H.King Sopwith Aircraft 1912-1920 (Putnam)
To the first Sopwith torpedo-dropper (the Type C seaplane reviewed much earlier in this volume) the Cuckoo - the first torpedo-dropper in the world built to operate from the flying-deck of an aircraft-carrier - owed little or nothing. To the B.1 Bomber, however, it stood, if not precisely in debt, then in close relationship though less so than first appearances suggest. To the Blackburn Aeroplane & Motor Co Ltd it owed a great deal, not only for the development of its specialised torpedo gear, but for its production in quantity. (Blackburn, indeed, did much the same job with the Cuckoo in the First World War as they were to do with the Fairey Swordfish in the Second, though in the latter instance they were much concerned with applications other than torpedo-dropping).
The relationship between the B.1 Bomber and the Sopwith T.1, as the Cuckoo was styled until given its name after the Armistice - one official rendering in 1918 being doubly parenthetical, viz 'Sopwith Torpedo Plane (200 h.p. Sunbeam Arab) (T.1)' - is of the kind which may confidently be classed as a 'chicken or egg?' affair. And here the 'egg' analogy is especially apt, for the very name 'Cuckoo' has sometimes been associated with the propensity of this aeroplane for 'laying its eggs in other people's nests'. More properly, perhaps, it could be said that this particular Sopwith 'bird' found its true incubation in the sometimes chilly Blackburn nests up in Yorkshire - a phenomenon thus expressed in 1919:
"Their [Blackburn's] first connection with the torpedo arose over the design of the G.P. (general purpose) seaplane in 1915-16. Although not purely a torpedo machine this twin-engined machine was arranged to carry a light torpedo as one of the numerous forms of armament to which it was susceptible, and with it the firm gained some experience of the fitting, carrying and dropping gear necessary to this class of work.
'When the Sopwith "Cuckoo" was produced, and had been tested and found satisfactory as far as the aeroplane part was concerned, it was decided that the work of putting it onto a production basis should be put into the hands of a firm conversant with the essential torpedo problems, and the work was therefore entrusted to the Blackburn firm, who with the assistance of experts from the R.N.A.S. carried out much work in connection with the torpedo-dropping and aiming gear, the silencing of the engine exhaust, and the fitting of warming gear to prevent freezing-up of the air passages in the torpedo itself - a phenomenon which occurred frequently at high altitudes and which effectively demoralised the torpedo by preventing the torpedo engine functioning.
'The problems of the "Cuckoo" being satisfactorily solved and the final pattern in production. Blackburns were asked to design a machine to carry a still heavier torpedo and at a higher speed and with a greater climb ...'
The account then proceeded with reference to the Blackburn Blackburd and Kingfisher designs - though not, having regard to the date (1919) to their line of successors in the service of the Royal Navy after the Cuckoo, namely the Dart, Ripon, Baffin, Shark, Firebrand and Buccaneer.
Yet the Cuckoo was very much a Sopwith aeroplane, and its full technical and operational significance, rather than minutiae of development and deployment, must be our first concern, in order that to Sopwith may rightly go the credit for having designed the aeroplane described at the outset as 'the first torpedo-dropper in the world built to operate from the flying-deck of an aircraft-carrier'. The concept of such an aeroplane had, in fact, far earlier origins possibly in the ideas of the Frenchman Clement Ader, thus expressed in 1909:
'Air is everywhere. We know how aeroplanes have to land on the ground. And on the sea? The ever-increasing power of the navy, the possibility of having to fight an ironclad, make the problem apparently impossible to solve. However, if we do not hope to succeed in finishing-off an ironclad straight away, we think it will be possible to damage it considerably at the first hit and even to sink it if attacked by a sufficient number of aeroplanes. We foresee ... the use of the big torpedo of 100 to 200 kilos; but now we must work out how to use it against warships. If we had to attack an enemy squadron in French or allied waters within proximity of land, the operation would be easy, aeroplanes could land and load their torpedoes on areas near the coast. It would be different in the middle of the sea. Therefore, an aeroplane-carrying ship becomes indispensible.'
Having described a "modern" form of aircraft-carrier, Ader declared that the 'torpedoes' used (which clearly, from his quoted weight, would not correspond to any form of locomotive torpedo current at the time, though the weight might conceivably have represented the explosive content) would have a device 'which will make it possible to have them explode under water at various depths ...'
Irrespective of the precise form of weapon proposed, however. Ader had the notion of the aircraft-carrier much in the form that the Sopwith Cuckoo was to use. That a torpedo-dropping aircraft was itself a difficult proposition will have been gathered from the note that introduced the chapter on the Type C floatplane of 1914 - to the effect that the Italian Guidoni in 1912 had been led, in his pioneering torpedo-dropping work, to resort to twin engines and hydrofoil floats. But if a floatplane was "difficult", then how much more so was a wheeled aeroplane, capable not only of operating from the confines of a ship's deck but of being borne in numbers in its hull.
Against this background, then, must be viewed the familiar (though still historic) letter to T. O. M. Sopwith from Commodore Murray Sueter. Sent in October 1916, this document requested inquiry into the feasibility of torpedo-carrying aeroplanes having specified performance and lifting ability and 'probably' catapult-launched. This last-named technique was already old in concept, though new to Britain, for the US Navy had made experiments in 1912 - these having stemmed, it seems, from interest expressed in 1911 by the Bureau of Ordnance in a catapult for launching aeroplanes 'somewhat in the manner of launching torpedoes' (!)
