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.
90-485: The Bristol Pegasus is a British nine-cylinder, single-row, air-cooled radial aero engine . Designed by Roy Fedden of the Bristol Aeroplane Company , it was used to power both civil and military aircraft of the 1930s and 1940s. Developed from the earlier Mercury and Jupiter engines, later variants could produce 1,000 horsepower (750 kilowatts) from its capacity of 1,750 cubic inches (28 L) by use of
180-411: A 14-cylinder twin-row version of the firm's 80 hp Lambda single-row seven-cylinder rotary, however reliability and cooling problems limited its success. Two-row designs began to appear in large numbers during the 1930s, when aircraft size and weight grew to the point where single-row engines of the required power were simply too large to be practical. Two-row designs often had cooling problems with
270-562: A 7,600 km (4,700 mi) flight over the Andes in 1950 as a Missione di Italianità (Mission of the Italian Spirit). In 1953, the same aircraft flew across the arctic, raising the international profile of the Italian aerospace industry still further. In the fifties Alfa Romeo continued to collaborate with Fiat, producing jet engines, but production remained below pre-war levels. In 1952, of
360-447: A 9-cylinder 980 cubic inch (16.06 litre) displacement diesel radial aircraft engine, the 225 horsepower (168 kW) DR-980 , in 1928. On 28 May 1931, a DR-980 powered Bellanca CH-300 , with 481 gallons of fuel, piloted by Walter Edwin Lees and Frederick Brossy set a record for staying aloft for 84 hours and 32 minutes without being refueled. This record stood for 55 years until broken by
450-660: A 9-cylinder radial diesel aero engine, was used in the M1A1E1 , while the Continental R975 saw service in the M4 Sherman , M7 Priest , M18 Hellcat tank destroyer , and the M44 self propelled howitzer . A number of companies continue to build radials today. Vedeneyev produces the M-14P radial of 360–450 hp (270–340 kW) as used on Yakovlev and Sukhoi aerobatic aircraft. The M-14P
540-664: A build-it-yourself kit. Verner Motor of the Czech Republic builds several radial engines ranging in power from 25 to 150 hp (19 to 112 kW). Miniature radial engines for model airplanes are available from O. S. Engines , Saito Seisakusho of Japan, and Shijiazhuang of China, and Evolution (designed by Wolfgang Seidel of Germany, and made in India) and Technopower in the US. Liquid cooling systems are generally more vulnerable to battle damage. Even minor shrapnel damage can easily result in
630-537: A consistent every-other-piston firing order can be maintained, providing smooth operation. For example, on a five-cylinder engine the firing order is 1, 3, 5, 2, 4, and back to cylinder 1. Moreover, this always leaves a one-piston gap between the piston on its combustion stroke and the piston on compression. The active stroke directly helps compress the next cylinder to fire, making the motion more uniform. If an even number of cylinders were used, an equally timed firing cycle would not be feasible. As with most four-strokes,
720-512: A contract to produce the Armstrong Siddeley Lynx seven and nine cylinder radials under license. At the end of the twenties, Alfa Romeo director, Prospero Gianferrari, decided to diversify the company's business, and invest in the design and construction of aircraft engines in addition to trucks and buses. To demonstrate the new prowess, and the way that their expertise spread between aviation and motoring, in 1931 Alfa Romeo organized
810-399: A few French-built examples of the famous Blériot XI from the original Blériot factory — to a massive 20-cylinder engine of 200 hp (150 kW), with its cylinders arranged in four rows of five cylinders apiece. Most radial engines are air-cooled , but one of the most successful of the early radial engines (and the earliest "stationary" design produced for World War I combat aircraft)
900-454: A future armed conflict. Soon aircraft production was generating almost 80% of Alfa Romeo's sales revenue. In this context, in 1938, it was decided to build a production plant in Pomigliano d'Arco, near Naples, dedicated to the design and assembly of aircraft engines. In the following years the plant in Pomigliano d'Arco reached levels of quality and technological achievement that put it among
990-521: A geared supercharger . Further developments of the Pegasus created the fuel-injected Bristol Draco and the diesel Bristol Phoenix , both types being produced in limited numbers. In contrast, by the end of production over 30,000 Pegasus engines had been built. Aircraft applications ranged from single-engine biplanes to the four-engined Short Sandringham and Sunderland flying boats . Several altitude and distance records were set by aircraft using
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#17330863078081080-582: A license to build the Bristol Jupiter IV, an air-cooled nine cylinder radial engine. These engines were then used on reconnaissance and observation aircraft like the IMAM Ro.1 , Meridionali Ro.1 and Caproni Ca.97 . They were also used, experimentally, on the Caproni Ca.102 bomber and Ansaldo AC.3 fighter. In 1928, Pasquale Gallo, who replaced Nicola Romeo at the head of Alfa Romeo, also managed to win
