The Hispano-Suiza 8 is a water-cooled V8 SOHC aero engine introduced by Hispano-Suiza in 1914 that went on to become the most commonly used liquid-cooled engine in the aircraft of the Entente Powers during the First World War. The original Hispano-Suiza 8A was rated at 140 hp (100 kW) and the later, larger displacement Hispano-Suiza 8F reached 330 hp (250 kW).
64-543: Hispano-Suiza 8 engines and variants produced by Hispano-Suiza and other companies under licence were built in twenty-one factories in Spain, France, Britain, Italy, and the U.S. Derivatives of the engine were also used abroad to power numerous aircraft types and the engine can be considered as the ancestor of another successful engine by the same designer, the Hispano-Suiza 12Y (and Soviet Klimov V12 derivative aero-engines) which
128-459: A rotary engine of equivalent power. This empty weight does not include the radiator and coolant fluid. Generally, air-cooled engines are lighter than their equivalent horsepower water-cooled counterparts. For example, the Bentley BR.2 rotary put out 230 hp (170 kW) and weighed 220 kg (490 lb), Clerget 9B rotary 130 hp (97 kW), 173 kg (381 lb). The new engine
192-500: A 36-litre water-cooled V-12 with the two cast aluminium cylinder banks set at 60 degrees to each other. The cylinder heads were not removable, instead both cylinder banks could be quickly removed from the crankcase section of the engine. This made it somewhat famous for being leak-proof, a design feature that was considered by other designers and almost became a part of the Rolls-Royce Merlin . The major design change from
256-711: A First World War ace with 21.5 victories. Lambert flew the S.E.5a as an American member of the Royal Flying Corps and the Royal Air Force. The Air Force Museum Foundation also helped buy the aircraft. It is painted to represent an S.E.5e of the 18th Headquarters Squadron, Bolling Field, Washington, D.C., in 1925. Another four original airframes are statically displayed at: the Science Museum , London, UK; Royal Air Force Museum , London, UK; South African National Museum of Military History , Johannesburg, South Africa; and
320-537: A clockwise (viewed from in front, otherwise known as a left hand tractor) rotation propeller. Related development Comparable engines Related lists Hispano-Suiza 12Y The Hispano-Suiza 12Y was an aircraft engine produced by Hispano-Suiza for the French Air Force before the Second World War . The 12Y became the primary French 1,000 hp (750 kW) class engine and
384-476: A conventional tractor biplane fighter aircraft. The fuselage was a wire-braced box girder structure while the wings were furnished with wooden spars and internal ribs . The fuselage was narrower than many contemporary aircraft, which provided the pilot with good all-round visibility. The aircraft had considerable structural strength, which was credited with improving the type's crashworthiness and survivability. It could also withstand high-g manoeuvres and
448-479: A few S.E.5s were issued to other squadrons due to an acute shortage of the S.E.5a. Deliveries of the S.E.5a suffered from delays due to a shortage of available engines with which to power the type. Due to the shortage of aircraft, there was a very slow initial build-up of new S.E.5a squadrons, which lasted well into 1918. Once the Wolseley Viper -powered model became plentiful, many more units were re-equipped with
512-414: A further 56 aircraft were assembled using already-delivered components. At first, airframe construction outstripped the very limited supply of French-built Hispano-Suiza engines and squadrons earmarked to receive the new fighter had to soldier on with Airco DH 5s and Nieuport 24s until early 1918. The troublesome geared "-8b" model was prone to have serious gear reduction system problems, sometimes with
576-400: A more conventional (and comfortable) seating position. No complaints seem to have been made about the view from the cockpit; in fact, this was often cited as one of the strong points of the type. While pilots, some of whom were initially disappointed with the S.E.5, quickly came to appreciate its strength and fine flying qualities, it was popularly judged to have been underpowered; this failing
640-399: A retractable underslung radiator. Its performance was little better than the S.E.5a, with the extra drag of the big upper wing offsetting gains from the more streamlined fuselage. The S.E.5b was not considered for production. In January 1919, it was tested with standard S.E.5a wings and in this form survived as a research aircraft into the early twenties. The Royal Aircraft Factory S.E.5 was
704-535: Is a British biplane fighter aircraft of the First World War . It was developed at the Royal Aircraft Factory by a team consisting of Henry Folland , John Kenworthy and Major Frank Goodden . It was one of the fastest aircraft of the war, while being both stable and relatively manoeuvrable. According to aviation author Robert Jackson, the S.E.5 was: "the nimble fighter that has since been described as
