Interrupter gear
An interrupter gear is a device used on military aircraft
Military aircraft
A military aircraft is any fixed-wing or rotary-wing aircraft that is operated by a legal or insurrectionary armed service of any type. Military aircraft can be either combat or non-combat:...

 and warship
A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuvrable than merchant ships...

s in order to allow them to target opponents without damaging themselves.

The term covers two related technologies: the first, more accurately referred to as synchronization gear, or a gun synchronizer, is attached to the armament of a tractor-type craft so that it can fire through the arc of a spinning propeller
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

 without the bullets striking the blades. Introduced during the First World War, the gun synchronizer was a significant development in the history of aerial warfare
Aerial warfare
Aerial warfare is the use of military aircraft and other flying machines in warfare, including military airlift of cargo to further the national interests as was demonstrated in the Berlin Airlift...

 and remained in operational use until the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...

, after which the universal adoption of propeller-less jet aircraft
Jet aircraft
A jet aircraft is an aircraft propelled by jet engines. Jet aircraft generally fly much faster than propeller-powered aircraft and at higher altitudes – as high as . At these altitudes, jet engines achieve maximum efficiency over long distances. The engines in propeller-powered aircraft...

 rendered such gears unnecessary.

The other, true interrupter gear stops the firing of the machine gun when some part of the aircraft is in the way. For much of the early history of the fighter aircraft this was limited to the propeller. This would change with the introduction of gun turret
Gun turret
A gun turret is a weapon mount that protects the crew or mechanism of a projectile-firing weapon and at the same time lets the weapon be aimed and fired in many directions.The turret is also a rotating weapon platform...

 mounts on bomber aircraft.

Though their effects were the same, there was a subtle difference between the concept of the interrupter and the synchronizer. A machine gun fitted with interrupter gear had the trigger normally enabled and the interrupter mechanism would disable the trigger when a propeller blade was in the way. A machine gun fitted with synchronization gear had the trigger normally disabled and the synchronizer mechanism would enable the trigger when the propeller was clear, essentially with the rotating parts of the engine (the crankshaft
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which translates reciprocating linear piston motion into rotation...

 and other parts connected to it with an inline engine
Inline engine (aviation)
In aviation, an inline engine means any reciprocating engine with banks rather than rows of cylinders, including straight engines, flat engines, V engines and H engines, but excluding radial engines and rotary engines....

, the crankcase
In an internal combustion engine of the reciprocating type, the crankcase is the housing for the crankshaft. The enclosure forms the largest cavity in the engine and is located below the cylinder, which in a multicylinder engine are usually integrated into one or several cylinder blocks...

 with a rotary engine
Rotary engine
The rotary engine was an early type of internal-combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary and the entire cylinder block rotated around it...

) firing the gun. In reality, the technical difficulties associated with reliably halting, or co-ordinating, the firing of a Maxim
Maxim gun
The Maxim gun was the first self-powered machine gun, invented by the American-born British inventor Sir Hiram Maxim in 1884. It has been called "the weapon most associated with [British] imperial conquest".-Functionality:...

-type machine gun meant that no working interrupter system was ever developed — all successful implementations used the concept of synchronization.


Experimentation with gun synchronization had been underway in France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 and Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 before the First World War. August Euler applied for German Patent No. DRP 248.601 for a fixed forward mounting on an airplane for a machine gun in 1910. Later that year, aviation pioneer Gabriel Voisin
Gabriel Voisin
Gabriel Voisin was an aviation pioneer and the creator of Europe's first manned, engine-powered, heavier-than-air aircraft capable of a sustained , circular, controlled flight, including take-off and landing. It was flown by Henry Farman on January 13, 1908 near Paris, France...

 dared to sketch a 37mm cannon mounted on one of his pusher
Pusher configuration
In a craft with a pusher configuration the propeller are mounted behind their respective engine. According to Bill Gunston, a "pusher propeller" is one mounted behind engine so that drive shaft is in compression...


However, the engineers involved received little support or encouragement from the military who disregarded the need for armed aircraft, believing them solely useful for reconnaissance
Reconnaissance is the military term for exploring beyond the area occupied by friendly forces to gain information about enemy forces or features of the environment....

