Born on July 15, 1906, Rudolf Uhlenhaut was an engineer and designer of Anglo-German descent, who later sat on the Board of Management at Daimler-Benz. He fathered designs for many vehicles, including the Silver Arrows, the 300 SL with the famous gullwing doors and the Mercedes-Benz 300 SLR. Some of the larger series also owe a debt to Uhlenhaut.
Uhlenhaut, son of an English mother and German father, was born in London, where his father was the manager of a branch of Deutsche Bank. From there the family moved first to Brussels, later to Bremen. As a student he followed his passion for skiing and headed to Munich to study mechanical engineering. He joined Daimler-Benz in Stuttgart as a young engineer in 1931 and began his career in the test department under Fritz Nallinger, where he experimented with carburettors and worked on developments such as the Mercedes-Benz 170 V.
In 1936 Uhlenhaut took over as head of the racing department. As its new technical director his brief was to put racing cars sporting the three-pointed star back on course for success – and that is precisely what he did. The young engineer spent many thousands of kilometres at the wheel, testing the racing cars himself in order to get a feel for their deficiencies. That the W 25 Silver Arrow once again became competitive was largely thanks to Uhlenhaut. After extensive revision, the W 125 Silver Arrow was the supreme car of the 1937 Grand Prix season, and Rudolf Caracciola was crowned European champion. This car was succeeded by the W 154 which dominated the 1938 and 1939 seasons.
With the outbreak of the Second World War, Mercedes-Benz did not develop another competitive sports car until the early 1950s. In April 1949 Uhlenhaut was appointed head of the passenger car test department. On June 15, 1951, the Daimler-Benz board took the decision to return to international racing. But with a change to Formula One regulations expected for the 1954 season, the company decided to wait until these had been announced.
In the meantime it developed a sports car that would revive the tradition of success built over the major international long-distance races of the 1930s. Taking as his starting point the production engine from the Mercedes-Benz 300, Uhlenhaut encased this in a tubular frame and aluminium body. The legendary 300 SL “Gullwing” was born – initially as a thoroughbred racing sports car (W 194).
Despite a string of race victories, the carmakers from Untertürkheim were not interested at first in bringing out a version of the car for public use. Then one day a businessman by the name of Maximilian (“Maxi”) Hoffman got in touch from the USA. His plan was to import 1,000 road versions of the car and he managed to convince the Board of Management of the efficacy of his idea. Eventually a road version of the 300 SL (W 198) and the smaller open-topped 190 SL (W 121) were unveiled to the motoring world at the International Motor Sports Show in New York in 1954. From that moment, crowned heads and celebrities alike clamoured for a chance to be seen in the new sports car.
It was equipped with the first four-stroke engine to feature direct petrol injection, a unit that delivered 215 hp (158 kW). Another of the car’s innovative features was its space frame. For reasons of stability the frame of the coupé had to be raised down either side of the car, making the use of conventional doors impossible. This gave Uhlenhaut the idea of “gullwing” doors.
In parallel to passenger car development, Uhlenhaut also designed the new W 196 Formula One car, the Silver Arrow for the post-war period. Uhlenhaut never managed more than to drive the car under test conditions – he was debarred from entering races because the Board of Management was unwilling to risk losing one of its most able members. However, his official car will live long in the memory, the legendary Uhlenhaut Coupé, which thanks to its thoroughbred racing technology gave a top speed of 290 km/h (180 mph) and made it the fastest car of its day authorised for road use.
Uhlenhaut was always thinking of improvements for his racing cars, and he was not averse to rolling up his sleeves at dusty rallies and taking a spanner to the cars himself. Cases involving his drivers are many and well-documented. In 1955 after a test session on the Nürburgring, for example, world champion driver Juan Manuel Fangio reported that the car was not quite set up as it should be. So after a substantial lunch Uhlenhaut climbed into the car, dressed in suit and tie, and lapped the Ring three seconds faster than the world champion. When Uhlenhaut pulled up alongside Fangio he told him it was nothing a little practice wouldn’t put right.
When Daimler-Benz withdrew from Grand Prix racing in 1955, Uhlenhaut focused his attention as Chief Engineer in Passenger Car Development exclusively on production models. He was jointly responsible for all model series of the day up to and including the S-Class of 1972 (W 116). He also had a major influence on another eye-catching design from Sindelfingen, the 230 SL – christened by car fans the Pagoda on account of its spectacular roof design.