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#1732872187226768-693: The American Expeditionary Force to equip already-deployed US Army squadrons, the US Government issued multiple orders to the Curtiss Aeroplane and Motor Company for the manufacture and delivery of around 1,000 S.E.5s to be produced in the United States. However, only one Curtiss-built aircraft would be completed prior to the end of the conflict, after which demand for the S.E.5 had effectively evaporated, production being quickly halted after
832-561: The Armistice that ended the conflict; some were transferred to various overseas military operators, while a number were also adopted by civilian operators. The S.E.5 ( S cout E xperimental 5 ) was designed by Henry Folland , John Kenworthy and Major Frank Goodden of the Royal Aircraft Factory in Farnborough . It was built around the new 150 hp (112 kW) Hispano-Suiza 8 , a V8 engine that, while providing excellent performance,
896-642: The Australian War Memorial , Canberra, Australia. Two full-scale replica S.E.5a aircraft were built by Miles Aircraft in 1965 for use in film making and were transferred to the Irish civil aircraft register in 1967 while the two were employed in flying scenes for the 1966 war movie The Blue Max . Three flightworthy reproductions (designated SE5a-1), along with a single static example, were constructed by The Vintage Aviator Limited in New Zealand. According to
960-404: The Hispano-Suiza 12Ycrs which used a hollow propeller shaft to allow a 20 mm cannon to fire through the propeller spinner (a combination known as a moteur-canon ). All later versions shared this feature. The 12Ydrs was the next major series, with a basic rating of 836 hp (623 kW) at sea level with a compression ratio of 5.8:1. The Armée de l'Air changed their nomenclature, so
1024-489: The M.S.450 called the D.3802 and then the final version called the D.3803 . In the mid-1930s, Russian engineer Vladimir Klimov was sent to France to obtain a license for local production of the 12Y. A series of design changes were added to cope with cold weather operation, and the engine entered production in 1935 as the Klimov M-100 with about 750 hp (560 kW). However a series of continual upgrades increased
1088-599: The Morris Cup race in 1927. An original S.E.5a may be seen at the Shuttleworth Collection at Old Warden , England, UK. This aircraft was originally serial F904 of No. 84 Squadron RAF , then flew as G-EBIA from September 1923 to February 1932. It was stored between 1933 and 1955, before being restored to a flightworthy condition by staff at the Royal Aircraft Establishment and then passed onto
1152-584: The Royal Aircraft Factory (200), Vickers (2,164) and Wolseley Motors Limited (431). Shortly following the American entry into World War I , plans were mooted for several American aircraft manufacturers to commence mass production of aircraft already in service with the Allied powers, one such fighter being the S.E.5. In addition to an order of 38 Austin-built S.E.5a aircraft which were produced in Britain and assigned to
1216-501: The S.E.5a . The initial models of the S.E.5a differed from late production examples of the S.E.5 only in the type of engine installed – a geared 200 hp Hispano-Suiza 8b , often turning a large clockwise-rotation four-bladed propeller, replacing the 150 hp H.S. 8A model. In total 5,265 S.E.5s were constructed by six manufacturers: Austin Motors (1,650), Air Navigation and Engineering Company (560), Curtiss (1), Martinsyde (258),
1280-449: The SOHC cylinder heads. The inlet and exhaust ports were cast into the blocks, the valve seats were in the top face of the steel cylinder liners, which were screwed into the blocks. Using a rotating bevel gear -driven tower shaft coming up from the crankcase along the rear end of each cylinder bank, with the final drive for each cylinder bank's camshaft accommodated within a semicircular bulge at
1344-782: The Western Front before the Camel, there were fewer squadrons equipped with the S.E.5 than with the Sopwith fighter. Together with the Camel, the S.E.5 was instrumental in regaining allied air superiority in mid-1917 and maintaining it for some time, ensuring there was no repetition of " Bloody April " 1917 when losses in the Royal Flying Corps were much heavier than in the Luftstreitkräfte . The S.E.5s remained in RAF service for some time following
