The term "radial engines" refers to a type of internal combustion engine typically used in aircrafts. The word is spelled using the phonetic transcription /ˈreɪdiəl ˈɛndʒɪnz/. The first syllable is pronounced with the long "a" sound (as in "ray"), followed by "dee" and "əl" for the second and third syllables respectively. The second word starts with the "e" sound followed by "n" and "dʒ" for the second and third syllables, and finally "ɪnz" to complete the word. Knowing the phonetic transcription can help improve spelling accuracy.
Radial engines are a type of reciprocating internal combustion engine commonly used in aircraft. This engine design features cylinders arranged in a circular manner around a central crankshaft. The cylinders are evenly spaced, resembling the spokes of a wheel, hence the term "radial" engine.
These engines are characterized by their unique design. They typically have fixed cylinders in a radial configuration, with a single crankshaft at the center. The cylinders are attached directly to the crankcase, allowing the pistons to move in and out while rotating around the crankshaft. The crankshaft itself remains stationary, while the propeller is attached to the engine case and rotates with it.
The radial engine design offers several advantages. It provides excellent cooling as the cylinders are exposed to the air, and the increased surface area facilitates efficient heat transfer. Additionally, this configuration offers a relatively simple construction, minimizing the number of moving parts and making maintenance more straightforward. Radial engines also deliver high torque at low speeds, making them well-suited for aviation applications.
These engines were widely used during the early years of aviation, particularly in World War I and World War II. However, their usage has diminished with the rise of more advanced engine designs, such as the inline and turbine engines. Nevertheless, radial engines are still employed in a variety of vintage and specialty aircraft due to their unique characteristics and nostalgic appeal.
The word "radial" in "radial engines" comes from the Latin word "radius", meaning "spoke of a wheel" or "ray of light". It was first used in the late 18th century to describe the arrangement of spokes radiating from a wheel's hub. This term was later applied to engines with a similar arrangement, where the engine cylinders are arranged in a circular fashion around a central crankshaft, resembling the spokes of a wheel. Hence, "radial engines" are named after their radial arrangement.