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73-422: The Model A version was powered by the ubiquitous Curtiss OX-5 , and featured a welded steel-tube truss fuselage with metal and fabric skinning. The wings, constructed of Spruce and plywood were also covered with metal and fabric skinning. The Model A had a reasonable performance for an OX-5 powered aircraft. The Model A's ease of handling led to its entry into the 1929 Guggenheim Safety Airplane contest, where it

146-434: A "nose on" viewpoint, while the crankshaft (which unlike other designs, never "emerged" from the crankcase) and other internal parts spun clockwise at the same speed, so the set was effectively running at 1800 rpm. This was achieved by the use of bevel gearing at the rear of the crankcase, resulting in the eleven-cylindered Siemens-Halske Sh.III , with less drag and less net torque. Used on several late war types, notably

219-423: A brazed-on steel jacket instead. Cylinder heads were also attached to the crankcase, using X-shaped tie-downs on the top of the head attached to the block via four long bolts. Fuel was carbureted near the rear of the engine, then piped to the cylinders via two T-shaped pipes, the cylinders being arranged so the intake ports of any two in a bank were near each other. The cylinders had one intake and one exhaust valve,

292-506: A former watchmaker, constructed rotary engines in the 1890s. He was interested in the rotary layout for two main reasons: Balzer produced a 3-cylinder, rotary engined car in 1894, then later became involved in Langley 's Aerodrome attempts, which bankrupted him while he tried to make much larger versions of his engines. Balzer's rotary engine was later converted to static radial operation by Langley's assistant, Charles M. Manly , creating

365-439: A good deal of practice to acquire the necessary knack. After starting the engine with a known setting that allowed it to idle, the air valve was opened until maximum engine speed was obtained. Throttling a running engine back to reduce revs was possible by closing off the fuel valve to the required position while re-adjusting the fuel/air mixture to suit. This process was also tricky, so that reducing power, especially when landing,

438-594: A large gyroscope . During level flight the effect was not especially apparent, but when turning the gyroscopic precession became noticeable. Due to the direction of the engine's rotation, left turns required effort and happened relatively slowly, combined with a tendency to nose up, while right turns were almost instantaneous, with a tendency for the nose to drop. In some aircraft, this could be advantageous in situations such as dogfights. The Sopwith Camel suffered to such an extent that it required left rudder for both left and right turns, and could be extremely hazardous if

511-669: A result of its slow RPM, which made it useful for civilian aircraft. The OX-5 was used on the Swallow Airplane Swallow , Pitcairn PA-4 Fleetwing II , Travel Air 2000 , Waco 9 and 10 , the American Eagle , the Buhl-Verville CW-3 Airster , and some models of the Jenny. The primary reason for its popularity was its low cost after the war, with almost-new examples selling as low as $ 20. It

584-539: A split type bolted together and held in place by lock screws. The pistons were cast aluminum. The OX-5 was not considered particularly advanced, nor powerful, for its era. By this point rotary engines such as the Oberursel or Gnome-Rhône were producing about 100 hp (75 kW), and newer inlines were becoming available with 160 hp (120 kW) or more. Nevertheless, the OX-5 had fairly good fuel economy as

657-535: The Clerget and Le Rhône companies used conventional pushrod-operated valves in the cylinder head, but used the same principle of drawing the fuel mixture through the crankshaft, with the Le Rhônes having prominent copper intake tubes running from the crankcase to the top of each cylinder to admit the intake charge. The 80 hp (60 kW) seven-cylinder Gnome was the standard at the outbreak of World War I, as

730-569: The Powerwheel , a wheel with a rotating one-cylinder engine , clutch and drum brake inside the hub, but it never entered production. Besides the configuration of cylinders moving around a fixed crankshaft, several different engine designs are also called rotary engines . The most notable pistonless rotary engine , the Wankel rotary engine has been used by NSU in the Ro80 car, by Mazda in

