How Prop-driven Cars Work

You can call them early hybrids -- the propeller-driven cars of the early 1900s. On a prop-driven car, the motor doesn't turn the wheels; instead, it powers a propeller, much like that of an airplane (and often borrowed from one), mounted on the front or back of the car. The speed is controlled only by a throttle lever; no transmission (or gearbox) is used. At the time, this simplicity was believed to increase fuel economy, although, as it turned out, that wasn't always the case.

A propeller-driven car is a much simpler machine than our modern autos, but its stripped-down drivetrain has potential for peril. The propeller eliminates the need for a transmission, clutch and brakes, which in turn takes away a lot of the driver's control. However, it should be pointed out that the brakes could be quickly augmented by simply reversing the propeller's flow. Other aspects of the cars were similarly ingenious.

Though a handful of resourceful folks contributed to the propeller-driven car's maturation, French engineer Marcel Leyat is credited with most of the innovation and development that resulted in a somewhat usable vehicle. Based on his previous experience as an airplane builder, Leyat thought propeller-driven cars could achieve better fuel economy since the mechanics of the machine were simpler. Many of the first prop-driven cars were reconfigurations of existing cars, but eventually, other engineers realized that a car that was pushed forward by air should work with the airflow, not against it. Cars that were designed specifically to work with propellers (not just existing autos that were adapted) featured futuristic pod-like designs to cut smoothly through the air. The aerodynamic shape remains a noteworthy innovation; some of the same design principles are still evident -- even in our modern "green" cars.

These cars could really move, too, at speeds of up to 85 miles per hour (136.8 kilometers per hour). Modern prop-driven car experiments have yielded even higher speeds, up to 170 miles per hour (273.6 kilometers per hour. But the prop-driven cars' development and its integration into polite society were not a matter of smooth sailing. Simply consider the design: As a 1912 New York Times article pointed out, the propeller blades and related debris presented a considerable hazard to the car's occupants or "to any inquisitive person." And, just like now, weren't most people inquisitive back then?

How did the prop-driven car gain traction?

Marcel Leyat, the French engineer, developed the Helica, which achieved a reputation as one of the most prominent prop-driven cars of the day. The prototype was completed in 1913, and Leyat began selling it in 1919, with a production run of just six cars over two years. Leyat built other prop-driven models until 1926, for a total of about 25 to 30 cars. The Lane Motor Museum in Nashville counts a Helica replica among its collection. It employs an 18-horsepower Harley-Davidson engine (though a 1922 Helica advertisement refers to an 8-horsepower, V-twin, Anzani motor).

The Helicron, another French model, is a rare case of a gem actually found in a barn. Some point after its 1932 debut, the Helicron was stored in France, to be rediscovered in 2000. The Lane Motor Museum's professional restoration makes this one-off car a great example for studying their general design.

On different models, the propeller's mount varies from front and back, but both designs have disadvantages. A front-mounted prop will create considerable discomfort for the car's occupants from wind resistance and airborne objects, while the rear option is only efficient on a tapered body profile. The Helicron's propeller was front mounted and the car was steered by the rear wheels, which resulted in some control issues. The open cockpit might be a bit startling (after all, the car was notoriously difficult to control and capable of notably high speeds), but it was typical of aircraft and even other automobiles of the time.

Compared to modern safety standards, it might be a surprise that the Helicron, and prop-driven cars of similar design, were allowed on open roads. The sleek wooden craftsmanship offers some semblance of solidity, but according to the Lane Motor Museum, the Helicron's weight is only 1,000 pounds (453.6 kilograms) (the Leyat Helica, constructed mostly of aluminum, weighed in nearly 400 pounds (181.4 kilograms) less; for comparison, a VW Rabbit weighs about 1,700 pounds (771.1 kilograms).

Designed with an ABC Scorpion engine, the Helicron is currently powered by a Citroen GS 1.3 liter powerplant that achieves a cruise of 30 to 40 miles per hour (48.3 to 64.4 kilometers per hour). The Helicron is kept in good condition for the driving enjoyment of the museum's administrators, and often makes appearances at vintage car shows and Concours events. According to the 1912 New York Times, the ride was surprisingly smooth and "gondola-like."

Up next, we'll discuss what became of these soon-to-be-legendary vehicles.

