‍The Incredible Benz Tropfenwagen, The First Mid-Engine Racecar

August 22, 2022

We take mid-engine cars for granted. Nearly every race car we watch or supercar we drool over has the engine behind the driver. When one looks back on the history of the automobile, this design that offers demonstrably better performance took a very, very long time to catch on. Most of us think back to the thunderous Auto Unions in the mid-30s and the little Cooper-Climax T43 that first saw F1 action in 1957. 

Nearly lost to history is the story of the Jewish engineer that first conceived of the design that would be the grandfather of the mid-engine layout, and gave rise to the Auto Unions, Porsches, and Coopers. His name was Edmund Rumpler and under the Third Reich’s terror, he was imprisoned and died in 1940, with his name being nearly erased. Let’s take a look at his incredible innovation and how it changed automobile design forever.

A Taube aircraft at the Rumpler manufacturing company in Berlin.

From Cars to Planes

Rumpler was born in Vienna, then part of the Austro-Hungarian Empire, in 1872. He was an automotive engineer by training during the early days of the car. At age 25, he collaborated with noted designer Hans Ledwinka to develop the Präsident -- the first car from what would be known as Tatra. 

It’s worth noting that Ledwinka also introduced the Rennzweier in 1900, a racecar that had its engine in the rear. However, it was a primitive machine, and this location was simply a different place to mount the engine, not a purposeful design to improve performance. Certainly, Rumpler made a mental note of this concept, as it would influence his thinking two decades later.

Edmund Rumpler

Rumpler moved on for a few years to Daimler, before taking over as head of technical design for German auto and motorcycle maker Adler in 1902. There he developed the design for the first engine to fully incorporate a gearbox as a single unit. His most notable invention, for which he was issued a patent, was the swing axle, a simple version of independent rear suspension. 

Rumpler got very excited about the Wright Brothers’ recent invention of the airplane in 1903. He left Adler in 1907 to launch Rumpler Aircraft Construction in 1910, one of the first airplane manufacturing companies in Germany. Mind you, he had never built an airplane in his life! 

He ended up licensing a design from a countryman for a monoplane called the Taube, or “pigeon.” Not long after, the Great War broke out and Rumpler’s plane was used by the military as a scouting aircraft. Afterward, the manufacture of airplanes was punitively banned for the losing Central Powers countries of Austria-Hungary, Germany, and the Ottoman Empire. Rumpler needed to find a new business, so he returned to his initial interest in cars.

Rumpler Tropfenwagen, the first mid-engine production road car.

Pioneering Aero Design

He took his newfound ideas on aerodynamics from planes, and wanted to apply them to automobiles. His first attempt was a passenger car that was in the shape of a teardrop. Thus, it was called the Tropfenwagen, or “teardrop vehicle.” Rumpler started with a clean sheet with his inspiration being a gondola under a zeppelin. 

Conventional cars of that era had the engine up front, with the gearbox attached on the back end, and the passenger compartment behind that. The front had a grill to hold the radiator for cooling, so it was very “draggy” and the rear was a block, which also disturbed the air and slowed the vehicle. 

The futuristic teardrop design had a rounded, bulbous front end that tapered to a point at the rear. Given the space available, it demanded the passenger compartment be positioned at the very front. The driver was in the center, with four passengers seated behind.

To make the drivetrain fit, he tucked a compact W-6 engine immediately behind the passengers, connected to a gearbox and differential. The Tropfenwagen had other features to smooth its shape including integrated front headlights, air intakes at the rear of the car for cooling, and a completely enclosed underbody. 

The new design had an astoundingly low drag coefficient of 0.28, which is impressive even by today’s standards. The great innovation that yielded the mid-engine was not yet known to improve driving performance, but rather for the reallocation of space to achieve better aerodynamic properties. 

The car debuted at the 1921 Berlin Auto Show. It was quite a spectacle, but the public didn’t know what to make of it. However, Willy Waub, the Berlin representative of Benz and future team director of Auto Union, saw the Rumpler Tropfenwagen and started getting some interesting ideas. 

The Rumpler Tropfenwagen went into production in 1921 as the first mid-engined production car. It was unusual, and had some drawbacks around reliability and luggage space, but it did get used in Berlin as a taxicab.

