А.Шепс Самолеты Первой мировой войны. Страны Антанты

Сопвич "Долфин" (Dolphin) 1917 г.

   Появление этой машины было вызвано необходимостью борьбы с германскими высотными бомбардировщиками "Гота" и "Штаакен", участвовавшими в налетах на территорию Англии. Поскольку на высоте более 4000 м ротативные двигатели теряли мощность, новый истребитель получил рядный двигатель жидкостного охлаждения "Испано-Сьюиза" мощностью 233 л. с. Самолет во многом повторял конструкцию своих предшественников, однако из-за более тяжелого двигателя пришлось удлинить фюзеляж, а верхнее крыло имело отрицательный вынос. Кроме двух синхронных "Виккерсов" в кабине пилота, расположенной между верхними крыльями, устанавливался пулемет "Льюис", стреляющий вперед-вверх. Радиаторы устанавливались по бортам фюзеляжа. Всего было построено около 1500 самолетов 5F.1 "Долфин".

H.King Sopwith Aircraft 1912-1920 (Putnam)

5F.1 Dolphin

   In several respects the Dolphin was the most remarkable (though by no means the most renowned) of all the Sopwith fighters. The backward-staggered two-bay high-aspect-ratio wings, by which it was chiefly distinguished, conferred upon it (having an area roughly the same as the Snipe's, and appreciably more than the Camel's) an especially good high-altitude potential, or alternatively the ability to carry an exceptionally heavy armament. The pilot's view for combat was the prime consideration in providing backward stagger, while the invariable use of an efficient Hispano-Suiza water-cooled engine conferred additional advantages - not least for further development, with French encouragement for the ‘Dauphin' being shown in the more exotic variants. (In describing Hispano-Suiza engines as 'efficient', which in a purely technical sense they surely were, one is not oblivious to the faults of some when fitted with reduction gear).
   To Sopwith the significance of the Dolphin was not, however, merely technical, for they themselves were given orders for well over a thousand of the 1.500 built before the Armistice, with production at Kingston succeeding that of Camels and preceding work on Snipes at Ham. Even so, as production went ahead the parent firm continued to set the pace for airframe and engine development. That only four squadrons were Dolphin-equipped reflects little diminution in the merits of the type, already emphasised. Though no Naval version is known to have existed, night-flying for Home Defence was an area of specialised application; and so successful and adaptable did the Dolphin prove as an 'all-round' fighter and so full of promise did it remain in spite of its defects (real or imagined) - that American interest ran high, and French, perhaps, even higher. Curiously, the last Dolphins on active service equipped some Polish units in the fighting with the Russians during 1920, when Polish forces penetrated deep into the Ukraine. Less surprisingly, a single Dolphin only came upon the British Civil Register, though even this (G-EATC) was a demonstrator for Handley Page. The few two-seat trainer Dolphins were Service conversions.
   Like so many other aeroplanes, the Dolphin suffered badly at the mouths of rumour-mongers, their tales of woe and terror being aggravated by recollections of the similarly back-staggered D.H.5; by the Dolphin's unusual spinning characteristics; the vulnerability of the pilot's head in a landing accident; engine difficulties; and prejudice in any case against the unconventional. (Even the sloping nose of the Service type was sometimes regarded not so much as an aid to the pilot's outlook as a feature detrimental to his flying ability - in that he was unable to 'keep the nose on the horizon"). The fact that advantages were rarely set against these strictures is understandable; likewise that the Dolphin was never acclaimed in its time - as it has been by later commentators as 'the world's first multi-gun fighter', for not only was there secrecy to be observed, but the full complement of guns was seldom mounted.
   The Dolphin's back-stagger having been mentioned as a salient feature, with concomitant advantages to pilot-view, a word on the fuller significance of this feature is in order. Although it is well known that the D.H.5 of 1916 was the first operational aeroplane of any note to have a negative, or backward, stagger, and that the dubious reputation of that fighter, especially respecting the stall, was attributed to this same feature, one is none the less left wondering why, in his autobiography Sky Fever, Sir Geoffrey de Havilland made no allusion whatsoever to the "5", though types of lesser fame are there. Perhaps the unusual wing-arrangement was officially inspired (though Harald Penrose attributes it to 'D.H.'s' own 'daring', and Oliver Stewart to his 'genius'). But whatever the facts of the matter, the staggering of wings in either direction was not entirely novel, for even in 1902 there was a mention in Wright/Chanute correspondence of" 'staggering surfaces back' - or 'arranging the surfaces in steps' as Wilbur put it. Nevertheless, the D.H.5, Dolphin wing-arrangement in a fighting aeroplane (with the upper wing supposedly blanketed in a spin by the lower one) was something to which initially high accident rates for both types were sometimes ascribed. Little did pilots know that America's 'Staggerwing Beech' was to remain in production from 1933 to 1948! To Sopwith moreover back-stagger meant not only "Dolphin" alone, but Hippo, Snail and Cobham also - while even the D.H.6 trainer received a slight degree of negative stagger, jointly with other 'improvements'.
   Whatever the arguments for and against back-stagger, it was officially affirmed that 'A negative stagger increases the interference between the planes and is therefore only employed when, for overwhelming reasons, some property such as unobstructed upward view is required.’
   The first Sopwith 5F.1, later named Dolphin, was apparently designed more or less in parallel with the Hippo, and was cleared by Sopwith's Experimental Department on 23 May, 1917. It carried no identifying number, and differed from the production form in notable respects. Most notable of all, it had a frontal radiator (instead of flanking surfaces) though the particular radiator fitted, which was to be officially criticised as 'inefficient', was far too deep and narrow for the common description 'car-type' so deep, in fact, that even the high-set thrust-line of the geared 200 hp Hispano-Suiza engine was well below the upper lip. Of such a depth, moreover, was the whole nose ahead of the top wing that the two Vickers guns were contained wholly within it, while behind the wing the fuselage was similarly deep, meeting as it did the rear steel-tube cross-member of the open 'centre-section'. The tail resembled a Camel's though its small size was largely disguised by the lengthy lever-arm of the sharply tapered fuselage.
   This first Dolphin was flown by Harry Hawker at Brooklands before May 1917 was out; was officially tested - with plywood decking extended aft - at Martlesham Heath in the following month, when it was deemed to be nose-heavy and was ballasted accordingly; and on the 13th of that same month (June 1917) was flown to St Omer for Service trials. The ferry pilot was H. T. (later Sir Henry) Tizard, who had joined the RFC from the army in 1915 and who did so much not only for ‘Martlesham methods' but in founding the station itself.
   At the end of June (confirming how well the Dolphin was regarded - being faster than the Camel and more manoeuvrable than the S.E.5) five hundred Dolphins were ordered from Sopwith themselves, with contracts quickly following to the Darracq Motor Engineering Co Ltd, and Hooper & Co Ltd. both of which firms were London-based. The name Darracq must be especially remembered here for at least two reasons. First, this same company had earlier received an order for two hundred examples of the D.H .5 back-staggered fighter; second, as the Dolphin was built to lake a vee-8 engine of 200 nominal horsepower, it may be recalled that Darracq had made a racing-car engine of these same characteristics though far heavier as early as 1905. (That a young man named Moore-Brabazon had been apprenticed to the company is possibly less relevant). Hooper, of course, were famed for their fine coachwork, and already had Sopwith associations through the 1 1/2 Strutter and Camel. Thus was Dolphin production centred round Surrey and South London.
   The first Dolphin, with its unmistakable deep frontal radiator, having earlier received attention in this chapter, it can now be recorded that the second machine of the type embodied new features which went some way to meet Service desires, notably respecting pilot-view, but met new problems of its own. Most notable on this second specimen, the seemingly simple frontal radiator was abolished, the cooling for the engine being now provided by two small triangular surfaces, set one near the root of each upper wing, and revised at least once. However inefficient, this new system (apart from being in the top wing rather than the bottom one) did at least presage the twin-radiator installation tried on the Hornbill - Hawker's very first 'water-cooled' fighter, though as the Hornbill's Condor gave nearer 700 hp than 200 the radiators were in greater prominence.