The British Naval officer who (with the possible exceptions of Sueter and Longmore) has been most closely associated with the Cuckoo is Sir David Beatty, who had opened the Battle of Jutland in 1916 and later succeeded Lord Jellicoe - 'the victor of Jutland’ - as commander of the Grand Fleet, which was responsible for guarding the shores of Britain. Nevertheless, one other officer quite intimately concerned was none other than 'Rutland of Jutland', whose name will be remembered from the chapter on the Pup and now forms yet another link between the Cuckoo and the greatest British Naval battle since Trafalgar. (One point of contention after Jutland, incidentally, was whether a fleet should turn away from or towards a massed torpedo-attack). Flight Commander Rutland had faith in ship-borne torpedo-dropping aircraft, and this faith was given expression in proposals jointly prepared by Rutland and Admiral Sir Herbert Richmond. Towards the end of 1917 Beatty brought to the Admiralty's attention the Richmond/Rutland considerations relating to an attack by torpedo aircraft on the German High Seas Fleet in the Wilhelmshaven area, the date then foreseen being the Spring of 1918, and eight specially adapted merchant ships being involved though the state of torpedo-aircraft development was not considered by the Admiralty to warrant the provision and the preparation of the ships.
In the ultimate, as we shall see, the aircraft-carrier HMS Argus became the chosen instrument; but meanwhile what of the development of the 'Sopwith Torpedo Plane' (T.1), as it began to germinate from the Sueter/Sopwith letter of October 1916, already mentioned? Sueter himself was removed from the immediate scene by a posting to Italy only a few weeks later (January 1917) though the testimony of Wing Cdr (later Air Chief Marshal Sir Arthur) Longmore survives to this effect: that in February 1917 he visited the Sopwith works; that there he saw the T.1 fuselage suspended from the beams of one of the shops; and that the airframe was completed at his instigation - these facts according well with the recorded clearance of the T.1 by the makers' Experimental Department at Kingston-on-Thames on 6 June, 1917. By this time, let it be remembered, the closely related B.1 Bomber had already been delivered to Dunkirk for Service trials - a point of particular interest as the complementary use of bombs and torpedoes in attacking an enemy fleet (especially at base) was much in the Navy's mind. It must immediately be emphasised, however, that the T.1, or Cuckoo, was not a deck-landing 'torpedo-bomber', though it has sometimes been so styled; for the term torpedo bomber connoted an aircraft capable of carrying either a torpedo or a bomb-load, and was first introduced by the Blackburn Dart which, though still a single-seater like the Cuckoo, remained with the RAF from 1922 to 1933.
But although it could not carry bombs as an alternative load to its torpedo, the Cuckoo had one other characteristic in common with the Dart: it carried no guns, either for offence or defence. In the latter regard its faculty lay more in its good manoeuvrability (after release of torpedo) and in its structural strength for taking evasive action perhaps at near sea-level against fighters or anti-aircraft fire.
The first T.1 airframe having been cleared for flight-testing on 6 June, 1917, as earlier noted, it was quickly sent for official trials at the Isle of Grain, the engine then being a 200 hp water-cooled eight-cylinder vee-type Hispano-Suiza, installed as in the B.1 Bomber, with circular frontal radiator. In both cases the high-set propeller boss signified that the engine had reduction gearing (as was especially desirable in the T.1 for the lifting of a torpedo) and this may have been a factor in the allocation of Licence No.6 to cover the construction of both types of aircraft.
Tests of the T.1 at the Isle of Grain during July proved successful, and an order for 100 machines of the type was placed (conceivably 'confirmed' might be more apt) on 16 August, 1917, with the Fairfield Shipbuilding and Engineering Co Ltd of Glasgow. Though inexperienced in aircraft construction this company had long experience with fast ships, often with special characteristics and sometimes having special armament. Interestingly enough (the Cuckoo's torpedo, like other British Naval patterns, being basically of Whitehead type) Sir Hiram Maxim recorded the following facts not long before his death in 1916:
‘In the winter of 1884-5 there was a good deal of discussion among naval officers and others regarding the efficiency of the Whitehead torpedoes. It was claimed by many that it would be very difficult to hit a ship even at short range if the ship were in motion at the time. While this discussion was at its height, Bryce Douglas, a very clever and well-known Scotch engineer, came to see my gun at Hatton Garden. The very fact that I had made a gun that would load and fire itself more than ten times in a second seemed to make him believe that I might be of some use in other directions. He told me that he did not believe the Whitehead torpedo would be of any use in the Navy... He was in favour of increasing the size of the torpedo and of propelling it through the air instead of through the water. He believed that if a large torpedo were exploded within a few feet of the hull of a ship it would open a large hole which would let in more water than could be dealt with; and he asked me if I could produce a gun of very large bore for throwing aerial torpedoes. I told him that I could ...
'Having designed the gun, I took the drawings up to Glasgow, where Bryce Douglas was employed as Chief Engineer at the Fairfield Shipbuilding Works. My drawings being approved of, Bryce Douglas made a model of the gun ...’
Novel methods of launching torpedoes (of whatever denomination, for the term 'aerial torpedo' was confusingly applied in many contexts) were thus nothing new to Fairfield; and, in particular, they had been concerned with the highly secret, amazingly fast, but sadly doomed K-class submarines - one of which ultimately became the aircraft-carrying M.2!
It has already been emphasised, however, that Blackburn, not Fairfield, was the name pre-eminent in Cuckoo development and production; but in any case, back now from the north country to Kingston, Surrey (or establishments likewise in the south), with the Cuckoo-to-be still more or less in its original form, with Hispano-Suiza engine, and bearing the Service number N74, or simply the letter T.
The main differences between this aeroplane and the B.1 Bomber were in the fitting of three-bay wings (instead of two-bay) thus giving notably greater span and area; provision of wing-folding arrangements (the fold occurring at the innermost set of the three-a-side pairs of interplane struts, the foremost strut being 'split' accordingly); provision also of a special divided type of landing gear to permit operation with a torpedo - the outermost attachment-points of the landing gear being at the lower centre-section extremities, near the wing-fold point; and the placing of the pilot's cockpit further aft, precisely in line with the trailing edges of the unstaggered wings. Thus, compared with the Bomber, the pilot and projectile load changed places, though the torpedo could not be stowed internally, as were the companion-type's bombs.