. Swiss
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

 engineer Franz Schneider
Franz Schneider
Franz Schneider was an engineer granted the first patent on 15 July 1913 for a synchronisation device allowing a machine gun to fire between an aircraft's spinning propeller blades...

, working for Luftverkehrs Gesellschaft
Luftverkehrsgesellschaft m.b.H. was a German aircraft manufacturer based in Berlin-Johannisthal, which began constructing aircraft in 1912, building Farman-type aircraft. The company constructed many reconnaissance and light bomber biplanes during World War I.The raid on London in 1916 was...

, designed and patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

ed a synchronizer in 1913. French aircraft designer Raymond Saulnier built and patented a practical gun synchronizer in April 1914, having borrowed a machine gun from the army for testing. No design was developed to the point of being operational in the field, one significant problem being the inconsistency of ammunition propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...

 resulting in hang fire
Hang fire
Hang fire refers to an unexpected delay between the triggering of a firearm and the ignition of the propellant. This failure was common in firearm actions that relied on open primer pans, due to the poor or inconsistent quality of the powder. Modern weapons are susceptible, particularly if the...


Saulnier pursued a simpler method using armour
Armour or armor is protective covering used to prevent damage from being inflicted to an object, individual or a vehicle through use of direct contact weapons or projectiles, usually during combat, or from damage caused by a potentially dangerous environment or action...

ed propeller blades. In December 1914, French pilot Roland Garros approached Saulnier to arrange for this device to be installed on his aeroplane but it was not until March 1915 that he took to the air with a forward-firing Hotchkiss
Hotchkiss machine gun
Hotchkiss machine gun:*Hotchkiss M1909, light machine gun also known as the "Hotchkiss Mark I" in British service*Hotchkiss M1914, medium machine gun*Hotchkiss M1922, light machine gun*13.2 mm Hotchkiss machine gun, heavy machine gun...

 8 mm (.323 in) machine gun mounted on his Morane-Saulnier Type L
Morane-Saulnier Type L
-Bibliography:* Bruce, J.M. The Aeroplanes of the Royal Flying Corps . London:Putnam, 1982. ISBN 0 370 30084 x.* Green, William and Swanborough, Gordon. The Complete Book of Fighters. New York: Smithmark, 1994. ISBN 0-8317-3939-8....

. In addition to the armoured blades, Garros's mechanic, Jules Hue, attached deflector wedges to the blades. While this reduced the chance of a dangerous ricochet
A ricochet is a rebound, bounce or skip off a surface, particularly in the case of a projectile. The possibility of ricochet is one of the reasons for the common firearms safety rule "Never shoot at a flat, hard surface."-Variables:...

, the wedges diminished the propeller's efficiency.

On 1 April 1915, flying for MS26, Garros shot down his first German Albatros, killing both the crew. On 18 April 1915, having shot down three German aircraft, Garros' plane was forced down in German territory. Before he could burn his aircraft, he was captured and the gun and propeller were sent for evaluation by the Inspektion der Fliegertruppen (Idflieg) at Döberitz near Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...


Fokker's synchronizer

This initiated a concentrated phase of consideration of the interrupter gear concept. The Dutch
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 aircraft designer Anthony Fokker
Anthony Fokker
Anton Herman Gerard "Anthony" Fokker was a Dutch aviation pioneer and an aircraft manufacturer. He is most famous for the fighter aircraft he produced in Germany during the First World War such as the Eindecker monoplanes, the Fokker Triplane the and the Fokker D.VII, but after the collapse of...

 was heavily involved in this process but the story of his conception, development and installation of a synchronisation device in a period of 48 hours (first found in an authorised biography of Fokker written in 1929) has been shown to be not factual. The available evidence points to a synchronisation device having been in development by Fokker's team including engineer Heinrich Lübbe
Heinrich Lübbe
Heinrich Lübbe was a German engineer working for Dutch aircraft designer Anthony Fokker during the First World War, invented the interrupter gear which enabled a machine gun to fire through the arc of a fighter aircraft's propeller without the bullets striking the blades.In 1921 Lübbe purchased...

, and probably based on Schneider's patent, for perhaps six months prior to the capture of Garros' machine.

