27-462: The Rolls-Royce Goshawk was a development of the Rolls-Royce Kestrel that used evaporative or steam cooling . In line with Rolls-Royce convention of naming piston engines after birds of prey , it was named after the goshawk . The engine first ran in 1933 and provided 660 horsepower (490 kW). Only a few engines were built as the aircraft designs intended to use it were not adopted by
54-847: A fighter aircraft. Goshawks were used by all three officially sponsored prototypes, the Supermarine Type 224 ( K2890 ),the Westland F.7/30 ( K2891 ) and the Blackburn F3 ( K2892 ), which only taxied with the Goshawk fitted and did not fly, in addition to two private venture entrants, the Bristol Type 123 and the Hawker P.V.3 . The Goshawk also powered Hawker's privately developed "High Speed Fury Mk 2" ( K3586 ) and "Intermediate Fury" 2" (the latter Hawker's own development aircraft and "hack" serial G-ABSE ) and
81-489: A mainstay of British air power during the early 1930s. Development continued and the V model introduced the centrifugal supercharger, increasing power to 695hp (520kW). Increased availability of higher octane aviation fuels in the late 1930s allowed the engine to be boosted to higher power levels without suffering from detonation . The mark-XVI engine used in the Miles Master M.9 prototype delivered 745hp (500kW), and
108-631: The Royal Air Force . The Goshawk was used to power the Short Knuckleduster , the Supermarine Type 224 (a predecessor to the Supermarine Spitfire ) and other prototype aircraft. The Goshawk was developed from the Kestrel IV prototype engine, to use evaporative (also known as "steam") cooling. Rather than keep the cooling liquid below its boiling point in the cooling system, the coolant
135-518: The Westland Pterodactyl V ( K2770 ) and was installed for trials in the Gloster TSR.38 ( S1705 ), and the first Gloster Gnatsnapper prototype ( N227 ). Data from Lumsden Related development Comparable engines Related lists Rolls-Royce Kestrel The Rolls-Royce Kestrel (internal type F ) is a 21.25 litre (1,295 in³) V-12 aircraft engine from Rolls-Royce . It
162-623: The CR-2s were fitted with floats for the Schneider Trophy race and redesignated CR-3 . The aircraft took first and second place, piloted by David Rittenhouse (average speed 177.977 mph (154.658 kn; 286.426 km/h) and Rutledge Irvine 173.932 mph (151.143 kn; 279.916 km/h). After the 1924 Schneider Trophy race was cancelled, CR-3 A6081 was flown by Lt. G.T. Cuuddihy to set up new World's closed-course seaplane record oc 188.07 mph (163.43 kn; 302.67 km/h). A6081
189-641: The German Messerschmitt Bf 109 and the Junkers Ju 87 "Stuka" dive-bomber, as the Junkers Jumo 210 engines were not ready to be fitted. Several examples of the Kestrel engine remain airworthy today. Earlier in-line engine designs were generally built on top of a cast aluminum crankcase, with the cylinders, individually-machined steel cylinders, bolted on top. Given the forces involved, the system connecting
216-577: The Peregrine and Vulture engines were curtailed, before eventually being cancelled, to allow increased resource developing the Merlin engine during the war. As a response to the fuel injection systems developed by Bosch, in 1936 a Kestrel engine was fitted with a pressurised carburettor system to improve fuelling at high altitudes. The resulting behaviour of the engine when flight tested by the Farnborough institute
243-495: The R-6s by using the aircraft to break the world airspeed record before 1922 was over, Gen Billy Mitchell flying one to 224.28 mph (359.72 km/h) on 18 October. In March the following year, an R-6 flown by Lt. Maughan lifted the record to 236.587 mph (380.74 km/h). The R-6 design was developed in 1923 into the longer-winged XPW-8, the prototype of the PW-8 fighter. In 1923,
270-479: The XXX variant of 1940 saw service at 720hp (537kW). One key advance in the Kestrel was the use of a pressurised cooling system. Water boils at 100°C at standard atmospheric pressure , but this pressure decreases as altitude increases, and therefore the boiling point of water decreases with altitude . The amount of heat rejected by an air-to-air cooling system is a function of the maximum coolant temperature and volume, so
297-607: The aircraft for the same heat load. The Kestrel was built to maintain coolant pressure to keep the boiling point at about 150°C. In early Kestrel variants, unsupercharged engines were available in two compression ratios, 'A' engines had a compression ratio of 6:1, and 'B' engines a high compression ratio of 7:1. The Kestrel was designed to be fitted with a gear-driven supercharger , in early Kestrel variants 'MS' engines were moderately supercharged and 'S' engines were fully supercharged. A number of Kestrel variants were produced by rebuilding or modifying earlier Marks. During 1927, once
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#1732844731277324-459: The cylinders to the crankcase had to be robust, adding weight, and as a whole the engine was reliant on the structure of the crankcase to hold it together. In 1923, the Curtiss CR won the 1923 Schneider Trophy . The CR was powered by the recently introduced Curtiss D-12 engine, which replaced the individual cylinders with a cast aluminum block. This gave the engine much greater strength, allowing
351-508: The designer of the Napier Lion engine, joined Rolls-Royce in 1921 to take up the role as "Chief Assistant to Mr F. H. Royce". Rowledge built a team to introduce a new engine using the cast block, but set the goal to surpass the D-12. This would be accomplished using supercharging at all altitudes, allowing it to outperform naturally aspirated engines. Previously, supercharging (and turbocharging)
378-577: The prototype of the Kestrel was complete, a need for a larger and more powerful engine was conceived for use in flying boats, and development began on an engine which utilised a 6" cylinder bore, compared to the Kestrel's 5", this became the Rolls-Royce Buzzard . The Buzzard (or "H") engine was further modified for use in the Schneider Trophy as the Rolls-Royce R engine. In 1935 the Kestrel design
