H.King Sopwith Aircraft 1912-1920 (Putnam)
'The machine is, we believe, known as the Sopwith Snapper’, coyly ventured Flight in commenting on the single-seat biplane, wearing racing number 17, that was to have been flown by Harry Hawker in the 1919 Aerial Derby (the 'Victory Aerial Derby' as this fourth of the series was promoted). Apart from one or two scintillating snippets of intelligence - such as the aeroplane concerned having 'one pair of struts on each side' - it was further disclosed that 'the authorities' had refused to give permission for the machine to take part in the race, for the reason (it was believed) that the engine was Government property.
Although it was otherwise declared that the ban had been imposed because the engine was still on 'the Secret List' it can now, at least, be confidently asserted that this hapless aeroplane was indeed a Sopwith Snapper; that the engine was an A.B.C. Dragonfly I radial of 320 hp; that although the aircraft bore the registration K-149 on the fuselage side-panels it was later allotted the letters G-EAFJ; that this particular Snapper was seemingly one of three that had been designed (as the Snark had been) to the RAF Type I specification; and that all three of these were at the Royal Aircraft Establishment, Farnborough, as late as June 1920.
Aerodynamically and structurally the type had inter-related features of special interest, notably that, although having a single-bay wing cellule, this structure was uncommon in embodying a broad-span top centre section that was strut-braced well inboard of the attachment points for the outer panels, and also in having the single set of interplane struts placed far outboard. The result was to emphasise that the Snapper was no mere biplane version of the Snark (though there were common points in geometry), for the Snark's top centre-section struts were splayed out to the main attachment points. Simply stated, it looked as though the Snapper was asking to become a 1 1/2 Strutter once again, so that Flight's seemingly naive remark about 'one pair of struts on each side' may have been less superficial than it seemed.
The wings were relatively broad in chord and the moderate aspect ratio gave a lower service ceiling than was attainable by the Dragon or the Mk.II Dolphin. Nevertheless, this very feature of broad chord accentuated the Snapper's trim appearance, though this was somewhat marred because the two staggered Vickers guns were largely exposed (even though they were emplaced in troughs) by reason of the small cross-section of the fuselage. Had a Snark-type monocoque fuselage been used, as was at first intended (hence, perhaps, the 'M' in one recorded designation R.M.1) the guns might have been enclosed, with advantage to appearance and performance. As things turned out, the Snapper bore a striking resemblance to the Pup - and so (allusion having already been made to the 1 1/2 Strutter) Sopwith fighter design appeared in the Snapper to have turned almost full circle.
Although three examples, numbered F7031-F7033, were ordered early in 1918, and by May/June work on the first was well advanced (the monocoque scheme having by then been abandoned) it was at one stage intended to reduce the order to one, with an ordinary wire-braced wooden fabric-covered fuselage. In the event, all three Snappers were completed (though well after the Armistice) the first of these, F7031, appearing at Brooklands in April 1919, apparently in the form shown in photographs reproduced that is, with the Dragonfly engine having a large rounded crankcase-cowling but no spinner. Quite shortly afterwards - in June 1919 the civil-registered K-149, referred to at the outset as a would-be participant in the Aerial Derby, was briefly and prematurely in the public eye as will have been gathered from the story of the 'secret engine'. The RAF identity of this machine if any is indeterminate, and the fact that K-149 was unarmed, and faired accordingly, has scant significance. It could well have been F7031 in a new guise - as indeed could the Snapper that was tested (with Service markings, and with armament installed) at Martlesham Heath in September 1919. The most obvious modification on this last-mentioned version, however, was a much-revised installation of the Dragonfly engine. In this instance the nose fairing was of such proportions that it could no longer be termed a crankcase-cowling, leaving, as it did, much less of each cylinder exposed to cooling air. It was fronted, moreover, by a very large blunt-nosed open-centred spinner, which left the front flange of the propeller hub exposed and conformed in all essentials with that used on the Rainbow racer, and shown in close-up in the rightful context.
That a considerable measure of official interest in the Snapper (of a technical nature, perhaps, rather than military) was sustained until well after the Armistice is suggested by work on F7033 that was still in hand as 1919 ended and by the presence of all three specimens at the RAE in June of the following year. General superiority was, nevertheless, conceded to the Nieuport Nighthawk, for its two-bay wings notwithstanding - it was as fast as, if not faster than, the Snapper and its service ceiling was higher. Both these fighters carried two Vickers guns, synchronised by C.C. hydraulic gear, but the guns of the Nighthawk were internally mounted; both types carried 40 gal (182 litres) of petrol and 4 gal (18 litres) of oil.
Characteristic Sopwith features perpetuated in the Snapper were the staggered guns, as on the Salamander, and the form of tail that was first seen on the Snipe with an almost rectangular fin partly overhung by the rudder horn-balance.
