Paper 8: The NSU Prinz Engine

As the automobile becomes an indispensable consumer article for all strata of society, its importance as the status symbol of a definite social position declines more and more. This natural process of development has obviously been accelerated by special traffic problems the origin of which must be looked for in the good economic circumstances of the past years. Only they could cause motorization to take such great steps forward.

Amongst the many constructions which were created with the intention of combining the requirements of daily professional and town traffic with a comfort sufficient also for extensive holiday travel, the NSU Prinz, as designed in 1955 and then produced in series as Prinz I and II and since May 1961 in its present form, seems to meet the requirements of a large and steadily increasing circle of buyers.

The maintainable speed of about 120 km/h, which is quite sufficient even for fast roads and motorways, has been obtained with a motor performance of 30 hp at an air resistance c_w = 0·43 and a front area of 1·57 m², which allows good elbow and head room to the passengers. A four-stroke motor of relatively expensive construction with hemispherical combustion chamber and overhead camshaft was chosen which enables the car to have a good fuel economy. In consideration of town traffic we have stressed the good combustion in the neutral position and the lower partial load range, in order to keep the CO content of the exhaust gases low. We succeeded, in designing the body, in keeping the change of the yawing moment in accordance with the angle of attack, within very modest limits.

The dry weight of 537 kg is far below average and could only be attained with considerable effort and after extensive measurements had been carried out. In this manner the drive unit, inclusive of suction and exhaust devices, weighs 100 kg, the chassis (axles, wheels, suspensions and steering parts) 127 kg, the body (raw) 168 kg, glass 28 kg and seats and fittings 114 kg.

The ratio of vehicle weight to permissible total weight of 1:1·86 naturally requires an exact study of the chassis and distribution of weight. The centre of gravity changes its position with the different loads in a longitudinal direction by less than 5 per cent from the centre of the wheel base to the front and to the back. This small deviation causes a type of steering behaviour which remains almost static with all loads. In every case the vehicle is slightly under-steered. In this connection we obtained the measurement values for μθ of 0·55 with one passenger and of 0·54 with four passengers.

Thus we believe that the driving behaviour of this vehicle takes into account the circumstances of modern traffic and that the usable space offers sufficient comfort for four or five people. For how long the shape of body will correspond to the public taste is a matter of conjecture: however we hope and also believe that the choice which can today be observed, of the simple form which refuses any superfluous decoration, will last for rather a long time.