1170-419: A loss of coolant and consequent engine overheating, while an air-cooled radial engine may be largely unaffected by minor damage. Radials have shorter and stiffer crankshafts, a single-bank radial engine needing only two crankshaft bearings as opposed to the seven required for a liquid-cooled, six-cylinder, inline engine of similar stiffness. While a single-bank radial permits all cylinders to be cooled equally,
1260-565: A new managing director, Ugo Gobbato , was appointed. Development and production of aircraft engines resumed. The D2 engine was used to power the Breda Ba.25 , the most widely used Italian basic trainer of the 1930s, and the Caproni Ca.101 . It was complemented by further development of the license-built Jupiter, the Alfa Romeo 125 , 125 RC.35, 126 RC.10 , 126 RC.34, 128 RC.18 , 128 RC.21 and 129 RC.32 , some of which saw widespread use. For example,
1350-648: A number of experiments and modifications) enough cooling air to the rear. This basic concept was soon copied by many other manufacturers, and many late-WWII aircraft returned to the radial design as newer and much larger designs began to be introduced. Examples include the Bristol Centaurus in the Hawker Sea Fury , and the Shvetsov ASh-82 in the Lavochkin La-7 . For even greater power, adding further rows
1440-525: A piston engine can be calculated by multiplying the charge per cylinder by the number of cycles per second; the Mercury improved both and thereby produced more power for a given size. The primary advantage was a much improved power-to-weight ratio due to better volumetric efficiency . The Pegasus was the same size, displacement and general steel/aluminium construction as the Jupiter, but various improvements allowed
1530-501: A power-to-weight ratio near that of contemporary gasoline engines and a specific fuel consumption of roughly 80% that for an equivalent gasoline engine. During WWII the research continued, but no mass-production occurred because of the Nazi occupation. By 1943 the engine had grown to produce over 1,000 hp (750 kW) with a turbocharger . After the war, the Clerget company was integrated in
1620-634: A race between an Alfa Romeo 8C 3000 Monza driven by Tazio Nuvolari and a Caproni Ca.100, also Alfa Romeo powered. Tazio Nuvolari beat the airplane by a small margin. The first big result of this change in strategy was the production, in 1932, of the first aircraft engine completely designed, developed and built by the Alfa Romeo, the D2 . Unfortunately, this development was too late for Alfa Romeo who were declared bankrupt in 1933. The state-owned Istituto per la Ricostruzione Industriale stepped in to take control and
1710-701: A similarly sized five-cylinder radial four-stroke model engine of their own as a direct rival to the OS design, with Saito also creating a series of three-cylinder methanol and gasoline-fueled model radial engines ranging from 0.90 cu.in. (15 cm ) to 4.50 cu.in. (75 cm ) in displacement, also all now available in spark-ignition format up to 84 cm displacement for use with gasoline. The German Seidel firm formerly made both seven- and nine-cylinder "large" (starting at 35 cm displacement) radio control model radial engines, mostly for glow plug ignition, with an experimental fourteen-cylinder twin-row radial being tried out -
1800-478: A single bank (or row) and an unusual double master connecting rod. Variants were built that could be run on either diesel oil or gasoline or mixtures of both. A number of powerhouse installations utilising large numbers of these engines were made in the U.S. Electro-Motive Diesel (EMD) built the "pancake" engines 16-184 and 16-338 for marine use. Zoche aero-diesels are a prototype radial design that have an even number of cylinders, either four or eight; but this
1890-585: Is also used by builders of homebuilt aircraft , such as the Culp Special , and Culp Sopwith Pup , Pitts S12 "Monster" and the Murphy "Moose" . 110 hp (82 kW) 7-cylinder and 150 hp (110 kW) 9-cylinder engines are available from Australia's Rotec Aerosport . HCI Aviation offers the R180 5-cylinder (75 hp (56 kW)) and R220 7-cylinder (110 hp (82 kW)), available "ready to fly" and as
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#17330863078081980-621: Is closed while moving from Kemble Airport to Filton. There is also an engine on display at the Brooklands Museum at Weybridge. As of October 2010 two Bristol Pegasus engines remain airworthy in England. They power the two Fairey Swordfish aircraft operated by the Royal Navy Historic Flight . Data from Lumsden. Related development Comparable engines Related lists Radial engine The radial configuration
2070-412: Is not problematic, because they are two-stroke engines , with twice the number of power strokes as a four-stroke engine per crankshaft rotation. A number of radial motors operating on compressed air have been designed, mostly for use in model airplanes and in gas compressors. A number of multi-cylinder 4-stroke model engines have been commercially available in a radial configuration, beginning with
