F.Manson British Bomber Since 1914 (Putnam)
Sopwith Admiralty Type 860
Experience with the early torpedo-carrying seaplanes had demonstrated to two of the three main Admiralty contractors that the smaller Salmson and Sunbeam engines were inadequate to enable torpedo-carriers to lift off the water when carrying full fuel load. After the unsuccessful attempts by the Sopwith Special No 170 to lift a torpedo into the air in August 1914, its manufacturers decided to produce a smaller aircraft, powered by the 225hp Sunbeam (later named the Mohawk). In the meantime Sopwith persevered with another of its seaplanes, No 138 (also powered by a 200hp Canton Unne engine), and on 29 August 1914, flown by Longmore, this machine succeeded in lifting and launching an 810 lb torpedo at Calshot.
Continuing frustration with the recalcitrant Canton Unne engine encouraged Sopwith to adopt the 225hp Sunbeam, at the time the most powerful engine available to the RNAS; no prototype of the new aircraft was built as such, a total of 22 examples of this aircraft being ordered during the autumn of 1914. All but four were completed between December that year and early in 1915. The first ten examples were numbered 851-860, and were referred to as Admiralty Type 860s (although confusion was compounded when the RNAS equipment list erroneously referred to them as Type 157s, suggesting that they were a production batch of Sopwith Type Cs). The first flight by a Type 860 with a torpedo was made by Victor Mahl, a Sopwith pilot, at Calshot on 27 January 1915.
The big Sunbeam engine, driving either a two- or four-blade propeller, featured a frontal radiator and a prominent stack of twelve vertical exhaust pipes extending upwards immediately forward of the upper wing. The single-step main pontoon floats were attached by long struts to the lower fuselage longerons, the 14in torpedo being carried on crutches at the centre of the cross-bars between the floats (when the aircraft was at rest on the water the torpedo was partly submerged). A single tail float was provided, as well as stabilizing wingtip floats.
Folding wings of at least three alternative designs appeared on the production aircraft; the original three-bay wings of equal span were fitted with double-acting ailerons on upper and lower surfaces. Some aircraft were fitted with two-bay wings of unequal span with ailerons on the upper wing only; the outboard upper wing extensions were wire-braced with kingposts, but some aircraft featured outwardly raked struts in place of interplane wire bracing. At an early stage in production the fin, originally a small triangular structure, was enlarged to incorporate a curved leading edge. Further redesign resulted in a rectangular fin being fitted.
The Sopwith Type 860 was flown from the rear cockpit, a surprising feature of this aircraft having regard for its torpedo-dropping role. The observer's cockpit was located beneath a large aperture in the upper wing centresection, suggesting that it was intended to mount an upward firing Lewis gun though no evidence has been found to suggest that this was ever fitted, despite being called for in the original Admiralty purchase order.
Production Type 860s are said to have been test flown from the Solent and subsequently served briefly with the RNAS at Grain, though without much distinction. The greater experience gained by Short Bros in numerous aspects of naval seaplane design inclined the Admiralty to favour that company's parallel project, the Type 184, which was to become one of the outstanding British seaplane bombers of the First World War. Certainly the Sopwith aircraft never launched a torpedo in anger.
Type: Single-engine, two-seat, two- or three-bay biplane, torpedo-carrying twin-float seaplane.
Manufacturer: The Sopwith Aviation Co Ltd, Kingston-upon-Thames, Surrey.
Powerplant: One 225hp Sunbeam Mohawk twelve-cylinder, water-cooled, in-line engine driving a two- or four-blade propeller.
Dimensions, Weights and Performance: No records traced.
Armament: Provision to carry one 810 lb 14in Whitehead torpedo. Provision may have been made to mount a Lewis gun above the observer's cockpit.
Prototypes and Production: Total of 22 aircraft ordered, Nos 851 -860 and 927-938, but four (Nos 833, 834, 836 and 837) not completed. No 851, possibly regarded as the prototype, is believed to have first flown in December 1914.
Summary of Service: At least three Sopwith Type 860s were flown at the RNAS Station, Isle of Grain, in 1915, and two may have been present during the Dardanelles campaign that year.
H.King Sopwith Aircraft 1912-1920 (Putnam)
The primary points to note concerning this big production-type torpedo-dropping float plane of late 1914 are the following:
(1) It bore a near relationship to the experimental Type C, and, especially when provided (as it was in some instances) with strut-braced overhang on the top wings, resembled that aircraft very closely.
(2) It was more or less contemporary with the Short Admiralty Type 184 and the Wight Admiralty Type 840, and was intended to meet similar requirements.
(3) Like the Short and Wight types just named, it was designed specifically for the new 225 hp Sunbeam engine - a powerplant so important in the development of British Naval aircraft that the Short Type 184, upon which it was decided to standardise (especially after the torpedo-dropping requirement became secondary, following initial successes by Shorts during the Dardanelles campaign of 1915) was familiarly known as the 'Short 225’.