The pilot's view, of course, was by no means ideal for torpedo work, having regard to the length of the nose (the same consideration applying to operation from a carrier's deck). On the other hand, the absence of upward view from the Bomber (the pilot being under the top wing) had led to the criticism that attack from above would be hard to avoid; whereas with the new cockpit position this handicap was mitigated, while avoiding action - or even straight flying - near sea-level would itself preclude the danger of fighter attack from below.
However unorthodox its purpose, N74 embodied no new structural features, the wooden framework being braced by steel wire and covered with fabric, except for the decking round the cockpit - which, in official notes later prepared, was quite understandably described as the 'top deck'.
After its initial trials at the Isle of Grain, N74 was returned to Sopwith for further work before being re-erected at Grain for further tests, especially at high all-up weights, beginning in January 1918. At about this time Hispano-Suiza engines were in heavy demand for the S.E.5a and the corps reconnaissance version of the Bristol Fighter, though in the event the latter had the Sunbeam Arab instead. Now, once again, the Sunbeam associations with Naval torpedo-dropping aircraft (already established by the Short '225' and ‘320’) were renewed by the adoption of the Arab for the Sopwith T.1. This was not a very dramatic departure, for the Arab resembled the Hispano-Suiza not only in general outline, but even in bore and stroke (120 mm x 130 mm). It was made in both geared and direct-drive forms, and fitted nicely in the Sopwith torpedo-dropper, having a frontal radiator as formerly (for the torpedo pistol stop precluded an underslung arrangement as in the Arab-engined Bristol Scout F) though the radiator was now of inverted-horseshoe form, instead of round.
In February 1918 (at about the time when N74 was having an Arab fitted by Blackburn) two hundred and thirty T.1s were ordered from Blackburn as well as fifty from Pegler & Co Ltd of Doncaster (again, up in Yorkshire) though Pegler, like Fairfield, were inexperienced in aircraft construction, and part of their contract was taken over by Blackburn. Problems, numerous and intricate, were encountered, and, hardly surprisingly it was Blackburn backed with a certain amount of indigenous construction, as well as 100-odd B.E.2cs and series-production of the Sopwith Baby as already recounted - who were first to deliver the new Sopwith torpedo-droppers in quantity. These deliveries began in May 1918, whereas the first Fairfield - built example emerged only in September and the first from Pegler in October. When the Armistice came on 11 November, 1918, orders totalled 350, of which just over ninety had been delivered. By August, in fact, Blackburn alone had finished eighty; so our opening laudation of that company was by no means out of order. Deliveries, however, were cut back well short of orders - for the Cuckoo, alas, was numbered among those aeroplanes that were 'just too late for the war'.
When, eventually, the type was given publicity, one typically effusive claim perhaps officially inspired was thus advanced: 'It was a type designed to replace destroyers and submarines in attacking enemy surface craft and would undoubtedly, but for the Armistice, have rendered brilliant service. Its career has only just begun.'
Effusive though the foregoing may have been, it was partly true at least, especially at the end - and more especially if the final 'Its career’ be interpreted as the instigation and development of a long line of carrier-borne torpedo-dropping aircraft of which the T.1, or Cuckoo, was the archetype. The career of the Sopwith type itself was in fact brief, though its design had originated in late-1916 and it was not operational until some two years later - and even then largely by reason of subcontracting and official experiment and development, with Sopwith playing a part by supplying drawings and having some hand in modifications.
After the initial Arab installation by Blackburn, already recorded (and not overlooking the fact that this company's G.P. seaplane, with torpedo potential, as mentioned at the outset, was Sunbeam-powered) N74 was delivered back to the Isle of Grain, where it used for further trials a special dummy deck and apparatus for measuring speed against distance. The most serious mishap seems to have been the shearing of a propeller shaft in the air (while the aircraft was carrying ballast in an under-fuselage container, in place of the torpedo) some damage thus resulting to the port lower wing.
Modifications to the Sunbeam Arab engine (which was especially prone to vibration) had been, and continued to be, frequent, and production of this engine fell far behind schedule. Although it has been described - especially in the Cuckoo context - as a heavier engine than the corresponding Hispano-Suiza, thus requiring tail-adjustment on the aircraft to compensate, the actual weight difference was not, apparently, very great; for though engine-weights differed widely in those times by reason of modification standard, materials, accessories and other factors, it can be said with some confidence that a typical Hispano-Suiza would weigh about 500 lb and an Arab about 530 lb. Special engine-bearers for the Arab, however, could have made an added contribution; radiator and propeller were other variables - and even torpedo gear could make a difference.
In any case, the airframe had an adjustable tailplane as a standard fitting; in which connection it was notified: 'The Tail Plane is braced on the under surface by two Bracing Wires, which extend from the Bottom Longerons to Front and Rear Spars respectively, and on the upper surface by two Bracing Wires, which extend from the Fin to the Front and Rear Spars respectively ... The Tail Plane, which is adjustable, is set at the zero Angle of Incidence for trial flight. The Rear Spar is supported at the centre by a vertical telescopic fitting, which is fixed in the Fuselage just in front of the Sternpost. The telescopic fitting has an inner screwed spindle, which may be raised or lowered by means of a sprocket wheel in the Pilot's Cockpit, a cable from which passes round a drum on the spindle. To allow for movement of the Tail Plane, when the Rear Spar is raised or lowered by means of the telescopic fitting, the Front Spar is hinged by means of a cylindrical casting in bronze bearings, which are bolted to Top Transverse Strut No.15.'
The four ailerons were operated by a wheel on the control column, though control-cable arrangements differed, those to the tail of production Cuckoos being wholly external. The tailskid was taller on production Cuckoos and taller still when (later) fixed to a massive inverted pyramidal structure. Sometimes associated with this last-named feature were a larger rudder and an offset fin, though on the Arab-engined aircraft as first taken into service riggers were instructed to see that the fin and rudder were 'set straight and square' with the machine.
