BMW K1 (automobile)

BMW
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K1
Presentation year:	1938/39 (test car / one-off)
Vehicle fair:
Class :	Upper class
Body shape :	limousine
Engine:	Otto engine : 3.5 liters (66 kW)
Length:	approx. 5000 mm
Width:	approx. 1700 mm
Height:	approx. 1500 mm
Wheelbase:	2984 mm
Empty weight:	approx. 1500 kg
Production model:	none

Early streamlined experimental sedan of the Romanian Aurel Persu in the streets of Berlin, built around 1925 - using such basic shapes as a basis, Wunibald Kamm developed his vehicles in streamlined form with a “cut off” rear end

Early streamlined experimental sedan by the Englishman Dennistoun Burney , the Burney Car from Streamline Cars Ltd. , designed in 1927 - in contrast to the Kamm-Wagen a vehicle with a long and flat tail

The BMW K1 was an innovative test vehicle from Bayerische Motoren Werke AG (BMW) from 1938/39 based on the BMW 335 . The alternative spellings K-1 (with hyphen) or K 1 (with spaces) are also used, and more often the designation Kamm-Wagen K1 .

It was a designed for high travel speeds and low consumption four-door sedan of the luxury class with comfortable furnishings and five full-size seats, pontoon body in a streamlined shape with comb-rear and 3.5-liter six-cylinder - inline engine (links to pictures :).

The K1 was not developed in the BMW main plant in Munich or in the Eisenach plant responsible for automobile production at the time (the former Dixi plant ), but by Professor Wunibald Kamm at the Research Institute for Automotive Engineering and Vehicle Engines (FKFS) in Stuttgart . Special features of the K1 were its aerodynamically extremely favorable body and numerous technical innovations, some of which only entered series production decades later.

background

Until the 1930s, aerodynamics did not play a significant role in vehicle construction - apart from a few record-breaking and racing vehicles. This changed in the 1930s with engines with higher performance and better stability as well as improved chassis technology . These now allowed passenger cars to travel at speeds of over 100 kilometers per hour, above which the air resistance has an increasing effect. In addition, there was the rapid expansion of the Reichsautobahn in Germany . At the end of the 1930s, there was therefore a need for aerodynamically more favorable bodies in order to be able to achieve higher speeds and lower fuel consumption.

Many pioneers of automobile aerodynamics had previously gained experience in the construction of glider planes , gliders and motorized planes as well as airships . These pioneers included Edmund Rumpler and Paul Jaray (both from around 1921) as well as the now largely forgotten Gottlob Espenlaub with his early Espenlaub automobiles (from 1928) or the Romanian Aurel Perșu (from 1922). This was followed in the 1930s by Ferdinand Porsche , Reinhard von Koenig-Fachsenfeld , Karl Schlör and the author Wunibald Kamm, who are more famous today , as well as Hans Ledwinka (for Tatra ) and, in France, Gabriel Voisin .

Rumpler and initially also Jaray chose superstructures that were relatively tall and narrow and where the air was mainly directed past the side of the body. It turned out that this shape was not yet optimal, even if Jaray's designs already indicated the aerodynamically favorable wing profile. The streamline "with the rear cut off", as shown by the BMW K1 , was derived from this: the flow is largely guided over the roof, which slopes gently towards the rear, with the rear pulled in at the side and almost straight. Wunibald Kamm had already explained this form in his lectures in 1933, but did not patent it and initially did not put it into practice. Koenig-Fachsenfeld also claimed to have discovered or (co-) developed this aerodynamically favorable shape.

Emil Everling , lecturer at the Technical University of Berlin-Charlottenburg, completed the first vehicle based on this principle in 1938, the electric car , built at Voll & Ruhrbeck in Berlin with a value of 0.31. It was followed in the same year by the BMW K1 from Kamm and BMW with a value of 0.23, which is still outstandingly favorable by today's standards. ${\displaystyle c_{w}}$ ${\displaystyle c_{w}}$

History of the K1

As early as April 1, 1930, Kamm was appointed professor for automotive engineering and vehicle engines at the Technical University of Stuttgart . In the same year he founded the research institute for automotive engineering and vehicle engines Stuttgart (FKFS) , which was not geared towards making a profit . In collaboration with industry, this enabled him to conduct research outside the rigid university structures, in particular with the companies Daimler-Benz and BMW based in southern Germany .

From 1935, research on streamlined vehicles in the German Reich was funded by the state. The funds that flowed to the FKFS under its head Kamm in particular came from 1937 onwards from the Reich Research Council, which was founded especially for this purpose .