2160-642: The Fiat G.91 programme, one of a number of examples of cooperation between the companies during the decade, and was the European distributor of the General Electric J85 and CJ610 turbojets. It was also involved, alongside FIAT, FN of Belgium and BMW , in the European production programme for the production of a FIAT (General Electric) J79-GE-11A turbojet to power the Lockheed F-104 Starfighter that
2250-605: The Kawasaki Ki-100 and Yokosuka D4Y 3. In Britain, Bristol produced both sleeve valved and conventional poppet valved radials: of the sleeve valved designs, more than 57,400 Hercules engines powered the Vickers Wellington , Short Stirling , Handley Page Halifax , and some versions of the Avro Lancaster , over 8,000 of the pioneering sleeve-valved Bristol Perseus were used in various types, and more than 2,500 of
2340-710: The Pegas . Approximately 32,000 Pegasus engines were built. The Pegasus set three height records in the Bristol Type 138 : in 1932, 1936 and 1937. It was used for the first flight over Mount Everest in the Westland Wallace , and in 1938 set the world's long-distance record in Vickers Wellesleys . In service the Pegasus was generally reliable with the exception that the valves were prone to failure. The valves were operated by rocker-boxes, which were lubricated by oil pads on
2430-576: The Pegasus XVIII ) and 100-octane fuel. This gave rise to the claim "one pound per horsepower" reflecting the excellent power-to-weight ratio. Some notable users of the Pegasus were the Fairey Swordfish , Vickers Wellington , and Short Sunderland . It was also used on the Anbo 41 , Bristol Bombay , Saro London , Short Empire , Vickers Wellesley and the Westland Wallace . Like the Jupiter before it,
2520-613: The Reggiane Re.2001 and Macchi M.C.202 . The Second World War left many signs in the Portello plant and the production site of Pomigliano d'Arco, which was considered a very important war supplier. Because of its strategic importance, the plant in Milan suffered two heavy bombing raids on 14 February and 13 August 1943. The final raid came on October 20, 1944, which was the heaviest bombardment that Milan had suffered, destroying more than 60% of
2610-521: The Rutan Voyager . The experimental Bristol Phoenix of 1928–1932 was successfully flight tested in a Westland Wapiti and set altitude records in 1934 that lasted until World War II. In 1932 the French company Clerget developed the 14D, a 14-cylinder two-stroke diesel radial engine. After a series of improvements, in 1938 the 14F2 model produced 520 hp (390 kW) at 1910 rpm cruise power, with
2700-627: The SNECMA company and had plans for a 32-cylinder diesel engine of 4,000 hp (3,000 kW), but in 1947 the company abandoned piston engine development in favour of the emerging turbine engines. The Nordberg Manufacturing Company of the United States developed and produced a series of large two-stroke radial diesel engines from the late 1940s for electrical production, primarily at aluminum smelters and for pumping water. They differed from most radials in that they had an even number of cylinders in
2790-491: The Westland Lysander , Bristol Blenheim , and Blackburn Skua . In the years leading up to World War II, as the need for armored vehicles was realized, designers were faced with the problem of how to power the vehicles, and turned to using aircraft engines, among them radial types. The radial aircraft engines provided greater power-to-weight ratios and were more reliable than conventional inline vehicle engines available at
Bristol Pegasus - Misplaced Pages Continue
2880-789: The 126 RC.34 was installed on five different airplanes: the Savoia-Marchetti S.74 , SM.75 , SM.79 , SM.81 and Cant Z.506 . Other aircraft engines derived from foreign designs in this decade included the 110 , based on the De Havilland Gypsy Major , the 115 , based on the De Havilland Gypsy Six and the Mercurius, based on the Bristol Mercury . At the same time, Alfa Romeo developed and produced its own propellers, both fixed and variable pitch, made from duralumin . In
2970-400: The 500 employed at the factory in Pomigliano d'Arco, only 160 worked in activities primarily link to aviation. Although management of the operation returned to Alfa Romeo, activities at Pomigliano d'Arco were limited, reduced to the repair and the construction of combustion engines. In 1962 it was decided to reorganize the plant. Alongside the "Vehicles" and "Diesel" sections, a "Avio" division
3060-649: The American Pratt & Whitney company was founded, competing with Wright's radial engines. Pratt & Whitney's initial offering, the R-1340 Wasp , was test run later that year, beginning a line of engines over the next 25 years that included the 14-cylinder, twin-row Pratt & Whitney R-1830 Twin Wasp . More Twin Wasps were produced than any other aviation piston engine in the history of aviation; nearly 175,000 were built. In
