Reciprocating aircraft engine

Reciprocating aircraft engine

A fuel-burning internal combustion piston engine specially designed and built for minimum fuel consumption and light weight in proportion to developed shaft power. The rotating output shaft of the engine may be connected to a propeller, ducted fan, or helicopter rotor.

Reciprocating aircraft engines are used in about 86% of all powered aircraft flying in the United States. Most of the aircraft powered by these engines belong to the general aviation segment of the domestic aviation fleet. The reciprocating aircraft engine is used to power single-engine and multiengine airplanes, helicopters, and airships. It is the principal engine used in aircraft for air taxi, pilot training, business, personal, and sport flying as well as aerial application of seed, fertilizer, herbicides, and pesticides for farming.

Predominantly, reciprocating aircraft engines operate on a four-stroke cycle, where each piston travels from one end of its stroke to the other four times in two crankshaft revolutions to complete one cycle. The cycle is composed of four distinguishable events called intake, compression, expansion (or power), and exhaust, with ignition taking place late in the compression stroke and combustion of the fuel-air charge occurring early in the expansion stroke. These spark-ignition engines bum specially formulated aviation gasolines. See Internal combustion engine

Most modem aircraft using engines with up to 336 kW (450 hp) output are powered by air-cooled, horizontally opposed, reciprocating engines. The trend in modern reciprocating engine development is toward lower engine weight and improved fuel economy rather than increased power.