The first drivable result of the work of the FKFS and Kamm in 1938/39 was the BMW K1 test car with an extremely streamlined body and numerous technical innovations in the engine and chassis area. Three more sedans followed between 1939 and 1940, including the K2 and K3 models on the chassis of the smaller Mercedes-Benz 170 V , while the BMW K4 and the K1 were based on the “big” BMW 335 . Kamm also supplied the pattern for the BMW 328 - “racing limousine” - which was later successful in racing, especially at the Mille Miglia .

The BMW K1 was designed from the outset as test cars, thus not for mass production. Extensive test drives took place in 1939 and 1940, during which two large vertical air guide fins were temporarily installed at the end of the roof. The progressive bodywork and the technical innovations have proven to be functional and highly efficient. However, the external shape with its full pontoon body, the unusual rear, the completely covered front and rear wheels and the temporarily mounted roof fins differed greatly from the series vehicles of the time. The optics met with some very harsh criticism from the audience. The K1 therefore remained a one-off.

There was no predecessor in the narrower sense of the K1, neither from BMW nor from Kamm or the FKFS . The idea of ​​Paul Jaray's test car based on a Dixi 6/24 PS Type G 2 was similar . This was a narrow, tall streamlined limousine with the characteristic nickname "Walfisch", which was presented at an automobile exhibition in 1923 and for Purchase was offered, but met with widespread rejection from the public. The relationship between the two models results from the fact that the automobile manufacturer Dixi was bought by BMW in 1928 .

Typology

The BMW K1 , unlike the pre-war BMW cars planned for series production from 1933 onwards, starting with the 303 (1933–1934) model, does not have a model designation with three digits and a "3" at the beginning. Like numerous later concept vehicles, it was given a model designation with a letter and a single-digit number, similar to the later BMW E1 . Unlike the BMW M1 or the BMW Z1, however , the BMW K1 did not find its way into series production in this form.

The K stands for "Kamm-Wagen" or "Kamm-Heck", the 1 for the first vehicle of this series of the FKFS and BMW .

The BMW K1 is the only BMW automobile that shares its name with a BMW motorcycle model , the innovative sports tourer BMW K1 presented in 1988 with an aerodynamically clad front wheel, full fairing including small luggage cases, an engine with a regulated catalytic converter and, for an additional charge, one of the first anti-lock braking systems in the two-wheeler sector. The name is derived in this case from the BMW K series , a motorcycle series with longitudinal in- line engines instead of the traditional two - cylinder boxer engines . It is not known whether the name of the motorcycle model is deliberately based on the name of the K1 car model , but it can be assumed in view of the sophisticated aerodynamics in both cases and its status as an innovator.

Vehicle model details

The BMW 335 sedan, presented in autumn 1938, in series production from 1939 - a pre-series chassis of this type provided by BMW provided the basis for the BMW K1 developed by Wunibald Kamm in Stuttgart in 1938/39

The BMW 335 , here as a four-door convertible, the conservatively designed series model for the innovative BMW K1 test car

Body and equipment

The most striking feature of the BMW K1 is its extremely unusual, aerodynamically almost ideal body with its -value of 0.23 and a very spacious and comfortable interior. At that time, values ​​of 0.5 to 0.6 were common for sedans. ${\displaystyle c_{w}}$ ${\displaystyle c_{w}}$

The low drag coefficient was achieved by an aerodynamically favorable full pontoon body with a wing profile, an unusually round and deeply drawn-down front with flush headlights, fully clad front and rear wheel cutouts and a smooth, clad underbody. Another detail was the four-segment windscreen with rounded-off elements, as curved windscreens were still unusual. In addition, there were completely smooth body side parts, flush fitted front, rear and side windows as well as the absence of outer door handles for the rear doors. Aerodynamically particularly important was the relatively long, gently sloping hatchback with gently drawn-in side panels and a relatively straight cut-off rear end. This resulted in relatively clean aerodynamic tear-off edges on the rear, lower edge of the flat rear window as well as in the side and lower body area.

Atypical for a BMW , the K1 did not have the BMW kidney grille , which has otherwise been common since 1933 , but an oval, standing cooling air opening integrated into the flowing body lines and clad with longitudinal struts. The arrangement of the four doors, however, was typical of pre-war BMW models, as had already proven itself in the 326 : the front doors were hinged at the back (so-called " suicide doors "), while the rear doors were hinged at the front. So the doors ran in opposite directions, the door hinges each attached to the B-pillar .

The two large vertical tail fins, which were temporarily mounted on the roof of the K1 , were supposed to guide the airflow over the roof and behind the vehicle more favorably; In practice, the advantages of the fins turned out to be too small, as they also impaired crosswind stability and straight-line stability .

The design was aerodynamically extremely consistent and designed without taking contemporary taste into account, which is why any chrome elements and other ornaments were omitted on the outside , as well as bumpers , which could have avoided damage to the body in everyday life.