What became of the prop-driven car?

In 1912, The New York Times described a hypothetical future in which all disillusioned traditional automobile owners could remedy their woes by throwing "the offending details on the scrap heap" and modifying their cars with propellers, causing airplane makers to weep for the future. Well, that hasn't quite been the case, though there have been some new, successful propeller-driven builds and a few survivors from the olden days. Two of Marcel Leyat's Helicas are still in existence, as well as a handful of other rare, privately owned specimens. The Lane Motor Museum has hosted a couple other models of prop car, and similar technology has even been used to give bicycles a boost.

The latest prop-driven cars have generally been one-of-a-kind experiments. A Florida man by the name of Franklin Ratliff achieved moderate Internet fame after he spent $17,000 to build a tube-frame prop car capable of 50 to 60 miles per hour (80.5 to 96.6 kilometers per hour). He enlisted the help of motorsports experts for the design, and spent nearly 10 years completing the project.

At times, people have considered modern attempts to revive the prop-driven car for the masses. As recently as six decades ago, California was considering population reduction in the form of mass-produced, easily available propeller cars. Obviously, the idea never gained much traction, and it's just as well; in light of the state's current environmental crisis, no good could have come from a notoriously inefficient propeller mated to the planned Chevy 6-cylinder powerplant -- but at least there are plenty of hybrids roaming the streets.

The next page will breeze you toward more information about propeller cars and other unusual vehicles.

Faster than the Wind

Prop-driven cars use a small motor to spool up a propeller, which generates power to the wheels. By pushing the power transfer a few steps farther, however, a team called "Faster than the Wind" built a new record-setting propeller-driven cart. It works like this: The wind pushes the cart and as the wheels roll, they generate power, which is transferred to power the propeller, which generates more power to be transferred back to the wheels. Thanks to a super resilient transmission, all of this power enabled the cart to travel at 2.8 times the speed of the wind.

Lots More Information

Sources

Barry, Keith. "Proving It: Wind-Powered Car Goes Faster Than The Wind." Wired. July 29, 2010. (Feb. 23, 2011) http://www.wired.com/autopia/2010/07/its-settled-downwind-faster-than-the-wind-officially-possible/
Dark Roasted Blend. "Cars with Propellers: an Illustrated Overview." Dec. 31, 2008. (Feb. 16, 2011) http://www.darkroastedblend.com/2008/12/cars-with-propellers-essential.html
Diseno-art. "Helicron No.1." (Feb. 23, 2011) http://www.diseno-art.com/encyclopedia/strange_vehicles/helicron.html
Lane Motor Museum. "A Closer Look: The 1919 Leyat Helica Replica." Dec. 2, 2009. (Feb. 23, 2011) http://blog.lanemotormuseum.org/2009/12/a-closer-look-at-the-1919-leyat-helica/
Modern Mechanix. "Prop-Driven Car Makes 85 M.P.H." Feb. 12, 2008. Originally printed November 1934. (Feb. 16, 2011) http://blog.modernmechanix.com/2008/02/12/prop-driven-car-makes-85-mph/
New York Times, The. "Successful Test of Air-Propelled Car -- British Auto Expert Admits Real Advantages for Machine Minus Clutch and Gearbox." Aug. 25, 1912. (Feb. 20, 2011) http://query.nytimes.com/mem/archive-free/pdf?res=F30E1EFA3A5E13738DDDAC0A94D0405B828DF1D3
Riley, Greg. "Riding the Wind -- The Helicron." Old Cars Weekly. (Feb. 23, 2011) http://www.oldcarsweekly.com/article/Riding_the_Wind_The_Helicron/
Roadable Times. "The Helica." (Feb. 23, 2011) http://www.roadabletimes.com/roadable_experi_helica.html
Spinelli, Mike. "Prop-Driven Car Draws Flames." Jalopnik. Jan. 5, 2006. (Feb. 20, 2011) http://jalopnik.com/#!146820/prop+driven-car-draws-flames
Strohl, Daniel. "SIA Flashback -- Cars That Woosh." Hemmings Blog. Dec. 21, 2008. (Feb. 20, 2011) http://blog.hemmings.com/index.php/2008/12/21/sia-flashback-cars-that-whoosh/