H.King Sopwith Aircraft 1912-1920 (Putnam)
The fact that the Rhino, or Sopwith 2B.2, was a triplane tended to screen from view, and thus from full appreciation, aspects of design and equipment that merit careful study, and command far more respect than derision. Certainly it was a worthier Sopwith product than - and in some ways very sharply in contrast with - that other large single-engined multi-seat triplane the L.R.T.Tr. of 1916, a fact that must be attributed at least in part to its later design, for work on this was not in hand until the latter part of 1917. The Rhino was, in any case, produced to meet wholly different requirements (being a bomber, and not a fighter); and even though it shared the distinction of having a water-cooled engine, the unit concerned was of the tall-and-slender B.H.P. six-in-line type, as fitted in the comparable D.H.9. As triplanes go (or went) the Rhino was a notable example.
To the form of the 230 hp B.H.P. engine must be attributed in part the very deep fuselage, though another influential factor was the internal bomb-stowage beneath the pilot's seat. The matter of bomb-stowage is one that renders this Sopwith private-venture bomber (for its construction was authorised under Licence No.14) an especially valuable object-lesson when compared with the D.H.9 - a bomber strongly stamped by heredity, expediency and official dictation. True, the D.H.9 itself possessed internal bomb-stowage; but this was a secondary, as distinct from a primary, feature, and was forward of, and not below, the pilot.
The first of the two Rhinos built (X7) was air-tested at Brooklands late in October 1917, was delivered to Martlesham Heath for official trials on 4 January, 1918, and was followed to Brooklands by a second specimen (X8) in February 1918. The differences between these two machines were interesting (as will be recounted) though fairly minor ones, whereas those which distinguished the Rhino from the L.R.T.Tr. were fundamental. First, whereas the big fighter had been a three-bay 'three-winger' with surfaces of high aspect ratio, and further characterised by a huge landing gear, the new bomber was not even of two-bay, but of single-bay, form, with low-aspect wings and a landing gear that looked minute. Lacking on the Rhino, of course, was the gun-nacelle perched on the topmost wing, though height was emphasised by the very broad centre section which, notwithstanding the widely splayed struts supporting it, overhung those struts by a noticeable margin. Chord of the top wing was constant, but at the roots of the middle and bottom wings were trailing-edge cut-outs, while between the spars of the middle wing were oblong apertures to improve the pilot's view (for his seat was above and a little behind). More prominent still were the large horn-balances for the ailerons on all three wings and the strut between the middle and bottom ailerons on each side (the middle and upper ailerons being connected by cable only). Later the horn-balanced ailerons of X7 were replaced by plain surfaces, as fitted also on X8: and when plain ailerons were fitted the mainplane tips were reshaped.
That the tail surfaces resembled those of the Bulldog is not surprising, for the two aircraft types were more or less contemporary; thus, taken in sum, the foregoing facts may help to emphasise that - its physical appearance and unenviable reputation notwithstanding - the Rhino was a relatively late-comer to the Sopwith menage or menagerie, and by no means as quaint or 'old-fashioned' as sometimes suggested. This point is further stressed by the recognition that almost the last of the military Sopwiths (the Snark single-seat fighter and the Cobham twin-engined bomber) were themselves triplanes. Nor must we forget here Herbert Smith's Mitsubishi triplane for the Japanese Navy (1922).
A particular point was made early in this account of the influence exercised by the fitting of a 230 hp B.H.P. engine - a powerplant chosen for large-scale production (especially by the Siddeley-Deasy Car Co) and precursor of the Siddeley Puma as installed in the Cobham, the Sopwith 'twin' just named. The cooling of the Rhino's engine was achieved in part by admitting air through a deep nose-intake, into which the front end of the crankcase projected, but more particularly by two low-set radiators in the sides of the cowling and flanking the bottom half of the crankcase, below the engine's eight supporting 'feet'. The radiators were of the general type used on production Dolphins: that is, each block was fronted by an adjustable flap to regulate the exposure of cooling surface. By reason of the cowling shape, and because each of the two cylinder blocks of the B.H.P engine (for two it had, even though it was a 'six-in-line') comprised the cylinder heads, water jackets, valve passages and inlet manifold for three cylinders, these cylinder blocks were largely exposed. This necessitated provision of a fairing at the forward end, though even so, the cast-on legend '230 BHP' was clearly visible on the front cylinder block. Though changes in coolant, fuel and oil systems were made in the course of development none appears to have been basic; so attention may now be transferred to armament.
