Credit Leonardo DaVinci for creating what many historians believe was the first depiction of a self-powered vehicle. It was powered by springs. And in the centuries since then, engineers have found increasingly complex and interesting solutions for vehicle propulsion.
Steam came first. Nicolas-Joseph Cugnot’s 1769 steam tractor is generally believed to be the first self-propelled road vehicle. By the 1830s steam carriages carried passengers on roadways in Britain. During this period another technology was emerging. In the 1830s, American blacksmith Thomas Davenport’s experiments with electricity and electromagnetism led him to patent an electric motor. When battery technology finally caught up with this vision in the 1880s, the recipe for the first electric cars was born.
By the early 20th century, EVs accounted for 38% of all cars manufactured in the U.S., nearly eclipsing the popularity of steam. But the boiler bunch didn’t die easily. Stanley, the Massachusetts-based company most closely associated with steam cars, stayed in business until 1924.
Ironically, it was Thomas Edison who predicted that horseless vehicles wouldn’t run on electricity or steam. In 1895 he rightly opined that future vehicles likely “will be run by a gasoline or naptha motor of some kind.”
The key enabler emerged on January 10, 1901 at Spindletop, a presumed oil field near Beaumont, Texas. When the prospectors struck oil there, the resulting gusher raged for nine days at an estimated rate of 100,000 barrels per day. This set off the Texas oil boom, making the U.S. the world’s biggest petroleum producer—and making an abundant motor fuel available for mass consumption.
With cheap oil and easy-to-use cars that could be produced at an affordable price—led by Henry Ford’s Model T in 1908—the internal combustion engine finally had everything required to establish its dominance for over a century. Over the years various challengers to the ICE have appeared, some of them produced in volume. This year’s ever-popular SAE Mobility History Committee display and presentations at WCX’19 highlight some of the more interesting alt-power propositions.
Gas turbines: Vehicle OEMs began exploring the potential for gas-turbine-powered cars and trucks soon after World War II. Chrysler Corp. created a dedicated R&D group that ultimately developed seven generations of small turbine engines through the 1970s. They were installed in a series of testbed vehicles, the most famous being the 50 identical 1963 “Turbine Cars”—two-door Chrysler coupes painted in “Turbine Bronze” livery. They were demonstrated to the public at the 1964 World’s Fair. One example of the nine that are known to exist today is owned by FCA and on display at WCX’19.
The Turbine Cars were powered by the fourth-generation Chrysler-engineered and manufactured A-831 engine. It was rated at 130 hp (97 kW) at 36,000 rpm, and 425 lb⋅ft (576 N⋅m). Idle speed was 18,000-22,000 rpm. The engine weighed 410 lb (186 kg) and could operate on a variety of fuels—even tequila, as Chrysler engineers proved during a driving demonstration with Mexican president Adolfo López Mateos at the wheel.
Nuclear reactors: Another propulsion idea that emerged from the technologies of World War II was that of nuclear power for ships, aircraft…and ground vehicles. Ford’s Nucleon, a 1958 concept, was a modernistic pickup theme that explored how the future of energy might impact automotive design. It was to be powered by a small reactor mounted under the rear bed. A lead shield was envisioned to protect occupants from the radioactivity.
Ford believed a production Nucleon could deliver 5000 miles of operation before the reactor core would require uranium refueling—something that planners surmised could be done at dedicated refueling stations. The Nucleon concept never made it past a single 3/8-scale model (shown) that resides in The Henry Ford museum in Michigan. Ford revived the nuke idea on its Seattle-ite XXI concept in 1962. Studebaker-Packard also showed an atom-splitting concept, the Astral in 1957.
Fuel cells: During the Cold War an old technology began its slow trek into automobiles. The hydrogen fuel cell, originally conceived in 1801 and first built in 1842, returned as an important power-source during the space race. In the 1960s and ‘70s NASA used fuel cells as on-board power generators in the Apollo capsules and lunar modules. During this period General Motors began testing the use of fuel cells in vehicles. The stacks and their fuel tanks consumed so much space that GM developed an entire vehicle, the ElectroVan, around the propulsion system.
