H.King Sopwith Aircraft 1912-1920 (Putnam)
B.1 and Derivatives
French interest and influence were both apparent by early 1917 in a large single-engined single-seat bomber, intended to succeed the special version of the 1 1/2 Strutter which had been characterised (as already described) by internal bomb stowage behind the single seat. That there should accordingly be a distinct relationship between the wholly new B.1 Bomber (as the type was generally named) and the T.1 Cuckoo torpedo-carrier was not unexpected the bomber requiring its large wing area to lift a relatively small load to high altitude, with long range and security as prime considerations, and the torpedo-carrier needing it to lift its heavier war-load from an aircraft-carrier's deck and drop it from very low level. (A postwar attempt to combine both the high-level bombing and the low-level torpedo-delivery capabilities in a single type-exemplified by the Hawker Harrier of 1927 proved a notable failure, even though deck-operation was not a requirement).
For the new Sopwith single-seat bomber (or Bomber) the type-designations B.1 and B.2 were both utilised, and as far as possible the significance of these will later be explained. First, however, it must be noted that interest in a two-seat carrier-borne Government-adapted version called the P.V. N50 Grain Griffin was such that this quite widely differing type came to assume a distinct importance and identity of its own; and of this type likewise more later.
The first Sopwith B.1 Bomber was built under Licence No.6, was initially test-flown at Brooklands early in April 1917 and - such was the future contemplated for the type by both the French and British Governments - that it was ferried to Dunkirk for a joint assessment as early as mid-May. By that time the aircraft had been officially declared to be tail-heavy with full bomb load and nose-heavy when light, in spite of full tailplane adjustment. Further, it was 'tiring to fly’; yet controllability in the air and on the ground were reckoned 'very good’.
In general the airframe was similar to that of the first Cuckoo, the most notable differences being in the cockpit arrangement and landing gear, for in both cases the engine was a 200 hp Hispano-Suiza with a circular frontal radiator. This means that the equal-span non-folding wings were of two-bay construction, with cable-connected ailerons on all four panels, though the pilot sat in the middle of the four 'centre-section' struts (quotation-marks are explained by the top wing being in a single piece) whence he had a good forward and downward view for target-sighting and bomb-aiming; and the landing gear was of the familiar Sopwith V-type. Thus, instead of being of the new and advanced wholly divided form as on the Cuckoo, the gear was 'split' only in the sense that each wheel was on a half-axle of steel tube, this assembly moving vertically in guides against the tension of coiled rubber cord at the apex of each of the two 'Vs'. The tail unit appeared to be identical with that of the Cuckoo.
That the foregoing description applies to a type called B.1 is sure and that the B.1 designation is used in Sopwith captions to photographs illustrating two forms of a generally similar aircraft (the later one numbered B1496, and otherwise distinguished by external elevator-cables running from rocking-levers near the front of the bomb bay) is equally sure. No less certain, however, is that the designation B.2 was also applied to the second form mentioned B1496 - and neither letter/number combination can be identified with or linked with the Grain Griffin two-seater.
Clearly the B.1/B.2 Bomber (as it may here be conveniently styled) was something quite new in its class, especially because of its relatively large size - roughly that of a Bristol Fighter - its single seat and its armament, for in this last regard the interest lay not only in the bomb stowage and in the bombs themselves, but in respect of gunnery also.
The bomb bay was close behind the cockpit, its location being proclaimed by access panels that are clearly seen in photographs. Though the bay appears to have had provision for nine British 50 lb bombs, carried nose-up as in the D.H.9, bombs of French type were provided for, and -as witness an official report dated April 1917 - were actually carried as a test-load. This last-mentioned load was contemporarily described as comprising twenty 28 lb 'Analyte' bombs, whereas a later report (May 1918) - quoting a bomb load of 560 lb without reference to the bombs themselves - doubtless involved the same projectile load. That the rearranged elevator controls earlier mentioned could well have had some connection with bomb-stowage may have been gathered from the remark, earlier in this present account, that the external rocking-levers were 'near the front of the bomb bay.’