Snapper (A.B.C Dragonfly)
Span 28 ft (8.5 m): length 20 ft 7 in (6.2 m): wing area 292 sq ft (27.1 sqm). Empty weight 1,462 lb (663 kg); maximum weight 2,190 lb (993 kg). Maximum speed at 3,000 ft (910 m) 140 mph (225 km/h); maximum speed at 17.000 ft (5.180 m) 126 mph (203 km/h); climb to 16.800 ft (5,120 m) 17 min 10 sec: service ceiling 23.100 ft (7,040 m).
P.Lewis The British Fighter since 1912 (Putnam)
One more single-seat fighter, the Snapper, remained to emerge under the name of Sopwith from the Kingston factory. It was completed during the Spring of 1919 under the R.A.F. Type 1 requirement with a normal wooden box-girder fuselage; the original intention was to provide it with one of mono- coque type. In common with several latecomers on the British fighter scene at the end of the War, the Snapper used the 360 h.p. Dragonfly 1A radial engine from which so much had been expected and which endowed the single-bay biplane with a top speed of 140 m.p.h. The machine’s armament was the typical one of two Vickers guns and the Snapper terminated the line of Sopwith scouts and fighters which had been sparked off some five years previously with the Tabloid.
F.Mason The British Fighter since 1912 (Putnam)
Last of the Sopwith fighters to fly was the Snapper, enigmatically referred to in some old company records as the R.M.1. Its design started during the spring of 1918, soon after the issue of RAF Specification No I, and seems to have been motivated as an attempt to produce the smallest viable fighter powered by the new 320hp ABC Dragonfly I radial engine, and carrying a normal armament of twin Vickers guns. As originally conceived, the Snapper was intended to have a wooden monocoque fuselage but, in the interests of ease and speed of production, this was abandoned in June 1918, and another start was made, reverting to the time-honoured wooden box-girder structure. The delay was further compounded by a three-month wait while delivery of the more powerful Dragonfly IA was arranged.
The first of three prototypes, F7031-F7033, finally appeared in April 1919. It was a single-bay staggered biplane with the cockpit set well back and with wing trailing-edge cutouts and ailerons on upper and lower wings. The familiar crankcase cowling enclosed much of the Dragonfly engine and was neatly faired into the flat-sided centre and rear fuselage section.
By placing the cockpit well aft, it was possible to mount the front guns, semi-buried in the front decking without need of a humped nose. The now-familiar near-rectangular fin with semi-circular leading edge appeared once again with horn-balanced rudder hinged on the sternpost.
F7031 was first flown at Brooklands in May 1919, and was soon followed by the other two aircraft which featured a re-contoured crankcase cowling which matched the outline of a large spinner with central aperture. One of these aircraft was temporarily admitted to the British Civil Register as K149/G-EAFJ in June for entry by Harry Hawker in that year’s Aerial Derby, but its participation was officially forbidden on the grounds that its engine was still on the Secret List; this was not strictly correct, and a more likely reason was that the Dragonfly IA engine had only been cleared for short flying hours and, in any case, was still technically the property of the Air Ministry.
The first prototype underwent Martlesham trials in September 1919, returning the excellent speed of 140 mph at sea level and 133 mph at 15,000 feet. There is some circumstantial evidence to suggest that the aircraft may have encountered symptoms of wing flutter at this time - though hardly severe enough to endanger the aircraft. Little was known of this phenomenon at that time. The aircraft was returned to Sopwith for some modifications to the wings during October and November, but the nature of these has not been traced. In December the aircraft returned to Martlesham where, it is said, two-bay wings were fitted. The other two Snappers were delivered to the RAE for trials on the Dragonfly engines, and their ultimate fate is not known.
Type: Single-engine, single-seat, single-bay biplane fighter.
Manufacturer: The Sopwith Aviation Co Ltd, Kingston and Brooklands, Surrey.
Air Ministry Specification: RAF Type I Specification of 1918.
Powerplant: One 360hp ABC Dragonfly IA seven-cylinder radial engine.
Dimensions: Span, 28ft 0in; length, 20ft 7in; height, 10ft 0in; wing area, 292 sq ft.
Weights: Tare, 1,462lb; all-up, 2,190lb.
Performance: Max speed, 140 mph at sea level; climb to 10,000ft, 7 min 50 sec; service ceiling, 23,000ft.
Armament: Two synchronized 0.303in Vickers machine guns semi-buried in nose upper decking.
Prototypes: Three, F7031-F7033. (F7031 first flown, May 1919). No production.