Interest in FCVs as a potential solution for reducing vehicle and well-to-wheels emissions began to grow. But fuel cells didn’t become viable for mass-production vehicles until 2001 with the invention of the 700-bar hydrogen tank. This technology greatly reduced the package space required and extended the FCV’s range. Since then GM, Daimler, Hyundai, Honda and Toyota launched FCV development programs. Hyundai’s latest FCV, the Nexo, debuted in 2018. It is on display at WCX’19 in Hyundai’s floor exhibit.
According to Hyundai engineers, the Nexo achieves 60% fuel cell system efficiency, compared to 55% on the previous-generation (Tuscon-based) FCV. Based on this improvement, along with an increase in the hydrogen storage available on board—three tanks that each hold 6.3 kg (13.9 lb) of hydrogen—the Nexo's driving range could reach over 800 km (497 mi) in NEDC city mode, and over 370 miles on the U.S. test cycle. The Tuscon FCV’s range was rated at 265 miles in the U.S.
The Mazda rotary: In 1961, Mazda parent Toyo Kogyo was pursuing engine technology to differentiate it from the Japanese mainstream. Company leaders saw great promise in the smooth running, power-dense and package-efficient rotary invented by Felix Wankel. They licensed technology from Wankel GmbH and NSU Motorenwerke, and a team of 47 young engineers under Kenichi Yamamoto began development. At the time, sealing of the rotor tips against their friction surface was an ongoing challenge. It took the R&D team nearly two years to design, engineer and validate a robust seal made from aluminum-carbon composite. Their innovation enabled the rotary engine to blossom at Mazda.
Single-rotor engines led to twin-rotor units, first available in the 1967 Cosmo Sport 110S. Its 10A engine generated just 110 hp and 96 lb·ft, but the car’s low mass made it peppy and nimble. Mazda put many iterations of its rotaries in sports cars, sedans, pickup trucks, even buses. Twin-turbocharged versions of the three-rotor 20B engine delivered 300 hp and 300 lb-ft in the RX-7. A 700-hp, four-rotor race version powered a Mazda prototype to overall victory at Le Mans in 1991.
Mazda engineers worked hard to keep the rotary emissions-compliant under tightening global air-quality regulation. They developed a unique thermal reactor to burn HC residuals, and continued to make significant efficiency gains. An all-new ‘Renesis’ version debuted in 2003 to power the RX-8, but by then Mazda had moved primarily to a piston-engine strategy. A hydrogen-fuel development program showed promise for extending the rotary’s life, and in 2006 Mazda offered H2-powered RX-7 RE models for lease.
While the 13B rotary became a favorite of homebuilt aircraft builders, Mazda also never gave up on it. New highly optimized single-rotor engines are under development. They’re aimed at range-extender duty in hybrid-electric vehicles in the 2020s.
Pioneering Prius: Say the word “hybrid” and the obvious association is “Prius.” Launched by Toyota in late 1997, the first mass-produced gas-electric hybrid vehicle was the fruit of a five-year development program to create a scalable, practical, low-emission family of vehicles. To date more than 7 million Priuses have been sold globally, representing the majority of the world’s hybrids—a propulsion concept first used in 1898 by Ferdinand Porsche.
Three elements were critical to the new Toyota Hybrid System’s success. First was the 1.5-L 1NZ-series gas engine running the Atkinson thermodynamic cycle. Second was stable and reliable nickel metal-hydride batteries. Lastly, was the novel 2-motor power-split drive unit. The system delivers 50-mph economy and has proven so bulletproof-reliable that Prius has become a popular choice of the world’s cabbies.
Ford’s titanic T: The early automakers frequently used cutaway illustrations to tout the technical features under the skin of their cars. This one shows the brilliant simplicity and overall robust design of Ford’s 2.7-L, 22-hp gasoline four-cylinder in the iconic Model T. Note the compact flywheel magneto and two-speed planetary transmission—today these would be considered good examples of “systems engineering.”
Vanadium steel alloys allowed Ford to reduce the size of the gears in its planetary drive, compared with previous transmissions. This helped reduced the unit’s overall size and allowed it to be fully enclosed. The transmission shared the engine’s crankcase oil. This view shows (from left) the planetary gearset; the three bands controlling reverse, low gear, and high gear; the clutch; and clutch spring. With the simple addition of a torque converter and hydraulic control, this unit would be functionally equivalent to a modern automatic transmission.
—with Erika Anden, SAE Mobility History CommitteeContinue reading »