Two distinct types of bomb must now be considered in the order of their mention: thus, first, the 50 lb British pattern, or 'Bomb, H.E.R.L., 50 lb". Designed primarily for vertical (nose-up) stowage, this amatol-filled bomb actually weighed, when fused, 49 1/8 lb. Its length was 28 3/4 in well within the depth of the Sopwith bomber's fuselage-and its diameter was 7 in.
The second type of bomb was not only French, but was entirely different in conception. Alternatively (and apparently more correctly) called the anilite bomb - or liquid-anilite bomb - it required very careful handling on account of its sensitivity, for the explosive content was (according to one account) 80 per cent nitrogen peroxide and 20 percent hydrocarbon, the mixing of these two substances taking place after the bomb had been released. Professor A. M. Low, who may well have possessed first-hand knowledge by virtue of his wartime activities, described this 'ingenious French bomb' (or one form of it) as follows: 'The explosive was actually manufactured during the flight of the bomb. The bomb had two separate compartments, one containing petrol and the other liquid nitric oxide. Pressure of the air on a small propeller in the bomb opened the two compartments immediately the missile was released and the two liquids flowed together. Nitric oxide is a violent oxidizing agent and the mixture formed an exceedingly sensitive explosive which detonated as the bomb struck. No detonator was required, the impact itself being sufficient.'
Certainly, at least one official British list of bombs includes the entries '10 kg anilite' and '20 kg experimental model’ - the latter, by implication, likewise connoting ‘anilite', while another British document alludes to tests with an anilite bomb of 'about 20 kg' weight. This last figure - representing about 44 lb - would approximate to the 'actual' weight of the 'Bomb, H.E.R.L., 50 lb', already quoted at 49 1/8 lb.
But the armament interest of the new type of Sopwith bomber extended also to gunnery; for though it originally had no gun at all, the first example, as service-tested in bombing raids together with D.H.4s of the RNAS Fifth Wing at Dunkirk, was fitted with a synchronised Lewis gun on the centre line of the fuselage ahead of the cockpit. The type of synchronising gear employed is not known, though for the Lewis gun in particular the French Alkan system was devised in 1916.
Finally, a brief note on the closely-related two-seat reconnaissance aircraft, the P.V. N50 Grain Griffin, the development of which followed the delivery to Port Victoria of the Sopwith Bomber which had been flown to Dunkirk for assessment in its designated role. After close deliberations in October 1917, folding wings and wireless were installed in a modified example, numbered N50, and the addition of a hydrovane landing gear and a pillar-mounted swivelling bracket for a free Lewis gun behind the rear cockpit further proclaimed the new-found application. Drastic redesign of the whole aircraft was quickly found to be necessary, and the seven aircraft formally named Grain Griffin (N100-N106) were built accordingly. These were somewhat larger aeroplanes, powered by the Sunbeam Arab or Bentley B.R.2 engine; and though they still owed much to the basic Sopwith design, they were not true inmates of the 'zoo'. Certainly they would have done it little credit respecting handling, though during 1919 Griffins, together with Camels, 1 1/2 Strutters and Short 184s were aboard HMS Vindictive (formerly Cavendish) in the Baltic on anti-Bolshevik operations.
B.1 Bomber (200 hp Hispano-Suiza)
Span 38 ft 6 in (11.7 m); length 27 ft (8.2 m); wing area 460 sq ft (42.7 sq m). Empty weight 1.700 lb (770 kg): maximum weight 3,050 lb (1,380 kg). Maximum speed at 10.000 ft (3.050 m) I 10 mph (177 km/h); maximum speed at 15.000 ft (4,570 m) 98.5 mph (159 km/h): climb to 10.000 ft (3,050 m) 16 min 25 sec; climb to 15.000 ft (4.570 m) 34 min 10 sec; service ceiling 17,000 ft (5.180 m).
N.B. Weight and performance data relate to the aircraft with Lang 5150 propeller. Tests were also made with a Lang 3280 propeller, the aircraft's maximum weight - with the same bomb load of 560 lb (254 kg) - then being given as 2,945 lb (1,335 kg), the service ceiling as 19,000 ft (5,790 m), the climb to 15,000 ft (4.570 m) as 29 min 36 sec, and the endurance as 3 3/4 hr. At least two different Hispano-Suiza engines were installed, and the greatest altitude attained (possibly the absolute ceiling without bombs) was 22.000 ft (6.700 m).
