Born from the visionary mind of German engineer Felix Wankel, the Wankel Engine has left an indelible mark on the history of internal combustion.
Felix Wankel: A Visionary Pioneer: Felix Heinrich Wankel, born on August 13, 1902, in Lahr, Germany, had a keen interest in engineering, aviation, and inventive design. Wankel's early years were characterized by an insatiable curiosity about machines. His interest in aviation led him to become a pilot, but it was his involvement with aircraft engines that set the stage for the revolutionary Wankel engine. Wankel's experiences in the aviation industry fueled his desire to create a more efficient and compact engine.
The Birth of a Revolutionary Concept: In the early 1920s, Wankel began exploring the idea of a rotary engine that could offer advantages over traditional piston-driven designs. His breakthrough came in 1929 when he patented the concept that would later bear his name. The Wankel engine, also known as the rotary engine, featured a rotor that moved in an epitrochoidal (oval) housing, eliminating the need for conventional pistons and cylinders.
Felix Wankel's journey continued in 1938 with research on rotary compressors, evolving into the development of a practical internal combustion engine post-World War II. In 1964, the NSU Wankel Spyder became the first car to feature a Wankel engine. However, it was the NSU Ro80, acclaimed Car of the Year in 1968, that brought the Wankel engine fame. With its twin-rotor engine, it could reach an impressive 110mph.
Twin Rotors for Smooth Performance: Unlike traditional engines, the Wankel engine employs twin rotors that drive an output shaft running through their center. This innovative design not only converts reciprocating motion into rotary motion but also provides an exceptionally smooth engine operation. By setting the rotors 180° out of phase, one rotor cancels out any vibrations produced by the other rotor, ensuring a comfortable and enjoyable driving experience.
Challenges and Triumphs: Wankel's innovative engine design faced skepticism and resistance from established automotive circles. The early development stages were marked by challenges, and Wankel's ideas were not immediately embraced. Despite the controversies, Wankel persisted in refining his concept, believing in its potential to revolutionize internal combustion.
Collaboration with NSU and Licensing Agreements: Wankel's breakthrough gained traction in the 1950s when he collaborated with NSU Motorenwerke AG. In 1957, the first working prototype of the Wankel engine, the DKM 54, was fired up, producing 21 horsepower. This successful demonstration led to licensing agreements with various manufacturers, propelling the Wankel engine into the spotlight.
Divergent Paths: NSU and Curtiss-Wright: In 1960, NSU and Curtiss-Wright entered into an agreement where NSU focused on low and medium-powered Wankel engines, while Curtiss-Wright delved into high-powered variants, even for aircraft applications. This collaborative effort marked a pivotal moment in the history of the Wankel engine, as manufacturers worldwide began exploring the possibilities of this novel technology.
Mazda's Pioneering Spirit: Among the early adopters, Mazda emerged as a trailblazer, showcasing its commitment to the Wankel engine. In 1964, NSU introduced the first rotary-powered car, the NSU Spider, but it was Mazda that made significant strides with models like the Cosmo 110S and later the iconic RX series. Mazda's dedication to solving sealing and lubrication issues, especially with apex seals, helped establish the Wankel engine as a viable option.
CITROËN GS Birotor: A Unique Chapter
Unveiled at the Frankfurt Auto Show in September 1973, the Citroën GS Birotor was a surprising entry into the automotive scene. Featuring a water-cooled twin-rotor Wankel engine, the Birotor boasted a simple yet effective design with eight key elements. Its valve-free four-stroke system, comprising trochoids, an intermediate section, side sections, rotary pistons, and the motor shaft, showcased innovation. The Birotor's perfectly balanced design delivered an exceptionally low noise level, even at high rev ranges, thanks to the absence of vibrations.
Despite its groundbreaking design, the Birotor faced an early demise due to shifting market dynamics, particularly the energy crisis that emerged in late 1973. The focus on fuel consumption during this period played a pivotal role in the fate of this unique engine.
The RX-7 Era: Mazda's RX-7, introduced in 1978, marked a new chapter in the Wankel engine saga. With the RX-7 FB and subsequent FC and FD generations, Mazda demonstrated the engine's prowess, achieving both performance and commercial success. The RX-7's sleek design and rotary powerplant became iconic, solidifying Mazda's position as a key player in the rotary engine's history.
Challenges and Resilience: Despite its successes, the Wankel engine faced challenges, especially related to emissions, fuel consumption, and durability. Mazda's dedication to overcoming these obstacles led to the development of the Renesis engine for the RX-8, incorporating innovations to enhance efficiency and reduce environmental impact.
The Future of the Wankel Engine: Rumors of Mazda's ongoing development of a new rotary engine, dubbed the '16x,' keep enthusiasts hopeful for a resurgence of this innovative technology. LiquidPiston, a company founded by Alexey Shkolnik, aims to breathe new life into the rotary design with advancements such as the X Mini engine. With promises of increased efficiency, reduced weight, and a new thermodynamic cycle.
While details remain speculative, the potential for a modern, more fuel-efficient rotary engine suggests that the Wankel's journey might not be over. The Wankel engine might yet carve its path in the future of transportation.
Sources:
"How a Rotary (Wankel) Engine Works." How a Car Works, link.
"A Brief History of the Rotary Engine and its Road-Going Applications." Car Throttle, link.
"Mazda's Wankel Rotary Engine." Popular Mechanics, link.
"Wankel 2.0: The Return of the Rotary Engine." Engineering.com, link.
"Brief History of the Rotary Engine." Rotary Revs, link.