BMW’s K4 streamliner – Throwback Thursday
Throughout a tour of the French motor research facility in 1946, Autocar’s Paris correspondent, WF Bradley, happened upon two rare BMWs that were grabbed from the Stuttgart research base in the finish of World War Ii.
The very first was simple to identify – the 328 Berlinetta Touring that were driven to BMW’s first and just victory within the Mille Miglia in 1940 – however the second was more curious. The job of prominent aerodynamicist Wunibald Kamm, the K4 was an experimental vehicle created to investigate “streamlining, highspeed road-holding and economy of operation”, within the words of Bradley.
Bereft of solid detail, Autocar’s man gleaned what he could in the French engineers. “The is both intriguing and surprising, the surprising feature becoming an almost vertical rear panel,” he authored. “The under surface is perfectly flat, the headlights are positioned in to the wings, the windshield is rounded in to the side panels and also the driving wheels are enclosed.”
It had been certainly distinctive, broadly in line with the luxurious 335 model and including front ‘suicide doors’ that hinged from the B-support beams, as did the traditional rear doorways.
The K4 were built with a drag coefficient of .196 at any given time when contemporary saloons were around .5Cd, but tinkering with the rules of aerodynamics without using computational fluid dynamics meant research would be a situation of learning from mistakes.
To make the vehicle stable as fast as possible, there was experiments with fins. “A single fin, without or with slots, has little impact on stability and might be harmful,” authored Bradley. “To be useful, the fin should have excessive dimensions. Two fins without slots isn’t any better. There is a inclination to deviate the automobile from the straight course, and they’ve a lifting effect in the rear.
“The the best results are acquired by a set of slotted fins, really composed of the fin along with a rudder. The machine is performed in Plexiglas.”
The K4 were built with a 3.5-litre six-cylinder engine, producing 88bhp. The engine was outfitted having a dual carburettor, “part being employed for normal running and yet another part entering action over the past movement from the throttle pedal”.
A four-speed gear box driving the trunk wheels was augmented with a planetary overdrive. “Road tests through the French revealed the outstanding the best-selling overdrive,” Bradley remarked.
Although the engineers tested on roads comprising hillsides, high-traffic and built-up areas, the K4 still came back impressive gas mileage. At 77mph and 1950rpm, it had been measured at 24.4mpg at 35mph and 900rpm it improved to 32mpg. “Certainly far better results might have been acquired around the German autobahnen,” mulled Bradley.
Because of the poor condition from the K4’s tyres, the engineers were not able to check the vehicle at its maximum speed of 90mph. The vehicle also had automatic steering wheel pressure regulation to modulate moving resistance, even though some areas of the machine were missing and also the engineers were not able to ensure its usefulness.
The fate from the K4 is unclear, but it’s likely it had been dismantled through the French engineers curious to understand all its secrets. The philosophy behind the vehicle continues to be vital that you BMW as always, with 2009’s Vision Efficient Dynamics concept hailed like a modern equal to the K4 and as a result inspiring the i8.
12 April 1946
Previous Throwback Thursdays
16 May 1987 – Ford Escort XR3i Cabriolet
17 October 1981 – The ￡12,000 baby Aston Martin
16 The month of january 1985 – The launch from the Sinclair C5
15 April 1960 – Porsche’s four-cylinder roots
17 August 2004 – The Honda NSX’s last hurrah
11 October 1986 – Hyundai’s second United kingdom market foray
15 March 1980 – Triumph’s TR7 Drophead
13 Feb 1991 – Mercedes F100 predicts future vehicle technology
16 April 1997 – A contemporary ‘Blower’ Bentley
19 June 1991 – Volkswagen Polo G40 tested
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