Although - as on the 1 1/2 Strutter - bomb-sighting presented major problems, the stowage of the bombs themselves was exemplary. As already noted, this stowage was beneath the pilot's seat; but, although this situation was favourable to c.g. location, it inhibited - jointly with a petrol tank - the fitting of a Negative Lens sight for the pilot's use (as, for example, on the D.H.9 and comparable types) while the employment of an external sight, of C.F.S. or other pattern, was rendered difficult, if not impossible, by the fuselage shape, with its tumblehome decking. The bombs - four 112 lb or nine 50 lb or twenty 20 lb - were in a cellular 'crate' which was winched into place, complete with closely associated bomb-release gear, by a system of pulleys attached to the middle-wing spar, or spars, inside the fuselage.
Between Rhinos X7 and X8 (Nos.1 and 2 as they were otherwise known) the differences were largely in respect of gun-armament. Whereas on X7 the pilot's Vickers gun was mounted on the fuselage centre line immediately ahead of the cockpit (with the feed block faired over, the fairing also affording some protection to the pilot) on X8 the gun was wholly forward of the pilot's normal-type windscreen - a fitting absent on X7 - and there was a fairing ahead of the feed block.
Rear armament on X7 was a Lewis gun on a rocking-pillar mounting at the rear of the second cockpit (as on the Bulldog) but X8 had a redesigned gunner's position, with a Scarff ring-mounting fitted on the top longerons, the gunner thus having a deep protective coaming ahead of him. Provision for a downward-firing 'belly gun' has been mentioned in connection with the Rhino, and would not seem incompatible, for such an installation was not unknown on the D.H.9.
Certainly, X8 was tested at Martlesham Heath during February and March 1918 not only with a revised armament installation and plain ailerons but with a Lang 4020 propeller instead of other patterns tried. This being so - and also having regard to the Sopwith type-number used jointly with the Rhino's name to head this present chapter - it may be remarked that a magnifying glass proclaims the following stamping on the propeller hub seen in the Sopwith 'nose close-up’ picture S.182: 'DRG. L.4020. 230 H.P. B.H.P. SOPWITH. 2.B.2.'
Its unimpressive showing and seemingly derisory name notwithstanding, the Rhino, if developed with a later engine (see under 'Cobham') might have made a distinctly useful addition to the final rhino-like bombing 'charge' by the RAF. And should this prospect, jointly with the pictures shown, occasion shock, then one would only remark that this merely shows how deceptive (as well as instructive) photographs can be; for the Rhino was little bigger than a Hawker Hart!
Rhino (230 hp B.H.P.)
Span 41 ft (12.5 m)*; length 30 ft 3 in (9.2 m); height 10 ft (3 m); wing area 612 sq ft (56.8 sq m). Empty weight 2,185 lb (990 kg); maximum weight 3,590 lb (1,628 kg). Maximum speed at 10,000 ft (3,050 m) 103 mph (166 km/h); climb to 10,000 ft (3,050 m) 24 min 50 sec; service ceiling 12,000 ft (3,658 m); endurance 3 3/4 hr.
* Although the span would clearly differ according to the type of ailerons fitted, the generally quoted figure of 33 ft (10 m) is apparently incorrect whatever allowances are made.
N.B. Rhino X8 without bombs and weighing 3,061 lb (1,388 kg) is known to have reached a service ceiling of 14,500 ft (4,420 m). In this instance the fuel and oil load was 465 lb (211 kg), though in another case, with a military load of 538 lb (244 kg) the fuel and oil load was 507 lb (230 kg).
F.Manson British Bomber Since 1914 (Putnam)
Sopwith 2B.2 Rhino
The Sopwith Rhino two-seat triplane bomber was a private venture, not intended to approximate to any official requirement, and therefore subject of a special licence (No 14) for the manufacture of two prototypes, X7 and X8. Designed during the late summer of 1917, the first aircraft was flown at Brooklands in October, powered by a 230hp BHP six-cylinder in-line water-cooled engine. The dominant feature, apart from the triplane wings, was the exceptionally deep fuselage, necessitated by the internal bomb bay beneath the pilot's cockpit, the bombs being loaded into a self-contained structure which was winched into the aircraft's bomb bay. The choice of the BHP engine, which was fully cowled, also resulted in a deep nose profile. The second Rhino was flown around the end of the year.
Although the engine was cooled by an orthodox water-circulation system, with radiators on the sides of the nose (each with an adjustable ramp shutter), a small frontal air intake was incorporated above the propeller shaft to provide additional cooling of the tandem cylinder blocks and exhaust manifold.
The single-bay wings, of generous area, were all fitted with ailerons and were rigged with slight stagger. The ailerons on both prototypes were originally horn-balanced, extending beyond the wing structure, but were later shortened to blend with the profile of the wing tips. The lower pairs of ailerons were interconnected by faired struts, and the upper pairs by cables.
Front gun armament comprised a single synchronized Vickers gun above the nose decking, and rear protection was afforded by a Lewis gun on the rear cockpit; on X7 the rear gun was pillar-mounted, and on X8 a Scarff ring was provided. No bomb sight could be titled, and downward view for the pilot (situated directly below the upper wing) was assisted by cutout panels in the roots of the centre and lower wings.