803-564: The Siemens-Schuckert D.IV fighter, the new engine's low running speed, coupled with large, coarse pitched propellers that sometimes had four blades (as the SSW D.IV used), gave types powered by it outstanding rates of climb, with some examples of the late production Sh.IIIa powerplant even said to be delivering as much as 240 hp. One new rotary powered aircraft, Fokker's own D.VIII , was designed at least in part to provide some use for

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876-424: The 3-cylinder, then very shortly thereafter 5-cylinder rotary engines later in 1906, as another early American automaker utilizing rotary engines expressly manufactured for automotive use. Emil Berliner sponsored its development of the 5-cylinder Adams-Farwell rotary engine design concept as a lightweight power unit for his unsuccessful helicopter experiments. Adams-Farwell engines later powered fixed-wing aircraft in

949-585: The Central Aerohydrodynamic Institute), constructed one of the first practical single-lift rotor machines with their TsAGI 1-EA single rotor helicopter, powered by two Soviet-designed and built M-2 rotary engines, themselves up-rated copies of the Gnome Monosoupape rotary engine of World War I. The TsAGI 1-EA set an unofficial altitude record of 605 meters (1,985 ft) with Cheremukhin piloting it on 14 August 1932 on

1022-537: The French V-form Hispano-Suiza 8 and the inline-six cylinder series of Mercedes D.I through D.III German engines. Built by several contractors in large numbers, the OX-5 suffered from uneven quality control. However, while the overwhelming majority of training accidents in the U.S. were in JN-4s, this was because JN-4s were flown by the vast majority of trainee pilots, and the accident rate in

1095-625: The Gnome Lambda, and it quickly found itself being used in a large number of aircraft designs. It was so good that it was licensed by a number of companies, including the German Motorenfabrik Oberursel firm who designed the original Gnom engine. Oberursel was later purchased by Fokker , whose 80 hp Gnome Lambda copy was known as the Oberursel U.0. It was not at all uncommon for French Gnôme Lambdas, as used in

1168-587: The Oberursel factory's backlog of otherwise redundant 110 hp (82 kW) Ur.II engines, themselves clones of the Le Rhône 9J rotary. Because of the Allied blockade of shipping, the Germans were increasingly unable to obtain the castor oil necessary to properly lubricate their rotary engines. Substitutes were never entirely satisfactory - causing increased running temperatures and reduced engine life. By

1241-720: The U.III of the same power rating. While an example of the Double Lambda went on to power one of the Deperdussin Monocoque racing aircraft to a world-record speed of nearly 204 km/h (126 mph) in September 1913, the Oberursel U.III is only known to have been fitted into a few German production military aircraft, the Fokker E.IV fighter monoplane and Fokker D.III fighter biplane, both of whose failures to become successful combat types were partially due to

1314-652: The US after 1910. It has also been asserted that the Gnôme design was derived from the Adams-Farwell, since an Adams-Farwell car is reported to have been demonstrated to the French Army in 1904. In contrast to the later Gnôme engines, and much like the later Clerget 9B and Bentley BR1 aviation rotaries, the Adams-Farwell rotaries had conventional exhaust and inlet valves mounted in the cylinder heads. The Gnome engine

1387-507: The US for primary training was four times less than the advanced training rate in France (virtually all US airmen getting advanced training in France), approximately 2800 flying hours in the US primarily in OX-5 powered JN-4s per fatality to 761 hours per fatality in France in other types. Very few fatal accidents were caused by engine failure, although the lack of power may have been the cause of

1460-549: The blip switch is useful while landing, as it provides a more reliable, quicker way to initiate power if needed, rather than risk a sudden engine stall, or the failure of a windmilling engine to restart at the worst possible moment. Félix Millet showed a 5-cylinder rotary engine built into a bicycle wheel at the Exposition Universelle in Paris in 1889. Millet had patented the engine in 1888, so must be considered

1533-445: The bottom of the basically circular cowling on most rotary engines to be cut away, or fitted with drainage slots. By 1918 a Clerget handbook advised maintaining all necessary control by using the fuel and air controls, and starting and stopping the engine by turning the fuel on and off. The recommended landing procedure involved shutting off the fuel using the fuel lever, while leaving the blip switch on. The windmilling propeller made