The Mercedes-Benz 300 SL (W 194 series) racing car unveiled in 1952 was clearly engineer Rudolf Uhlenhaut’s achievement. For it was Uhlenhaut, one of the rare automotive specialists with a great talent for design, who created it, laying the basis for racing successes as well as for the subsequent 300 SL (W 198) production sports car.
After his graduation in 1931, Rudolf Uhlenhaut was recruited by Research Director Fritz Nallinger, initially as plant assistant for testing. Nallinger rapidly recognised Uhlenhaut’s skill as a “driving engineer.” Because Uhlenhaut would drive whatever he could get his hands on – and did so rapidly and consummately tackling anything, for example, from the monstrous Mercedes-Benz G 4 three-axle off-road vehicle to the 500 K lightweight sports roadster, the latter in the tour “2000 km through Germany” – Uhlenhaut felt at home in any and everything that had wheels. His successful career as a racing-car developer from 1936 was also initiated by Nallinger.
But how did Uhlenhaut’s brilliant creations come about? The answer lies in his multifaceted personality. He was born in London in 1906 – English was his first language – and embraced engineering as a career. However, if one were to imagine him as a designer in a white lab coat standing at the drawing board, as was usual in those times, one would have to think again! Because Uhlenhaut was more likely to be found in some vehicle or other, or in the workshops devising solutions with his colleagues. There is a famous anecdote from the 1950s: on one occasion he sent two young engineers to his friend Josef Müller in the design department and announced them by phone with the following statement: “Josef, I’m sending two of my youngsters over. Please have your people retrace whatever they tell you. And mind you, I mean retrace, and not rethink!”
Two things were highly typical of Uhlenhaut: he developed his ideas from practical experience and he always treated his colleagues, whether in the workshop or in the office, as equals and never patronised them. His composure and authority coupled with his competence meant that his superiors also treated him on an equal standing, too.
After the Second World War, Uhlenhaut soon became involved with sports vehicles again. He was employed by British Colonel Michael McEvoy of the Royal Electrical and Mechanical Engineers to build a small racing car for him. Both had been acquainted in the pre-war years, when McEvoy was working on the installation of Zoller compressors in racing engines. Uhlenhaut designed a frame made from closed tubular triangles for the small racing car. The individual tubular segments were only stressed through pressure or tensioning. This enabled the frame to be lightweight yet sturdy, guaranteeing a high degree of torsional and bending rigidity. The idea of segments subjected only to tensional and compressive forces was new although tubiform frames had in fact existed before then. Uhlenhaut adopted the space frame principle for the 300 SL racing car (W 194 series): the frame had a final weight of between 64 and 68 kilograms, which not only made it lighter but also more torsionally rigid than the X-oval tubular frame of the pre-war W 154.
Due to time and cost constraints, it was imperative for Uhlenhaut to use the engine from the prestigious Mercedes-Benz 300 saloon (W 186 series) for the 300 SL, so he reflected on ways to reduce the vehicle’s aerodynamic resistance. The solution: rotating the engine by 50 degrees towards the left and providing it with a dry-sump lubrication system enabled the height to be reduced. Thanks to this change the 300 SL had a very low front and low head resistance.
Uhlenhaut’s concept was successful. In December 1952 he summed up the sports performance of the 300 SL with the following words: “The races run in 1952 have shown that the 300 SL with a naturally-aspirated engine was at least equal – if not superior – to even the strongest opponent; but also that its acceleration on good roads was significantly less than that of the Ferrari 4.1 litre, and somewhat lower than that of the Ferrari 3 litre and 2.3-litre Gordini. However, the opponents’ inferior operational reliability and the great endurance of the 300 SL generally led to victory for our brand.”
Uhlenhaut’s concept for the 300 SL – and in particular the car with chassis number 11, further developed and prepared by him for the 1953 racing season – was so convincing that it was adopted for the new racing cars for the 1954/55 seasons. As Head of Development for Passenger Cars he had a decisive role in the development and suspension tuning of all SL models up until the 107 series that had its premiere in 1971.
During his lifetime Rudolf Uhlenhaut never owned a car of his own. In old age he needed a hearing aid, something he attributed to a lifetime driving and testing his racing cars. He took retirement in 1972.
Rudolf Uhlenhaut died in Stuttgart on May 8, 1989, at the age of 82 years.