   Though the Dolphin's new wing-mounted radiators were not themselves successful, they did allow incorporation of a downward-sloping nose, which was in essence to become so characteristic of the type in service and which left the two Vickers guns partly exposed, though in the second form of Dolphin, now discussed, the top of the cowling retained its great depth at the rear. The enhanced field of view conferred by the sloping nose was supplemented by large cut-outs in the bottom wings; and had these spaces served to accommodate radiators (as they might well have done in the ultimate) then the Hornbill analogy would be all the more apt.
   Also to be seen on the second form of the Dolphin were a new fin and a horn-balanced rudder, this last-named feature having been officially proposed because the first Dolphin had been tiring to fly by reason of the coarse left-rudder required at full throttle.
   Clearly, however, the radiator system was the Dolphin's real bete noir, and the third form of the aircraft had an altogether new arrangement, for although this was again based on the use of two surfaces, these were now of deep block form, mounted not in the wings but on the fuselage sides, well aft, and in line with the rear of the cockpit. Just forward of each block was a shutter for varying the cooling area exposed. The fin was now enlarged, so that the horn-balanced rudder was matched to its contour. Ahead of the cockpit the decking was at one stage somewhat lowered; but interest lay very largely in the armament, which, although it was not exactly 'doubled' as is sometimes averred, comprised two Lewis guns (drum-fed, and mounted on the tubular, front, centre-section spar) in addition to the two fuselage-mounted synchronised Vickers guns (belt-fed, with Prideaux disintegrating links). Here then, we have the inception of what has sometimes been termed, as earlier noted, the 'world's first multi-gun fighter'; though of Dolphin armament there will be more to say.
   On the fourth pre-production form of the Dolphin (circa October 1917) the fuselage behind, as well as forward of. the cockpit was shallower, and the cockpit rims cut deeper into the fuselage sides, giving a generally 'leaner' look; though the landing gear struts were still of sturdy ash, and not of thinner steel-tube as later, on production machines. The backward stagger, too, remained unaltered at 13 in (330 mm), though on production Dolphins this was reduced to 12 in (305 mm).
   As Dolphin production was to run in parallel with that of the similarly engined S.E.5a of the Royal Aircraft Factory one of the pre-production Dolphins was tried (though unsuccessfully) with a four-blade S.E.5a propeller; but a two-blade Lang pattern was standardized - one advantage of such a form being not merely in respect of propulsive efficiency, but in the synchronising of the two Vickers guns.
   By the end of 1917, production of the Dolphin was so well advanced that 121 had been delivered, the first unit equipped being No.19 Squadron (January 1918). Together with Nos.79, 23 and 87, No. 19 remained Dolphin-equipped until the war was over, and perpetuated thereafter in its unit badge was the image of a Dolphin. (The name and symbol of the Elephant, of course, was stolen from the Sopwith 'Zoo' by No.27 Squadron, while the Fox, Hind, Hart and Gamecock passed in due time to the custody of Nos. 12, 15, 33 and 43 respectively).
   From the armorial, however, to the harder facts of armament; for in the Dolphin special problems had been presented by the closely concentrated masses of two fixed Vickers guns and two movable Lewis guns. The solution of these problems had, in fact, been discussed at a meeting between Sopwith and Service personnel held as early as June 1917 - shortly after completion of the very first Dolphin, which had two Vickers guns only, as had the standard Camel. Soon after the meeting just mentioned there was another, and on this occasion the RNAS was represented as well as the RFC - the first-named Service by Engineer Lieutenant F. W. Scarff (note promotion to commissioned rank since the early days of the 1 1/2 Strutter). Details of how the Lewis guns were to be installed were apparently the primary concern of Sopwith's Mr Allman, and to limit the training of these guns a three-position ratchet was the fitting approved. The extent to which two Lewis guns were actually fitted as well as the two 'built-in' Vickers - either at the manufacture or the service stage - remains unclear; for although a single Lewis gun was far more normal in the field, a familiar photograph of Sopwith production shows C3786 at least, prominently in the foreground with both Lewis guns fitted, while C3787 and others far beyond along the lines have their Vickers guns only, complete with C.C. hydraulic synchronising gear.
   Special mountings for six Home Defence Dolphins were apparently the responsibility of the Royal Aircraft Factory; but to Lieut 'Guns' Knight of No.87 Squadron credit is evidently due for the design of the fixed installation of two Lewis guns on the bottom wings - each gun about 18 in (460 mm) inboard of the inner pair of interplane struts, though with the lines of fire outboard of the propeller arc, so that synchronising gear was not required. Though ground attack may well have been the primary object of the outboard wing-mounting scheme referred to, which certainly preceded that on the Snark though we must not too readily dismiss the American scheme of 1917 referred to under 'Triplanes (Hispano-Suiza)' - the Dolphin weapon-load for low attack could be augmented by the usual 'four twenty- pound Cooper' bombs. These little anti-personnel bombs (the targets officially prescribed were, in fact, 'personnel and aerodromes') were crutched in a carrier under the fuselage.
   For work at the higher altitudes the Dolphin's inherent attributes showed clearly at their best - a warm cockpit being not the least among them; thus for Home Defence duties at night the type was much to be desired, especially so with the German raiders coming over at great heights, and with defending fighters having difficulty not only in merely intercepting them and keeping them clearly in view, but in reaching their level at all (at least, with sufficient time in hand for effective attack).
   Militating against the Dolphin's safe employment at night, however, were not only engine difficulties (relative slowness in warming-up, persistent unreliability by reason of reduction-gear troubles and other factors) but the pilot's obvious vulnerability in the event of an accident. ('This would be an unpleasant machine in which to turn over on the ground' was Oliver Stewart's first remark on entering the cockpit, later explaining: 'The pilot's head came above the top plane, and he was completely surrounded by longerons, spars, cross-bracing wires and tie rods, and the feeling of being boxed in with the head exposed in a vulnerable position was experienced at once. With the engine in his lap and the petrol tanks in the small of his back, it seemed to the pilot that he had little chance of escaping injury in the event of a bad landing').
   Not for nothing was 'Blockbuster' one vulgar name conferred on Sopwith's fine new fighter, and - much as on the Bristol M.1 monoplane - special pylons or 'cabanes' (or even a so-called 'rolling hoop') were in requisition, though whether the mounting of a single Lewis gun on one particular form of crash pylon above the cockpit was primarily anti-German or pro-British remains conjectural. Half-hoops of steel above the attachments for the inner pairs of interplane struts were a feature of Sopwith's own ‘Dolphin Night Flyer', shown in a photograph. Although no aircraft-number is visible on the fuselage, the fin is stencilled C3858, and, of more technical interest, this surface is associated with a variable-incidence tailplane. (Rigging instructions for the standard Dolphin remarked that normal incidence was zero, adding that 'any adjustments can be made after tests').
   In the happy event of a Dolphin pilot surviving a bad upset, he might, with luck, find his escape facilitated by specially modified centre-section bracing or even by a removable cockpit-side panel, with quick-release. As used by No. 141 Squadron at Biggin Hill (a unit not already numbered among the Dolphin-equipped squadrons, for it used only a few of the type) flare-brackets were fitted under the lower wings, though there is no evidence of flame-damping exhaust tailpipes possibly because these last might impede the pilot's exit.
   Operational requirements aside, the Dolphin's development was very closely linked with powerplant vicissitudes, and it was, in fact, a shortage of Hispano-Suiza engines which precluded the operational fulfilment of at least one other Dolphin squadron (No.90) early in 1918.
   The engine for which the Dolphin was designed was the compact vee-8 200 hp Hispano-Suiza, which, although it had reduction gearing, nevertheless possessed an excellent power weight ratio. In France this engine was built by many companies, and eventually in other countries also, the wartime total of engines of this general pattern reaching nearly 30,000. In Britain the 200 hp Hispano-Suiza was made by Wolseley Motors Ltd, who called it (in developed form) the Adder; but from French production - notably Mayen - came other units of the type in big numbers. As is well known, crankshaft failures plagued the Wolseley-built geared engines; but there was far more to the story than this, and the following official notes, prepared just after the war of 1914-18, are relevant.