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1606-443: The coupe-switch was depressed, allowing it to cut out all spark voltage to all nine cylinders, at evenly spaced intervals to achieve the multiple levels of power reduction. The airworthy reproduction Fokker D.VIII parasol monoplane fighter at Old Rhinebeck Aerodrome, uniquely powered with a Gnome 9N, often demonstrates the use of its Gnome 9N's four-level output capability in both ground runs and in flight. Rotary engines produced by

1679-658: The crankshaft, but it rotated in the opposite direction to the cylinder block, thereby largely cancelling out negative effects. This proved too complicated for reliable operation and Redrup changed the design to a static radial engine, which was later tried in the experimental Vickers F.B.12b and F.B.16 aircraft, unfortunately without success. As the war progressed, aircraft designers demanded ever-increasing amounts of power. Inline engines were able to meet this demand by improving their upper rev limits, which meant more power. Improvements in valve timing, ignition systems, and lightweight materials made these higher revs possible, and by

1752-442: The cylinders pointing outwards from a single crankshaft, in the same general form as a radial, but there were also rotary boxer engines and even one-cylinder rotaries. Three key factors contributed to the rotary engine's success at the time: Engine designers had always been aware of the many limitations of the rotary engine, so when static style engines became more reliable and gave better specific weights and fuel consumption,

1825-407: The days of the rotary engine were numbered. The late World War I Bentley BR2 was the largest and most powerful rotary engine; it reached a point beyond which this type of engine could not be further developed, and it was the last of its kind to be adopted into RAF service. It is often asserted that rotary engines had no throttle and hence power could only be reduced by intermittently cutting

1898-441: The desired setting (usually full open) and then adjust the fuel/air mixture to suit using a separate "fine adjustment" lever that controlled the air supply valve (in the manner of a manual choke control). Due to the rotary engine's large rotational inertia, it was possible to adjust the appropriate fuel/air mixture by trial and error without stalling it, although this varied between different types of engine, and in any case it required

1971-411: The difference between the internal motions of the two types of engine. Like "fixed" radial engines, rotaries were generally built with an odd number of cylinders (usually 5, 7 or 9), so that a consistent every-other-piston firing order could be maintained, to provide smooth running. Rotary engines with an even number of cylinders were mostly of the "two row" type. Most rotary engines were arranged with

2044-532: The earliest examples of the Bristol Scout biplane, to meet German versions, powering Fokker E.I Eindeckers in combat, from the latter half of 1915 on. The only attempts to produce twin-row rotary engines in any volume were undertaken by Gnome, with their Double Lambda fourteen-cylinder 160 hp design, and with the German Oberursel firm's early World War I clone of the Double Lambda design,

2117-574: The early post-war years, the 1914-origin Avro 504 K, had a universal mounting to allow the use of several different types of low powered rotary, of which there was a large surplus supply. Similarly, the Swedish FVM Ö1 Tummelisa advanced training aircraft, fitted with a Le-Rhone-Thulin 90 hp (67 kW) rotary engine, served until the mid thirties. Designers had to balance the cheapness of war-surplus engines against their poor fuel efficiency and

2190-414: The end of the war the average engine had increased from 1,200 rpm to 2,000 rpm. The rotary was not able to do the same due to the drag of the rotating cylinders through the air. For instance, if an early-war model of 1,200 rpm increased its revs to only 1,400, the drag on the cylinders increased 36%, as air drag increases with the square of velocity. At lower rpm, drag could simply be ignored, but as

2263-487: The engine continue to spin without delivering any power as the aircraft descended. It was important to leave the ignition on to allow the spark plugs to continue to spark and keep them from oiling up, so that the engine could (if all went well) be restarted simply by re-opening the fuel valve. Pilots were advised to not use an ignition cut out switch, as it would eventually damage the engine. Pilots of surviving or reproduction aircraft fitted with rotary engines still find that

