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Aircraft Piston Engines

The aircraft piston engine, or reciprocating engine, is a type that has served powered flight since its inception, acting as the most common power plants for general aviation aircraft even to this day. While there are numerous piston engine types that slightly differ in their construction, all operate according to the four-stroke cycle of intake, compression, power, and exhaust. To conduct such operations, piston engines rely on pistons and cylinders that are assembled in various ways to achieve different flight characteristics. In this blog, we will provide a brief overview of the most common piston engine types so that you may be more familiar with their differences and capabilities.

The earliest internal combustion engine types for aircraft came in the form of in-line engines, those of which featured cylinders in a straight line such as would be seen in an automobile. Due to the narrow and compact design of such engines, light aircraft could be constructed with a narrow fuselage. The fuselage design also provided greater pilot visibility and the ability to install shorter landing gear. The drawbacks of such engines, however, were that they could not optimally rely on airflow for the proper cooling of surrounding components. As a result, such engines implemented liquid cooling which reduced the overall power-to-weight ratio of aircraft.

After in-line engines came rotary piston engines, those of which featured an odd number of cylinders placed in rows around a central stationary crankshaft. Rotary piston engines sought to remedy the issues of their predecessor in regard to power output, weight, and reliability, utilizing its construction to increase airflow for optimal cooling. As the cylinders rotate as a unit and are devoid of reciprocating parts at the engine mounting point, rotary piston engines also have very smooth running. Despite this, inherent limitations of such engines led to their eventual obsolescence as newer and more improved designs came about.

The opposed, horizontally opposed, or O-type reciprocating engine is one in which two banks of cylinders are set opposite from one another with a central crankshaft. While accommodating both liquid and air cooling systems, the latter is more popular for aviation applications. With a low weight-to-horsepower ratio and narrow construction, such engines are best suited for twin engine aircraft and are typically implemented on the wings.

V-type engines are a type that have the appearance of two in-line engines connected in a V-shape. Such light aircraft engines will often have 12 cylinders, those of which may be liquid or air cooled. While such engines commonly served aircraft during World War II, they have since been limited to older models as more powerful engine types have come about. Despite this, such configurations continue to popularly be used within automobiles of all types.

The radial engine is sometimes confused with the rotary piston engine, featuring one or more rows of odd-numbered cylinders placed around a central crankshaft. Unlike the rotary type, radial engines have reciprocating pistons that cause the central crankshaft to rotate. With their method of operation, such piston engine types are smooth during flight and may achieve efficient airflow for cooling.

As varying engine types feature their own set of advantages and drawbacks, the choice between each will sometimes depend upon one’s personal preferences, aircraft type, and requirements. If you are in need of various aviation parts for your internal combustion engine or light aircraft, look no further than Purchasing Union. Purchasing Union is a leading distributor of aircraft parts with a plethora of new, used, and obsolete items readily available for purchase at any time on our website. Take the time to explore our expansive catalogs at your leisure, and our team of industry experts are readily on standby to assist you through the purchasing process as necessary. Get started today and see why customers steadily choose to rely on Purchasing Union for all their aviation needs.


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