   Wolseley had received a British contract for 100 direct-drive 150 hp Hispano- Suiza engines, but also (now to quote the official notes) 'for a much larger number of engines of similar type but provided with a reduction gear and adapted to run at 2000 r.p.m. developing over 200 h.p. at this speed. This particular geared model was based upon drawings supplied by the French, but no engines of this kind had at that time been built. The reduction gear consisted of a pair of large diameter spur gears (with helical teeth of an angle of 4 50 ) which raised the propeller shaft above the crankcase, and the shaft was hollow so that a machine gun could tire through it. The Wolseley Co. obtained permission to modify the drawings in the direction of fitting a scavenger oil pump and employing a different method of securing the reduction gear on the propeller shaft.
   'The French at the same time were working on a 200 hp geared engine without the scavenger oil pump and with the propeller shaft gear wheel keyed on a taper on the propeller shaft. This method of fixing gave considerable trouble and the reduction gears on the French engine were the cause of frequent failure due partly to the high tooth pressure and partly to the use of air hardening steel. The Wolseley Co. used a 5% nickel case hardening steel for both gears and had little or no trouble ... The feature of firing through the propeller shaft was not used however.
   'The 150 hp engines of both French and English manufacture gave practically no trouble. In a short time the compression was raised from 4.7 to 5.3 to 1 and the speed raised to 1750 r.p.m. resulting in about 200 hp under these conditions.
   'The first difficulty to arise in the manufacture of the Hispano engines in this country concerned the propeller hub fixing ... The remedy finally adopted was to use a different taper for the hub from that of the shaft ... The tests are still (Dec, 1918) continuing at the Isle of Grain as this trouble was found most serious on Seaplanes.
   'The cylinder holding down studs frequently broke and to meet this difficulty the studs at each end of each block were lengthened and either a long nut or nuts and deep collars were used.
   'When about ten 200 hp engines had been delivered from the Wolseley Works, an epidemic of crankshaft breakage was experienced.’ (Then followed a lengthy account of measures taken) and it was later recorded:
   ‘In view of the crankshaft failures, and the trouble with the propeller hubs, and the serious failures of reduction gears on French engines, it was considered necessary to reduce the number of geared English built Hispanos, and turn out an ungeared engine capable of a normal speed of 2000 r.p.m. This was the "Viper", which without doubt proved the most satisfactory of the Hispano series ...
   'The French 200 hp engine evidently did not receive the required care in manufacture as is evidenced by the fact that individual engines gave exceedingly good results, particularly from the point of view of weight/power ratio, but the majority require continual overhaul, chiefly owing to the difficulty in maintaining the required oil pressure ... It should be recognised that the 200 hp Hispano engine was a development of a very satisfactory 140 hp engine, but that certain features, including the oil pump, were pushed beyond their capacity in the higher powered engine.'
   In February 1918 (at which time Dolphins were arriving in France in some numbers) the Ministry of Munitions Department of Aircraft Production issued a Report upon Troubles with 200 h.p. French Hispano in Service, touching especially on excessive vibration and defective lubrication and largely relating to the 'SPAD Bitrailleuse' (or 'Bi-mitrailleuse' as it was otherwise called in the same document) and the 'SPAD two-seater'. Like these French fighters and the British S.E.5 series, the Dolphin was wedded to the Hispano-Suiza form of engine (an installation of the Sunbeam Arab was schemed, if not tried) and the end of the war found the following British Marks of the Dolphin in being - all distinguished by their engine: Dolphin I with 200 hp geared Hispano-Suiza engine; Dolphin II with the new 300 hp Hispano-Suiza, of which more later; Dolphin III with engine essentially as Dolphin I though with reduction gear removed. (N.B. An officially styled '200 h.p. Mayen Hispano Engine Converted to Direct Drive’, when tested at the Royal Aircraft Establishment in the summer of 1918, 'ran satisfactorily throughout' and gave 201 hp at 1,800 rpm and 220.5 hp at 2.000 rpm. Some geared engines also delivered about 220 hp).
   Of the three Marks of Dolphin listed the Mk.II is now of greatest interest - and equally it interested the French, who made the first installation in D3615 and placed the new combination in production. The presence of the new engine was distinguished by the greater bulk of the cowling (with the two Vickers guns completely submerged beneath it); by exhaust tailpipes extended further aft than usual, and thus having to be cranked to clear the tops of the radiator blocks on the fuselage flanks; and by a telescopic carburetter-air intake (intended to reduce the risk of a carburetter fire) the front whereof was prominent between the cylinder banks.
   The number of 300 hp Hispano-Suiza installations made is uncertain; but what is sure is that Harry Hawker went over to fly the first conversion. Though snags were suspected or known, Hawker did rolls and spins. Later the structure was strengthened for production. As for the engine itself, a Mayen-built example was tested at Farnborough, and in July 1918 was the subject of the following interim report on calibration tests:
   'The engine was dismantled for examination, then reassembled and placed on a test bed for calibration tests. The maximum power obtainable after tuning up was 280 h.p. at 1800 r.p.m. although on previous tests on a similar engine (150 m/m stroke in both cases) 316 h.p. was obtained at 1800 r.p.m. On trying the compression three cylinders were found to be O.K., three had poor compression, and on the remaining two there was no evidence of compression, when the engine was turned by hand. The cylinder blocks were therefore removed and were found to be leaking badly round several of the spark plug adaptors ...'
   As for the supercharged Hispano-Suiza engine much earlier mentioned in passing (‘Other Men's Aeroplanes') this was nominally of 220 hp. but had a Rateau "turbocompresseur", which gave the Dolphin thus powered its best performance at considerable heights. The maximum speed of 130.5 mph (210 km h) was, in fact, attained at 8.700 ft (2.650 m), but at low level the speed was reduced to only 119 mph (192 km/h).
   For the 300 hp Hispano-engined Dolphin, as intended for French and American use, a variable-incidence tailplane was standardised, partly owing to the large petrol capacity demanded and the distribution of its changing weight. (Petrol and oil systems for the Dolphin varied widely, but the 200 hp versions typically called for 27 gal (123 litres) of petrol and 4 gal (18 litres) of oil). Like the British, the French experimented with various propellers (typical for a 200 hp British Dolphin was a Lang of over 9 ft diameter) though for 'Sopwith Dolphin C1 No.3618, 300 h.p.' designs by Lumiere, Gallia, Ratmanoff and Levasseur were tried. The best speed measured in one series of trials was apparently with a Gallia - 221 km/h (137 mph) at 4,000 m (13,120 ft) though the best climb was afforded by a Ratmanoff - 4,000 m (13,120 ft) in 12 min 13 sec. Ceiling with several patterns of propeller was quoted as 7,500 m (24,600 ft).
   Thus we perceive the Dolphin positively entering the 'postwar’ performance bracket; and in furtherance of this perception it can be noted that one Dolphin was experimentally fitted (and flown to France) with a Calthrop parachute, stowed in the top decking, and that another (Sopwith-built D3747) had a jettisonable petrol tank. Even so, one is left with a feeling that, like its namesake in nature, this fighter may not, even yet, have yielded up all its secrets; though in partial proof of our contention at the outset that the Dolphin was one of the most remarkable of all the Sopwith fighters there may be instanced the victories of No.79 Squadron's aircraft alone - 64 enemy aircraft and eight kite-balloons destroyed.
   Nevertheless, ferocious though it was in combat the Dolphin was in its way tame, Martlesham Heath, for instance, crediting one of the first experimental models (with the first Hank radiators) with an unstick run of 60 yd (55 m) and the ability to 'pull up with engine stopped' in 90 yd (82 m).
   Production orders for the Dolphin were as follows:
   Sopwith C3777-C4276; D3576-D3775; E4424-E4623; E4629-E5I28.
   Darracq C8001-C8200; F7034-F7133 (J1151-J250 were cancelled).
   Hooper D5201-D5400; J1-J150 (order not completed).