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#17328721872261408-467: The aileron and rudder , whilst adjustment of the elevator trim made it possible to fly in a 'hands off' manner. The S.E.5 was powered by various engines, initially adopting a Hispano-Suiza 8 V8 engine . The Hispano-Suiza engine was advanced for the era, incorporating such features as an aluminium cylinder block with steel liners, dual ignition and forced lubrication that aided cooling; especially compared with contemporary rotary engines , it had
1472-412: The dihedral of the wings in order to increase its manoeuvrability and the removal of the head fairing to increase the pilot's visibility to the rear. James McCudden , an ace pilot and former RFC mechanic, was famous for his prolific fine-tuning of his aircraft in order to produce improved performance from it; McCudden was able to increase the top speed by 9 mph and to raise the service ceiling from
1536-584: The fuselage with the breech inside the cockpit , at a slight upwards angle. Typically, spare magazines for the Lewis gun would have been placed within most of the free space in the cockpit including the forward areas, such as the instrumentation panel. The standard instrument panel included a compass , altimeter , tachometer, oil pressure indicator, airspeed gauge, radiator temperature dial, fuel air pressure indicator, fuel selector, and air exchange; these were somewhat difficult to view due to their low-set position in
1600-404: The ' Spitfire of World War One'". In most respects the S.E.5 had superior performance to the rival Sopwith Camel , although it was less immediately responsive to the controls. Problems with its Hispano-Suiza engine, particularly the geared-output H-S 8B -powered early versions, meant that there was a chronic shortage of the type until well into 1918. Thus, while the first examples had reached
1664-474: The Camel's two, but it also had a wing-mounted Lewis gun fitted on a Foster mounting , which enabled the pilot to fire at an enemy aircraft from below. This armament configuration was much appreciated by the pilots of the first S.E.5 squadrons as the new hydraulic-link "C.C." synchronising gear for the Vickers machine gun was unreliable at first. The Vickers gun was mounted on the forward left dorsal surface of
1728-604: The HS-12Ycrs and HS-12Ydrs were built in quantity and were more commonly known by these names rather than any Czechoslovakian designation. Aircraft powered by these engines included the Czechoslovak Avia B-34 , Avia B-534 , Avia B-71 , Avia B-35 , Avia B-135 and the Yugoslav Rogožarski IK-3 . Switzerland license built and assembled several different versions of the basic 12Ycrs for use in several aircraft:
1792-513: The Imperial Gift in 1919, and the type went on to be the newly formed R.A.A.F.’s main fighter type until the late 1920’s. A number of machines found roles in civilian flying after the war. On 30 May 1922, the first use of skywriting for advertising occurred when Cyril Turner, a former RAF officer, spelt out "London Daily Mail " in black smoke from an S.E.5a at The Derby . Others were used for air racing ; one such privately owned aircraft won
1856-418: The S.E.5 as "arguably the best British-built fighter of World War I". In March 1917, the S.E.5 entered service with No. 56 Squadron RFC , although the squadron did not deploy to the Western Front until the following month. Everyone was suspicious of the large "greenhouse" windscreens fitted to the first production models. These were designed to protect the pilot in his unusually high seating position, which
1920-469: The S.E.5: "It was very fine to be in a machine that was faster than the Huns, and to know that one could run away just as things got too hot." Sholto Douglas who commanded No. 84 Squadron RFC which was initially equipped with the S.E.5a, listed the type's qualities as being: "Comfortable, with a good all-round view, retaining its performance and manoeuvrability at high level, steady and quick to gather speed in
1984-594: The Shuttleworth Collection. An extensive refurbishment of this aircraft was performed in 2007. It has been re-registered as G-EBIA , it was first painted as D7000 , then as F904 . An original S.E.5e may be seen in the National Museum of the United States Air Force at Dayton , Ohio, USA. The museum acquired the S.E.5e through a donation by the estate of Lt. Col. William C. Lambert , USAF Ret,
Hispano-Suiza 8 - Misplaced Pages Continue
2048-565: The advantage of being easy to operate by most pilots. An expansion tank for the cooling system was integrated into the leading edge of the upper wing's centre section. One of its greatest advantages over the Sopwith Camel was its superior performance at altitude, making it a much better match for the Fokker D.VII when that fighter arrived at the front. The S.E.5 was armed with a single synchronised .303 -inch Vickers machine gun in contrast to