Having regard to the torpedo-dropping and deck-landing requirements it was the landing gear which called for special study - especially so as its steel-tube components were at first prone to fracture. An authentic description of the production-type landing gear follows:
The Chassis consists of two Undercarriages which are identical. Each Undercarriage is formed of steel tubes welded and pinned together, and consists of two portions. One portion, which is in the shape of a V, is placed parallel to the fuselage, the End Lugs being bolted to the front and rear Spars of the Centre Section Lower Plane. The other portion has one End Lug bolted to the Bottom Longeron, and is bent so as to form the Axle for one wheel, the other end resting in the apex of the V. Shock Absorbers are formed by 28 feet of 15 mms. diameter elastic, which is given ten complete turns round the Axle and the apex of the V. The Steel Struts are stream-lined by means of wood fairing attached by metal clips, the whole being wrapped with fabric and then doped.’
By the same tokens (torpedo-dropping and deck operation) the wide-span, three-bay, folding wing cellule was no less a basic feature, and the nature of its assembly was thus described for the edification of technical personnel: 'To assemble the Centre Section, first attach the four Outer Centre Section Struts by their Bottom Sockets to the Centre Section Lower Planes. Before fitting the Centre Section Upper Plane into position place it upside down on trestles, and fix and split-pin all Centre Section Bracing Wires ... The Hinges on the Centre Section Upper Plane should be vertically over the Hinges on the Centre Section Lower Planes. Adjust by the Side Bracing Wires and Incidence Wires, and check by dropping plumb lines from the Hinges on the Upper Plane ... The Incidence is 3 throughout both Upper and Lower Centre Section Planes ...
'The Main Planes are assembled with their Leading Edges on the ground. All Interplane Struts are fitted and the Incidence and Outer Flying Wires are loosely connected ... The Main Planes are hinged at the Root of the Rear Spars. Fit the male hinge pieces at the ends of the Rear Spars into the forked hinge pieces at the ends of the Rear Spar of the Centre Section Lower Planes, and insert the hinge pins. The fork and eye attachments, by which the roots of the Front Spars are connected by the Front Spars of the Centre Section Lower Planes, are secured by inserting a locking pin through the Leading Edge. The locking pin is fixed in position by means of a wood screw ...The Dihedral is 2 1/2 for both Upper and Lower Main Planes ... The Incidence is 3 ... There is no "Wash in" or "Wash out" ...'
On themes more mechanical, it must first be remarked that, as an alternative to the Sunbeam Arab engine, some aircraft had the Wolseley Viper - another unit of Hispano-Suiza vee-8 character. Post-Armistice Cuckoos so powered were designated Cuckoo Mk. II, the Arab version being Cuckoo Mk. I. Flotation bags, larger rudder, extra-large tailskid, and torpedo-warming exhaust tailpipes running beneath the fuselage were likewise characteristic of the Mk.II - also a folding pistol-stop for the torpedo. (Had this last not been the case, and a massive pylon structure been fitted under the nose, as seen in the accompanying close-up study of a Blackburn-built aircraft with torpedo slung, then the Cuckoo might have been seen in flight with an inverted pyramid at each end - the prominent tailskid-attachment having already been mentioned. A veritable mirage ... or was it a case of 'hence the pyramids’?
In describing the Wolseley Viper as an engine of Hispano-Suiza character one has understated the matter, for more precisely it was a development - so much so in fact that on at least one occasion in 1921 the Cuckoo was officially listed as having an Hispano-Suiza Viper F. (The engine series-number was at least correct).
Well before the Cuckoo was declared obsolete in April 1923, the biggest of all its engines had been tried experimentally - the twelve-cylinder Rolls-Royce Falcon, fitted in N7990 during 1919. Having four extra cylinders compared with its predecessors, and weighing the best part of 700 lb (317 kg) the Falcon must have posed some pretty installation problems, and was never standardised.
The standard postwar engine was, in fact, the Viper which, having no reduction gear, could be identified in a Cuckoo by a lower thrust-line. Postwar modifications and additions (including sometimes wireless) were numerous and possibly dangerous, and in 1920 RAF pilots were warned to dive 'modified' and Viper-engined Cuckoos only with half-empty petrol tanks.
The Cuckoo's 18-in Mk.IX torpedo, nominally weighing 1,000 lb, though typically nearer 1,100lb, was a special lightweight (and short) aircraft pattern of the Whitehead type. In one early form of installation, on Blackburn-built aircraft at least, the massive inverted-pyramid pylon structure already mentioned apparently served the dual function of helping to steady the torpedo and of acting as a pistol-stop, though latterly the standard pistol-stop was of simple rearward-folding type. In any case, a steel crutch, or pair of crutches, semi-circular in form, were the principal means of steadying the torpedo, jointly with the flexible sling.
The torpedo sight was a small ring near the pilot's eye (fitted port and starboard, as shown in the instructional drawing) used in conjunction with a transverse row of beads laterally displaced by distances corresponding to the speed of a ship (for example, 5, 10, 15 knots and up). Training aids such as the one shown ('Aerial Diagrams' as they were officially called) should certainly have proved helpful to the new torpedo-dropping pilots needed for the Cuckoos - pilots, incidentally, who were far more concerned with taking-off from a carrier's deck than landing back on it, for a land base was foreseen as 'journey's end' whenever possible (though the Cuckoo enjoyed a good 'ditching' reputation).
The "working-up" and operational career of the Cuckoo can be summarised as follows:
Summer 1918. Blackburn-built aircraft to the Torpedo Aeroplane School. East Fortune (near Dunbar and North Berwick, Scotland); pilots thus trained were posted to an operational squadron which joined the Fleet on 7 October, 1918, and embarked (19 October) in HMS Argus - 14.450 tons, flush-decked, and formerly - before conversion by Beardmore - the Italian liner Conic Rosso (at one period Cuckoos were aboard Argus together with Camel 2F.1s and Short 184 floatplanes); after the war Cuckoos served also in the carriers Furious and Eagle; the type briefly equipped Nos. 185, 186 and 210 Squadrons, and was used for development work in torpedo-carrying and dropping at Gosport, Hants (near HMS Vernon, the Royal Navy's torpedo 'school'); No.210 Squadron disbanded at Gosport in April 1923, when the Cuckoo was declared obsolete - even for coast defence from shore bases, though the RAF continued to develop aircraft for this function (e.g., a version of the Hawker Horsley).