Dolphin I (200 hp geared Hispano-Suiza)

   Span 32 ft 6 in (9.9 m); length 22 ft 3 in (6.7 m): wing area 263.25 sq ft (24.7 sq m). Maximum weight (with two Vickers guns and one Lewis gun) 1,959 lb (889 kg). Maximum speed at 10.000 ft (3.050 m) 121.5 mph (195 km/h); maximum speed at 15,000 ft (4,570 m) 114 mph (183 km/h): climb to 10,000 ft (3,050 m) 12 min 5 sec; climb to 15,000 ft (4.570 m) 23 min: service ceiling 20,000 ft (6.095 m).


Dolphin II (300 hp direct-drive Hispano-Suiza)

   Span 32 ft 6 in (9.9 m): wing area 263.25 sq ft (24.7 sq m). Empty weight 1.566 lb (710 kg): maximum weight (two Vickers guns only) 2.358 lb (1.068 kg). Maximum speed at 10,000 ft (3.050 m) 140 mph (225 km h); maximum speed at 16.400 ft (5.380 m) 133 mph (214 km h): climb to 10.000 ft (3.050 m) 8 min 20 sec; climb to 16,400 ft (5.380 m) 12 min 10 sec; service ceiling 24,600 ft (8.050 m).


Dolphin III (200 hp direct-drive Hispano-Suiza)

   Span 32 ft 6 in (9.9 m): wing area 263.25 sq ft (24.7 sq m). Empty weight 1.466 lb (655 kg); maximum weight (two Vickers guns only) 2.000 lb (907 kg). Maximum speed at 10.000 ft (3.050 m) 117 mph (188 km/h); maximum speed at 15.000 ft (4.570 m) 110 mph (177 km/h); climb to 10.000 ft (3,050 m) 11 min 20 sec; climb to 15,000 ft (4.570 m) 21 min 50 sec; service ceiling 19.000 ft (5,790 m).

P.Lewis The British Fighter since 1912 (Putnam)

The Sopwith designers did not rest on their laurels after turning out the Camel and followed it in May, 1917, with their 5F.1 Dolphin. The new fighter bore little, if any, resemblance to its illustrious predecessor and was notable in incorporating back-stagger in its two-bay, equal-span wings. The biplane’s gap was comparatively small, so that the pilot’s head projected through the upper centre-section.
   A deep nose radiator at first served the 200 h.p. Hispano-Suiza engine in the prototype Dolphin but was afterwards replaced by side radiators mounted one on each side of the cockpit. The prototype’s original fin and rudder, which followed the outline of the Camel’s, were changed for new surfaces complete with horn balance incorporated in the rudder. Further alterations to the vertical tail surfaces and to the fuselage around the cockpit area to improve the view took place before the Dolphin was considered ready to be issued to the squadrons. The Dolphin’s firepower was increased by the addition of a pair of Lewis guns, mounted in the centre-section on each side of the pilot, to fire forwards and upwards at around 45°. These extra Lewis guns did not prove particularly popular in use as they tended to swing during flight and to hit the pilot. Consequently, they were often discarded by the units using the machine but No. 87 Squadron, R.F.C., took to mounting the Lewis guns on the lower wings to fire outside the propeller disc. In each case, however, the main armament of two Vickers guns in the decking ahead of the pilot was retained. The Dolphin proved to be a sturdy and popular machine in service, one of the few adverse criticisms of it being the risk of injury to the pilot in a nose-over on landing. To guard against this the night-flying version was equipped with metal hoops above the inner pairs of interplane struts. The normal production Dolphin used the geared version of the 200 h.p. Hispano- Suiza but, as an alternative, the direct-drive 200 h.p. Hispano-Suiza was employed in the Dolphin Mk.III and the Dolphin Mk.II had the advantage of 300 h.p. delivered by the more powerful version of the Hispano-Suiza engine.

F.Mason The British Fighter since 1912 (Putnam)