405-443: The realisation that large wing-mounted condensing radiators would be vulnerable to combat damage caused the project to be cancelled, although valuable lessons had been learned and were put to good use with development of the later Merlin . The Goshawk was the power unit specified for the twin engined Short Knuckleduster flying boat ( K3574 ) to Specification R24/31 and "preferred" for submissions to Air Ministry specification F7/30 for
432-432: The rest of the engine to be greatly simplified, making it much lighter overall, as well as easier to assemble as the two parts simply bolted together in a single operation. It was also easy to convert existing assembly lines to the new system as the cast blocks were already being produced for the crankcase, and all that was required was new machines to mill the blocks to the accuracy needed for the pistons. The Curtiss D-12
459-424: The resulting decrease in cooling capacity became a limiting factor for aero engine power in this period, as the coolant has to be kept below boiling point. The solution was to pressurise the engine's entire cooling system, thereby raising the temperature at which the coolant would boil: not only does this help mitigate the decrease in cooling performance with altitude, but allows a smaller cooling system to be used in
486-562: Was a racing aircraft designed for the United States Navy in 1921 by Curtiss . It was a conventional single-seater biplane with a monocoque fuselage and staggered single-bay wings of equal span braced with N-struts. Two essentially similar landplane versions were built as the CR-1 and CR-2 , which were both eventually converted to seaplanes as the CR-3 in 1923 and CR-4 in 1924. A refined version
513-486: Was allowed to boil; the phase change from liquid to vapour takes more heat from the engine, so less weight of coolant is needed. However, the radiator had to be bulkier to accommodate coolant in its gas phase, which increased drag. Twenty engines were built, and flew only in prototypes as a few manufacturers' private ventures and "one-offs". Powers for individual installations are quoted between 650 and 700 hp (520 kW). Problems with coolant leaks, coolant pumping and
540-586: Was developed for the US Army Air Service under the designation R-6 . These latter two aircraft featured refined aerodynamics included surface-mounted radiators. The Curtiss CRs enjoyed successful racing careers. Their first major win was at the 1921 Pulitzer Trophy race, where piloted by Bert Acosta the CR-1 took first place with an average speed of 176.75 mph (283.49 km/h), nearly two minutes ahead of its closest rival. The following year, this aircraft
567-504: Was first run in 1926, and one first flew in 1927, with a power rating of 450hp (335kW). The engine was normally aspirated in its initial form. The engine was first produced in 1927 at 450 hp (335 kW), which was soon improved in the I-B version to 525 hp (390 kW) by increasing the compression ratio to 7:1. The I-B variant saw widespread use in the Hawker Hart family of aircraft,
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#1732844731277594-825: Was modified and redesignated CR-2 and joined in the Pulitzer race by a second aircraft built to the same new standard, plus two R-6s flown by Army pilots. These Curtiss aircraft took first through fourth place, the two R-6s followed by the two CR-2s. The race was won by Lt. Russell Maughan with an average speed of 205.856 mph (330.172 km/h) with Lt. Lester Maitland in second place (198.850 mph/318.936 km/h). Maughan's effort incidentally broke every closed-circuit airspeed record up to 124 mi (200 km). The CR-2s took third and fourth places piloted by Lt Harold Brow (average speed 193.695 mph/310.667 km/h) and Lt Jg Al Williams (average speed 187.996 mph/301.527 km/h). The Army built upon this success with
621-587: Was one of the most powerful engines of its era, and continued to exchange records with other contemporary high-power engines such as the Napier Lion . At the time, none of the British aero engine manufacturers could offer an engine which offered a similar power rating which was also as light and compact as the D-12. The D-12 was licensed by Fairey and introduced to the UK as the Felix. Arthur Rowledge , Chief Designer at Napier and
648-432: Was primarily used for high-altitude designs to offset the loss of ambient air pressure as the aircraft climbed, and thereby maintain power. But with the new construction technique, the engine would be so strong that it could be supercharged at all altitudes without overstressing the cylinders, allowing a smaller engine to operate as if it was larger, and thus improving its power-to-weight ratio . The prototype Kestrel engine
675-570: Was seen to be "...one of the smoothest engines they had used at high altitudes". From Lumsden, the Kestrel may not be the main power-plant for these types. A handful of Rolls-Royce Kestrel engines remain airworthy as of March 2024, powering original or restored Hawker biplane types: Preserved examples of the Rolls-Royce Kestrel engine are on public display at the: Data from Lumsden Related development Comparable engines Related lists Curtiss CR The Curtiss CR
702-536: Was their first cast-block engine, and used as the pattern for most of their future piston-engine designs. Used during the interwar period , it was fitted to a number of British fighters and bombers of the era, including the Hawker Fury and Hawker Hart family, and the Handley Page Heyford . The Kestrel engine was also sold to international air force customers; in this role it was used to power prototypes of
729-637: Was used as the basis to develop the Rolls-Royce Merlin . The Kestrel design was used as a base for both the Goshawk , however the aircraft which were intended to be fitted with the Goshawk engine were cancelled, so the project was scrapped. The Kestrel was also used as the basis for the Peregrine (and therefore the Vulture ), all utilising the same 5" piston bore and 5.5" piston stroke. In practice, development of
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