After the Armistice many Cuckoos on order were cancelled; but in 1921 six Viper-engined examples were taken to Japan by the British Air Mission to the Imperial Japanese Navy, the Mission being led by Col the Master of Sempill, who had joined the RFC in 1914, transferred to the RNAS and was at one time assisting in the testing of Robey-built Sopwith Gun Buses. In Japan, the former Sopwith designer Herbert Smith was responsible, at about this time, for the Mitsubishi Navy Type 10 (1MT1), adopted by that country as a standard carrier-borne torpedo-dropper. This, however, was a triplane, and was first flown (by former Camel-pilot Capt W. L. Jordan) in August 1922. Twenty examples were built with the British Napier Lion engine. More closely resembling the Cuckoo in external form being a three-bay biplane was Smith's Navy Type 13 (B1M), completed in 1923 and very extensively developed and operated by the Japanese. This type, however, was used for duties other than torpedo-dropping when operated from shipboard - a technique pioneered by the historic Sopwith Cuckoo.
Apart from N74, Sopwith themselves built no other Cuckoos, production orders being:
Blackburn N6900-N6929; N6950-N6999; N7150-N7199; N7980-N8079 (production of final batch apparently ended with N8011).
Fairfield N7000-N7099 (production ended with N7049).
Pegler N6900-N6949 (first part of contract taken over by Blackburn - see above). N6930 completed September 1918.
T.1 Torpedo Plane (N74) (200 hp Hispano-Suiza)
Span 46 ft 9 in (14.2 m); length 28 ft 6 in (8.7 m): wing area 566 sq ft (52.6 sq m). Empty weight 1.840 lb (835 kg); maximum weight 3,370 lb (1,529 kg). Maximum speed at 10.000 ft (3,050 m) 100 mph (160 km/h); climb to 6,500 ft (1,980 m) 14.5 min; climb to 10,000 ft (3,050 m) 26 min; range 420 miles (676 km).
Cuckoo Mk.I (Sunbeam Arab)
Span 45 ft 9 in (13.9 m); length 28 ft 6 in (8.7 m). Empty weight 2,199 lb (993 kg); maximum weight 3,883 lb (1,761 kg). Maximum speed at 2,000 ft (610 m) 103.5 mph (166 km/h): maximum speed at 10,000 ft (3.050 m) 98 mph (157 km/h); climb to 2.0(H) ft (610 m) 4 min; climb to 10.000 ft (3.050 m) 31 min: service ceiling 12.100 ft (3.960 m): endurance 4 hr.
N.B. Performance of the Cuckoo Mk.II (Wolseley Viper) with typical ‘extras' was generally poor, and figures would not surpass those given above for the Mk.I. Tests with the Rolls-Royce Falcon, made in 1919, were disappointing (possibly in part because the propeller used was suited to a Bristol Fighter). Maximum weight was increased to 4,350 lb (1.970 kg), which, nevertheless, was still over 2,000 lb (910 kg) less than that of the Cuckoo's successor, the Blackburn Dart (Napier Lion engine). Speed with the Falcon was much the same as given above for the Cuckoo Mk.I.
F.Manson British Bomber Since 1914 (Putnam)
Sopwith T.1 Cuckoo
The single-seat Sopwith T.1 torpedo aircraft was the subject of a discussion between T O M Sopwith and Murray Sueter at the Admiralty at the beginning of October 1916. The fact that Sopwith took with him to the meeting project drawings of the aircraft suggests, though not conclusively, that the idea of a single-seat torpedo-carrying landplane originated at Kingston; it is, however, clear that the Admiralty tentatively suggested that either one or two torpedoes should be carried together with fuel for four hours' flying. Sopwith would have ruled out the two-torpedo capability in a single-engine aircraft small enough to be accommodated in any aircraft carrier likely to be planned in the foreseeable future. This discussion was confirmed in an Admiralty memorandum, dated 9 October, requesting that the Sopwith company should go ahead with the aircraft, expressing the view that some sort of catapult would be made available to assist the heavily-laden aircraft into the air (an innovation that was possibly brainchild of Murray Sueter himself).
With the posting of Commodore Sueter to the Mediterranean in January 1917, the Admiralty's interest in the project was temporarily shelved, but the following month Wg-Cdr Arthur Longmore, who was shown the half-completed T .1 prototype during a visit to Sopwith, suggested that the aircraft should be completed forthwith, and shortly afterwards arranged for a licence, No 6, to be issued for its manufacture. In the event, the prototype was made the subject of an Admiralty contract and the licence was transferred to the B.1 Bomber at Sopwith's suggestion as the two designs were interrelated, and the B.1 would be ready to fly first.
The prototype T .1 , which probably flew first in June 1917, was powered by a 200hp Hispano-Suiza engine and underwent official trials at the Isle of Grain the following month, the performance report being dated 20 July. The three-bay, unstaggered wings spanned 46ft 9in and were made to fold on the plane of the inner pairs of interplane struts; these struts were constructed in halves along their length, the outboard halves being attached to the folding sections o f the wings, and the inboard halves fixed so as to provide rigidity of wing structure. The undercarriage, attached to the fixed inboard wing section, comprised sturdy double-V struts.
Like the first B.1, the tail control cables were enclosed in the rear fuselage for much of their length but, as on the second B.1, the production T.1, named the Cuckoo, featured external tail control cables. The production aircraft were also fitted with a much lengthened tailskid to allow greater ground clearance for the rear of the torpedo, which was slung below the fuselage between the split-axle mainwheels.
The first production order for 100 Cuckoos was placed on 16 August with the Fairfield Shipbuilding & Engineering Company o f Glasgow (Sopwith being fully occupied with production of Camel fighters). Shortly afterwards Sir David Beatty, commanding the Grand Fleet (later Admiral of the Fleet Earl Beatty GCB, OM, GCVO, DSO, 1st Sea Lord) put forward an ambitious plan for 200 Cuckoos to launch a torpedo offensive against the German Fleet in their harbours. Although this was not accepted as a realistic undertaking, an order was nevertheless placed for a further 50 Cuckoos with Pegler & Co Ltd of Doncaster.