Sopwith Dolphin

   Yet another fighter aircraft, designed with the Hispano-Suiza engine in mind, was the Sopwith 5F.1 Dolphin. Designed by Herbert Smith, the Dolphin was almost certainly conceived as the result of promise being shown by the Factory’s S.E.5, yet features of other, less prominent aircraft clearly influenced the Sopwith product, not least the back-staggered D.H.5 with the magnificent field of view for the pilot. Like the Camel, designed by R J Ashfield, and whose fierce manoeuvrability was largely attributable to the concentration of all principal masses within a compact space, Smith placed propeller, engine, radiators, pilot, fuel, guns and ammunition in the front 8ft 9in of the fuselage; before long, two further guns would be added within this space...
   One of the novel ideas in vogue at Sopwith was a small design sub-department whose job was to accelerate the manufacture of promising prototype aircraft at the behest of Ashfield and Smith. And thereby two or three Dolphin prototypes were put in hand very quickly. The first was almost certainly flown early in June 1917, powered by one of the few 150hp Hispano-Suiza geared engines released for prototype work. Though by no means a satisfactory aircraft as it stood, this prototype showed such promise, returning a speed of around 136 mph at sea level and providing a superb tactical field of view for the pilot, that on 29 June the War Office provisioning department awarded Sopwith a contract for no fewer then 500 production aircraft - the largest single order yet received by the company - worth over half a million pounds, a staggering sum for a ‘private sector’ aircraft manufacturer at the time.
   The Dolphin featured the simple wooden box-girder fuselage, wire-braced and with rounded top decking, and a tail unit not unlike that of the Camel, with unbalanced rudder. The two-bay, two-spar wings were back-staggered twelve inches, and constructed with spindled spruce spars with spruce interplane struts. The upper wing structure was discontinued at the roots, but steel tubular carry-through members formed part of a tubular superstructure which surrounded the cockpit, with the pilot’s head projecting above, thereby allowing an unrestricted field of view in the upper hemisphere. Because the front fuselage was very deep, the wing gap was maintained at a constant 4ft 3in. The nose cowling was also exceptionally deep, in part on account of the frontal car-type radiator and also to the front Vickers guns being buried in the top decking.
   The prototype went to France for operational trials on 13 June as at least two further prototypes were nearing completion at Brooklands. These early trials showed that the deep frontal radiator was unsatisfactory, and was discarded in favour of a pair of vertical radiator matrices mounted on the fuselage sides adjacent to the cockpit. A horn-balanced rudder replaced the initial unbalanced unit, although this temporarily resulted in a smaller fin. The repositioning of the radiator allowed much cleaner nose contours, thereby giving the pilot a better (though not ideal) view both forwards and downwards, as well as exposing the front halves of the gun barrels. The second prototype also featured fairly generous cutouts in the lower wing roots to extend the pilot’s view downwards.
   At least two of the Dolphin prototypes were in France for Service trials in June, one of which appears to have been forced down behind the enemy lines during July, as a Dolphin featured in the periodic list, issued by the Germans, of Allied aircraft which had fallen into their hands.
   The series of modifications showed considerable promise and provided the basis for a standard of preparation in the production aircraft. Further re-styling of the nose immediately forward of the cockpit resulted in improved view for the pilot and the lower wing root cutouts were abandoned. The fin and rudder were tidied up, the rudder horn balance being faired into an enlarged fin, allowing a smooth curve over the upper line. The upper decking of the fuselage aft of the cockpit, previously fabric-covered, was changed to ply for a length of about four feet to allow for hatch access to the wireless bay behind the cockpit. In this form the Dolphin underwent final Service trials at Martlesham Heath in August 1917, returning a performance slightly better than the original evaluation.
   Production Dolphins began appearing in October, albeit slowly owing to the continuing shortage of reliable Hispano engines. These aircraft featured a pair of Lewis guns mounted on the front carry-through wing member directly in front of the pilot’s face (incidentally making the Dolphin the most heavily armed single-seat fighter to enter service thus far). However, these additional Lewis guns were unpopular as, in the fierce manoeuvring of combat, the Lewis guns tended to swing about and had a habit of striking the pilot in the face. In due course, individual pilots expressed their own ideas in the matter of armament, usually discarding one or both the Lewis guns.
   Because of sub-standard manufacture of the Hispano-Suiza engines (the reduction gears were inconsistently case-hardened, leading to disintegration), it was decided to start by re-equipping home-based squadrons, the first being No 87 at Hounslow in December, commanded by Capt C W J Darwin, followed immediately by No 79 at Beaulieu in Hampshire, commanded by Maj M W Noel; these two Squadrons moved to France early in 1918, by which time No 87 Squadron had decided to mount the two Lewis guns on the Dolphin’s lower wings, firing outside the propeller arc - even though this meant that the guns could not be reloaded after a single 97-round drum had been fired by each.
   In January 1918 Dolphins started delivery to No 141 Squadron, a night fighter Home Defence unit formed for the specific defence of London under the 24-year-old Maj Philip Babington mc, afc (later Air Marshal Sir Philip, kcb, MC, AFC, RAF). To this Squadron fell the task of flying the Dolphin at night, and in this the aircraft was hopelessly unsuitable. Landing a Dolphin at any time was tricky enough, but judging height at night was found to be well-nigh impossible, and the aircraft quickly earned the sobriquet ‘Blockbuster’: if, as the result of a misjudged landing approach, the Dolphin overturned, the pilot, whose head projected above the upper wing, was in danger of being decapitated, or at least burned alive if the fuel tank immediately behind him ruptured. This hazard was to some extent reduced in February when Dolphins appeared with crash pylons of various designs above the wings or cockpit. So congested and confined was the Dolphin’s cockpit that no Service pilot could ever express confidence that the aircraft had been designed with the safety and comfort of the pilot uppermost in mind.
   Moreover, as with the S.E.5A, the length of time needed to warm up the Hispano engine rendered the Dolphin unsuitable for the interceptor role, and it was quickly replaced by the Bristol F.2B Fighter with Home Defence squadrons.
   The first Squadron to re-equip with Dolphins in France during January 1918 was No 19 at Sainte Marie Capelle under Lt-Col William Douglas Stock Sanday dso, mc. By the time the great German offensive opened on 21 March Nos 19, 23 and 79 Squadrons were operational in France, with No 87 arriving the following month. No 87 Squadron was to undertake offensive patrols during the final Allied push during September and October. In a combat typical of this period, Dolphins of No 19, escorting D.H.9 bombers of No 98 Squadron, were attacked by a large formation of enemy fighters; the British aircraft shot down ten of the enemy, but five Dolphins and four D.H.s were lost.
   It had been intended to retain Dolphins in service as standardized equipment in the peacetime RAF but, although the quality and supply of the Hispano engine seemed to be under control at last, British engines seemed to be the logical choice. Two late variants of the Dolphin were the Mark II with the 300hp direct-drive Hispano-Suiza (and a maximum speed of about 146 mph at sea level), and the Mark III with 200hp direct-drive Hispano-Suiza. Of these, the Mark II was certainly the most promising, as demonstrated by the prototype, D3615, and was almost certainly the fastest fighter in 1918; moreover, being without the suspect reduction gears, the Hispano had become an altogether more reliable engine.
   Nevertheless, it must be said that the previous delays and troubles besetting the Hispano-Suiza engines resulted in an extraordinary waste of money and effort on aircraft such as the Sopwith Dolphin, for almost three-quarters of all those built - over 2,000 of them - never left the storage depots, where they were awaiting their engines, before being scrapped.


   Type: Single-engine, single-seat, two-bay biplane fighter.
   Manufacturers: The Sopwith Aviation Co Ltd, Kingston-upon-Thames, Surrey; The Darracq Motor Engineering Co Ltd, Fulham, London; Hooper & Co Ltd, London SW.l
   Powerplant: Mark I: One 200hp Hispano-Suiza geared engine. Mark II: 300hp Hispano- Suiza direct-drive engine. Mark III: 200hp Hispano-Suiza direct-drive engine.
   Structure: Wire-braced box-girder fuselage with spruce longerons and spacers. Twin spindled-spruce spars in back-staggered two-bay wings with steel tubular carry-through centre section structure in upper wing; cockpit located beneath this superstructure.
   Dimensions: Span, 32ft 6in; length, 22ft 3 in; height, 8ft 6in; wing area, 263.25 sq ft.
   Weights: Tare, 1,410lb; all-up, 1,959lb.
   Performance: Max speed, 136 mph at sea level, 114 mph at 15,000ft; climb to 10,000ft, 12 min 5 sec; service ceiling, 20,000ft.
   Armament: Two synchronized 0.303in Vickers machine guns on top decking of nose with Constantinesco hydraulic interrupter gear; either one or two Lewis machine guns usually mounted on forward carry-through wing spar member. Provision to carry up to four 25lb bombs.
   Prototypes: Believed to be three (the first probably flown at the beginning of June 1917). One prototype Mark II was D3615 (a modified Mark I).
   Production: Total of 2,074 aircraft completed, excluding initial prototypes (Sopwith, 1,400: C3777-C4276, D3576-D3775, E4424-E4623 and E4629-E5128; Darracq, 365: C8001- C8200, F7034-F7133 and J151-J215; Hooper, 309: D5201-D5400 and J1-J109).
   Summary of Service: Dolphins served operationally with Nos 19,23,79 and 87 Squadrons, RFC and RAF, in France; with No 141 Squadron, RFC, on Home Defence duties between January and March 1918; served non-operationally with Nos 81 and 123 Squadrons (these Squadrons became Nos 1 and 2 Squadrons, Canadian Air Force, respectively); and with Nos 90 and 91 Squadrons, RAF, non-operationally in the United Kingdom).

W.Green, G.Swanborough The Complete Book of Fighters

SOPWITH 5F.1 DOLPHIN

   Designed to provide the pilot with the best possible view in tactically important directions, the 5F.1 Dolphin was unusual in being a two-bay equi-span biplane with negative stagger. The pilot was seated with his head in the open framework connecting the upper mainplanes. Primarily of fabric-covered wire-braced wooden construction with an upper centre section of steel tube, the Dolphin was powered by a 200 hp Hispano-Suiza geared eight-cylinder water-cooled engine in its initial production form. Armament consisted of two fixed and synchronised 0.303-in (7,7-mm) guns and either one or two guns of similar calibre mounted over the wing centre section and movable, but usually firing forwards and upwards. The prototype was flown in late May 1917, the first production contract was placed in the following month, on 29 June, and quantity deliveries to the RFC began late in the year. The first Dolphin squadron was deployed to France in February 1918, and the decision was taken to licence-build a version for the US Air Service in France. This, the Dolphin Mk II powered by a 300 hp Hispano-Suiza engine, was to be manufactured by the SACA (Societe Anonyme des Constructions Aeronautiques) and the Air Service anticipated taking delivery of 2,194 by mid 1919. In the event, only a few Dolphin Mk IIs were completed before the Armistice prompted cancellation of all contracts. Difficulties with the reduction gear of the original 200 hp engine led to the conversion of many to direct drive, aircraft fitted with the modified power plant being designated Dolphin Mk III and some engines having their compression ratio raised to boost output to 220 hp. Production of the Dolphin totalled 1,532 aircraft, of which all but 121 were built during 1918. Both Dolphin Mks I and III were finally withdrawn from RAF service mid 1919. The following data relate to the Dolphin Mk III.

