History of The Rotary Engine

Early Rotary Applications

NSU/Wankel Spider, 1963

DSC_0766

ENGINE: KKM 502
DISPLACEMENT: 497 cc Single Rotor
POWER: 50 hp @ 6,000 rpm

Based on an existing convertible prototype from Bertone, the in-house design studio converted the Sport Prinz into an open-top, sleek two-seater. To ensure production that was halfway efficient, as many elements of the coupé as possible had to be incorporated into the new Spider. In June 1963, the first prototype, referred to initially as the NSU Type 56 “Spider”, was moving under its own power.

In September 1963, it was presented to the trade press and the public as the NSU/Wankel Spider during the International Motor Show in Frankfurt. Just one year later, on 29th September 1964, the first Spider rolled off the production line. It was preceded by a pilot series of thirteen vehicles, the first five of which were pure test vehicles for a range of rotary piston test engines. As a way of thanking the employees, NSU drew lots to give away the first Spider to someone in the workforce. Willi Kapp, a body construction worker, was the lucky recipient; unfortunately for him as a family man with two children, the Spider was not really a suitable car. NSU was accommodating towards him and swapped the car for a new Prinz 1000.

Many of the design features from the Sport Prinz were changed for the Spider. The floor assembly is flat, has a diagonal cross and solidly reinforced longitudinal struts, so as to strengthen the roofless chassis. The interior was extremely puristic and illustrated the sporty character of the car; in particular the cockpit with a central rev counter was incredibly sleek. The entire dashboard including switches, levers and instruments were completely redesigned, including its grey padded lining.

Both of the individual seats offer firm support and the gear lever is extremely easy to reach in the middle, adding to its sporty aesthetic. At the front the water cooler and the 35 litre fuel tank restrict the amount of luggage space, but there is another storage option above the engine located at the rear. In inclement weather, a fabric roof can be pulled over both passengers, although it does not have much head room; The convertible top is less of an obstacle to the car’s aerodynamics. The new Spider received rapturous praise in the press: It was acclaimed as a wonder car and touted as the means of transport of the future. For all the euphoria, customers were fairly reticent; just 2375 units of this first Wankel-powered car were built from September 1964 through to July 1967.

The Engine of the NSU/Wankel Spider

What was really sensational about the vehicle was it’s drive. The Wankel Spider was the first mass-produced car to be powered by a single-disc rotary engine. The KKM 502 type engine had a chamber volume of 497 cc and delivered 50 hp. With what is known as an underfloor drive, the unit was positioned very deep in the rear of the car. If one opened the flaps, the first sight took a little getting used to. Visually in comparison with a reciprocating piston engine, the rotary unit is round by virtue of the engine housing. The auxiliary units arranged around it – such as the alternator, Bosch thyristor ignistion system, starter motor, and oil cooler placed on the left of the flat-side Solex carburettor – also looked unusual at first glance in comparison to the norm of the time. The required fresh air was sucked in from above the tailgate, and to reduce noise, the intake air passed through an airbox integrated into the tailgate beforehand. The engine, with its single dry clutch, was installed behind the driveshafts, and the sychronised four speed manual was in front. To relieve the weight, NSU installed the oil cooler and an electric fan in the nose. The 11.5 litres of coolant were stored at the front and were passed through a central cooling tunnel to the engine at the rear.

The NSU/Wankel Spider in Motorsport

With its small, lightweigh engine, the Spider was also successful in motorsport. Thanks to an enlarged trochoid, a new intake manifold and carburettor from Stromberg, a new gearbox and a stiffer chassis, the Spider now produced 90 hp and was ready for competition. In 1966, Karl Heinz Panowitz and Rainer Strunz claimed five 1st places and three 2nd place finishes of their eight races in the Spider, which meant they won the German GT Rally Championship in all classes. They thus became the world’s first motor racing champions to drive a Wankel engined vehicle. In the same year, Siegfried Spiess came second behind a Porsche in the German Hill Climb Championship for GT and sports cars and went one better than this result a year later by winning the German Automobile Hill Climb Championship for all capacity classes and categories. He managed the same feat once again in 1968. This meant three championships for the Spider in three successive years in Germany alone. The Spider also boasted success abroad; Alexander Maniatopoulos became Greek Automobile Champion in 1966 and Christine Beckers became Belgian Hill Climb Champion in 1967, both thanks to the nimble Spider.

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