Introducing the Cuckoo into production was beset about with problems and delays. The Royal Aircraft Factory was given priority for deliveries of the Hispano-Suiza engine for its S.E.5A fighter, and as a result the heavier 200hp Sunbeam Arab was selected as an alternative; this change occasioned extensive alterations to the Cuckoo's nose structure, and the engine was further delayed by unsatisfactory performance and reliability during development.
Moreover, neither of the original contractors possessed any significant knowledge of aircraft production, and both were very slow to set up their production lines. In February 1918, therefore, 230 further aircraft were ordered from the Blackburn Aeroplane & Motor Company, its first two Cuckoos being completed only two months later. (The first Fairfield-built Cuckoo was not delivered until September 1918, and the first of only 20 Pegler aircraft the next month.)
Fifty Blackburn-built Cuckoos had been completed by the end of August, and production was allowed to continue into 1919, by which time the company had built 162 aircraft in its factory at Sherburn-in-Elmet, Yorkshire. Early production examples were delivered for pilot training at East Fortune, East Lothian, with the Torpedo Aeroplane School, and in October began to equip No 185 Squadron, RAF, also at East Fortune. This Squadron began to embark in HMS Furious on the 19th of that month, but did not take part in any war operations before the Armistice, and was disbanded on 14 April 1919.
In July 1919 Cuckoos joined No 186 Squadron for naval co-operation duties at Gosport, remaining in service until April 1923 (this Squadron being renumbered No 210 on 1 February 1920).
An alternative to the Arab engine had been sought and a number of Cuckoos (all the Fairfield-built aircraft and about nine from the Blackburn production) were fitted with the 275hp Wolseley W.4A Viper, and became known as the Cuckoo Mk II; another aircraft, N7990, was flown experimentally with the 275hp Rolls-Royce Falcon III, but neither this nor the Viper gave any significant improvement in performance.
Once the Arab's early unreliability had been improved, the Cuckoo came to be generally liked by Service pilots, and its replacement by the Blackburn Dart in 1923-24 was more on account of a preference, then being expressed, for two-seat torpedo-bombers than any appreciable performance shortcoming in the Cuckoo.
Type: Single-engine, single-seat, three-bay biplane torpedo-carrier.
Manufacturers: The Sopwith Aviation Co Ltd, Kingston-upon-Thames, Surrey (prototype only); The Blackburn Aeroplane and Motor Co Ltd, Leeds, Yorkshire; Fairfield Shipbuilding and Engineering Co Ltd, Govan, Glasgow; Pegler & Co Ltd, Doncaster.
Powerplant: Prototype. 200hp Hispano Suiza. Production. 200hp Sunbeam Arab; 200hp Wolseley W4.A Viper. Experimental: 275hp Rolls-Royce Falcon III.
Dimensions (Arab engine): Span, 46ft 9in; length. 28ft 6in; height, 10ft 8in; wing area, 566 sq ft.
Weights (Arab engine): Tare, 2,199 lb; all-up (with 18in torpedo), 3,883 lb.
Performance (Arab engine): Max speed, 103.5 mph at 2,000ft; climb to 6,500ft, 15 min 40 sec; service ceiling, 12,100ft; endurance, 4 hr.
Armament: No gun armament nor provision to carry bombs. War load comprised one 18in Mark IX Whitehead torpedo weighing nominal 1,000 lb.
Prototype: One, N74 (Sopwith-built), first flown in June or July 1917.
Production: A total of 350 production Cuckoos was ordered, of which 232 were built: Blackburn. 162 (N6900-N6920, N6950-N6999, N7150-N7199 and N7980-N801I; N8012-NS079 cancelled); Pegler. 20 (N6930-N6949); Fairfield. 50 (N7000-N7049; N7031-N7099 cancelled).
Summary of Service: Sopwith Cuckoos served with No 185 Squadron, RAF, at East Fortune from October 1918 to April 1919; with No 186 Squadron at Gosport from July 1919 to February 1920 (this became No 210 Squadron and continued to fly Cuckoos at Gosport until April 1923).
P.Lewis British Bomber since 1914 (Putnam)
The Sopwith Aviation Company had shown an early interest in the torpedo-carrying aeroplane, and, at the instigation of Commodore Murray F. Sueter in his capacity as Superintendent of Aircraft Construction at the Air Department of the Admiralty, T. O. M. Sopwith discussed with him in October, 1916, the idea of designing a machine with an endurance of four hours and the capacity to transport one or even two torpedoes, taking into account the possibility of catapult launching from ships.
For the period, the assignment was a tough one, but, shortly, the Kingston firm came forth with the Sopwith T.1 design. The layout envisaged was that of a single-engine biplane carrying a pilot only. Authority was given to proceed with construction of a prototype, but with Sueter’s departure from the Air Department in January, 1917, the fire went out of the project as far as official circles were concerned and was not revived until the partly completed airframe was noticed at Kingston during February, 1917, by Wg. Cdr. A. M. Longmore, who managed to press for its completion.
The T.1 N74 was finished on 6th June, 1917, and - although somewhat greater in span - bore the strongest possible resemblance to the B.1. Three-bay folding wings were incorporated, the pilot sat in line with the trailing edges, and separate main undercarriage units enabled the 18 in. 1,000 lb. Mk. IX torpedo to be accommodated in the optimum launching position. The nose housed the 200 h.p. Hispano-Suiza engine under a circular cowling.
Trials with N74 were satisfactorily carried out from the Isle of Grain during July, 1917, and were followed in August by an order for one hundred T.1s to be produced by the Glasgow firm of Fairfield Shipbuilding and Engineering Co. Ltd. The name Cuckoo was applied to the T.1, and modifications were drawn up for the production aircraft. To counter the shortage of Hispano-Suiza engines the 200 h.p. Sunbeam Arab was specified, an enlarged tailskid was fitted to ensure sufficient clearance for the torpedo while on the ground, and minor alterations were made to the tail unit.
