds and lower fuel consumption for a given quantum of energy input (fuel consumption).

2014 Shelby American Cobra 427 50^th Anniversary Edition in aluminium (left) and 1964 Shelby Daytona Coupe (right).

The AC Shelby Cobra (1962-1967) was small, light and powerful which made it an instant success on the race tracks but, ruggedly handsome though it was, its aerodynamics limited the top speed and on the some fast, open European circuits it gave away as much as 50 km/h (30 mph) to less powerful but more streamlined machines.  More power wasn’t the solution but a new Kammback body was and the Daytona duly won its class in the 1965 World Sports Car Championship.  All used the 289 cubic in (4.7 litre) Ford Windsor V8 although one briefly was fitted with a 390 (6.5) FE V8 and the planned 427 (7.0) version (CSX3027, the so-called “Daytona Super Coupe”) was never completed until sold by Shelby some 17 years later in a “rummage sale”.  The Kammback Daytona was the work of US designer Pete Brock (b 1936) and in a macabre coincidence, his namesake, the Australian racing driver Peter Brock (1945–2006) was killed while competing (in retirement) in a replica Daytona Coupe during the now defunct Targa West (2005-2021) in Western Australia.

Before the Kammback, the state of the aerodynamic art was the airship-like "streamliner" which, although it probably didn't cross the engineers' minds, owed something to the train of a bride's gown.  1939 Lincoln Zephyr V12 Coupe (left) and 1937 Mercedes-Benz 540K (W29) Special Roadster (originally delivered to Mohammad Zahir Shah (1914–2007; the last King of Afghanistan 1933-1973).

What soon became clear was that the shape of the dirigible (better known as the “airship” or “blimp”) was close to ideal and needed to be tweaked only by honing it into a “teardrop shape” with a rounded nose, extending to a long, tapered tail, a shape which in the 1930s caught the imagination of designers who rendered some memorable designs although the most famous were impractical and inefficient in terms of packaging, thus suitable only for the then small market niche which sought speed.  It was to try to gain the benefits of streamlining in a shape more suitable for mass production that Professor Kamm and others took their slide-rules to the wind tunnel began to experiment.  The solution which emerged was to terminate the lovely, long flowing roofline with an abrupt end at a surface which was either vertical or close to it, an unexpected benefit being an improvement in high-speed stability, obviating the need for (a usually central) stabilizing fin (a la an aircraft’s tail).  By 1938, BMW had produced a car with a Kammback and although World War II (1938-1945) interrupted development by the late 1940s the shape had begun to appear in showrooms and in little more than ten years it was common in specially bodied racing cars.  That didn’t mean the allure of the teardrop went away because the aerodynamicists (who now had both access to bigger wind tunnels in which higher speeds could be tested and the novelty of computers which could process previously unimaginable quantities of data) could still prove ultimate slipperiness could be attained only with the teardrop.

Pre-Kammback & non-Kammback.  Porsche 917LH (Langheck (long tail)) at Arnage, Le Mans 24 hour, 1969 (left) and 2020 McLaren Speedtail (right).  Such things are now possible.

It was this which convinced Porsche to use such a tail on their revolutionary 917 in 1969 and having encountered no stability issues on their test track, sent the car to the circuits where it proved as fast as expected.  Unfortunately, the size of the Porsche test facility limited the 917 to 290 km/h (180 mph) and when on the long straights of some European circuits when speeds exceeded 320 km/h, it was clear the thing was lethally unstable.  Although the drivers killed at the wheel of the early 917s didn’t die at such velocities, it was understood it would be only a matter of time so the rear bodywork was redesigned.  When in 2018 McLaren returned to the teardrop for the “Speedtail” (a car which sacrificed just about anything not mandated by law in the quest for top speed), it was able to achieve a safe (it’s a relative term) 400 km/h (250 mph) because advances in aerodynamics, computing and hydraulics had made such things possible although the packaging inefficiencies remained, something not significant for the target market.