F.Manson British Bomber Since 1914 (Putnam)
Although comprehensive records of the origins of this Sopwith aeroplane do not appear to have survived, it is known that early in October 1916 T O M Sopwith entered discussions with the Admiralty on the subject of two related proposals, one for a single-seat bomber and the other for a similar aircraft capable of carrying an 18in torpedo. The basis of the Sopwith proposals was the belief that both aircraft could be sufficiently small (spanning less than 40 feet) to avoid the necessity for folding wings. When, however, the Admiralty issued its formal requirement for a single-seat torpedo-bomber, the demand for sufficient fuel for four hours' flying at full throttle indicated the need for larger wings to provide more lift. The greater span thus demanded wing folding and, in order to avoid fouling the tail surfaces, a longer fuselage.
Admiralty interest in the smaller bomber project proved to be little more than academic (as the D.H.4 promised to be adequate to meet foreseeable requirements), and Sopwith decided to pursue it as a private venture, and managed to secure a licence (No 6) to go ahead with a prototype - as demanded by the 1917 regulations - basing the design on use of a 200hp Hispano-Suiza geared engine in an installation similar to that being used in the second Sopwith Hispano Triplane fighter.
Thus the B.1 bomber design was in effect a scaled down version of the T.1 torpedo aircraft (later to appear as the Cuckoo), but there the relationship ended. The longer fuselage of the bomber was dictated, not by the span of the two-bay wings but by the inclusion of a bomb bay located in the fuselage aft of the cockpit, capable of accommodating nine 50 lb HE RL (amatol) bombs, stowed vertically and suspended by their nose rings (as in the Avro Type 529A). However, further discussions with the Admiralty elicited the information that the RNAS in France was interesting in using the French 10kg 'liquid-anilite' bomb (This bomb's explosive filling comprised petrol (the hydrocarbon element) and liquid nitric oxide in separate cells; after release from the aircraft, a small wind-driven vane ruptured the separating diaphragm, allowing the elements to mix and thus 'arming' the highly sensitive explosive compound. No impact detonator was therefore required) as an alternative to the British HE RL, and in order to cater for twenty of these weapons the bomb suspension beams in the Sopwith were moved further apart by about two inches (without alteration to the overall dimensions of the bomb bay).
The B.1 prototype, believed to have been numbered X.6 (although no photographs have come to light showing this serial on the aircraft), was first flown at Brooklands early in April 1917 and underwent brief assessment at the Isle of Grain in the same month. During these trials the aircraft was loaded with twenty 10kg anilite bombs and, at an all-up weight of 2,945 lb, returned a maximum speed of 118.5 mph at 10,000 feet.
Although this was regarded as an exceptionally good performance, the B.1 was criticised for its lack of longitudinal control, being found to be tail heavy while carrying the full bomb load, and nose heavy when flying light, a lack of trim that could not be fully countered, even with the adjustable tailplane at its limits of travel. The ailerons were also criticised, though probably owing to undue friction in the control circuits.
Nevertheless the Admiralty stepped in and purchased this aircraft and it was delivered to the RNAS 5th Wing at Dunkerque for Service trials, participating in raids by the naval squadrons flying from Petite Synthe and Coudekerque alongside their D.H.4s. During these operations the B.1 was armed with a single synchronized Lewis gun mounted above the engine.
On return to the United Kingdom, the engine (still Sopwith's property) was removed and returned to Kingston, while the airframe was delivered to the Admiralty's Experimental Construction Depot at Port Victoria. Here it was rebuilt as a two-seat naval reconnaissance aircraft; as such, and given the experimental naval serial number N50, it became the prototype of the Grain Griffin. Later, seven production examples were built by the ECD (N100-N106), powered by the 200hp Sunbeam Arab; one aircraft, N101, was later fitted with a 230hp Bentley B.R.2 rotary engine.