The Cuckoo’s passage into production was far from smooth, however. Delays occurred, particularly in developing the Arab into a satisfactory operational power plant, and the entire programme lagged. Eventually, the first squadron was ready to take its place with the Fleet some three weeks before the Armistice, but it was too late then for the Cuckoo to be used operationally. As the Mk.I’s Arab engine was so fractious, a Mk. II version of the Cuckoo was prepared using the 200 h.p. Wolseley W.4A Viper, and October, 1919, saw yet another version - using the 275 h.p. Rolls-Royce Falcon III - under test.
O.Thetford Aircraft of the Royal Air Force since 1918 (Putnam)
Sopwith Cuckoo Mks I and II
One of the earliest landplane torpedo-bombers, the Sopwith Cuckoo first joined the RAF in June 1918, but saw no first-line war service. Cuckoos joined No 185 Squadron in October 1918, No 186 Squadron in July 1919 and finally No 210 Squadron, serving until April 1923. Beginning in May 1918, production totalled 232 aircraft, with serial numbers between N6900 and N8011. Powerplant: Mk I, one 200hp Sunbeam Arab, or a Wolseley Viper in the Mark II as a retrofit. Span, 45ft 9in; length, 28ft 6in. Loaded weight, 3,833lb. Max speed, 100mph at 10,000ft; endurance, 4hr; service ceiling, 12,000ft. Production was undertaken by Blackburn.
O.Thetford British Naval Aircraft since 1912 (Putnam)
The Cuckoo was something of a landmark in British naval aircraft design; it was the first landplane torpedo-carrier capable of operation from a flying-deck. Before the advent of the Cuckoo the torpedo could be carried only by seaplanes which were severely restricted in their capabilities. They suffered not only the weight handicap of their floats, but also the inability to operate from any but the calmest of seas. The idea of using a landplane first came from that staunch advocate of the torpedo, Commodore Murray Sueter, who made the suggestion to Sopwith in October 1916.
The prototype Sopwith T.I (N74), later named Cuckoo, first appeared in June 1917 powered by a 200 hp Hispano-Suiza engine. Contracts finally totaled 300 but in the event only 232 were completed as cancellations followed the Armistice in 1918. Blackburn built 162 (N6900#6929, 6950-6999, 7150-7199 and 7980-8011) and the sub-contractors Pegler (N6930--6949) and Fairfield (N7000-7049) twenty and fifty respectively. The first Cuckoo delivered was Blackburn's N6900 in May 1915. Subsequently, about 20 Cuckoos were converted into Mk.IIs which were fitted with the Wolseley Viper engine in place of the Sunbeam Arab of the production Mk.I. Additionally, from N8005, a larger rudder was introduced.
The Cuckoo first entered service with the Torpedo Aeroplane School at East Fortune, and equipped No.185 Squadron in November 1918. The Armistice intervened before the squadron could prove itself in action.
Cuckoos served only briefly in Argus and with shore-based torpedo squadrons. They were finally withdrawn when NO.210 Squadron disbanded at Gosport in April 1923.
No. 185 Squadron (East Fortune), No.186 Squadron (Gosport) and No.210 Squadron (Gosport). Aircraft-carriers Argus and Furious.
TECHNICAL DATA (CUCKOO MK.I)
Description: single-seat carrier-borne or shore-based torpedo-carrier. Wooden structure, fabric covered.
Manufacturers: Sopwith Aviation Co Ltd. Kingston-on-Thames. Sub-contracted by Blackburn Aeroplane & Motor Co Ltd. Leeds; Fairfield Shipbuilding & Engineering Co Ltd. Glasgow: Pegler & Co Ltd, Doncaster.
Power Plant: One 200 hp Sunbeam Arab.
Dimensions: Span, 46ft 9 in. Length, 28 ft 6 in. Height, 10ft 8 in. Wing area, 566 sq ft.
Weights: Empty, 2.199 lb. Loaded, 3.883 lb.
Performance: Maximum speed, 103 1/2 mph at 2.000 ft; 98 mph at 10,000 ft. Climb, 4 min to 2.000 ft; 31 min to 10.000 ft. Endurance, 4 hr. Service ceiling, 12.100 ft.
Armament: One 18 in Mk.IX torpedo carried below the fuselage.
H.King Armament of British Aircraft (Putnam)
Cuckoo. The Cuckoo has the distinction of being the first torpedo-dropping aircraft designed to operate with a wheeled undercarriage from the deck of a ship. It was closely related to the B.1 Bomber and likewise dated from 1917. production being initiated by the Blackburn company in 1918. Distinctive features associated with the carrying of the torpedo (Mk.IX of nominal 1.000-lb weight) were the three-bay wings and split undercarriage. The torpedo gear was a Blackburn responsibility and led to developments by that company already described. The torpedo was heated either by warm air from long exhaust tail-pipes, ducted to the region of the buoyancy chamber as on the later Blackburn Swift and Dart, or by electrically heated mats. There appear to have been at least two types of torpedo installation. A photograph shows the torpedo slung by a cable which is visible between the V-struts of the undercarriage. A crutch is seen roughly in line with the wing trailing edge and there is a massive pylon structure associated with the nose of the torpedo. This appears to have the dual function of steadying the missile and of acting as a pistol stop, but in most other known photographs of Cuckoos it is absent. The same photograph shows the torpedo depth-setting gear, located to the left of the pilot's wicker seat.
Under the Blackburn heading, mention is made of the importance attached during the early days of torpedoplane development to a silent approach to the target, and it is known that silencers were fitted to some Cuckoos. During 1920 it was notified that there was a diving hazard since modifications had been made and the Viper engine installed: the Cuckoo was to be dived only with tanks half empty.