In 1916 LVG and Schneider sue
A lawsuit or "suit in law" is a civil action brought in a court of law in which a plaintiff, a party who claims to have incurred loss as a result of a defendant's actions, demands a legal or equitable remedy. The defendant is required to respond to the plaintiff's complaint...

d Fokker for patent infringement
Patent infringement
Patent infringement is the commission of a prohibited act with respect to a patented invention without permission from the patent holder. Permission may typically be granted in the form of a license. The definition of patent infringement may vary by jurisdiction, but it typically includes using or...

 — the battle continued until 1933 and though the courts repeatedly found in Schneider's favour, Fokker refused to acknowledge the rulings, all the way to the time of the Third Reich in 1933.

The only known date that is certain in the development of Fokker's pioneering Stangensteuerung system is on May 16, 1915, when an officer of the Bavarian armed forces, working with Idflieg
The Idflieg was the bureau of the German War Office that oversaw German military aviation prior to and during World War I....

, alerted his province of Germany that "firing trials of a interesting nature, from a light monoplane, were to take place on the 19th of 20th of May". The trials were meant to take place at the famous Döberitz
Dallgow-Döberitz is a municipality in the Havelland district, in Brandenburg, Germany.-Geography:It consists of the villages Dallgow-Döberitz, Rohrbeck and Seeburg. To the east it shares border with the Spandau borough of Berlin. Neighbouring Brandenburg municipalities are Falkensee in the north...

 proving ground near Berlin, but no record of any sort remains to definitively state what happened there.

Fokker's team adapted their system to work with the new Parabellum MG14
Parabellum MG14
The Parabellum MG14 was a 7.9 mm caliber World War I machine gun built by Deutsche Waffen und Munitionsfabriken. It was an adaptation of their Maschinengewehr 08 gun intended for use on aircraft and zeppelins. The MG08's belt-style ammunition feed was enclosed in a drum, the recoil casing was...

 machine gun fitted to a Fokker A.III unarmed single-seat monoplane
A monoplane is a fixed-wing aircraft with one main set of wing surfaces, in contrast to a biplane or triplane. Since the late 1930s it has been the most common form for a fixed wing aircraft.-Types of monoplane:...

 (a military version of the Fokker M.5K) usually flown for almost the entire first year of hostilities in World War I by Leutnant Otto Parschau
Otto Parschau
Leutnant Otto Parschau was a German World War I Flying Ace and recipient of the Pour le Mérite, Royal House Order of Hohenzollern, and Iron Cross, First Class. He was noted as one of the pre-eminent aces on the Fokker Eindecker...

, marked with the IdFlieg
The Idflieg was the bureau of the German War Office that oversaw German military aviation prior to and during World War I....

 number A.16/15. This aircraft, with factory serial number (or Werknummer) 216,  for the Fokker E.I
Fokker E.I
|-See also:-References:NotesBibliography* Boyne, Walter J. The Smithsonian Book of Flight for Young People. Washington, DC: Smithsonian Institution, 1988. ISBN 0-689-31422-1....

 — was demonstrated on 19–20 May 1915 and shipped to the Western Front on 30 May 1915. The five production prototype examples of the entire Fokker Eindecker series, with Fokker factory serial numbers 191 through 194, and s/n 198, received the IdFlieg military serial numbers E.1/15 through E.5/15, followed Parschau's A.16/15 aircraft into military trials very shortly thereafter, with Leutnant Parschau himself receiving E.1/15 as the replacement for his then worn-out No. 216 aircraft, which was returned to the Fokker factory for further trials with the lMG 08 "Spandau" air-cooled machine gun.

The solution used a cam
A cam is a rotating or sliding piece in a mechanical linkage used especially in transforming rotary motion into linear motion or vice-versa. It is often a part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path...

 attached to the propeller shaft that pressed on a long rod running to the trigger of the guns. The cam was set such that when the propeller was horizontal it pushed on the rod, and the rod in turn pressed the trigger to fire a bullet. The trigger operated by the pilot pulled the rod into position over the cam, essentially allowing the engine's own rotation to fire the gun.

