AUTO UNION D – year 1938

AutoUnion AG, Zwickau, Germany.

The Auto Union concern has prepared for the season 1938 a new car with a 12-cylinder capacity engine 2990 cm3 (∅ 65 x 75 mm), meeting the requirements of the new three-liter formula including engines and compressor. The shorter V-engine took up less space, so that the centrally located driver's seat could be moved to the rear. The chassis was also changed, retaining only the chromomolybdenum steel tubular frame - proven in A models, B i C. Rear, the swinging bridge was replaced by a de Dion rigid bridge. Lateral forces were transferred by Panhard rods. The springs were left unchanged, only torsion bars with softer characteristics were introduced. Hydraulic shock absorbers are used in the front, and at the rear - hydraulic-mechanical.

The 90 ° cylinder engine had three camshafts. The central shaft controlled the intake valves, and the side ones opened the exhaust valves. The crankshaft drove the Roots two-stage compressor under pressure 190 kPa. The main and crank pins were originally mounted in plain bearings, and later in rolling, which is why a crankshaft consisting of several parts was used. Individual elements were equipped with Hirth teeth used in aircraft engines and were connected with bolts. The engine reached its maximum power 357 kW (485 KM) by 7000 RPM. Huge fuel consumption (80-1151/100 km) required the installation of three fuel tanks. Vehicle with total weight 1195 kg was developing a maximum speed 290-340 km / h depending on the gear used. 28 January 1938 During the attempt to break the speed record on the Frankfurt-Darmstadt route, the main rider of the Auto Union team died in the year – Bernd Rosemeyer. For this reason, in the years 1938 i 1939 the company hired an excellent Italian driver Nuvolari, who won the Grand Prix in Monza in his first year (155,6 km/h) i w Donington (129,5 km/h). For the Grand Prix race in Reims, where it was possible to develop high speed, the D model was prepared with a streamlined body that also covers the wheels. However, during the training, player Hasse had an accident and work on the model was stopped, and Herman Paul Muller won in Reims, driving car with a classic body. In the same year, Nuvolari won another victory for Auto Union, reaching an average speed in the last pre-war Yugoslav Grand Prix race 129,9 km/h.