The most notable design feature of the Cuckoo to be influenced by armament was the split-axle undercarriage which allowed the torpedo to be carried and dropped. The following is a verbatim official description:
'The Chassis consists of two Undercarriages which are identical. Each Undercarriage is formed of steel tubes welded and pinned together, and consists of two portions. One portion, which is in the shape of a V, is placed parallel to the fuselage, the End Lugs being bolted to the front and rear Spars of the Centre Section Lower Plane. The other portion has one End Lug bolted to the Bottom Longeron, and is bent so as to form the Axle for one wheel, the other end resting in the apex of the V. Shock Absorbers are formed by 28 feet of 15 mms. diam elastic, which is given ten complete turns round the Axle and the apex of the V. The Steel Struts arc stream-lined by means of wood fairing attached by metal clips, the whole being wrapped with fabric and then doped.'
A.Jackson Blackburn Aircraft since 1909 (Putnam)
Sopwith T.1 Cuckoo
This was a single-seat, three-bay, folding-wing torpedo-carrying biplane of wood and fabric construction designed by the Sopwith Aviation Co Ltd in 1916 and powered by one 200 hp Hispano-Suiza water-cooled engine. In February 1918 the entire production was sub-contracted to three outside firms, including the Blackburn Aeroplane and Motor Co Ltd who were made responsible for developing suitable gear for carrying a standard 18-in Whitehead torpedo. As Hispano engines were all required for S.E.5As, the prototype Cuckoo, N74, was re-engined with a 200 hp Sunbeam Arab and delivered to Blackburns in March 1918 as a sample aircraft. It was then stripped and rebuilt with a divided undercarriage as a prelude to the commencement of large-scale production at Sherburn-in-Elmet, where 132 machines were built. Later versions had an enlarged rudder, first fitted to N8005 and flown from Brough to Martlesham for test on 23 June 1920.
The prototype, N74, and the first machine of the second production batch, N6950, were flown to the Great Yarmouth Air Station in May 1918 en route to the Isle of Grain for performance trials, but production aircraft were test flown at Sherburn-in-Elmet by R. W. Kenworthy and ferried to East Fortune, 80 being completed by August 1918. They equipped the Torpedo Aeroplane School, East Fortune, and Nos. 186 and 210 Squadrons, Gosport, and the first British aircraft carrier Argus embarked a full squadron on 19 October 1918.
At least eight Blackburn-built Cuckoos, N7151-N7155, N7192, N7193 and N7999, were fitted with the 200 hp Wolseley Viper engine. N7192 and N7193, used for tests at the Isle of Grain 1919-20, were joined on 11 September 1919 by N7990 which had been fitted with a 275 hp Rolls-Royce Falcon engine, this machine going to Gosport on 6 December. The Cuckoo was declared obsolete in April 1923, but six of the Viper-powered machines were taken to Japan in 1921 by the British Air Mission to the Imperial Japanese Navy.
SPECIFICATION AND DATA
Manufacturers: The Blackburn Aeroplane and Motor Co Ltd, Olympia Works, Roundhay Road, Leeds, and Sherburn-in-Elmet, Yorks.
Designers: The Sopwith Aviation Co Ltd, Canbury Park Road, Kingston-on-Thames, Surrey
One 200 hp Sunbeam Arab
One 200 hp Wolseley Viper
One 275 hp Rolls-Royce Falcon
Span 46 ft 9 in Length 28 ft 6 in
Height 10 ft 8 in Wing area 566 sq ft
Weights: Tare weight 2,199 lb All-up weight 3,883 lb
Maximum speed 103 mph Climb to 2,000 ft 4 min
Service ceiling 12,100 ft Endurance 4 hr
Two hundred and thirty aircraft ordered February 1918 under Contract A.S.3298 18 and comprising N6900-N6929 (quantity 30); N6950-N6999 (50*); N7150-N7199 (50); N7980-N8079 (100). Production is said to have terminated at N8011, reducing the total built to 132.
* Production rate: April 1918 (2aircraft), May (8), June (12), July (15), August (13).
Jane's All The World Aircraft 1919
THE SOPWITH CUCKOO
Produced in 1917. A very successful example of the British torpedo carrying machine.
Type of machine Tractor Biplane.
Name or type No. of machine "Cuckoo."
Purpose for which Intended Torpedo carrying.
Span 46 ft. 9 In.
Gap, maximum and minimum 6 ft.
Overall length 28 ft. 6 In.
Maximum height 11 ft.
Chord 6 ft. 3 In.
Span of tail 11 ft. 9 in.
Total area of empennage 35 1/2 sq. ft.
Area of elevators 18 1/2 sq. ft.
Area of rudder 8 sq. ft.
Area of fin 5.6 sq. ft.
Area of each aileron and total area 20 sq. ft.
Engine type and h.p. 200 h.p. Hispano-Suiza (Experimental).
220 h.p. Sunbeam Arab (Production).
Weight of machine empty 2140 lbs.
Load per sq. ft. 6.7 lbs.
Weight per h.p. 17.9 lbs.
Tank capacity In hours 4 hours at full speed.
Tank capacity in gallons 56 gallons.
Speed low down 90 kts.
Speed at 10.000 feet 85 kts.
To 10.000 foot 26 minutes.
Total weight of machine loaded 3880 lbs.
Flight, February 6, 1919.
THE SOPWITH MACHINES
The Sopwith "Cuckoo." (June 6, 1917)
There is a genuine humour in all the Sopwith type-names, and in none more so than in the "Cuckoo," which was encouraged to lay a very splendid egg in any German nest that could be located above the surface of the sea. The egg in this case was a special 18-in. torpedo, which the "Cuckoo" carried strung underneath her fuselage and between the wheels of the landing carriage, which, it will be observed, consists of two independent wheels, each separately mounted, and not, as is usual, united by a common or articulated axle.
This machine was built at the request of Commander Murray Sueter, R.N., and was of considerable dimensions. The treble-bay arrangement of struts will be noted from the photograph, as also the installation of the 200 h.p. Hispano-Suiza geared engine, with the elliptical radiator surrounding the propeller shaft.