Cessna 172S Skyhawk SP, Private JP6817606

aviation Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' includes airplane, fixed-wing and helicopter, rotary-wing types, morphable wings, wing-less lifting bodies, as well as aerostat, lighter- ...

, the term tractor configuration refers to an

aircraft An aircraft is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or by using the Lift (force), dynamic lift of an airfoil, or in ...

constructed in the standard configuration with its

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 ...

mounted with the

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 ...

in front of it so that the aircraft is "pulled" through the air. Oppositely, the

pusher configuration In an aircraft with a pusher configuration (as opposed to a tractor configuration), the propeller(s) are mounted behind their respective engine(s). Since a pusher propeller is mounted behind the engine, the drive shaft is in compression in n ...

places the airscrew behind and propels the aircraft forward. Through common usage, the word "propeller" has come to mean any airscrew, whether it actually propels or pulls the plane. In the early years of powered aviation both tractor and pusher designs were common. However, by the midpoint of the

First World War 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, ...

, interest in pushers declined and the tractor configuration dominated. Today, propeller-driven aircraft are assumed to be tractors unless it is stated otherwise.

Origins

The first airplane to have a "tractor" configuration was the

Goupy No.2 The Goupy No.2 was an experimental aircraft designed by and and built in France in 1909 at the Blériot factory at Buc. The Goupy No.2 is significant for two major and influential innovations in aircraft design: it was the first tractor confi ...

(first flight on 11 March 1909) designed by Mario Calderara and financed by Ambroise Goupy at the French firm

Blériot Aéronautique Blériot Aéronautique was a French aircraft manufacturer founded by Louis Blériot. It also made a few motorcycles between 1921 and 1922 and cyclecars during the 1920s. Background Louis Blériot was an engineer who had developed the first pra ...

. When it was constructed, it was the fastest airplane in existence. At that time a distinction was made between a propeller ("pushes the machine", akin to a ship's propeller) and a tractor- ircrew ("pulls the machine through the air")."Propellers and tractor-screws"
Correspondence ''Flight'' 23 April 1910. The

Royal Flying Corps "Through Adversity to the Stars" , colors = , colours_label = , march = , mascot = , anniversaries = , decorations ...

called the tractors "Bleriot type" after Louis Bleriot to distinguish them from pushers, or "Farman type".

World War I military aviation

The downside of a single-engine tractor aircraft was that it was initially impossible to fire a gun through the propeller arc without striking the propeller blades. Early solutions included mounting guns (

rifle A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...

s or

machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles ...

s) to fire around the propeller arc, either at an angle to the side – which made aiming difficult – or on the top wing of a

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While a ...

so that the bullets passed over the propeller arc. The first system to fire through the propeller was developed by French engineer Eugene Gilbert for Morane-Saulnier, and involved fitting metal "deflector wedges" to the propeller blades of a Morane-Saulnier L

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing con ...

. It was employed with immediate success by French

aviator An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its directional flight controls. Some other aircrew members, such as navigators or flight engineers, are also considered aviators, because they a ...

Roland Garros and was also used on at least one Sopwith Tabloid of the

Royal Naval Air Service The Royal Naval Air Service (RNAS) was the air arm of the Royal Navy, under the direction of the Admiralty's Air Department, and existed formally from 1 July 1914 to 1 April 1918, when it was merged with the British Army's Royal Flying Corps t ...

. A more workable solution was a ''gun synchronizer'', which utilized a

synchronization gear A synchronization gear (also known as a gun synchronizer or interrupter gear) was a device enabling a single-engine tractor configuration aircraft to fire its forward-firing armament through the arc of its spinning propeller without bullets str ...

developed by aircraft pioneer

Anthony Fokker Anton Herman Gerard "Anthony" Fokker (6 April 1890 – 23 December 1939) was a Dutch aviation pioneer, aviation entrepreneur, aircraft designer, and aircraft manufacturer. He produced fighter aircraft in Germany during the First World War suc ...

and fitted to the

Fokker E.I The Fokker E.I was the first fighter aircraft to enter service with the Fliegertruppe of the Deutsches Heer in World War I. Its arrival at the front in mid-1915 marked the start of a period known as the " Fokker Scourge" during which the E.I a ...

monoplane in 1915. The first British "tractor" to be specifically designed to be fitted with synchronization gear was the

Sopwith 1½ Strutter The Sopwith Strutter was a British single- or two-seat multi-role biplane aircraft of the First World War.Lake 2002, p. 40. It was the first British two-seat tractor fighter and the first British aircraft to enter service with a synchronise ...

which did not enter service until early 1916. Other solutions to avoiding the propeller arc include passing the gun's barrel through the propeller's hub or spinner – first used in production military aircraft with the World War I French SPAD S.XII – or mounting guns in the wings. The latter solution was generally used from the early 1930s until the beginning of the

jet age The Jet Age is a period in the history of aviation defined by the advent of aircraft powered by jet turbine engines, and by the social change this brought about. Jet airliners were able to fly much higher, faster, and farther than older pisto ...

References

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Origins

World War I military aviation

References

See also