The first victory using a synchronized gun-equipped fighter, based on late 20th century research of surviving German and French early World War I aviation records, is strongly believed to have occurred on 1 July 1915 when Leutnant Kurt Wintgens
Kurt Wintgens
Leutnant Kurt Wintgens was a German World War I fighter ace. He was the first military fighter pilot to score a victory over an opposing aircraft in an aircraft armed with a synchronized machine gun. Wintgens was the recipient of the Iron Cross and the Blue Max.-Background:Wintgens was born into a...

 of Feldflieger Abteilung 6b, flying the Fokker M.5K/MG aircraft that bore IdFlieg's serial number 'E.5/15', forced down a French Morane-Saulnier Type L
Morane-Saulnier Type L
-Bibliography:* Bruce, J.M. The Aeroplanes of the Royal Flying Corps . London:Putnam, 1982. ISBN 0 370 30084 x.* Green, William and Swanborough, Gordon. The Complete Book of Fighters. New York: Smithmark, 1994. ISBN 0-8317-3939-8....

 east of Lunéville
Lunéville is a commune in the Meurthe-et-Moselle department in France.It is a sub-prefecture of the department and lies on the Meurthe River.-History:...

. However the plane landed in French territory and the victory could not be confirmed, as with Wintgens' second engagement only three days later, against a second Morane Parasol. The first "confirmed" victory, in the official German records of that time, would finally go to Wintgens on July 15, 1915, after he was re-assigned to Feldflieger Abteilung 48 near Mühlhausen im Elsaß
Mulhouse |mill]] hamlet) is a city and commune in eastern France, close to the Swiss and German borders. With a population of 110,514 and 278,206 inhabitants in the metropolitan area in 2006, it is the largest city in the Haut-Rhin département, and the second largest in the Alsace region after...

 by downing a third Morane Parasol.

Sole possession of a working synchronizer enabled Germany to dominate the Western Front
Western Front (World War I)
Following the outbreak of World War I in 1914, the German Army opened the Western Front by first invading Luxembourg and Belgium, then gaining military control of important industrial regions in France. The tide of the advance was dramatically turned with the Battle of the Marne...

 skies in a period known as the Fokker Scourge
Fokker Scourge
The Fokker Scourge was a term coined by the British press in the summer of 1915 to describe the then-current ascendancy of the Fokker Eindecker monoplane fighters of the German Fliegertruppen over the poorly-armed Allied reconnaissance types of the period....

. Initially lacking a synchronizer, the Royal Flying Corps
Royal Flying Corps
The Royal Flying Corps was the over-land air arm of the British military during most of the First World War. During the early part of the war, the RFC's responsibilities were centred on support of the British Army, via artillery co-operation and photographic reconnaissance...

 relied on pusher aircraft such as the Vickers F.B.5 Gunbus and the Airco D.H.2 in which the propeller was behind the pilot, and therefore out of the way of forward firing guns. Germany was protective of the synchronizer system, instructing pilots not to venture over enemy territory in case they were forced down and the secret revealed, but the basic principles involved were already common knowledge, and by the middle of 1916 several Allied synchronizer gears were already available in quantity.

Further development

In December 1915, the Vickers-Challenger interrupter gear was put into production for the Royal Flying Corps
Royal Flying Corps
The Royal Flying Corps was the over-land air arm of the British military during most of the First World War. During the early part of the war, the RFC's responsibilities were centred on support of the British Army, via artillery co-operation and photographic reconnaissance...

 and in a few weeks a similar order for the Scarff-Dibovski gear was placed for the RNAS. Neither was a copy of the Fokker gear, as is sometimes reported - work on both was advanced before a captured Fokker was available for technical analysis. The first British aircraft to use these gears was the Sopwith 1½ Strutter
Sopwith 1½ Strutter
The Sopwith 1½ Strutter was a British one or two-seat biplane multi-role aircraft of the First World War. It is significant as the first British-designed two seater tractor fighter, and the first British aircraft to enter service with a synchronised machine gun...

 which arrived in April 1916, although some other service types were retrofitted with synchronised guns about this time, including the Nieuport 12
Nieuport 12
|-See also:...

 and the Bristol Scout
Bristol Scout
The Bristol Scout was a simple, single seat, rotary-engined biplane originally intended as a civilian racing aircraft. Like other similar fast, light aircraft of the period - it was acquired by the RNAS and the RFC as a "scout", or fast reconnaissance type...