The body was built by Walter Vetter Karosserie- und Fahrzeugbau in Fellbach near Stuttgart according to the plans of Kamm and the FKFS . The company, which still exists today, was known at the time primarily for the manufacture of car bodies based on Mercedes-Benz chassis, but also for bus bodies in streamlined form under a license from Paul Jaray.

The interior dimensions of the K1 were extremely generous due to the wide full pontoon body without flared fenders and running boards, but with a hatchback. The relatively steep front and side windows - despite the aim of achieving the best possible aerodynamics - also contributed to this. In the stern was a large trunk accessible from the outside. The interior was elaborate and comfortable to meet the demands of a long-haul touring limousine. Due to the larger body than the original BMW 335 and the complex interior, the weight of the K1 was relatively high at around 1500 kilograms and significantly higher than that of the standard 335 .

Chassis and running gear

The BMW K1 had a pre-production chassis of the 335 model , which BMW made available to FKFS in 1938 under the direction of Kamm. In terms of construction, it was derived from the 326 model , but compared to this it was reinforced and lengthened by 234 millimeters to 2984 millimeters. The K1 thus also had a drop-center box frame with a front wheel suspension made up of upper wishbones and a transverse spring at the bottom and a track width of 1306 millimeters. At the rear it had a rigid axle with two longitudinal spring bars and a track width of 1,404 millimeters. This was considered to be more comfortable, but less sporty than the rigid axle with semi-elliptical leaf springs of the 327 and 328 , which better met the demands of the K1 as a comfortable touring sedan. It had rack and pinion steering and hydraulically operated inner-shoe drum brakes on all four wheels with a cable-operated handbrake on the rear wheels.

An innovative feature of the BMW K1 was a tire pressure regulation system that made it possible to increase the tire pressure from the dashboard while driving, thereby reducing the rolling resistance of the tires ; This enabled fuel consumption to be reduced significantly on the well-developed new motorways, especially at higher speeds.

engine and gears

The BMW K1 also received the newly designed engine of the 335 , i.e. the water-cooled six - cylinder, four-stroke in-line engine with a displacement of 3485 cm³ and a long-stroke design ( bore 82 millimeters, stroke 110 millimeters). Like the smaller 2.0-liter version, it had a crankshaft with only four bearings and a side camshaft with overhead valves ( OHV valve control ) that were operated via bumpers and rocker arms . In contrast to the 2.0-liter version, the camshaft of the 3.5-liter version was not driven by a duplex chain , but by Novotex spur gears. At a compression ratio of 1: 5.8 with the two double made Register carburetors equipped engine 66 kW (90 hp) at 3500 min ^-1 . The power was transmitted in the usual way via a single-plate dry clutch to a manual four-speed gearbox with rear-wheel drive .

An innovative feature of the K1 was a special lean mixture at constant engine speeds to further reduce fuel consumption. A special overdrive made it possible to reduce the engine speed at higher speeds, thereby further reducing fuel consumption. In test drives, the FKFS and BMW achieved outstanding consumption values ​​of 7.6 liters per 100 kilometers at a constant 100 km / h, 10 liters per 100 kilometers at an average of 120 km / h and 12 liters per 100 kilometers at a constant 140 km / h. With the same output of 66 kW (90 hp), the BMW K1 reached a top speed of then and now - especially taking into account the size and weight of the vehicle - an impressive 183 km / h compared to 145 km / h of the production BMW 335 .

Influence on other vehicle models and whereabouts of the K1

Modern interpretation of a particularly energy-efficient multi-seat passenger car from BMW , the BMW Vision Efficient Dynamics from 2009 as the spiritual descendant of the innovative BMW K1

The experiences of FKFS and Kamm with the BMW K1 test car flowed into the other Kamm cars : the smaller and lighter models K2 (outwardly very similar to the K1 ) and K3 (outwardly somewhat more conservative), each based on the Mercedes-Benz 170 V. from 1938, as well as the BMW K4 from 1939/40, which, like the K1, was based on a pre-series chassis of the BMW 335 .

For BMW , the experience gained from testing the K1 was so helpful that Kamm was supported in developing the outwardly somewhat more conservative BMW K4 the following year . Furthermore, BMW's experience with the K1 and K4 flowed into the development of various planned series vehicles: the BMW 332 , the successor to the successful BMW 326 planned for 1940 , and the BMW 337 , the luxury or upper class model planned for 1941 of the BMW 335 .

The track of the BMW K1 is lost in the Second World War or at its end; he is now considered lost. Some sources claim that the K1 was the only Kamm car to survive the Second World War and belongs to the collection of the “Automobile Museum Schloss Langenburg ”. However, this is not true: The local vehicle is the smaller and lighter comb-car K3 based on the Mercedes-Benz 170 V .