3150-621: The American Evolution firm now sells the Seidel-designed radials, with their manufacturing being done in India. Alfa Romeo Avio The Alfa Romeo Avio was an Italian aviation company producing aircraft engines active since 1941. It was founded as a division of Alfa Romeo but was sold to Aeritalia in 1986 and then to Fiat in 1996. It was merged with Fiat Avio in 2003 as Avio S.p.A. The first Alfa Romeo engine used on an airplane
3240-588: The American single-engine Vought F4U Corsair , Grumman F6F Hellcat , Republic P-47 Thunderbolt , twin-engine Martin B-26 Marauder , Douglas A-26 Invader , Northrop P-61 Black Widow , etc. The same firm's aforementioned smaller-displacement (at 30 litres), Twin Wasp 14-cylinder twin-row radial was used as the main engine design for the B-24 Liberator , PBY Catalina , and Douglas C-47 , each design being among
3330-619: The Centaurus and rapid movement to the use of turboprops such as the Armstrong Siddeley Python and Bristol Proteus , which easily produced more power than radials without the weight or complexity. Large radials continued to be built for other uses, although they are no longer common. An example is the 5-ton Zvezda M503 diesel engine with 42 cylinders in 6 rows of 7, displacing 143.6 litres (8,760 cu in) and producing 3,942 hp (2,940 kW). Three of these were used on
3420-741: The German single-seat, single-engine Focke-Wulf Fw 190 Würger , and twin-engine Junkers Ju 88 . In Japan, most airplanes were powered by air-cooled radial engines like the 14-cylinder Mitsubishi Zuisei (11,903 units, e.g. Kawasaki Ki-45 ), Mitsubishi Kinsei (12,228 units, e.g. Aichi D3A ), Mitsubishi Kasei (16,486 units, e.g. Kawanishi H8K ), Nakajima Sakae (30,233 units, e.g. Mitsubishi A6M and Nakajima Ki-43 ), and 18-cylinder Nakajima Homare (9,089 units, e.g. Nakajima Ki-84 ). The Kawasaki Ki-61 and Yokosuka D4Y were rare examples of Japanese liquid-cooled inline engine aircraft at that time but later, they were also redesigned to fit radial engines as
3510-605: The Gnome and Le Rhône rotary powerplants, and Siemens-Halske built their own designs, including the Siemens-Halske Sh.III eleven-cylinder rotary engine , which was unusual for the period in being geared through a bevel geartrain in the rear end of the crankcase without the crankshaft being firmly mounted to the aircraft's airframe, so that the engine's internal working components (fully internal crankshaft "floating" in its crankcase bearings, with its conrods and pistons) were spun in
3600-533: The Italian Army. In 1974, Alfa Romeo began a collaboration with Rolls-Royce to design, develop and assemble gas turbines. In 1975 the workforce employed by Alfa Romeo Avio had grown to 2,000 workers, although by 1980 this had settled to 1,300 employees. The company focused its work on supporting Pratt & Whitney , Rolls-Royce and General Electric engines. However, development of indigenous engines did not halt. In 1979, Alfa Romeo achieved another milestone as it
3690-504: The Japanese O.S. Max firm's FR5-300 five-cylinder, 3.0 cu.in. (50 cm ) displacement "Sirius" radial in 1986. The American "Technopower" firm had made smaller-displacement five- and seven-cylinder model radial engines as early as 1976, but the OS firm's engine was the first mass-produced radial engine design in aeromodelling history. The rival Saito Seisakusho firm in Japan has since produced
Bristol Pegasus - Misplaced Pages Continue
3780-478: The Jupiter. Although other piston configurations and turboprops have taken over in modern propeller-driven aircraft , Rare Bear , which is a Grumman F8F Bearcat equipped with a Wright R-3350 Duplex-Cyclone radial engine, is still the fastest piston-powered aircraft . 125,334 of the American twin-row, 18-cylinder Pratt & Whitney R-2800 Double Wasp , with a displacement of 2,800 in (46 L) and between 2,000 and 2,400 hp (1,500-1,800 kW), powered
3870-498: The Pegasus was also licensed by the PZL company in Poland . It was used on the PZL.23 Karaś and PZL.37 Łoś bombers. In Italy Alfa Romeo Avio built both the Jupiter (126-RC35) and the Pegasus under licence, with the engine based on the Pegasus designated as the Alfa Romeo 126-RC34 with the civil version as the 126-RC10. In Czechoslovakia it was built by Walter Engines and was known as
3960-670: The Pegasus. The Bristol Siddeley company reused the name many years later for the turbofan engine used in the Hawker Siddeley Harrier and which became known as the Rolls-Royce Pegasus when Rolls-Royce took over that company. Two Bristol Pegasus engines remain airworthy in 2010, powering Fairey Swordfish aircraft operated by the Royal Navy Historic Flight (became Navy Wings in March 2019); other examples are preserved and on public display in aviation museums . The Pegasus
4050-659: The United Kingdom the Bristol Aeroplane Company was concentrating on developing radials such as the Jupiter, Mercury , and sleeve valve Hercules radials. Germany, Japan, and the Soviet Union started with building licensed versions of the Armstrong Siddeley, Bristol, Wright, or Pratt & Whitney radials before producing their own improved versions. France continued its development of various rotary engines but also produced engines derived from Bristol designs, especially