2112-578: The allowable RPM from the 12Y's fairly low 2,400 to 2,700, thereby increasing power to 1,100 hp (820 kW). The resulting design, the Klimov M-105 (VK-105) became one of the major Soviet engine designs during the war, powering all Yakovlev fighters. Tabulated data from Lage 2004 Data from Aircraft Engines of the World 1945 Comparable engines Related lists Royal Aircraft Factory S.E.5#S.E.5a The Royal Aircraft Factory S.E.5
2176-464: The art of designing a useful intake was not as well developed as in other countries, and high altitude performance was always lacking. The first 12Y test articles were constructed in 1932, and almost immediately the entire French aviation industry began designing aeroplanes based on it. At the time the engine developed only 760 hp (570 kW), but it was clear it had potential to the 1,000 hp (750 kW) class. An early modification led to
2240-431: The cockpit. According to "Dodge" Bailey, Chief Test Pilot of the Shuttleworth Collection , the S.E.5's cockpit was "the best of the bunch from the era". It was set amidships, making it difficult to see over the long front fuselage, but otherwise visibility was good. Individual in-service S.E.5s would often receive customisations and user-specified tweaks at the request of their pilots. Popular changes included reducing
2304-601: The conventional system of Hispano-Suiza(engine manufacturer) 8(no of cylinders) A(engine series) b(variant) r(attribute), thus Hispano-Suiza 8Abr . The 8B , 8Ba and 8Bb were used (a) to power the earliest versions of the S.E.5a , (b) along with the 8Bd , the SPAD S.XIII , (c) front-line active versions of the Sopwith Dolphin , and (d) several other Allied aircraft types, with its gear reduction easily identifiable in vintage World War I photos, from its use of
2368-594: The dive, capable of a very fine zoom, useful in both offence and defence, strong in design and construction, [and] possessing a reliable engine". Soon after the Armistice the S.E.5a was withdrawn from RAF service. It was retained for a time in Canada, and in 1921 a Viper-engined S.E.5a was taken to Japan by the British Aviation Mission to the Imperial Japanese Navy . Australia received 35 S.E.5a under
2432-418: The earlier 12X was to use a master-articulated connecting rod system, instead of the fork-and-blade type. A single overhead camshaft (SOHC) drove the valves , which were filled with liquid sodium for cooling. Only a single intake and exhaust valve were used, unlike most designs of the era which had moved to three or four valves per cylinder. A single-stage, single-speed supercharger was standard, although
2496-467: The engine, although the single-stage supercharging meant that it was unable to compete with designs from England and Germany above 15,000 ft (5,000 m). In the early 1930s Czechoslovakia gained rights to build a license version of the HS-12Y. This was produced by Avia ( Škoda ) at Prag - Čakovice . The engine was intended to become the standard powerplant of all Czechoslovak military aircraft. Both
2560-580: The group, the reproduction aircraft, which was the company's first project, combined some authentic components, such as the Hispano engines used, with newly-fabricated parts based on original archived drawings. The Museum of Flight in Seattle , Washington , US displays the reproduction SE.5a that Bobby Strahlman and his partners completed for collector Doug Champlin in 1989. This reproduction features one .303 Vickers and one .303-calibre Lewis machine gun, and carries
2624-507: The most used engine designs of the pre-war era, used in almost all French fighter designs and prototypes. A real effort to improve the performance of the engine in 1938 resulted in the Hispano-Suiza 12Y-45 , which used the S-39-H3 supercharger co-designed by André Planiol and Polish engineer Joseph Szydlowski . The Szydlowski-Planiol device was larger, but much more efficient than the mediocre Hispano-Suiza models. When used with 100 octane fuel,
Hispano-Suiza 8 - Misplaced Pages Continue
2688-718: The new rotary engines under development did not appeal to aircraft designers. French officials ordered production of the 8A to be started as soon as possible and issued a requirement for a new single-seat high-performance fighter aircraft using the new engine. The Louis Béchereau -designed SPAD VII was the result of this requirement and allowed the Allies to regain air superiority over the Germans. Some data from: British Piston Engines and their Aircraft Note: Hispano-Suiza company type numbers were prefixed by HS- or written in full as Hispano-Suiza Type 31 , but military designations used
2752-439: The next version was the Hispano-Suiza 12Y-21 , which increased the compression ratio to 7:1, when running on 100 octane gasoline . This boosted power to 867 hp (647 kW). In 1936 the connecting rod design was changed slightly to create the 12Y-31 , but the lower 5.8:1 compression ratio was retained and the power was increased only slightly over the drs model to 850 hp (630 kW). Nevertheless, this became one of