(4) An installation of a Sunbeam engine, though one of lower output (150 hp) was made in the Admiralty Type 806 Gun Bus, as noted in a preceding chapter.
(5) The wings - initially at least - were arranged to fold.
The earliest Service numbers known to have been allocated to Type 860 seaplanes were 851 -860 (ten aircraft), and of these No.854 was being tested, by Victor Mahl, over the Solent at the beginning of 1915. Twelve more (Nos.927- 938) were also ordered, and - except for numbers 933, 934, 936 and 937 - duly delivered, thus giving the RNAS a known total of eighteen Type 860 seaplanes - all Sopwith-built. Beyond the facts that the type was used in the Dardanelles and was flown from the Isle of Grain, however, little is known of its Service history. Thus it is worth noting that - in particular for Short Type 184s - demands for 225 hp Sunbeam engines (later named Mohawk) must have been heavy; and here too it is especially relevant to note the following recollection by Rear-Admiral Murray Sueter, who, as Captain Sueter, had been Director of the Air Department of the Admiralty before the 1914 war. This officer said:
'After the war broke out, we required all Mr. Sopwith's efforts and those of his factory to produce high performance machines, then just beginning to show some promise. But Hyde-Thomson and myself [the name Hyde-Thomson will be remembered from the chapter on the Type C] were quite determined to succeed with a torpedo machine. So I sent for that fine pioneer seaplane constructor, the late Mr. Horace Short. When I explained my requirements to him and the great weight that had to be lifted with a 225-h.p. Sunbeam engine ...'
But the successful outcome of that meeting - the historic 'Short 225' - is well enough known; and having now re-emphasised the Navy's special interest in Sunbeam engines we may proceed with our study of the Sopwith Type 860 torpedo-dropping seaplane, which appears to have continued in service (in however lowly a role) until 1916.
Here, once again, we are involved with the Sunbeam story, for one of the most arresting visible features of this big Sopwith was the immense solid-looking block, towering not only above the engine but the top wing also. This was not, in fact, the radiator - in the familiar Short-style location - but the exhaust manifold. The Sopwith's radiator was positioned in the nose, just behind the propeller (sometimes two-bladed, sometimes four-bladed).
Although existing photographs show clearly that Nos.851 and 859 had wings of unequal span - the strut-braced upper-wing extensions having additional top-surface bracing from kingposts - and although these particular machines were characterised also by the elegant 'Sopwith' tail surfaces (much as on the production Tabloids and Folder Seaplane) No.928 or 938, here depicted on the water, had wings of equal span and a much larger fin, no longer triangular, but curved.
In the Sopwith tradition by this time established, the two main floats were sprung, and like the tail float (seen well-nigh submerged) were carried on struts of great height. Being attached to the fuselage, and not to the wings, the main alighting gear, in the form depicted, would appear to have been less favourable to torpedo dropping than that of the Type C; though the point is by no means conclusive, having regard to the astonishingly low-slung torpedo stowage on the Short Type 184. Aiming the torpedo must, in any case, have been a truly hit-or-miss business, for the pilot occupied the rear cockpit. Defensive armament could well have been intended or improvised, jointly with the top-wing aperture over the front cockpit (especially so as Owen Thetford's Putnam book British Naval Aircraft since 1912 records that the Type 860 was used on patrols in home waters during 1915 and 1916); but as with many other points concerning this Sopwith type - there is no certainty in this regard. More positively it can be recorded that Nos.851 and 852 were not written off (in the clerical sense) until March 1917, and that Nos.931 and 932 were at the same time reduced to spares in the Supermarine works (successor to Pemberton Billing) at Woolston, Southampton.
The name Pemberton Billing having now been mentioned twice (formerly in the context of the Type 137) it is interesting - though not necessarily significant that those well-known Sopwith characters Howard Pixton and Victor Mahl were both present at early tests of the P.B.9 - the "seven day 'bus' - concerning which aeroplane some mysteries persist. Mahl, in fact, made the first flight shortly whereafter the little single-seater was seen at Brooklands.
O.Thetford British Naval Aircraft since 1912 (Putnam)
SOPWITH ADMIRALTY TYPE 860 SEAPLANE
Used by the RNAS on patrols in home waters during 1915 and 1916, the Type 860 was designed to carry an 810 lb 14 in torpedo. Twenty-four were delivered to the RNAS, numbered 851 to 860, 880, 897 to 899 and 927 to 938. The engine was a 225 hp Sunbeam or 220 hp Canton-Unne.
H.King Armament of British Aircraft (Putnam)
Type 860. Like its contemporary, the Short Type 184, this tractor seaplane of 1915 was designed to carry a 14-in torpedo. The crutches were attached to the two cross-ties joining the floats. There was a cut-out in the top centre-section, but whether this was associated with a gun mounting has not been established.
M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing