Curtiss AT-5a NACA Cowling - GPN-2000-001724

A cowling is the removable covering of a vehicle's

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

, most often found on automobiles, motorcycles, airplanes, and on outboard boat motors. On airplanes, cowlings are used to reduce drag and to cool the engine. On boats, cowlings are a cover for an outboard motor. In addition to protecting the engine, outboard motor cowlings need to admit air while keeping water out of the air intake.

Etymology

"Cowling" comes from "cowl", which originated from Middle English coule, from Old English cūle, from earlier cugele (“hood, cowl”). This, in turn, came from Ecclesiastical Latin cuculla (“monk's cowl”), from Latin cucullus (“hood”), of uncertain origin.

In aviation

In aviation, a cowling may be used for drag reduction or engine cooling by directing airflow. Examples in aviation include the

NACA cowling The NACA cowling is a type of aerodynamic fairing used to streamline radial engines installed on airplanes. It was developed by Fred Weick of the National Advisory Committee for Aeronautics (NACA) in 1927. It was a major advance in aerodynamic ...

and

Townend ring A Townend ring is a narrow- chord cowling ring fitted around the cylinders of an aircraft radial engine to reduce drag and improve cooling. Development The Townend ring was the invention of Dr. Hubert Townend of the British National Physica ...

. On an airplane, the cowling may also cover part of the

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

, the

nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...

s, the engine mount and part of the cockpit.Aviation Machinist's Mates' Manual. Navy Department. Bureau of Aeronautics, 1955. p. 4-15 The cowlings and the fairings are similar, as both streamline airflow, except that cowlings are usually removable (to permit engine inspections and repairs), whereas fairings are bolted in place. Engine-facing sides of the cowling must be made of metal. On jets, they are used as an air intake for jet engines. Cowlings may also be used for decorative purposes. On piston-engined planes, the cowling constitutes a symmetric, circular airfoil, in contrast to the planar airfoil of airplane wings. It directs cool air to flow through the engine where it is routed across the engine's hottest parts, that is, the

cylinders A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infini ...

and

heads A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may no ...

. Furthermore, turbulence after the air passes the free-standing cylinders is greatly reduced. The sum of all these effects reduces drag by as much as 60 percent. After tests in 1932 proved the effectiveness of NACA cowlings, almost every radial-engined aircraft were equipped with them.''Full-Scale Testing of N.A.C.A. Cowlings''
(

Theodore Theodorsen Theodore Theodorsen (January 8, 1897 – November 5, 1978) was a Norwegian-American theoretical aerodynamicist noted for his work at NACA (the forerunner of NASA) and for his contributions to the study of turbulence. Early yea ...

, M. J. Brevoort, and George W. Stickle, NACA Report # 592. Langley Memorial Aeronautical Laboratory: 1937) Porsche Carrera GT cowling

References

{{Reflist Auto parts Aircraft components

Etymology

In aviation

See also

References