4140-498: The animated illustration, four cam lobes serve all 10 valves across the five cylinders, whereas 10 would be required for a typical inline engine with the same number of cylinders and valves. Most radial engines use overhead poppet valves driven by pushrods and lifters on a cam plate which is concentric with the crankshaft, with a few smaller radials, like the Kinner B-5 and Russian Shvetsov M-11 , using individual camshafts within
4230-489: The aviation business were patented and later used in cars. One of the most famous metal alloys designed and developed by Alfa Romeo was "Duralfa". In the late thirties the political situation in Europe was changing as the winds of war brought many nations, including Italy, into an arms race. Alfa Romeo's production was directed away from civilian cars towards the assembly of the aircraft engines and trucks that would help Italy in
4320-460: The compression stroke, this liquid, being incompressible, stops piston movement. Starting or attempting to start the engine in such condition may result in a bent or broken connecting rod. Originally radial engines had one row of cylinders, but as engine sizes increased it became necessary to add extra rows. The first radial-configuration engine known to use a twin-row design was the 160 hp Gnôme "Double Lambda" rotary engine of 1912, designed as
4410-502: The crankcase and cylinders revolved with the propeller. It was similar in concept to the later radial, the main difference being that the propeller was bolted to the engine, and the crankshaft to the airframe. The problem of the cooling of the cylinders, a major factor with the early "stationary" radials, was alleviated by the engine generating its own cooling airflow. In World War I many French and other Allied aircraft flew with Gnome , Le Rhône , Clerget , and Bentley rotary engines,
4500-572: The crankcase for each cylinder. A few engines use sleeve valves such as the 14-cylinder Bristol Hercules and the 18-cylinder Bristol Centaurus , which are quieter and smoother running but require much tighter manufacturing tolerances . C. M. Manly constructed a water-cooled five-cylinder radial engine in 1901, a conversion of one of Stephen Balzer 's rotary engines , for Langley 's Aerodrome aircraft. Manly's engine produced 52 hp (39 kW) at 950 rpm. In 1903–1904 Jacob Ellehammer used his experience constructing motorcycles to build
4590-408: The crankshaft takes two revolutions to complete the four strokes of each piston (intake, compression, combustion, exhaust). The camshaft ring is geared to spin slower and in the opposite direction to the crankshaft. Its cam lobes are placed in two rows; one for the intake valves and one for the exhaust valves. The radial engine normally uses fewer cam lobes than other types. For example, in the engine in
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#17330863078084680-479: The early 1920s Le Rhône converted a number of their rotary engines into stationary radial engines. By 1918 the potential advantages of air-cooled radials over the water-cooled inline engine and air-cooled rotary engine that had powered World War I aircraft were appreciated but were unrealized. British designers had produced the ABC Dragonfly radial in 1917, but were unable to resolve the cooling problems, and it
4770-412: The engine with Alfa Romeo and the latter two companies taking responsibility for the rest of the aircraft. One product of this collaboration, an Alfa Romeo 110 powered Ambrosini S.1001 "Grifo" named Angelo dei Bimbi (Children's Angel), had a significant effect on the media. In 1949, the aircraft made the trip from Milan to Buenos Aires in 19 hours to raise funds for injured children injured, followed by
4860-434: The factory and closing the production site down. The plant in Pomigliano d'Arco suffered a similar fate on 30 May 1943, with the destruction of 70% of the factory by air attack. After the war, military production ceased and the factory in Pomigliano d'Arco was temporarily converted to produce cars, trucks, trolley buses, diesel engines, generators and marine engines, as well as testing car engines and chassis. Shortly after,
4950-558: The fast Osa class missile boats . Another one was the Lycoming XR-7755 which was the largest piston aircraft engine ever built in the United States with 36 cylinders totaling about 7,750 in (127 L) of displacement and a power output of 5,000 horsepower (3,700 kilowatts). While most radial engines have been produced for gasoline, there have been diesel radial engines. Two major advantages favour diesel engines — lower fuel consumption and reduced fire risk. Packard designed and built
5040-609: The four-engine Boeing B-29 Superfortress and others. The Soviet Shvetsov OKB-19 design bureau was the sole source of design for all of the Soviet government factory-produced radial engines used in its World War II aircraft, starting with the Shvetsov M-25 (itself based on the American Wright Cyclone 9 's design) and going on to design the 41-litre displacement Shvetsov ASh-82 fourteen cylinder radial for fighters, and