2816-598: The paint scheme of American ace George Vaughn who served with the Royal Flying Corps. The SE.5 was displayed at Champlin's fighter museum at Mesa , Arizona , US until the collection was transferred to Seattle in 2003. The Royal Aircraft Factory S.E.5 has been portrayed, both by original and replica aircraft, in various movies. These include Wings (1927), Hell's Angels (1930), Flying Down to Rio (1933), Crimson Romance (1934), Test Pilot (1939) and The Aviator (2004). Converted Stampe et Vertongen SV.4 trainer/tourer aircraft were used to portray S.E.5s in
2880-488: The period. While the S.E.5 was not as agile and effective in a tight dogfight as the Camel it was much easier and safer to fly, particularly for novice pilots. According to "Dodge" Bailey, the former Chief Test Pilot of the Shuttleworth Collection , it had "somewhat similar handling characteristics to a de Havilland Tiger Moth , but with better excess power". Only 79 original S.E.5 aircraft had been completed prior to production settling upon an improved model, designated as
2944-460: The propeller (and even the entire gearbox on a very few occasions) separating from the engine and airframe in flight, a problem shared with the similarly-powered Sopwith Dolphin . The introduction of the 200 hp (149 kW) Wolseley Viper , a high-compression, direct-drive version of the Hispano-Suiza 8a made under licence by Wolseley Motors Limited , solved the S.E.5a's engine problems and
3008-445: The rear end of each valve cover. Aluminium parts were coated in vitreous enamel to reduce leakage. All parts subject to wear, and those critical for engine ignition were duplicated: spark plugs for dual ignition reliability, valve springs, magnetos , etc. Engine reliability and power to weight ratios were major problems in early aviation. The engine and its accessories weighed 185 kg (408 lb), making it 40% lighter than
3072-643: The reconnaissance biplane the EKW C-35 , the multipurpose EKW C-36 , the Swiss assembled D-3800 copy of the French M.S. 406 fighter and Swiss built versions of the French M.S.412 fighter called the D.3801 . Saurer developed the engine further after the Fall of France into the YS-2 and YS-3 engines. These were used in more powerful follow-on versions of the same basic French fighter design,
3136-457: The squarer wings also gave much improved lateral control at low airspeeds. Like the other significant Royal Aircraft Factory aircraft of the war ( B.E.2 , F.E.2 and R.E.8 ) the S.E.5 was inherently stable, making it an excellent gunnery platform, but it was also quite manoeuvrable. It was one of the fastest aircraft of the war at 138 mph (222 km/h), equal at least in speed to the SPAD S.XIII and faster than any standard German type of
3200-438: The standard 17,000 ft to 20,000 ft. His adaptions included replacing the standard pistons with high compression versions, shortening the exhaust (saving weight and improving exhaust scavenging), and changes to mixture, ignition and other engine settings as well as fitting a salvaged German propeller spinner (which he himself credited as gaining 3 mph alone). Aviation authors Donald Nijboer and Dan Patterson describe
3264-446: The standard configuration of Birkigt's existing design: eight cylinders in 90° Vee configuration, a displacement of 11.76 litres (717.8 cu in) and a power output of 140 hp at 1,900 rpm. In spite of the similarities with the original design, the engine had been substantially refined. The crankshaft was machined from a solid piece of steel. The cylinder blocks were cast aluminium and of monobloc type that is, in one piece with
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#17328721872263328-541: The supercharger boosted to the -21's 7:1, increasing power to 900 hp (670 kW). Combined with the Ratier constant-speed propeller , this allowed the D.520 to perform as well as contemporary designs from Germany and England. Another improvement in supercharging led to the Hispano-Suiza 12Y-49 , whose performance improved from 850 hp (630 kW) at sea level to 920 hp (690 kW) at just over 10,000 ft (3,000 m). This improvement in power with altitude
3392-489: The type. By the end of the war, the S.E.5a was employed by a total of 21 British Empire squadrons as well as two U.S. units. Many of the top Allied aces of the Great War flew this fighter, including Billy Bishop , Andrew Beauchamp-Proctor , Edward Mannock and James McCudden . Legendary British ace Albert Ball was initially disparaging of the S.E.5, but in the end claimed 11 of his 44 victories flying it. McCudden wrote of
3456-424: Was a common feature of most engines of the era, the result of the supercharger "robbing" power at low altitudes while not boosting the power due to the possibility of detonation. The final major version was the 1,085 hp (809 kW) Hispano-Suiza 12Y-51 , which had just started into production at the time of the Armistice with Germany . The -51 was the first version that came close to the performance limits of