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2336-417: The engine in the surplus market made it common until the 1930s, although it was considered unreliable for most of its service life. The OX-5 was the last in a series of Glenn Curtiss designed V engines, which started as a series of air-cooled V-twins for motorcycles in 1902. A modified version of one of these early designs was sold as an aircraft engine in 1906, and from then on the company's primary market

2409-414: The engine was typically run at full throttle, and also because the valve timing was often less than ideal. Oil consumption was also very high. Due to primitive carburetion and absence of a true sump , the lubricating oil was added to the fuel/air mixture. This made engine fumes heavy with smoke from partially burnt oil. Castor oil was the lubricant of choice, as its lubrication properties were unaffected by

2482-425: The entire crankcase and its attached cylinders rotated around it as a unit. Its main application was in aviation, although it also saw use in a few early motorcycles and automobiles . This type of engine was widely used as an alternative to conventional inline engines ( straight or V ) during World War I and the years immediately preceding that conflict. It has been described as "a very efficient solution to

2555-536: The entire cylinder block rotates around it. In the most common form, the crankshaft was fixed solidly to the airframe, and the propeller was simply bolted to the front of the crankcase . This difference also has much impact on design (lubrication, ignition, fuel admission, cooling, etc.) and functioning (see below). The Musée de l'Air et de l'Espace in Paris has on display a special, "sectioned" working model of an engine with seven radially disposed cylinders. It alternates between rotary and radial modes to demonstrate

2628-417: The exhaust valve operated by a pushrod from a camshaft running between the banks and inlet valve operated by a pull rod/tube working from the same camshaft. This arrangement caused the outer exhaust valves to have a rather long rocker arm. The push/pullrods were arranged one inside the other, the exhaust valve rod being on the inside and the intake valve rod a tube around it. The aluminum camshaft bearings were

2701-410: The fuel (and lubricating oil) was taken into the cylinders already mixed with air - as in a normal four-stroke engine. Although a conventional carburetor, with the ability to keep the fuel/air ratio constant over a range of throttle openings, was precluded by the spinning crankcase; it was possible to adjust the air supply through a separate flap valve or "bloctube". The pilot needed to set the throttle to

2774-453: The ignition using a "blip" switch . This was only true of the "Monosoupape" (single valve) type, which took most of the air into the cylinder through the exhaust valve, which remained open for a portion of the downstroke of the piston. Thus the mixture of fuel and air in the cylinder could not be controlled via the crankcase intake. The "throttle" (fuel valve) of a monosoupape provided only a limited degree of speed regulation, as opening it made

2847-552: The inertia problem of rotary engines. As early as 1906 Charles Benjamin Redrup had demonstrated to the Royal Flying Corps at Hendon a 'Reactionless' engine in which the crankshaft rotated in one direction and the cylinder block in the opposite direction, each one driving a propeller. A later development of this was the 1914 reactionless 'Hart' engine designed by Redrup in which there was only one propeller connected to

2920-480: The interests of better cooling, and the world's first production rotary engine, the 7-cylinder, air-cooled 50 hp (37 kW) " Omega " was shown at the 1908 Paris automobile show. The first Gnome Omega built still exists, and is now in the collection of the Smithsonian's National Air and Space Museum . The Seguins used the highest strength material available - recently developed nickel steel alloy - and kept

2993-604: The inventor Roger Ravaud fitted one to his Aéroscaphe , a combination hydrofoil /aircraft, which he entered in the motor boat and aviation contests at Monaco. Henry Farman 's use of the Gnome at the famous Rheims aircraft meet that year brought it to prominence, when he won the Grand Prix for the greatest non-stop distance flown—180 kilometres (110 mi)—and also set a world record for endurance flight. The very first successful seaplane flight, of Henri Fabre 's Le Canard ,

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3066-698: The many stall and spins that took about forty five percent of training lives. Anyone seeing a JN-4 today struggling into the air with an OX-5 can see very quickly that the JN-4 had to be flown in a narrow envelope. Also, the replacement of the A7A in Standard J-1s was contemplated, but the cost of $ 2,000 per aircraft compared with the need (by the time the J-1s were grounded in June 1918 JN-4s were in sufficient supply) led to