. Later British mechanical gears included the Ross, and Sopwith-Kauper gears. The main problem with all early mechanical synchronizers was that the rate of fire of the machine gun was dependent on the engine revolutions, and was slowed, especially when the engine was throttled back. The mechanical linkages were also very liable to failure, resulting in the unfortunate pilot shooting away his own propeller.

Eventually all British aircraft were equipped with the superior Constantinesco synchronization gear (or "CC" gear, invented by Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...

n engineer George Constantinesco) which used sonic impulses transmitted by a column of liquid instead of a mechanical system of linkages. This was not only inherently more reliable, but delivered firing impulses at a much higher rate, so that a synchronised gun now fired at more or less the same rate as a normal machine gun, regardless of engine revolutions. The gear could also be easily fitted to any type of aircraft instead of having to have type-specific linkages designed. In addition, it was hard for the Germans to copy captured examples because it appeared to them to be a hydraulic system, whereas the actual principle of operation was based on Constantinescu's "theory of sonics
Theory of sonics
The theory of sonics is a branch of continuum mechanics which describes the transmission of mechanical energy through vibrations. The birth of the theory of sonics can be considered the publication of the book A treatise on transmission of power by vibrations in 1918 by the Romanian scientist Gogu...

", which remained secret until the end of the war. The Constantinesco gear remained in use with the Royal Air Force
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 until the Second World War, the Gloster Gladiator
Gloster Gladiator
The Gloster Gladiator was a British-built biplane fighter. It was used by the Royal Air Force and the Royal Navy and was exported to a number of other air forces during the late 1930s. It was the RAF's last biplane fighter aircraft and was rendered obsolete by newer monoplane designs even as it...

 being the last British fighter to be equipped with it.

A pilot would usually only have the target in his sights for a fleeting moment so a concentration of bullets was vital for achieving a kill. The obvious solution was to increase the number of guns. The final version of the Fokker Eindecker, the Fokker E.IV
Fokker E.IV
|-See also:...

, came with two Spandau machine guns
Maschinengewehr 08
The Maschinengewehr 08, or MG08, was the German Army's standard machine gun in World War I and is an adoption of Hiram S. Maxim's original 1884 Maxim Gun. It was produced in a number of variants during the war. The MG 08 remained in service until the outbreak of World War II due to shortages of...

 and this became the standard armament for all the German D-type scouts
Idflieg aircraft designation system
The Idflieg designation system was used to designate German heavier-than-air military aircraft from the early days of the Luftstreitkräfte to the end of World War I. The system necessarily evolved during this period, as new aircraft types were produced. It was never extended to aircraft operated...

 starting with the Albatros D.I
Albatros D.I
|-See also:...

. Fokker experimented with mounting three machine guns on the E.IV but the extra weight rendered the aircraft virtually unflyable. The Allies did not field an aircraft with twin synchronized guns until the Sopwith Camel
Sopwith Camel
The Sopwith Camel was a British First World War single-seat biplane fighter introduced on the Western Front in 1917. Manufactured by Sopwith Aviation Company, it had a short-coupled fuselage, heavy, powerful rotary engine, and concentrated fire from twin synchronized machine guns. Though difficult...

 and the SPAD S.XIII
|-See also:-Bibliography:* Bruce, J.M. The Aeroplanes of the Royal Flying Corps . London: Putnam, 1982. ISBN 0-370-30084-X.* Sharpe, Michael. Biplanes, Triplanes, and Seaplanes. London: Friedman/Fairfax Books, 2000. ISBN 1-58663-300-7....

 came into service (mid 1917).


