A spinner is an aircraft component, a streamlined fairing fitted over a

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

hub or at the centre of a

turbofan The turbofan or fanjet is a type of airbreathing jet engine that is widely used in aircraft engine, aircraft propulsion. The word "turbofan" is a portmanteau of "turbine" and "fan": the ''turbo'' portion refers to a gas turbine engine which ac ...

engine. Spinners both make the aircraft overall more streamlined, thereby reducing

aerodynamic drag In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding ...

, and also smooth the airflow so that it enters the air intakes more efficiently. Spinners also fulfill an

aesthetic Aesthetics, or esthetics, is a branch of philosophy that deals with the nature of beauty and taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed t ...

role on some aircraft designs.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 480. Aviation Supplies & Academics, 1997. Bingelis, Tony: ''Bingelis on Engines'', pages 196-210.

Experimental Aircraft Association The Experimental Aircraft Association (EAA) is an international organization of aviation enthusiasts based in Oshkosh, Wisconsin, United States. Since its inception, it has grown internationally with over 200,000 members and nearly 1,000 chapt ...

Aviation Foundation, 1995. Bingelis, Tony: ''Firewall Forward'', pages 269-273.

Aviation Foundation, 1992.

Piston engine spinners

Piston-powered aircraft often have spinners of one of two basic designs. The ''large spinner'' fits over the propeller, while the smaller ''skull cap'' style is directly attached to the propeller and just covers the propeller mounting bolts. The spinner may be constructed from

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

fibreglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...

. Often softer grades of aluminium are used to reduce the tendency to crack in service. Early fibreglass spinners introduced as kits for the

homebuilt aircraft Homebuilt aircraft, also known as amateur-built aircraft or kit planes, are constructed by persons for whom this is not a professional activity. These aircraft may be constructed from "scratch", from plans, or from assembly kits.Armstrong, Kenn ...

market in the early 1990s initially developed a poor reputation for cracking. More recent models have resolved these problems and they now function as well as aluminium ones do. The normal method of installation of a ''large spinner'' on a light aircraft involves installing a circular spinner back plate over the engine driveshaft, then the propeller, followed by a spinner front plate. The spinner dome is then mounted over this assembly and secured with screws to the back and front plates. Small plates are usually fitted behind the propeller to fill in the spinner dome cutouts and are secured to the backplate again with screws. Some spinner designs do not incorporate the front plate, although these are not suitable for higher-powered engines. The loss of a spinner in flight has caused damage to aircraft as well as accidents. If the spinner becomes partially detached then damage to the

engine cowling 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 cove ...

can result, along with a high degree of vibration that results in the need for an immediate engine shut-down and a forced landing. In cases where the spinner has completely departed the aircraft it often impacts the airframe or the windshield, with potentially catastrophic results. Because of their role as a rotating component and the risk of cracking and failure due to engine vibration, spinners require regular inspection, particularly of the back plate as well as the spinner dome itself.

History

Rolls Royce RB211 Turbofan engine low pressure (LP) fan

The first spinners were fitted to aircraft in the early 1910s. originally to reduce drag caused by the large-diameter

rotary engine 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 ...

s of that era, and also were prominent on

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was List of wars and anthropogenic disasters by death toll, one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, ...

-era aircraft, like the

Morane-Saulnier N The Morane-Saulnier N, also known as the Morane-Saulnier Type N, was a French monoplane fighter aircraft of the First World War. Designed and manufactured by Morane-Saulnier, the Type N entered service in April 1915 with the ''Aéronautique Mili ...

French monoplane fighter, and for the

Central Powers The Central Powers, also known as the Central Empires,german: Mittelmächte; hu, Központi hatalmak; tr, İttifak Devletleri / ; bg, Централни сили, translit=Tsentralni sili was one of the two main coalitions that fought in W ...

, Robert Thelen's Albatros D.I through D.V series of fighter designs. In some cases spinners were found to block airflow to the engine, causing overheating, a problem later solved by careful aerodynamic design.Century of Flight: Bloch MB 174
/ref>

References

External links

{{Aircraft piston engine components Propellers Jet engines