3139-405: The mixture too rich, while closing it made it too lean (in either case quickly stalling the engine, or damaging the cylinders). Early models featured a pioneering form of variable valve timing in an attempt to give greater control, but this caused the valves to burn and therefore it was abandoned. The only way of running a Monosoupape engine smoothly at reduced revs was with a switch that changed

3212-438: The normal firing sequence so that each cylinder fired only once per two or three engine revolutions, but the engine remained more or less in balance. As with excessive use of the "blip" switch: running the engine on such a setting for too long resulted in large quantities of unburned fuel and oil in the exhaust, and gathering in the lower cowling, where it was a notorious fire hazard. Most rotaries had normal inlet valves, so that

3285-404: The notable Manly–Balzer engine . The famous De Dion-Bouton company produced an experimental 4-cylinder rotary engine in 1899. Though intended for aviation use, it was not fitted to any aircraft. The Adams-Farwell firm's automobiles, with the firm's first rolling prototypes using 3-cylinder rotary engines designed by Fay Oliver Farwell in 1898, led to production Adams-Farwell cars with first

3358-578: The operating expense of their total-loss lubrication system, and by the mid-1920s, rotaries had been more or less completely displaced even in British service, largely by the new generation of air-cooled "stationary" radials such as the Armstrong Siddeley Jaguar and Bristol Jupiter . Experiments with the concept of the rotary engine continued. The first version of the 1921 Michel engine , an unusual opposed-piston cam engine , used

3431-699: The pilot applied full power at the top of a loop at low airspeeds. Trainee Camel pilots were warned to attempt their first hard right turns only at altitudes above 1,000 ft (300 m). The Camel's most famous German foe, the Fokker Dr.I triplane , also used a rotary engine, usually the Oberursel Ur.II clone of the French-built Le Rhone 9J 110 hp powerplant. Even before the First World War, attempts were made to overcome

3504-542: The pioneer of the internal combustion rotary engine. A machine powered by his engine took part in the Paris-Bordeaux-Paris race of 1895 and the system was put into production by Darracq and Company London in 1900. Lawrence Hargrave first developed a rotary engine in 1889 using compressed air, intending to use it in powered flight. Materials weight and lack of quality machining prevented it becoming an effective power unit. Stephen M. Balzer of New York,

3577-523: The poor quality of the German powerplant, which was prone to wearing out after only a few hours of combat flight. The favourable power-to-weight ratio of the rotaries was their greatest advantage. While larger, heavier aircraft relied almost exclusively on conventional in-line engines, many fighter aircraft designers preferred rotaries right up to the end of the war. Rotaries had a number of disadvantages, notably very high fuel consumption, partially because

3650-519: The power of its twinned M-2 rotary engines. Although rotary engines were mostly used in aircraft, a few cars and motorcycles were built with rotary engines. Perhaps the first was the Millet motorcycle of 1892. A famous motorcycle, winning many races, was the Megola , which had a rotary engine inside the front wheel. Another motorcycle with a rotary engine was Charles Redrup 's 1912 Redrup Radial , which

3723-402: The presence of the fuel, and its gum-forming tendency was irrelevant in a total-loss lubrication system. An unfortunate side-effect was that World War I pilots inhaled and swallowed a considerable amount of the oil during flight, leading to persistent diarrhoea . Flying clothing worn by rotary engine pilots was routinely soaked with oil. The rotating mass of the engine also made it, in effect,

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3796-514: The principle of a rotary engine, in that its "cylinder block" rotated. This was soon replaced by a version with the same cylinders and cam, but with stationary cylinders and the cam track rotating in lieu of a crankshaft. A later version abandoned the cam altogether and used three coupled crankshafts. By 1930 the Soviet helicopter pioneers, Boris N. Yuriev and Alexei M. Cheremukhin, both employed by Tsentralniy Aerogidrodinamicheskiy Institut (TsAGI,

