Flying deck chair

The NSU record motorcycles Baumm I, II, III and IV, known as the flying deck chair , were designs based on an idea by the graphic artist Gustav Adolf Baumm . They were clad in a streamlined manner and the driver sat almost on his back in front of the engine in a bucket seat.

NSU tree IV

History and Development

On March 27, 1951, Baumm presented his draft of a streamlined motorcycle to those responsible at NSU Motorenwerke in Neckarsulm , which primarily considered possible dangers at high speeds. A bow that is pulled far down should counteract a lift that reduces steerability. An extremely low design kept the overturning moment low and a tail fin was supposed to compensate for the yaw moment in order to prevent the vehicle from breaking away in cross winds as much as possible. Operating the motorcycle from the unusual seating position seemed difficult. The handlebars are almost vertical next to the driver's legs, which are stretched forward and only slightly bent; The throttle grip, clutch lever and brake lever for the front wheel are attached as usual. Shifting is done with the left foot, the rear brake is operated with the right foot. The driver can reach the roadway with his feet through two flaps to support himself when starting and stopping.

After Gerd Stieler von Heydekampf , Chairman of the Board of Management of NSU Motorenwerke since 1953, and Head of Design Walter Froede had the vehicle built, Baumm made the first test drives in early 1954 and on April 27, he hit the speed record of 92 km / h that had been set by the 50- cc displacement class. With a two-stroke engine from NSU Quickly that had been upgraded to 3.4 hp , Baumm reached 127.34 km / h. Then the engine was switched to alcohol operation and world records followed in the 75 class over the "flying mile" at 127.8 km / h and over the "flying five kilometers" at 124.1 km / h. In total, there were eleven new records that NSU set with the vehicle.

Baumm also wanted to take part in motorcycle races with his “deck chair”. He had a fatal accident during a demonstration drive on the Nürburgring on May 23, 1955, which was supposed to prove the suitability of his design for racing.

NSU Rennfox engine with vertical shaft

Records with Baumm II and III

NSU continued to pursue the "Flying Deck Chair" project. In May 1956, HP Müller drove an economy test over 65 laps or 500 kilometers at the Hockenheimring at an average speed of 100 km / h and consumed just 5.65 liters of fuel thanks to the extremely low air resistance. That was 1.13 liters for 100 kilometers. This Baumm III had the 125 cc four-stroke engine of the NSU Superfox , was more comfortably equipped and slightly shorter than the Baumm II and Baumm IV, which were designed for maximum speed.

Record runs with Baumm II on the Bonneville Salt Flats in the USA followed in August 1956. H. P. Müller drove the motorcycle with different engines. With a 20 hp 125 cm³ Rennfox engine, it reached 239 km / h over a distance of 5 kilometers.

Baumm IV with a 250 cm³ two-cylinder engine, power 40 hp, and a drag coefficient of 0.11 (measured without fin) was not used. During test drives on the salt lake in July 1956, Wilhelm Herz overturned the model with an updraft at around 320 km / h, but survived unharmed thanks to the stable construction of the aluminum cockpit.

Technical specifications

Record motorcycle Baumm II 1956
Parameters	50 cc	100 cc	125 cc
engine	Single cylinder two-stroke with supercharger	Single cylinder four stroke
Displacement	49 cc	99.7 cm³	125 cc
Bore × stroke	40 × 39 mm	56 × 40.5 mm	58 x 47.5 mm
power	10 hp (7.4 kW) at 11,000 rpm	15.5 hp (11.4 kW) at 11,000 rpm	20 hp (14.7 kW) at 11,000 rpm
compression	k. A.		9.8: 1
Valve control	-	V-shaped hanging valves, overhead camshaft, drive by vertical shaft
coupling	Multi-disc dry clutch
transmission	Four-speed	Six-speed
Rear axle drive	Roller chain
construction	Light metal body, self-supporting
Front suspension	Pushed long arm swing arm with spring legs
Rear suspension	Swing arm with rubber band and shock absorber
wheelbase	1800 mm
wheel size	2.5 × 16 ″
Brakes	Full hub drum brakes, ø 150 mm
Dimensions L × W × H	3800 × 770 × 820 mm
Weight (without driver)	127 kg	140 kg
Records 1956	Over 1 km: 196 km / h Over 5 km: 196 km / h	Over 1 km: 222 km / h Over 5 km: 220 km / h	Over 1 km: 242 km / h Over 5 km: 239 km / h

Remarks

↑ The c _w value of 0.11 was determined on the original vehicle without the tail fin. A more recent measurement on a 1: 5 model with a tail fin resulted in a c _w value of 0.1318.

Individual evidence

↑ Ernst Hornickel: Records with and without a beard . In: Internationaler Motorsport , yearbook 1954, published by ADAC and AvD, Europa-Contact-Verlags-GmbH, Döffingen.
^ Peter Schneider: The NSU story. Motorbuch Verlag, Stuttgart 2012, ISBN 978-3-613-03397-9 .
^ Wilhelm Herz, Stations of a Life . Retrieved June 9, 2020.

[3] The c _w value of 0.11 was determined on the original vehicle without the tail fin. A more recent measurement on a 1: 5 model with a tail fin resulted in a c _w value of 0.1318.

[1] Ernst Hornickel: Records with and without a beard . In: Internationaler Motorsport , yearbook 1954, published by ADAC and AvD, Europa-Contact-Verlags-GmbH, Döffingen.

[Schneider-2] Peter Schneider: The NSU story. Motorbuch Verlag, Stuttgart 2012, ISBN 978-3-613-03397-9 .

[4] Wilhelm Herz, Stations of a Life . Retrieved June 9, 2020.