A cowling is the removable covering of a vehicle's engine, 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.
"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, a cowling may be used for drag reduction or engine cooling by directing airflow. Examples in aviation include the NACA cowling and Townend ring. On an airplane, the cowling may also cover part of the fuselage, the nacelles, the engine mount and part of the cockpit. [1] 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. [1] Engine-facing sides of the cowling must be made of metal. [1] 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 and heads. 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. [2]
The rotary engine is an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration. The engine's crankshaft remained stationary in operation, while the entire crankcase and its attached cylinders rotated around it as a unit. Its main application was in aviation, although it also saw use in a few early motorcycles and automobiles.
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is called a "star engine" in some other languages.
The BMW 801 was a powerful German 41.8-litre (2,550 cu in) air-cooled 14-cylinder-radial aircraft engine built by BMW and used in a number of German Luftwaffe aircraft of World War II. Production versions of the twin-row engine generated between 1,560 and 2,000 PS. It was the most produced radial engine of Germany in World War II with more than 61,000 built.
NACA is the National Advisory Committee for Aeronautics, a former federal agency of the US government, the forerunner of NASA.
Richard Travis Whitcomb was an American aeronautical engineer who was noted for his contributions to the science of aerodynamics.
Aircraft engine controls provide a means for the pilot to control and monitor the operation of the aircraft's powerplant. This article describes controls used with a basic internal-combustion engine driving a propeller. Some optional or more advanced configurations are described at the end of the article. Jet turbine engines use different operating principles and have their own sets of controls and sensors.
In aeronautics, a spoiler is a device which intentionally reduces the lift component of an airfoil in a controlled way. Most often, spoilers are plates on the top surface of a wing that can be extended upward into the airflow to spoil the streamline flow. By so doing, the spoiler creates a controlled stall over the portion of the wing behind it, greatly reducing the lift of that wing section. Spoilers differ from airbrakes in that airbrakes are designed to increase drag without disrupting the lift distribution across the wing span, while spoilers disrupt the lift distribution as well as increasing drag.
A flap is a high-lift device used to reduce the stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing distance. Flaps also cause an increase in drag so they are retracted when not needed.
A propelling nozzle is a nozzle that converts the internal energy of a working gas into propulsive force; it is the nozzle, which forms a jet, that separates a gas turbine, or gas generator, from a jet engine.
The Republic XF-12 Rainbow was an American four-engine, all-metal prototype reconnaissance aircraft designed by the Republic Aviation Company in the late 1940s. Like most large aircraft of the era, it used radial engines, specifically the Pratt & Whitney R-4360 Wasp Major. The XF-12 was referred to as "flying on all fours" meaning: four engines, 400 mph (640 km/h) cruise, 4,000 mi (6,400 km) range, at 40,000 ft (12,000 m). The aircraft was designed to maximize aerodynamic efficiency. Although innovative, the jet engine and the end of World War 2 made it obsolete, and it did not enter production. A proposed airliner variant, the RC-2, was deemed uneconomical and cancelled before being built.
An airplane or aeroplane is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spectrum of uses for airplanes includes recreation, transportation of goods and people, military, and research. Worldwide, commercial aviation transports more than four billion passengers annually on airliners and transports more than 200 billion tonne-kilometers of cargo annually, which is less than 1% of the world's cargo movement. Most airplanes are flown by a pilot on board the aircraft, but some are designed to be remotely or computer-controlled such as drones.
Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. In all combustion engines, a great percentage of the heat generated escapes through the exhaust, not through the metal fins of an air-cooled engine (12%). About 8% of the heat energy is transferred to the oil, which although primarily meant for lubrication, also plays a role in heat dissipation via a cooler. Air-cooled engines are used generally in applications which would not suit liquid cooling, as such modern air-cooled engines are used in motorcycles, general aviation aircraft, lawn mowers, generators, outboard motors, pump sets, saw benches and auxiliary power units.
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 in 1927. It was a major advance in aerodynamic drag reduction, and paid for its development and installation costs many times over due to the gains in fuel efficiency that it enabled.
A NACA duct, also sometimes called a NACA scoop or NACA inlet, is a common form of low-drag air inlet design, originally developed by the U.S. National Advisory Committee for Aeronautics (NACA), the precursor to NASA, in 1945.
A Townend ring is a narrow-chord cowling ring fitted around the cylinders of an aircraft radial engine to reduce drag and improve cooling.
A motorcycle fairing is a shell placed over the frame of a motorcycle, especially racing motorcycles and sport bikes, to deflect wind and reduce air drag. The secondary functions are the protection of the rider from airborne hazards and wind-induced hypothermia and of the engine components in the case of an accident. A motorcycle windshield will usually be integrated into the design of the fairing.
The Stipa-Caproni, also known as the Caproni Stipa, was an experimental Italian aircraft designed in 1932 by Luigi Stipa (1900–1992) and built by Caproni. It featured a hollow, barrel-shaped fuselage with the engine and propeller completely enclosed by the fuselage—in essence, the whole fuselage was a single ducted fan. Although the Regia Aeronautica was not interested in pursuing development of the Stipa-Caproni, its design influenced the development of jet propulsion.
This article briefly describes the components and systems found in jet engines.
The Bristol Type 92, sometimes known as the Laboratory biplane, was an aircraft built by the Bristol Aeroplane Company to address the differences between wind tunnel cowling models and full scale cowling for radial engines and was designed as a scaled-up version of a wind tunnel model aircraft. One was built and flew in the mid-1920s.
The Propeller Research Tunnel (PRT) was the first full-scale wind tunnel at the National Advisory Committee for Aeronautics (NACA) Langley Research Center, and the third at the facility. It was in use between 1927 and 1950 and was instrumental in the drag reduction research of early American aeronautics. In 1929, NACA was awarded its first Collier Trophy for the NACA cowling which was tested and developed using the Propeller Research Tunnel.