3869-433: The problems of power output, weight, and reliability". By the early 1920s, the inherent limitations of this type of engine had rendered it obsolete. A rotary engine is essentially a standard Otto cycle engine, with cylinders arranged radially around a central crankshaft just like a conventional radial engine , but instead of having a fixed cylinder block with rotating crankshaft , the crankshaft remains stationary and

3942-504: The rejection of this idea. The successful civilian post-war use of the OX-5 (even in civilian purchased and converted J-1s) was due to its relative reliability in the more aerodynamically advanced designs of the 1920s, its simplicity of operation, and its low cost. By comparison the Hall Scott A7A created such a bad impression during the war that very few, if any, were used by civilian operators. The OX-5 itself would be replaced by

4015-448: The rev count rose, the rotary was putting more and more power into spinning the engine, with less remaining to provide useful thrust through the propeller. One clever attempt to rescue the design, in a similar manner to Redrup's British "reactionless" engine concept, was made by Siemens . The crankcase (with the propeller still fastened directly to the front of it) and cylinders spun counterclockwise at 900 rpm, as seen externally from

4088-431: The safety factor of a dual ignition system, and was the last known rotary engine design to use such a cylinder head valving format. The 9N also featured an unusual ignition setup that allowed output values of one-half, one-quarter and one-eighth power levels to be achieved through use of the coupe-switch and a special five-position rotary switch that selected which of the trio of alternate power levels would be selected when

4161-617: The time the war ended, the rotary engine had become obsolete, and it disappeared from use quite quickly. The British Royal Air Force probably used rotary engines for longer than most other operators. The RAF's standard post-war fighter, the Sopwith Snipe , used the Bentley BR2 rotary as the most powerful (at some 230 hp (170 kW)) rotary engine ever built by the Allies of World War I . The standard RAF training aircraft of

4234-410: The valve gear was fragile, and it had no provisions for lubrication other than grease and oil applied by hand, leading to an overhaul interval as short as fifty hours. Additionally the engine featured a single spark plug in each cylinder, and a single ignition system, in an era when ignition equipment was less reliable, with dual ignition already being fitted to more advanced aviation powerplants like

4307-464: The valve tappet rollers, a system later abandoned due to valves burning. The weight of the Monosoupape was slightly less than the earlier two-valve engines, and it used less lubricating oil. The 100 hp Monosoupape was built with 9 cylinders, and developed its rated power at 1,200 rpm. The later 160 hp nine-cylinder Gnome 9N rotary engine used the Monosoupape valve design while adding

4380-478: The weight down by machining components from solid metal, using the best American and German machine tools to create the engine's components; the cylinder wall of a 50 hp Gnome was only 1.5 mm (0.059 inches) thick, while the connecting rods were milled with deep central channels to reduce weight. While somewhat low powered in terms of units of power per litre, its power-to-weight ratio was an outstanding 1 hp (0.75 kW) per kg. The following year, 1909,

4453-434: The well-proven Wright Aeronautical -built version of the 150 hp Hispano-Suiza HS-8a V8 engine in the nearly 930 examples of the later production Curtiss JN-4 H Jenny biplanes. Rotary engine The rotary engine is an early type of internal combustion engine , usually designed with an odd number of cylinders per row in a radial configuration . The engine's crankshaft remained stationary in operation, while

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4526-525: Was a team effort; the team included Charles M. Manly , whose earlier Manly–Balzer engine had held the power-to-weight ratio record for 16 years. Curtiss continued the development of their V8 engines with demand for higher power outputs being largely driven by the US Navy ’s requirement for seaplanes . By 1912 Curtiss V8’s were developing 75 hp and were known as the Curtiss Model O . The Curtiss O

4599-516: Was a three-cylinder 303 cc rotary engine fitted to a number of motorcycles by Redrup. In 1904 the Barry engine , also designed by Redrup, was built in Wales: a rotating 2-cylinder boxer engine weighing 6.5 kg was mounted inside a motorcycle frame. The early-1920s German Megola motorcycle used a five-cylinder rotary engine within its front wheel design. In the 1940s Cyril Pullin developed

