What better time than the 70th anniversary of the first production Porsche to set the record straight on a little-known chapter of the company's history? The early roles played by Ferdinand, his son Ferry, and his son-in-law Anton Piëch are well documented. But there's rarely mention of Adolf Rosenberger who was both present at the creation and a major architect of Porsche's engineering direction.
Rosenberger, who died in 1967, was an accomplished race driver and engineer. He was also a Jew who was forced out of Nazi Germany in the 1930s. He eventually moved to the United States, took a different name and for a while worked as a day laborer after he was unable to resume his automotive career.
Born in 1900 to a wealthy family in Pforzheim, Germany, Rosenberger had the means to race both motorcycles and sports cars. In 1924 and 1925, he won Stuttgart's Solitude road race driving a Benz RH (Rennwagen Heckmotor, or rear-engine racer), a teardrop-shaped, midengine sports car more commonly called the Tropfenwagen.
At the first German Grand Prix in 1926, Rosenberger and archrival Rudolf Caracciola each drove a front-engine Mercedes SS designed by Mercedes' technical director Ferdinand Porsche. Rosenberger was quicker in the wet but he was overcome by fumes leaking from an onboard ether tank used to start the supercharged six-cylinder engine. He passed out and crashed into a timing hut resulting in the death of three course marshals.
The next year Rosenberger and Caracciola faced off for the Eifelrennen, the first major sports car race at the Nürburgring. Both men drove Mercedes SSKs in the over-5,000cc class. Rosenberger, who by that time had 40 victories under his belt, finished a close second to Caracciola who went on to earn three European Grand Prix championships for Mercedes-Benz in the 1930s.
After his ideas fell out of favor at Daimler-Benz, Ferdinand Porsche returned to his Austrian homeland to work at Steyr, and he eventually established an independent design office in Stuttgart. The office at Kronenstrasse 24 opened late in 1930 for an enterprise called Dr. ing. h.c. Ferdinand Porsche GmbH, Konstruktionsburo fur Motoren- und Fahrzeugbau (design office for engine and motor vehicle construction). The company operated with nine designers including son Ferry Porsche.
Rosenberger, who was well acquainted with the Porsches through racing, was managing director. The elder Porsche supplied 80 percent of the seed money while Rosenberger and Piëch each contributed 10 percent. The enterprise was successful from the start, but when customers were slow to pay, engineers took home partial salaries. On one occasion, Rosenberger provided additional funds to sustain operations.
The money man, Rosenberger, also supplied inspiration. In 1932, Ferdinand Porsche resorted to his favorite endeavor — designing race cars — with an eye toward the 750-kilogram (maximum weight) Grand Prix formula scheduled for implementation in 1934. In a 1952 interview with author Griffith Borgeson, Rosenberger recalled his Benz RH exposure in the 1920s.
"I happen to have been the first person to drive those cars to success in racing and had a good idea of their good and bad points," he said. "They had only 65 horsepower but in one of the Solitude races we beat one of the 125-horsepower blown Mercedes. It was my experience driving that baby that led us to design a rear-engine car."
In other words, Rosenberger was instrumental in convincing the Porsche design team — Ferdinand Porsche, chief engineer Karl Rabe, and engine expert Josef Kales — that locating the engine behind the driver in Porsche's speculative Grand Prix racer was the way to go. The success of that first car helped distinguish Porsche as a rear-engine specialist to this day.
The midengine configuration provided several advantages over front-engine rivals: more load on the drive wheels, opportunity for a larger engine due to the tidy powerplant/transaxle integration, and minimal change in balance as the fuel was consumed.