Max speed, 128 mph (206 km/h) at 6,500 ft(1 980 m).
Time to 6,500 ft (1980 m), 6.33 min.
Empty weight, 1,466 lb (665 kg).
Loaded weight, 2,000 lb (907 kg).
Span, 32 ft 6 in (9,90 m).
Length, 22 ft 3 in (6,78 m).
Height, 8 ft 6 in (2,59 m).
Wing area, 263.25 sq ft (24,46 m2).

J.Bruce British Aeroplanes 1914-1918 (Putnam)

Sopwith 5F.1 Dolphin

  THE Sopwith single-seat fighter which followed the Camel into service was a very different aeroplane from its stumpy little predecessor. The new machine had the Sopwith type number 5F.1, and was named the Dolphin.
  The Dolphin was passed out by the Sopwith experimental department on May 23rd, 1917. It was an equal span two-bay biplane of unusual appearance, powered by the 200 h.p. Hispano-Suiza engine, and was designed to give the pilot the best possible view in tactically important directions. The upper wing was set low on top of the fuselage, and the pilot sat with his head in the middle of the open framework which connected the upper mainplanes. He thus had a completely unobstructed view of the entire upper hemisphere. Since the position of the upper wing was thus determined, the lower wing had to be fitted in a position which would ensure the correct relationship between lift and the centre of gravity. In consequence, the Dolphin had negative stagger on its mainplanes.
  The prototype first appeared with a tall car-type frontal radiator immediately behind the airscrew. The rounded top-decking was deep and came up to the level of the spar members of the upper centresection structure; whilst the top of the engine cowling sloped upwards to the same level. Two Vickers machine-guns were mounted side-by-side under the cowling and fired forwards just above the top of the radiator. The fuel tanks were installed immediately behind the cockpit.
  The first official test report on the Dolphin is dated June, 1917, and probably relates to the prototype in its original form. A Dolphin went to France for operational trials on June 13th, 1917.
  Although unorthodox in appearance, the Dolphin was conventional in its structure. The fuselage had four spruce longerons and spruce spacers, cross-braced by wires and fabric-covered save for the sides and top-decking about the cockpit, which were covered with plywood. The wings had spars of spindled spruce; interplane struts were also of spruce, and external bracing was by Rafwires. Ailerons were fitted to upper and lower wings. The centre-section structure was of steel tubing. The undercarriage vees were made of ash and were remarkably small. The fin and rudder of the prototype at first resembled those of the Camel.
  The Dolphin underwent several modifications before the design was settled in its production form. The frontal radiator proved to be inefficient; it was therefore removed and a tapered engine cowling was fitted. The top line of this cowling sloped sharply down towards the airscrew; this improved the pilot’s view and exposed a short length of the barrel of each Vickers gun. At the same time the sides of the cockpit were cut a little lower at the front, and the modified prototype at one time had a large cut-out in each lower wing in order to improve the downward view. It was at first intended to fit the radiators to the upper wings, but ultimately a block was fitted on either side of the cockpit, and the cooling area could be varied by opening outwards a flap which was fitted in front of each radiator block.
  A new vertical tail assembly was fitted. An enlarged horn-balanced rudder replaced the original plain surface, and the fin consisted of a small rectangle with rounded forward end. The plywood covering on the top-decking behind the cockpit was extended farther aft. In this form the Dolphin underwent official tests in August, 1917.
  The fin and rudder were further modified and were again enlarged. The horn balance of the rudder was shortened, the fin was considerably enlarged, and the outline of the vertical tail was modified to have a smooth contour of typically Sopwith appearance.
  The final modification was to reduce the height of the fuselage top-decking behind the cockpit and to cut the cockpit lower at the sides. These modifications improved the pilot’s view in most downward directions, but lower wing cut-outs were not again used.
  By this time the armament had been augmented by the addition of two Lewis guns mounted on the front transverse member of the centre-section structure. These guns pointed forwards and upwards at an angle of about 45 degrees, but were capable of limited movement. The Dolphin thus became the first British multi-gun fighter.
  Tests were carried out with various armament combinations in January and February, 1918. A single Lewis gun was fitted on the centre-section and also (apparently) on the upper wing.
  By that time production was well under way and Dolphins were going into service in increasing numbers. A total of 121 had been delivered by the end of 1917. The type was received with a certain amount of suspicion in the R.F.C. Pilots recalled all that had been said about the allegedly dangerous habits of the D.H.5, which had also had negative stagger; and the Dolphin engendered a lively fear of decapitation if it happened to nose over in a bad landing. On at least one training aerodrome the Dolphin was known as “The Blockbuster” for that reason. To allay these fears, some Dolphins, especially those used by training squadrons, were fitted with two crash pylons, one on either side of the cockpit, to protect the pilot’s head. In one form these pylons consisted of steel tube bent to an angle and fitted above the centre-section structure. Dolphins with these crash pylons were also tested in February, 1918. The centresection bracing system was modified to enable the pilot to escape quickly in the event of a crash.
  During that same month a night-flying version of the design appeared. In this machine the crash pylons consisted of half-hoops of steel tube: one was fitted above the upper mainplane on each side, directly above the inner pair of interplane struts.
  In its production form the Dolphin proved to be pleasant to fly and by no means the dangerous aeroplane it was believed to be. It was tractable, comfortable and warm; but it suffered from the same engine troubles as afflicted the S.E.5a with the same Hispano-Suiza engine.
  Official statistics show that nineteen Sopwith Dolphins had reached France by the end of 1917. In January, 1918, they were issued to No. 19 Squadron, which was the first unit to have the type. On February 22nd, 1918, No. 79 Squadron, equipped with Dolphins, arrived in France in time to participate in the fighting which occurred during the German offensive which opened on March 21st. Offensive patrols were mounted, and as the fighting increased in intensity, No. 19 Squadron’s Dolphins undertook ground-attack duties, and bombed and machine-gunned enemy troops on the Third Army front.
  This work continued into April, in which month No. 23 Squadron replaced its Spads with Dolphins and (on the 26th) No. 87 Squadron arrived in France equipped with the type. No. 87 was with the III Brigade at the time of the Battle of Bapaume (August 21st, 1918), and the unit was required to maintain offensive patrols up to 10,000 feet during the battle.
  In squadron service the Dolphin underwent the usual personal modifications to meet the tastes of its pilots. Operational Dolphins seldom flew with both Lewis guns mounted on the centre-section: in the manoeuvres of combat they were liable to swing and strike the pilot in the face. Occasionally one was retained, and some pilots mounted their Lewis guns elsewhere while others preferred to remove them altogether. The Dolphins of No. 87 Squadron had their Lewis guns mounted on the lower wings well outboard, so that they cleared the airscrew; these guns fired straight ahead parallel to or convergent with the Vickers, but they could not be reloaded in flight.
  In the final Allied offensive of the war, the Dolphins of No. 19 Squadron flew in protection of British ground-attack aircraft and day bombers, and No. 87 Squadron combined ground-attack duties and offensive patrols. The Dolphins of No. 19 Squadron fought a sternly-contested action on October 30th, 1918, when they and the D.H.9s of No. 98 Squadron which they were escorting were attacked by a large formation of enemy fighters. Ten of the German machines were shot down, but five Dolphins and four D.H.9s were lost, and two more D.H.9s crashed on landing.
  With all of these squadrons the Dolphin remained in service until the Armistice. It was to have formed the equipment of other units: No. 90 Squadron had been given Dolphins for use in France, but was disbanded in August, 1918; No. 1 Squadron of the Canadian Air Force had Dolphins in England preparatory to going to France, but the Armistice was signed before the unit could join the R.A.F. in the field.
  The only Home Defence squadron to use the Dolphin was No. 141, to which seven machines were sent in 1918. The Dolphin was used by the squadron for only three months, after which it was replaced by the Bristol Fighter. The type was not adopted for Home Defence duties. Since it had the same engine as the S.E.5a, the Dolphin had the same disadvantage: its liquid-cooled engine required a longer warming-up period than contemporary rotaries, and consequently delayed take-off.
  The French-made geared Hispano-Suiza engine was a liability in itself. Its shortcomings are described in the history of the S.E.5, and it was largely responsible for the Dolphin’s comparative lack of success. In October, 1918, a Dolphin was tested with a 200 h.p. Hispano-Suiza engine which had a direct drive, presumably to eliminate the troubles caused by badly hardened gears. A number of Dolphins had this engine, and with it the machine was designated Dolphin Mk. III.
  In October, 1918, the American Expeditionary Force bought five standard Dolphins. Four of them were sent to America for study.
  The Dolphin Mk. II was a version which was in production in France at the time of the Armistice, and it has been reported that production was for both French and American units. The Mk. II was powered by the 300 h.p. Hispano-Suiza engine, and was a most promising aircraft. Its performance was better than that of any other type in service in 1918, and if the war had lasted a little longer the Dolphin II would have been a powerful weapon.
  The first installation of the 300 h.p. Hispano-Suiza was made in the Dolphin D.3615. It was characterised by a more bulbous engine cowling and by longer exhaust pipes which were cranked over the tops of the radiator blocks. The cowling was high enough to enclose the Vickers guns completely. The structure was strengthened against the more powerful engine, additional fuel tankage was provided, and an adjustable tailplane was fitted to improve longitudinal trimming.