4672-519: Was aircraft. The basic design had slowly expanded by adding additional cylinders until they reached the V-8 in 1906. They also started enlarging the cylinders as well, but this led to cooling problems that required the introduction of liquid cooling in 1908. These early engines used a flathead valve arrangement, which eventually gave way to a cross-flow cylinder with overhead valves in 1909, leading to improved volumetric efficiency . By this point engine design

4745-455: Was an early V-8 American liquid-cooled aircraft engine built by Curtiss . It was the first American-designed aircraft engine to enter mass production, although it was considered obsolete when it did so in 1917. It nevertheless found widespread use on a number of aircraft, perhaps the most famous being the JN-4 "Jenny" . Some 12,600 units were built through early 1919. The wide availability of

4818-708: Was awarded the highest ratings for a standard production aircraft. The Model A was awarded Group 2 approval no 2-33 in January 1929 for the first nine aircraft serial no. 1000 to 1008. Aircraft serial no. 1009 upwards were manufactured under Air Transport Certificate no. 101. The Model B followed on from the initial Bird design and was fitted with the uncowled Kinner radial engine. Production aircraft were designated BK . Data from: aerofiles.com Data from U.S. civil aircraft series:Vol.2 General characteristics Performance (Partial listing, only covers most numerous types) Curtiss OX-5 The Curtiss OX-5

4891-467: Was credited as the first engine able to run for ten hours between overhauls. In 1913 the Seguin brothers introduced the new Monosoupape ("single valve") series, which replaced inlet valves in the pistons by using a single valve in each cylinder head, which doubled as inlet and exhaust valve. The engine speed was controlled by varying the opening time and extent of the exhaust valves using levers acting on

4964-415: Was further developed into the 90 hp Curtiss OX. OX series production began in 1913. The OX-5 was built between 1915 and 1919 and was by far the most popular OX variant. Like most engines of the era, the OX-5's high-temperature areas were built mostly of cast iron , using individual cylinders bolted to a single aluminum crankcase, wrapped in a cooling jacket made of a nickel-copper alloy. Later versions used

5037-409: Was joined by his brother Laurent who designed a rotary engine specifically for aircraft use, using Gnom engine cylinders. The brothers' first experimental engine is said to have been a 5-cylinder model that developed 34 hp (25 kW), and was a radial rather than rotary engine, but no photographs survive of the five-cylinder experimental model. The Seguin brothers then turned to rotary engines in

5110-441: Was often accomplished instead by intermittently cutting the ignition using the blip switch. Cutting cylinders using ignition switches had the drawback of letting fuel continue to pass through the engine, oiling up the spark plugs and making smooth restarting problematic. Also, the raw oil-fuel mix could collect in the cowling. As this could cause a serious fire when the switch was released, it became common practice for part or all of

5183-572: Was often used in boats as well as in aircraft. The engine was considered unreliable, but unreliable is a relative term: aviation engine technology had not fully matured at the end of World War I. Certainly the JN4 with the OX-5 was underpowered, but the OX-5 proved a much better engine than the Hall Scott A7A that was the Achilles heel of the Standard J -1, the substitute primary trainer. In particular

5256-428: Was powered by a Gnome Omega on March 28, 1910, near Marseille . Production of Gnome rotaries increased rapidly, with some 4,000 being produced before World War I, and Gnome also produced a two-row version (the 100 h.p. Double Omega), the larger 80 hp Gnome Lambda and the 160 hp two-row Double Lambda. By the standards of other engines of the period, the Gnome was considered not particularly temperamental, and

5329-587: Was the work of the three Seguin brothers, Louis, Laurent and Augustin. They were talented engineers and the grandsons of famous French engineer Marc Seguin . In 1906 the eldest brother, Louis, had formed the Société des Moteurs Gnome to build stationary engines for industrial use, having licensed production of the Gnom single-cylinder stationary engine from Motorenfabrik Oberursel —who, in turn, built licensed Gnome engines for German aircraft during World War I. Louis

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