At Brooklands, investigation into the control criticisms expressed by the naval pilots suggested that the complex control linkage in the elevator circuit, previously located within the fuselage structure, made necessary to clear the mounting beams in the bomb bay, was restricting the full movement of the control surfaces. A second aircraft (Despite a number of statements suggesting that more than two B.1 aircraft were completed by Sopwith, an examination of Works manifests in 1958 indicated fairly conclusively that only two complete sets of components were manufactured for airframe assembly, these two airframes always being referred to in Works records as 'No 6' and 'No 1496') was therefore built with the elevator control cables and rocking arms located outside the fuselage, a much simpler circuit which appears to have cured the problem. It is not clear, however, whether changes were also made to the tailplane incidence controls, or to the aileron circuits.
This second aeroplane was also purchased by the Admiralty as B1496 and underwent further trials by Service pilots. However, no further interest appears to have been expressed in the project and the ultimate fate of this aircraft is not known.
Type: Single-engine, single-seat, two-bay biplane bomber.
Manufacturer: The Sopwith Aviation Co Ltd, Kingston-upon-Thames, Surrey.
Powerplant: One 200hp Hispano-Suiza eight-cylinder, watercooled, in-line engine driving two-blade propeller.
Dimensions: Span, 38ft 6in; length, 27ft 0in; height, 9ft 6in; wing area, 460 sq ft.
Weights: Tare, 1,700 lb; all-up (with max bomb load), 3,055 lb.
Performance (with max bomb load): Max speed, 118.5 mph at 10,000ft; climb to 10,000ft, 15 min 30 sec; service ceiling, 19,000ft; endurance, 3 3/4 hr.
Armament: Single, fixed, synchronized 0.303in Lewis machine gun located centrally on the nose decking (fitted only during Service trials in 1917); bomb load of twenty 25 lb HE RL bombs, or twenty 10kg anilite bombs, carried in internal bomb cell immediately aft of the cockpit.
Prototypes: Two, the first being authorised under Licence No 6, and first flown early in April 1917. A second example, B1496, was probably first flown in January 1918. No production.
P.Lewis British Bomber since 1914 (Putnam)
Although by 1917 the concept of the multi-seat bomber was accepted generally, the advantages inherent in the small, faster single-seater were still not neglected. Sopwith set to work to design a competent single-seat bomber, and the result emerged in the spring of 1917 as the B.1 B1496, a shapely two-bay, equal-span biplane fitted with the 200 h.p. Hispano-Suiza engine in a clean cowling. To endow the pilot with a good view for conducting his bombing attacks, the cockpit was set well forward between the centre-section struts. The bomb load of 560 lb. was borne internally and hung vertically in the fuselage bay which extended from the rear centre-section struts to the lower wings’ trailing edge. Armament for the B.1’s pilot consisted of a single Lewis gun mounted centrally to fire forwards from the top of the engine cowling. The first-class results obtained in the B.1’s tests of April, 1917, prompted service trials with the 5th Wing of the R.N.A.S. at Dunkirk. The original promise shown by the B.1 was not, however, rewarded by subsequent production.
O.Thetford British Naval Aircraft since 1912 (Putnam)
The B.1, which bore a close relationship to the Cuckoo, was a single-seat bomber which first appeared early in 1917. Only one example was built, serialled B1496, but it saw service with the Fifth Wing of the RNAS at Dunkirk, where it was used on bombing raids alongside D.H.4s. One 200 hp Hispano-Suiza engine. Loaded weight, 2.945 lb. Maximum speed, 118 1/2 mph at 10.000 ft. Climb, 15 1/2min to 10.000 ft. Service ceiling, 19.000 ft. Span, 38 ft 6 in. Length, 27 ft. The bomb load was 560 lb.
H.King Armament of British Aircraft (Putnam)
Bomber. Laid out along the lines of the single-seat bomber version of the 1 1/2 Strutter, with internal bomb stowage behind the pilot, this larger aircraft of 1917 was at first unarmed. While undergoing operational trials, however, it had a synchronised Lewis gun on the centre line of the fuselage ahead of the cockpit. The bomb compartment had an access panel on each side and appears to have had provision for nine 50-lb bombs, carried nose-up as in the D.H.9. J. M. Bruce records a total load of 560 lb and a test-load of twenty 28-lb Analyte bombs.