SPECIFICATION
  Manufacturers: The Sopwith Aviation Company, Ltd., Canbury Park Road, Kingston-on-Thames.
  Other Contractors: The Darracq Motor Engineering Co., Ltd., Townmead Road, Fulham, London, S.W.6: Hooper & Co., Ltd., St. James’s St., London, S.W.1.
  Power: Dolphin Mk. I: 200 h.p. geared Hispano-Suiza; Mk. II: 300 h.p. direct-drive Hispano-Suiza; Mk III: 200 h.p. direct-drive Hispano-Suiza.
  Dimensions: Span: 32 ft 6 in. Length: 22 ft 3 in. Height: 8 ft 6 in. Chord: 4 ft 6 in. Gap: 4 ft 3 in. Stagger (negative): 12 in. Dihedral: 2° 30'. Incidence: 2°.
  Areas: Wings: upper 132 sq ft, lower 131-25 sq ft, total 263-25 sq ft. Ailerons: each 9-5 sq ft, total 38 sq ft. Tailplane: 17 sq ft. Elevators: 13-5 sq ft. Fin: 3-5 sq ft. Rudder: 8 sq ft.
  Tankage: Petrol: 27 gallons. Oil: 4 gallons. Water: 7 1/2 gallons.
  Armament: Two fixed, forward-firing Vickers machine-guns above the engine, synchronised by Constantinesco gear to fire through the airscrew. Additionally, one or two Lewis guns could be carried on the forward spar member of the centre-section; these guns could be moved, but generally fired forwards and upwards over the airscrew. In No. 87 Squadron the Lewis guns were mounted on the lower wings outboard of the airscrew, and fired forwards. Four 25-lb bombs could be carried for ground-attack duties.
  Service Use: Western Front: R.F.C. Squadrons Nos. 19, 23, 79, 87. Home Defence: No. 141 Squadron. Training: No. 90 Squadron; No. 1 Squadron, Canadian Air Force; Schools of Aerial Fighting at Freiston, Marske, Sedgeford and Turnberry; 23rd Training Wing, South Carlton; Training units at Cranwell, Hooton Park, Scampton and Gosport.
  Production and Allocation: Production of Dolphins totalled 1,532; of these, 121 were built in 1917, the remainder in 1918. Only 621 were distributed to units of the R.F.C. and R.A.F.: 400 went to France, seven to No. 141 (Home Defence) Squadron, and 214 to training units. On October 31st, 1918, the R.A.F. had 1,055 Dolphins on charge. One hundred and forty-nine were with the squadrons in France; seven were with experimental units; 104 were with training squadrons and other Home Establishment units; eight were with squadrons mobilizing; ninety-seven were at Aircraft Acceptance Parks and with contractors; thirty-eight were at Aeroplane Repair Depots; and 652 were in store. Five were bought by America in October, 1918.
Serial Numbers:
Serial Nos. Contractor Contract No.
B.7927 and B.8189 Southern Aeroplane Repair Depot Probably rebuilds
C.3777-C.4276 Sopwith A.S.17137
C.8001-C.8200 Darracq A.S.18920
D.3576-D.3775 Sopwith A.S.35977
D.5201-D.5400 Hooper A.S.17566
E.4424-E.4623 Sopwith A.S.3294
E.4629-E.5128 Sopwith 35A/305/C.195
F.7034-F.7133 Darracq 35A/1459/C.1545
J.1 onwards, probably to J.100 at least - -

  Notes on Individual Machines: Used by No. 19 Squadron: C.3788, C.3792, C.3796, C.3799, C.3818, C.3828, C.3829, C.3837, C.4017, E.4501. Used by No. 23 Squadron: C.3905 (“C”), D.3669, D.3691, D.3749, E.4717 (“M”), E.4729 (“P”). Used by No. 79 Squadron: B.7927 (“K”), B.8189 (“N”), C.3849, C.3859, C.3879 (“Q”), C.3887, C.3892 (“G”), C.3898 (“D”), C.3944 (“N”), C.4046, C.4059, C.4127, C.4176, C.4182, C.8075, 8121, C.8189, D.3584, D.3727, D.3745, D.3771, E.4425, E.4585 (“J”), E.4589, E.4712, E.4716. Used by No. 87 Squadron: C.4136, C.4155, C.4156, C.4157, C.4158, C.4159, C.4230, C.8072, C.8109, C.8163, C.8165, C.3719, D.3764, E.4451, E.4493. Used by No. 1 Squadron, Canadian Air Force: E.4764, F.7076, F.7085, J.3. Used at Hooton Park: C.3862, C.3875, C.3911, C.3915, C.3998, C.3999, C.4138, C.4142, C.4169, C.4233, C.4235 (“R”), E.4505 (“V”). Other machines: C.3783: used at Turnberry. C.4172: School of Special Flying, Gosport. D.3615: fitted with 300 h.p. Hispano-Suiza engine. E.4698: flown at Cranwell.
  Costs:
   Airframe without engine, instruments and guns £1,010 13s.
   200 h.p. Hispano-Suiza engine £1,004 0s.