5130-599: The largest-displacement production British radial from the Bristol firm to use sleeve valving, the Bristol Centaurus were used to power the Hawker Tempest II and Sea Fury . The same firm's poppet-valved radials included: around 32,000 of Bristol Pegasus used in the Short Sunderland , Handley Page Hampden , and Fairey Swordfish and over 20,000 examples of the firm's 1925-origin nine-cylinder Mercury were used to power
5220-447: The late-war Hawker Sea Fury and Grumman F8F Bearcat , two of the fastest production piston-engined aircraft ever built, using radial engines. Whenever a radial engine remains shut down for more than a few minutes, oil or fuel may drain into the combustion chambers of the lower cylinders or accumulate in the lower intake pipes, ready to be drawn into the cylinders when the engine starts. As the piston approaches top dead center (TDC) of
5310-433: The leading factories of the period. After the outbreak of World War II, plant director Ugo Gobbato (1888–1945) decided to establish a separate division for aircraft products. Thus, in 1941, Alfa Romeo Avio was born. The aircraft engines produced by the Alfa Romeo in this period were almost all air-cooled radial engines. One exception was the RA 1000 RC.41 , which was licensed from Daimler-Benz and used fighter planes like
5400-454: The level of local skills. Turnover of Alfa Romeo Avio increased by 34% from 1968 to 1969 and in the second half of the sixties the company successfully exhibited its aircraft engines in various international air exhibitions. In the seventies, in the civil field, Alfa Romeo repaired all the types of turbine engines used by Alitalia and other Italian airlines, while, in the military arena, Alfa Romeo concentrated mainly on piston engines used by
5490-426: The majority used a geared supercharger, either single-speed or two-speed. Variant differences included compression ratios , propeller reduction gear ratios and accessories. Note: Bristol Pegasus engines can be viewed installed in aircraft at the Royal Air Force Museum London and the Imperial War Museum Duxford . An unrestored Pegasus recovered from the sea bed is in the care of the Bristol Aero Collection, which
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#17330863078085580-426: The massive, 58-litre displacement Shvetsov ASh-73 eighteen-cylinder radial in 1946 - the smallest-displacement radial design from the Shvetsov OKB during the war was the indigenously designed, 8.6 litre displacement Shvetsov M-11 five cylinder radial. Over 28,000 of the German 42-litre displacement, 14-cylinder, two-row BMW 801 , with between 1,560 and 2,000 PS (1,540-1,970 hp, or 1,150-1,470 kW), powered
5670-436: The maximum engine speed to be increased from 1,950 to 2,600 rpm for take-off power. This improved performance considerably from the Jupiter's 580 hp (430 kW), to the first Pegasus II with 635 hp (474 kW), to 690 hp (510 kW) in the first production model Pegasus III , and eventually to the late-model Pegasus XXII with 1,010 hp (750 kW) thanks to the two-speed supercharger (introduced on
5760-548: The opposing direction to the crankcase and cylinders, which still rotated as the propeller itself did since it was still firmly fastened to the crankcase's frontside, as with regular umlaufmotor German rotaries. By the end of the war the rotary engine had reached the limits of the design, particularly in regard to the amount of fuel and air that could be drawn into the cylinders through the hollow crankshaft, while advances in both metallurgy and cylinder cooling finally allowed stationary radial engines to supersede rotary engines. In
5850-472: The production leaders in all-time production numbers for each type of airframe design. The American Wright Cyclone series twin-row radials powered American warplanes: the nearly-43 litre displacement, 14-cylinder Twin Cyclone powered the single-engine Grumman TBF Avenger , twin-engine North American B-25 Mitchell , and some versions of the Douglas A-20 Havoc , with the massive twin-row, nearly 55-litre displacement, 18-cylinder Duplex-Cyclone powering
5940-409: The rear bank of cylinders, but a variety of baffles and fins were introduced that largely eliminated these problems. The downside was a relatively large frontal area that had to be left open to provide enough airflow, which increased drag. This led to significant arguments in the industry in the late 1930s about the possibility of using radials for high-speed aircraft like modern fighters. The solution
6030-465: The same is not true for multi-row engines where the rear cylinders can be affected by the heat coming off the front row, and air flow being masked. A potential disadvantage of radial engines is that having the cylinders exposed to the airflow increases drag considerably. The answer was the addition of specially designed cowlings with baffles to force the air between the cylinders. The first effective drag-reducing cowling that didn't impair engine cooling