1923 Benz Typ RH without its body.

Inspiring a New Racecar

Based on Waub’s excitement, Benz’s technical director Hans Nibel made a deal with Rumpler for Benz to build a mid-engine car under license. In exchange, he let Rumpler use a more reliable Benz engine for his production cars. The first Benz mid-engine production car was essentially a convertible version of Rumpler’s car.

With that car under its belt, Nibel and his chassis builder Max Wagner took Rumpler’s ideas and applied the aerodynamic design to a race car, the Benz Typ RH -- which is widely known as the Benz Tropfenwagen. The car was produced in 1923 and made its mark on history as the first race car to use a mid-engine layout.  

The Typ RH was powered by an inline 6-cylinder engine with twin overhead camshafts operating 24 valves, with twin Zenith carbs. The normally aspirated engine produced 90 bhp. The inline six and 3-speed gearbox were compactly mounted between the cockpit and the rear axle.

A notable feature of the car was the radiator. To preserve the aero integrity of the bullet-shaped nose, the radiator was mounted just behind the cockpit above the engine. It was elegantly shaped so did not create significant drag.

The car made its debut in 1923 at the Grand Prix of Europe at Monza. Of three RH’s entered, two finished in fourth and fifth position. It was a promising start, but the cars were badly outmatched by the FIAT’s that used a blown engine. Had Benz opted for a supercharger, it may have brought on the mid-engine era a full decade sooner!

While the design was about aerodynamics, they realized that the driving dynamics were superior. The Benz Tropfenwagen had all of its heavy components placed around the center of gravity which made it more agile. This set off a few light bulbs, but it was far from perfect. One big problem with the design was that the fuel tank was mounted above the driver’s legs, so it sat high and forward. As the tank emptied, the driving dynamics would change drastically. 

1923 Grand Prix of Europe at Monza.

The Die Was Cast

Rumpler’s Tropfenwagen road car design, which was later interpreted by Nibel, may have been ahead of its time. Benz’s production of a mid-engine road car did not succeed, putting the company in financial distress. Ultimately, it drove the company to join forces with Daimler in 1926, to create what is now known as Daimler-Benz, the parent of Mercedes-Benz. 

Daimler’s chief engineer at that time was a name familiar to all: Dr. Ferdinand Porsche. Nibel and Porsche worked at equal levels, but in reality, Porsche had more responsibility. That was until Dr. Porsche had a falling out with management and left in 1928 when Nibel ascended to the role of chief engineer.

Porsche started his firm to consult and design automobiles in 1930. One of his business partners was Adolf Rosenberger, who was a racer who had privately campaigned a 1923 Benz Tropfenwagen for years and spoke highly of its incredible handling and performance. 

Based on Rosenberger’s feedback, Porsche started Project 22, called the P-Wagen Project, a design for a new Grand Prix car. He had no customer in mind but refined it nonetheless. It had a mid-engine design and incorporated the principles embodied in the 1923 Benz Tropfenwagen, but with a much more powerful engine. 

Two important events occurred in consecutive years. In 1932, Auto Union Gmbh was formed from a union of four underperforming German car manufacturers. Then in 1933 at the Berlin Auto Show, Hitler announced a state-supported motor racing program to promote the prowess of the German automobile industry.

Auto Union took Porsche’s designs and used them as the basis for their Grand Prix cars, Types A-D. They became the dominant machines from 1934 through 1939, winning numerous races with their innovative designs and powerful, supercharged V-16 engines. Porsche also took many other ideas that were later used in the Volkswagen and Porsche 356, including Rumpler’s swing arm suspension designs.

While Rumpler’s designs were directly used for Auto Union's “Silver Arrows”  program, by this point he had already been jailed once in 1933. Although he was soon released, he was unable to find work. In September 1940, the New York Times reported Rumpler’s death “while on holiday in Germany,” but that sounds dubious considering what we now know of the treatment of Jews under the new regime. The Nazis destroyed all of his records.

It is a tragic end for a man that combined his knowledge of cars and planes, to create a design that in 40 years time would become the standard of performance. His contribution to automotive history has endured, and hopefully so will Rumpler’s name as one of the great innovators of automotive design.

Sources

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