H.King Armament of British Aircraft (Putnam)

Dolphin. From the standpoint of armament, as from other aspects, the Dolphin of 1917 was a fighter of exceptional interest. By reason of the fact that it carried two free Lewis guns in addition to two fixed Vickers guns, it has been correctly described as the world's first multi-gun single-seat fighter. Yet the first Dolphin, with its deep car-type frontal radiator, gave scant evidence of being armed at all. The Lewis guns were not, in fact, fitted on this machine, although the Vickers guns were present beneath the cowling, as proclaimed by the breech casings visible in the cockpit, ejection chutes, and two small ports in the nose cowling. The link chutes were above the cylinder-bank fairings and the case chutes behind the exhaust pipes. When lateral radiators were adopted, the cowling was lowered accordingly and the forward portions of the Vickers guns protruded. In the Dolphin Mk.II (300-hp Hispano-Suiza engine) the guns were again submerged.
   The rear ends of the Vickers guns were padded and came far back in to the sides of the cockpit at the level of the pilot's shoulders. The windscreen was far ahead of the cockpit and the centrally-mounted Aldis sight passed through it, being bracket-mounted at a point behind the screen and to the cross-tube which carried the Lewis guns. A ring-and-bead sight was mounted to starboard. C.C. gear Type B was fitted, and the guns had Hyland Type A or B loading handles. A prominent feature of the C.C. gear installation was the gear ring attached to the rear flange of the airscrew boss and the smaller gear wheel meshing with it below. Beneath the smaller gear wheel were two apertures in the cowling each exposing part of the box-type generator used with the Hispano-Suiza engine and a short length of the hydraulic pipeline leading to the trigger motor.
   The two Lewis guns were swivel-mounted on brackets attached to the ends of the cross member which was officially known as the 'front spar tube'. They pointed upwards at about 45 degrees and were restrained from firing into the airscrew by two cams, which nevertheless permitted their being trained to some extent outboard. The spade grips were removed, and the guns were fired by Bowden cable. Norman vane sights were sometimes fitted. When the guns were trained parallel, they were clamped above the pistol grips by fittings attached to the upper wing roots. The Lewis gun installation was not popular among pilots by reason of the guns' intrusion into an already cramped cockpit, and inevitably they affected performance. To fly the Dolphin, keep observation, operate the radiator, and use the Lewis guns as well as the Vickers guns was a one-man-band operation that few could have mastered. One or both guns were frequently removed, although a single Lewis gun was regarded as standard. In No. 87 Squadron the guns were transferred to fixed mountings on the lower wings, somewhat inboard of the inner pairs of interplane struts, where they fired outside the airscrew arc. There were probably other schemes, and certainly a fixed Lewis gun was fitted on the upper wing. Other non-standard installations were an Aldis sight attached to the front spar tube and a Lewis gun on the cross-bar of a crash pylon above the open centre-section. For night work, Hutlon illuminated sights were fitted. Four 20-lb bombs could be carried under the fuselage.

J.Davilla, A.Soltan French Aircraft of the First World War (Flying Machines)

Sopwith Dauphin

  The French were pleased with the performance of the 300-hp Hispano-Suiza 8F engine and for the C1 specification of 1918 a number of aircraft were designed to use it (SPAD 18, 20, 21, and 22; SAB 1, Moineau, Semenaud, De Marcay 2, Descamps 27, Nieuport 29, and the Hanriot Dupont HD.7). The French had learned that the British were planning to place the engine in a Sopwith Dolphin and ordered an example of the Mark 2 Dolphin for evaluation. If the type proved satisfactory it was planned to produce it under license for use by the French and Americans.
  The Dolphin (in French Dauphin) was a single-seat fighter with negatively staggered, two-bay wings. The Mark 1 was powered by a 200-hp Hispano-Suiza engine and an example (D 3615) was provided with the 300-hp Hispano-Suiza 8F in 1918. This aircraft was designated Dolphin 2 and featured a rounder cowling enclosing twin Vickers machine guns. Auxiliary mid-bay flying wires were fitted to the upper wing in the inboard bracing bay. An adjustable tailplane was also fitted.
  The aircraft was test flown by the French and had excellent performance, but the war ended before the type could be combat tested. In any event, the Nieuport 29, which used the same engine, was selected for series production. At least one Sopwith Dolphin was built by the French firm SACA (Societe Anonyme de Constructions Aeronautiques), presumably for evaluation, and, therefore, merits inclusion in this volume. The S.F.A. number of the French-built machine, 007, suggests that possibly as many as seven Dolphins were built by the French, but this cannot be confirmed. It had been anticipated that the SACA was to build as many as 2,194 Dolphin 2s for the American Expeditionary Force. However, the SACA failed to produce any machines before the Armistice and the American order was subsequently canceled.
  A Sopwith Dauphin was possibly the first plane to fly with a 220-hp Hispano-Suiza engine fitted with a Rateau supercharger. It attained a speed of 210 km/h at 2,650 m and 192 km/h at sea level.


Sopwith Dauphin Single-Seat Fighter with 300-hp Hispano-Suiza 8F
   Height 2.6 m; wing area 24.5 sq. m
   Empty weight 710 kg; loaded weight 1,072 kg
   Maximum speed: at 10,000 feet was 140 mph; climb to 10,000 feet in 8 minutes 20 seconds; ceiling 24,600 feet
   Armament: two 7.7-mm Vickers machine guns
   One example acquired by the French for evaluation; at least one was built by the SACA firm

O.Thetford Aircraft of the Royal Air Force since 1918 (Putnam)

Sopwith Dolphin

   The Dolphin followed the Pup, Triplane and Camel in the Sopwith family, but preceded the Snipe. It was notable for its back-staggered wings and joined No 19 Squadron in January 1918. By October 1918 it equipped Nos 19, 23, 79, 87 and 90 Squadrons of the RAF. Last in service were the Dolphins of No 79 Squadron at Bickendorf in July 1919. One 200hp Hispano-Suiza engine. Span, 32ft 6in; length, 22ft 3in. Loaded weight, 2,000lb. Max speed, 131mph; climb, 855ft/min; service ceiling, 21,000ft.

Журнал Flight

Flight, February 6, 1919.

"MILESTONES"

THE SOPWITH MACHINES

The Sopwith "Dolphin." (May 23, 1917)

   Two principal objects were borne in mind in the design of this single-seater fighter - firstly, to make good use of the 200 h.p. Hispano-Suiza engine (which had reached a productive stage), and, secondly, to afford the pilot a range of vision greater than that of any other existing aeroplane. The former necessitated a departure from the usual lines of the Sopwith fuselage, the upper surface of which in the rear of the cockpit is more pronouncedly arched than in previous types. The span of the planes was increased beyond that of the "Camel," and a double-bay arrangement of struts adopted in order to provide great structural strength. At the same time the gap was slightly diminished, and, what forms a strong characteristic of the type, a negative stagger was adopted, with the object of placing the main spar extensions of the top plane in such a position as not to interfere with the complete freedom of movement of the pilot, who occupies the rectangular space formed by them. On these tubular steel spar extensions - which are supported by four short vertical struts from the fuselage - are mounted two Lewis guns, capable of being aimed independently of the direction of the machine. Two fixed Vickers' guns firing through the propeller are arranged along the top of the engine, and are partially covered in by this cylinder fairing. The general arrangement of the front part of the fuselage is particularly neat, and its formidable appearance is well supported by the "Dolphin's" offensive capabilities. The radiator is divided into two portions, each carried on one side of the fuselage level with the pilot's cockpit. In front of each radiator is arranged an inclined and adjustable deflector, allowing the whole or any part of the cooling surface to be obstructed. Among other features of the "Dolphin" will be noted an empennage design differing markedly from that of previous Sopwith types. The fin is of a more upright shape and the rudder is balanced.

The 300 h.p. "Dolphin."

   In connection with this type it is of considerable interest to note that at the signing of the Armistice it was being built in quantities by the French Government, for themselves and the American Government in France. It is fitted with the 300 h.p. Hispano-Suiza, and an adjustable tail plane is employed, since the variable load is considerable, the French and American Governments calling for a very large quantity of petrol to be carried. The machine was reinforced in certain respects to allow for the considerable addition of power, and it had every promise of being an extremely formidable proposition.
   In general outline it was very similar to the 200 h.p. Hispano-Suiza "Dolphin." The guns were completely concealed under the cowling, being fitted in tunnels, and the air intake of the carburettor was fitted with a telescopic-type gas tube direct into the front cowl, considerably diminishing the risk of carburettor fire.