Individual design features of the K1 such as the basic idea of ​​the pontoon body and the aerodynamically influenced lines were found in the BMW 501/502 model series in the 1950s , even if these cars with their shaped fenders in the style of contemporary Austin were already back in the 1950s looked classic (nickname: "Baroque Angel").

A body with a hatchback that is visually very similar to the K1 can be found on the Borgward Hansa 2400, which was built from 1952 to 1955 .

To date (as of March 2010) BMW has not presented a revolutionary and aerodynamically favorable design comparable to that of the K1 . It is possible that it was precisely the sometimes harsh criticism of the shape of the K1 and the lack of understanding among contemporary car buyers that prompted BMW to maintain a more conservative design until the mid-1990s, before the courage to controversially discussed with the designer Chris Bangle Found styling elements.

To date (as of March 2010), no efforts by BMW have become known to have a replica of the BMW K1 made, as happened, for example, with individual prestigious 328 racing versions.

BMW only picked up the idea of ​​a large hatchback sedan in 2007 with the BMW Concept CS concept vehicle and in series production with the BMW X6 and BMW 5 Series Gran Turismo models in 2008 and 2009, respectively. The idea of ​​a particularly energy-efficient, large, multi-seat model can be found again in the BMW Vision Efficient Dynamics concept vehicle presented in 2009 .

literature

• Halwart Schrader: BMW automobiles . tape 1 : From the Wartburg and Dixi to the BMW 3200 CS Bertone 1898–1962 . Motorbuch Verlag, Stuttgart 2003, ISBN 3-613-02343-1 , p. 86 .
• Werner Oswald, Eberhard Kittler: All BMW automobiles since 1928 . Motorbuch Verlag, Stuttgart 2000, ISBN 3-613-02080-7 , p. 83 (with picture).
• Ralf JF Kieselbach: BMW rarities: cars that never went into series production . GeraMond Verlag, Munich 2007, ISBN 978-3-7654-7806-2 , p. 45-47 .
• Ralf JF Kieselbach: Streamlined Cars in Germany. Aerodynamics in car construction 1900 to 1945 . Kohlhammer Verlag, Stuttgart 1982, ISBN 3-17-007626-4 , p. 24, 25, 34, 76 (with picture).
• Erik Eckermann: World history of the automobile . Society of Automotive Engineers, Inc., Warrendale, PA (USA) 2001, ISBN 0-7680-0800-X , p. 117, 119 (English, with picture).
• Princeton Institute for Historic Research (Ed.): Automobile quarterly. Volume 21, Issue 2, 1983, pp. 185, 189 (English).

Web links

• BMW K1 test car. In: BMW history. BMW AG, accessed on November 27, 2012 (search in the BMW Group archive). 
• P. Isermann: Aerodynamics - From the first beginnings to the current state of development. ( Memento of November 18, 2004 in the Internet Archive ) on fachreporte.de , March 2004, there in particular no. 2.5, accessed March 17, 2010.
• bmwclubsa.asn.au ( Memento from August 18, 2010 in the Internet Archive ) Report on the BMW 332 and the test cars by Kamm (including the BMW K1 ) and Jaray on the website of the BMW Driver's Club of South Australia , accessed on March 17, 2010 (English).
• The BMW K1 and other BMW rarities on the BMWPower.lv website (in Latvian), accessed on March 17, 2010

References and comments

1. ^ Pictures of the BMW K1 : here , here , fkfs.de ( Memento from December 10, 2008 in the Internet Archive )
2. ↑ ^{a b c d e} P. Isermann: Aerodynamics - From the first beginnings to the current state of development. ( Memento of November 18, 2004 in the Internet Archive ) on fachreporte.de , March 2004, there in particular no. 2.5, accessed March 17, 2010.
3. ↑ ^{a b c d e f g h} Werner Oswald, Eberhard Kittler: All BMW automobiles since 1928 . Motorbuch Verlag, Stuttgart 2000, p. 83
4. ↑ ^{a b} History and background to Wunibald Kamm and the FKFS ( Memento of August 14, 2010 in the Internet Archive ), accessed on March 17, 2010
5. ↑ bmwclubsa.asn.au ( Memento from August 18, 2010 in the Internet Archive ) NN on streamlined vehicles from BMW and Dixi on the website of the BMW Driver's Club of South Australia (with a picture of Dixi "whale" at the end), accessed on 17. March 2010 (English).
6. ^ Ralf JF Kieselbach. BMW rarities: cars that never went into production. GeraMond Verlag, Munich 2007, pp. 45/46.
7. ↑ bmwclubsa.asn.au ( Memento from August 18, 2010 in the Internet Archive ) NN on the BMW K1 on the website of the BMW Driver's Club of South Australia , accessed on March 17, 2010 (English).
8. ↑ images and backgrounds to comb cars K3 on Mercedes basis on the website of Madle.org , accessed on March 17 of 2010.