3520-408: Was addressed by the introduction of the more powerful S.E.5a. In June 1917, the S.E.5a entered service and quickly began to replace the S.E.5. At this time 56 Squadron was still the only unit flying the new fighter; in fact it was the only operational unit to be fully equipped with the initial 150 hp S.E.5 – all other S.E.5 squadrons officially used the 200 hp S.E.5a from the outset – although
3584-415: Was despite being the most common type, then in use, for most aircraft. Also, rotary engines were getting close to the limits of their development at this time. Rotary engines of increased power generally had increased weight, which in turn increased the already serious gyroscopic torque generated by the engine's rotation. A further increase in torque was considered unacceptable, and the power to weight ratio of
3648-610: Was in service during the Second World War. At the beginning of World War I, the production lines of the Barcelona based Hispano-Suiza automobile and engine company were switched to the production of war materiel. Chief engineer Marc Birkigt led work on an aircraft engine based on his successful V8 automobile engine. The resulting engine, called the Hispano-Suiza 8A (HS-31), made its first appearance in February 1915. The first 8A kept
3712-410: Was in turn intended to improve vision over the upper wing. The squadron did not fly its first patrol with the S.E.5 until 22 April, by which time, on the insistence of Major Blomfield, 56 squadron's commanding officer, all aircraft had been fitted with small rectangular screens of conventional design. The problem of the high seating position was solved by simply lowering it, pilots in any case preferring
3776-544: Was initially underdeveloped and unreliable. The first of three prototypes flew on 22 November 1916. The first two prototypes were lost in crashes (the first killing the chief test pilot at the Royal Aircraft Factory, Major Frank Goodden, on 28 January 1917) due to a weakness in their wing design. The third prototype underwent modification before production commenced; the S.E.5 was known in service as an exceptionally strong aircraft which could be dived at very high speed –
3840-713: Was presented to the French Ministry of War in February 1915, and tested for 15 hours at full power. This was standard procedure for a new engine design to be admitted into military service. However, because of lobbying by French engine manufacturers, the Spanish-made engine was ordered to undergo a bench test that no French-made engine had yet passed: a 50-hour run at full speed. The HS-31 was therefore sent back to Chalais-Meudon on July 21, 1915, and tested for 50 hours, succeeding against all expectations. The design also promised far more development-potential than rotary engines. This
3904-801: Was produced under Hispano-Suiza licence in the Soviet Union as the Klimov M-100 . This design led to the highly successful Klimov VK-105 series that powered the Yakovlev and Lavochkin fighters as well as the Petlyakov Pe-2 bomber. Licensed production of the early models was also undertaken in Czechoslovakia as the Avia HS 12Ydrs and in Switzerland as the HS-77 . The 12Y was a fairly traditional in construction,
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#17328721872263968-404: Was promptly adopted as the type's standard powerplant. A number of aircraft were subsequently converted to a two-seat configuration in order to serve as trainer aircraft . The S.E.5b was a variant of the S.E.5 with a streamlined nose and upper and lower wings of different span and chord. The single example, a converted S.E.5a, first flew in early April 1918. It had a spinner on the propeller and
4032-492: Was relatively resistant to battle-damage. Unlike many of its peers, which were highly agile but unforgiving, the S.E.5 was comparatively stable and easy to fly; its stability enabling pilots to more readily fire upon enemies from further away with a greater degree of accuracy. It had a noticeably lower accident rate than comparable aircraft. The exception to its generally stability was an excessive amount of adverse yaw . The yaw could be compensated for by balanced application of
4096-521: Was used in a number of famous aircraft, including the Morane-Saulnier M.S.406 and Dewoitine D.520 . Its design was based on the earlier, and somewhat smaller, 12X . The 12X did not see widespread use before the 12Y replaced it and became one of the most powerful French designs on the eve of the war. The 12Z was being designed but this was ended by the fall of France and the German occupation . The 12Y
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