6120-577: The site reopened as a maintenance site for aircraft engines, but this activity was substantially smaller than even pre-war production, since the operations were initially only the repair of Bristol engines and production of replacement parts. In 1947 the management of the plant in Pomigliano d'Arco passed from Alfa Romeo to Metalmeccanica Meridionale, but in 1948 Alfa Romeo returned to aircraft engine production. In 1949 Alfa Romeo made an alliance with Fiat, SAI Ambrosini and Aermacchi to produce de Havilland aircraft, with Fiat sharing responsibility for
6210-453: The takeover by Nicola Romeo . During the Nicola Romeo ownership, the company received orders from the Italian war ministry to build 300 license Isotta Fraschini V6 engines for bombers used in the First World War. However, after the war ended, having made a prototype of a 600 horsepower (450 kW) V12 engine, the Alfa Romeo aviation business was temporarily suspended. Alfa Romeo resumed activity in aviation in 1924. Nicola Romeo purchased
6300-414: The thirties, the Alfa Romeo engines for the aviation industry became famous for their successful participation in the various attempts to break world records in aviation and for their sporting triumphs. The Alfa Romeo aircraft engines of this period, used largely on the aircraft of the Regia Aeronautica , helped to write important pages in the history of Italian aviation. Some of the metal alloys used in
6390-486: The time. This reliance had a downside though: if the engines were mounted vertically, as in the M3 Lee and M4 Sherman , their comparatively large diameter gave the tank a higher silhouette than designs using inline engines. The Continental R-670 , a 7-cylinder radial aero engine which first flew in 1931, became a widely used tank powerplant, being installed in the M1 Combat Car , M2 Light Tank , M3 Stuart , M3 Lee , and LVT-2 Water Buffalo . The Guiberson T-1020 ,
6480-476: The top of the cylinder heads. In hot climates the lubrication deteriorated which could lead to seizing of the valves. Also if a problem developed with the engine and the pilot shut it down it was not possible to "feather" the propeller and so it would continue to rotate creating drag and continue to turn the engine which had no lubrication being forced through it by the oil pump. The Pegasus was produced in many variants, early prototype engines were unsupercharged but
6570-492: The ultimate examples of which reached 250 hp (190 kW) although none of those over 160 hp (120 kW) were successful. By 1917 rotary engine development was lagging behind new inline and V-type engines, which by 1918 were producing as much as 400 hp (300 kW), and were powering almost all of the new French and British combat aircraft. Most German aircraft of the time used water-cooled inline 6-cylinder engines. Motorenfabrik Oberursel made licensed copies of
6660-402: The uppermost one in the animation, has a master rod with a direct attachment to the crankshaft. The remaining pistons pin their connecting rods ' attachments to rings around the edge of the master rod. Extra "rows" of radial cylinders can be added in order to increase the capacity of the engine without adding to its diameter. Four-stroke radials have an odd number of cylinders per row, so that
6750-616: The world's first air-cooled radial engine, a three-cylinder engine which he used as the basis for a more powerful five-cylinder model in 1907. This was installed in his triplane and made a number of short free-flight hops. Another early radial engine was the three-cylinder Anzani , originally built as a W3 "fan" configuration, one of which powered Louis Blériot 's Blériot XI across the English Channel . Before 1914, Alessandro Anzani had developed radial engines ranging from 3 cylinders (spaced 120° apart) — early enough to have been used on
6840-512: Was being built in Europe and was used extensively by many NATO air forces. Given that the activities at the plant were expanding, the leadership of the Alfa Romeo decided to invest in the training of workers and technicians. At the same time, politicians keen to see development in southern Italy, supported the creation of the Alfasud factory next to the Alfa Romeo Avio facility, greatly increasing
6930-505: Was carried out in the US, and demonstrated that ample airflow was available with careful design. This led to the R-4360 , which has 28 cylinders arranged in a 4 row corncob configuration. The R-4360 saw service on large American aircraft in the post- World War II period. The US and Soviet Union continued experiments with larger radials, but the UK abandoned such designs in favour of newer versions of
7020-420: Was commonly used for aircraft engines before gas turbine engines became predominant. Since the axes of the cylinders are coplanar, the connecting rods cannot all be directly attached to the crankshaft unless mechanically complex forked connecting rods are used, none of which have been successful. Instead, the pistons are connected to the crankshaft with a master-and-articulating-rod assembly. One piston,
7110-468: Was designed by Sir Roy Fedden as the follow-on to the Bristol Aeroplane Company 's very successful Bristol Jupiter , using lessons learned in development of the Mercury . Although having a capacity (25 L) almost 15% smaller, the Mercury produced about as much power as the Jupiter, through a combination of supercharging to improve the "charge", and various changes to increase the operating RPM . The power of
