Simanaitis Says

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THE 1921 RUMPLER TROPFENWAGEN—AERO WONDER AND MOVIE STAR. PART 1

WHAT DOES THE 1921 Rumpler Tropfenwagen have in common with the 1933 Napier-Railton? And, even more obscurely, what ties these two cars with my own personal driving experience?

An article in R&T, March 1956, prompted these queries. Indeed, tidbits follow in Parts 1 and 2 today and tomorrow. (I’m always delighted when something encourages additional sleuthing.)

The 1921 Rumpler Tropfenwagen. This and other images from R&T, March 1956

A Very Advanced Concept. “In 1915,” R&T wrote in March, 1956, “Dr. Rumpler, a well known German aeronautical engineer [he, of the Etrich Taube monoplane], drew up plans for a very advanced type of automobile, and the grotesque but efficient creation of these pages was the result.” 

Edmund Rumpler’s original 1915 design was a mid-engine open car, with twin spares carried beneath the floor.

“The original design premise,” R&T explained, “was based on the theory that a tear-drop shape would be more efficient, giving better economy and top speed with less horsepower.” The word Tropfenwagen literally means “drop car.” However, R&T noted, “… no one seems to know whether the name refers to the tear-drop shape or to the possibility of attaching the complete car to the underside of a Zeppelin, for carrying passengers gondola-style.” 

I’ll stick to the tear-drop. 

An Early Mid-Engine Design. The Rumpler’s integrated unit of engine, transmission, and final drive was mounted immediately ahead of the rear axle. “To reduce length somewhat, the designer chose a W-6 type engine, consisting of three banks of two cylinders each.”

The Rumpler chassis, with its three-bank W-6 mounted ahead of the rear axle. Cantilevered leaf springs were fitted, front and rear. Image from curbsideclassic.com.

The Rumpler and Napier-Railton. And therein lies the answer to my opening query: The Rumpler shared this W, aka broad-arrow, layout with the John Cobb’s Napier-Railton Brooklands record car. A significant difference: The Napier-Railton was a W-12, three banks of four displacing a total of 24.0 liters. The Rumpler’s W-6 displaced 2.8 liters.

Aerodynamic Features. The Tropfenwagen’s mid engine enhanced its teardrop aerodynamics. Its nearly flat “fenders” contributed considerably less drag than the classic airflow-grabbing variety. Front fenders were two-level; this, to enhance wheel-spray diversion. Rear fenders directed air into louvers for the water-cooled engine’s radiator.

The radiator for its rear-mounted W-6 profited from louvred airflow. Curved windscreen and two-level front fenders enhanced aerodynamics.

The car’s curved windscreen is noteworthy for the era. Its driver had a central seat, with two passengers aft. Optional jump seats added two more.   

Chassis Details. R&T, March 1956, wrote, “All four wheels were independently sprung, the rear end being the ‘swing-axle’ type.” Other sources report that the front suspension was a beam axle, not independent. However, a propensity for front-wheel shimmy was also noted.

“Brakes are something else,” R&T reported, “and a brief ride down Wilshire Boulevard in Los Angeles was a harrowing experience for both driver and passenger.” It’s likely that the car’s front-wheel shimmy, rear weight bias, and swing-axle contributed to the adventure.

Tomorrow in Part 2, we’ll learn more about Rumpler W-6 technicalities, my second query about personal links, and the car’s movie stardom. ds

© Dennis Simanaitis, SimanaitisSays.com, 2020 

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