The undercarriage comprised plain steel tubular V-struts with bungee-bound cross-axle, the whole wheel structure giving an impression of being understressed.
Both Rhinos were officially tested at Martlesham Heath in February and March 1918, but returned somewhat pedestrian performance figures with and without bomb load, and the aircraft was not accepted for production.
Type: Single-engine, two-seat, single-bay triplane bomber
Manufacturer: The Sopwith Aviation Co Lid, Kingston-upon-Thames, Surrey.
Powerplant: One 230hp Beardmore-Halford-Pullinger (BHP) six-cylinder, water-cooled, in-line engine driving two-blade propeller
Dimensions: (1) Span, 41ft; length, 30ft 3in; height, 10ft 11 in; wing area, 612 sq ft.
Weights: (2) Tare, 2,184 lb; all-up (with four 112 lb bombs), 3,590 lb.
Performance (with four 112 lb bombs) : Max speed, 114 mph at sea level, 103 mph at 10,000ft; climb to 10,000ft, 24 min 50 sec; service ceiling, 12,000ft; endurance, 3 3/4 hr.
Armament: One synchronized 0.303in Vickers machine gun located centrally on nose decking, and one Lewis gun on rear cockpit (with Scarff ring on second aircraft); bomb load of up to four 112 lb bombs or equivalent weight of smaller bombs carried in a detachable structure winched into internal bomb bay.
Prototypes: Two, X7 and X8, built under Licence No 14. X7 first flown in October 1917. No production.
(1) These figures are suspect, and a span of 33ft (sometimes quoted) is also believed to be incorrect; unfortunately no copies of the original Sopwith drawings appear to have survived, and Sopwith records themselves are inconsistent.
(2) Quoted from Martlesham Reports M.167A and B, dated February and March 1918.
P.Lewis British Bomber since 1914 (Putnam)
The Sopwith 2.B.2 Rhino was a Kingston prototype of 1917 intended as a two-seat day bomber. A return was made to the triplane formula in the design which consisted of equal-span, single-bay wings mounted on a fuselage, the fore portion of which was particularly deep in order to form an internal bomb-bay. X8 was the sole example constructed and carried the 230 h.p. B.H.P. engine in its nose, flanked by low-set radiators. The ponderous and ungainly Rhino relied on the ground on a tiny undercarriage unit which further contributed to the machine’s unlovely appearance.
One redeeming and laudatory feature, however, in an otherwise uninspired design lay in the Rhino’s self-contained bomb-pack, which was calculated to reduce rearming time between raids. The pilot’s cockpit was situated immediately above the bomb-bay, and the pack was lifted into place by hoisting gear fitted inside his cockpit. The pack contained alternative loads of four 112 lb., nine 50 lb. or twenty 20 lb. bombs; armament for the pilot consisted of a single forwards-firing Vickers, while that of the observer to his rear was a Lewis gun on a pillar mounting, later exchanged for a Scarff ring. In the course of its existence an alteration was made to the ailerons of the Rhino. Carried on all three planes, the first surfaces were horn-balanced, but these were later superseded by the same number in plain form, still retaining the upper wire and lower strut connections between them.
The prefix of the X8 serial number of the Rhino, granted under Licence No. 14, indicated that the machine was entirely a Private Venture but which was considered as a design project showing sufficient promise for the parent firm to be granted permission to proceed to construct a prototype at a time when materials and labour were at a premium.
Tests performed with the Rhino during February and March, 1918, failed to promote the machine’s chances of adoption, and the design was ultimately abandoned.
H.King Armament of British Aircraft (Putnam)
Rhino. A counterpart of the D.H.9, the Rhino single-engined bomber of 1917 had internal bomb stowage. This was located under the pilot's seat, and the bombs - four 112-lb or nine 50-lb or twenty 20-lb - were winched into place complete with release gear. The bombs being so placed, it was not possible to provide the pilot with a Negative Lens sight, as on the D.H.9. Between Rhinos Nos. 1 and 2, there were interesting variations in gun armament. On the first machine the pilot's Vickers gun was mounted on the centre line immediately ahead of the cockpit, with the feed block faired over, the fairing also affording some protection to the pilot. The gun retained its land-service handles. On the second example the gun was similarly mounted and was wholly forward of the windscreen (lacking on the first machine). There was a fairing ahead of the feed block. Rear armament on the first Rhino was a Lewis gun on a rocking pillar mourning at the rear of the cockpit, as on the Bulldog. The second machine had a redesigned cockpit with a Scarff ring-mounting on the top longerons, the gunner thus having a considerable depth of protective coaming ahead of him.