7200-662: Was developed in 1922 with Navy funding, and using aluminum cylinders with steel liners ran for an unprecedented 300 hours, at a time when 50 hours endurance was normal. At the urging of the Army and Navy the Wright Aeronautical Corporation bought Lawrance's company, and subsequent engines were built under the Wright name. The radial engines gave confidence to Navy pilots performing long-range overwater flights. Wright's 225 hp (168 kW) J-5 Whirlwind radial engine of 1925
7290-501: Was installed in 1910. Designed and created by designer Antonio Santoni and Alfa Romeo driver Nino Franchini, the airplane was equipped with the engine from an ALFA 24 HP designed by Giuseppe Merosi with a maximum power of 36 horsepower (27 kW). The Santoni-Franchini biplane made its first flight on 1 November 1910 in Milan, taking off from Baggio and landing in San Siro . Alfa Romeo's involvement in aviation continued after
7380-450: Was introduced with the BMW 801 14-cylinder twin-row radial. Kurt Tank designed a new cooling system for this engine that used a high-speed fan to blow compressed air into channels that carry air to the middle of the banks, where a series of baffles directed the air over all of the cylinders. This allowed the cowling to be tightly fitted around the engine, reducing drag, while still providing (after
7470-480: Was not considered viable due to the difficulty of providing the required airflow to the rear banks. Larger engines were designed, mostly using water cooling although this greatly increased complexity and eliminated some of the advantages of the radial air-cooled design. One example of this concept is the BMW 803 , which never entered service. A major study into the airflow around radials using wind tunnels and other systems
7560-717: Was not until the 1920s that Bristol and Armstrong Siddeley produced reliable air-cooled radials such as the Bristol Jupiter and the Armstrong Siddeley Jaguar . In the United States the National Advisory Committee for Aeronautics (NACA) noted in 1920 that air-cooled radials could offer an increase in power-to-weight ratio and reliability; by 1921 the U.S. Navy had announced it would only order aircraft fitted with air-cooled radials and other naval air arms followed suit. Charles Lawrance 's J-1 engine
7650-477: Was restored. The revived Alfa Romeo Avio began to diversify its operation. Its repair and maintenance side expanded to deal with repairing Curtiss-Wright R-1820 and R-3350 piston engines, Rolls-Royce Avon and Wright J65 turbojets, Rolls-Royce Dart turboprops and Rolls-Royce Conway turbofans mounted on Italian and Norwegian airplanes. Alfa Romeo license built the Bristol Siddeley Orpheus for
7740-455: Was sold to Fiat, the remaining shares still owned by Alfa Romeo was bought by Aeritalia. As a result, Alfa Romeo Avio became part of Finmeccanica , the owner of Aeritalia and at the time state-owned. With the privatization of state-owned companies, including Finmeccanica, in 1996, the ownership of Alfa Romeo Avio was passed to Fiat Avio, bringing with it a turnover of 300 billion lire and 1,500 workers. Since 2003, Alfa Romeo Avio has been part of
7830-534: Was the Salmson 9Z series of nine-cylinder water-cooled radial engines that were produced in large numbers. Georges Canton and Pierre Unné patented the original engine design in 1909, offering it to the Salmson company; the engine was often known as the Canton-Unné. From 1909 to 1919 the radial engine was overshadowed by its close relative, the rotary engine , which differed from the so-called "stationary" radial in that
7920-692: Was the British Townend ring or "drag ring" which formed a narrow band around the engine covering the cylinder heads, reducing drag. The National Advisory Committee for Aeronautics studied the problem, developing the NACA cowling which further reduced drag and improved cooling. Nearly all aircraft radial engines since have used NACA-type cowlings. While inline liquid-cooled engines continued to be common in new designs until late in World War II , radial engines dominated afterwards until overtaken by jet engines, with
8010-502: Was the first Italian company to design, develop and build a turboprop aircraft engine (the AR.138 ), which was installed on a Beechcraft King Air . In 1981, Alfa Romeo Avio took part, along with Oto Melara and Fiat Avio in the development of the supersonic Otomach missile derived from the successful Otomat . In 1982, Alfa Romeo transferred 10% of its shares in Alfa Romeo Avio to Aeritalia, that share grew to 60% in 1984. In 1986, when Alfa Romeo
8100-465: Was widely claimed as "the first truly reliable aircraft engine". Wright employed Giuseppe Mario Bellanca to design an aircraft to showcase it, and the result was the Wright-Bellanca WB-1 , which first flew later that year. The J-5 was used on many advanced aircraft of the day, including Charles Lindbergh 's Spirit of St. Louis , in which he made the first solo trans-Atlantic flight. In 1925
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