With the introduction of the "high speed" bomber came a need to protect the gunner from the elements and to give protection but retain the wide firing arcs and so the power driven multi-gun turret evolved. One of the first instances was the single nose mounted turret of the Boulton Paul Overstrand
Boulton Paul Overstrand
-See also:-References:NotesBibliography* Brew, Alec. Boulton Paul Aircraft since 1915. London: Putnam, 1993. ISBN 0-85177-860-7.* Halley, James J. Royal Air Force Aircraft: K1000 to K9999. Tonbridge, Kent, UK: Air-Britain Ltd., 1976. ISBN 0-851330-048-0.* Lewis, Peter. The British Bomber since...

 twin engine biplane bomber that served with the RAF, and the almost simultaneous introduction of the much more advanced Martin B-10
Martin B-10
The Martin B-10 was the first all-metal monoplane bomber to go into regular use by the United States Army Air Corps, entering service in June 1934...

 all-metal monoplane with the US Army Air Corps.

For maximum efficiency the bomber turret needed to be able to rotate in all directions and cover as wide a range of elevation as possible — this meant that there would be some combinations of elevation and direction where the turret was aiming at some part of the aircraft itself. To prevent the guns firing an electrical system was used. The guns were fired by solenoid
A solenoid is a coil wound into a tightly packed helix. In physics, the term solenoid refers to a long, thin loop of wire, often wrapped around a metallic core, which produces a magnetic field when an electric current is passed through it. Solenoids are important because they can create...

s and by introducing a break in the electrical power to the guns that coincided with the forbidden arcs of fire the aircraft would be safe from its own guns. The Boulton Paul design used a brass drum and brush contacts that corresponded to the direction of the turret and angle of the guns. Where the brass was removed and replaced with insulating material the electrical circuit would be broken and the guns prevented from firing.


The usefulness of synchronization gears naturally disappeared altogether when jet engine
Jet engine
A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...

s eliminated the propeller, at least in fighter aircraft; but gun synchronization, even in single piston engined aircraft, had already been in decline for the decade prior to this.

The increased speeds of the new monoplanes of the late 1930s meant that the time available to deliver a sufficient weight of fire to bring down an enemy was greatly reduced, and two guns were no longer enough. Since it was never practicable to mount more than two synchronized guns in the forward fuselage, any additional guns had to be mounted in the wings. Cantilever monoplane wings provided much more space than the fuselage to mount armament — and being much more rigid than the old cable braced wings they provided almost as steady a mounting as the fuselage. The retention of fuselage mounted guns, with the additional weight of their synchronization gear (which slowed their rate of fire, albeit only slightly, and still occasionally failed, resulting in damage to propellers) became increasingly unattractive as the extra firepower offered by two machine guns came to represent a decreasing percentage of a fighter's total armament.

Against these arguments, "centralised" guns still rewarded the true marksman, regardless of advances in gunsight technology: their range was limited only by ballistics, as they did not need the "harmonisation" necessary to concentrate the fire of wing mounted guns. These considerations resulted in a reluctance (especially in Germany, Russia, and Japan) to abandon fuselage-mounted guns altogether. In fact even the old (and highly problematic) idea of mounting a cannon to fire through the centre of the propeller hub was revived to this same end.

The very last synchronizer-equipped aircraft to see combat action were in fact the Lavochkin La-11
Lavochkin La-11
-See also:-References:NotesBibliography* Gordon, Yefim. Lavochkin's Piston-Engined Fighters . Earl Shilton, Leicester, UK: Midland Publishing Ltd., 2003. ISBN 1-85780-151-2....

 and the Yakovlev Yak-9
Yakovlev Yak-9
The Yakovlev Yak-9 was a single-engine fighter aircraft used by the Soviet Union in World War II and after. Fundamentally a lighter development of the Yak-7 with the same armament, it arrived at the front at the end of 1942. The Yak-9 had a lowered rear fuselage decking and all-around vision canopy...

 during the Korean War
Korean War
The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...


Further reading

  • Woodman, Harry, "CC Gun Synchronisation Gear", Aeroplane Monthly, September 2005
  • Jarrett, Phillip, "The Fokker Eindeckers", Aeroplane Monthly, December 2004
  • "The Electro-Hydraulic Turret", The Aeroplane No: 1654, February 1943
  • Grosz, Peter M., Windsock Datafile No. 91, Fokker E.I/II, Albatros Publications, Ltd. 2002. ISBN No. 1-902207-46-7
  • Guttman, Jon, et al. Pusher Aces of World War 1. Osprey Pub Co, 2009. ISBN 1846034175, 9781846034176.
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