W.Green, G.Swanborough The Complete Book of Fighters
SOPWITH SNAPPER UK
Designed in parallel with the Snark triplane and similarly intended to meet the requirements of the RAF’s Type I specification, the Snapper single-bay staggered equi-span biplane was destined to be the last fighter to bear the Sopwith name before the company went into liquidation in September 1920. Three prototypes of the Snapper were ordered on 6 June 1918, and, although originally designed with a plywood monocoque fuselage, all three aircraft were completed with conventional fabric-covered fuselages. Powered by a 320 hp A.B.C. Dragonfly I nine-cylinder radial engine and carrying the standard pair of synchronised 0.303-in (7,7-mm) machine guns, the first Snapper performed manufacturer's trials in the second half of July 1919, being delivered to Martlesham Heath for official trials on 1 August. Flight test was somewhat spasmodic owing to recurring difficulties with the engine, but all three Snappers were at the RAE, Farnborough, in mid-1920. It is presumed that trials continued until the decision was taken to discontinue further attempts to rectify the engine’s problems.
Max speed, 140 mph (225 km/h) at 3,000 ft (915 m).
Time to 3,000 ft (915 m), 1.93 min.
Empty weight, 1,462 lb (663 kg).
Loaded weight, 2,190 lb (993 kg).
Span, 28 ft 0 in (8,53 m).
Length, 20 ft 7 in (6,27 m).
Height, 10 ft 0 in (3,05 m).
Wing area, 292 sq ft (27,13 m2).
J.Bruce British Aeroplanes 1914-1918 (Putnam)
THE last Sopwith single-seat fighter to be built was the Snapper. Design work was begun in the spring of 1918, and the original conception of the aircraft incorporated a wooden monocoque fuselage. It appears that the construction of this fuselage was begun, but by June, 1918, it had been abandoned in favour of a conventional wire-braced wooden structure. The change inevitably delayed the completion of the Snapper, and the first machine did not appear until the spring of 1919.
In its completed form, the Snapper was a handsome single-bay biplane of workmanlike appearance, powered by the 360 h.p. A.B.C. Dragonfly IA radial engine. Its design embodied several features which were typical of Sopwith practice: the centre-section was wide, and overhung the centre-section struts; the tail-unit embodied the low rectangular fin and horn-balanced rudder which, in various slightly modified forms, had appeared on almost every type from the Snipe onwards; and the undercarriage had the usual Sopwith method of providing independent springing for each wheel. The wings were of equal span, and ailerons were fitted to upper and lower mainplanes.
The pilot sat a short way behind the wings, and had a good view in most of the important directions. His two Vickers guns were immediately in front of him, slightly recessed into the fuselage top-decking and with their breech mechanisms projecting backwards into the cockpit. Performance, both in level speed and rate of climb, was excellent when the Dragonfly engine was running properly.
The first Snapper had no spinner, but the nose lines of the second and third machines were improved by fitting a large blunt spinner to the airscrew; the contours of the engine cowling were suitably modified to blend with the form of the spinner. One of the Snappers went on to the British Civil Register as K.149 (later G-EAFJ), and was entered for the 1919 Aerial Derby. Its participation in the race was officially forbidden, however, because its Dragonfly engine was still regarded as semi-secret.
Manufacturers: The Sopwith Aviation Company, Ltd., Canbury Park Road, Kingston-on-Thames.
Power: 360 h.p. A.B.C. Dragonfly I A.
Dimensions: Span: 28 ft. Length: 20 ft 7 in. Height: 10 ft.
Areas: Wings: 292 sq ft.
Weights and Performance: No. of Trial Report: M.265. Date of Trial Report: September, 1919. Type of airscrew used on trial: L.5140. Weight empty: 1,462 lb. Military load: 218 lb. Pilot: 180 lb. Fuel and oil: 330 lb. Loaded: 2,190 lb. Maximum speed at 3,000 ft: 140 m.p.h.; at 6,500 ft: 139 m.p.h.; at 10,000 ft: 138 m.p.h.; at 15,000 ft: 133 m.p.h. Climb to 6,500 ft: 4 min 30 sec; to 10,000 ft: 7 min 50 sec; to 15,000 ft: 14 min. Service ceiling: 23,000 ft.
Armament: Two fixed, forward-firing Vickers machine-guns synchronised to fire through the airscrew.
Serial Numbers: F.7031-F.7033.
H.King Armament of British Aircraft (Putnam)
Snapper. The two Vickers guns of the Snapper single-seat fighter of 1919 were set in the top fuselage decking, widely spaced, with their breech casings in the cockpit and their barrels lying in long deep troughs. The windscreen was perforated for an Aldis sight, and there were ring-and-bead sights in addition. As on the Swallow, there were combined large ejection chutes for cases and links below the feed blocks.
A.Jackson British Civil Aircraft since 1919 vol.3 (Putnam)
Sopwith R.M.1 Snapper
Fabric-covered, wooden, single seat fighter powered by one 360 h.p. A.B.C. Dragonfly IA, built by the Sopwith Aviation Co. Ltd. at Kingston-on-Thames 1919. One civil aircraft only: K-149/G-EAFJ, c/n P.W.14, demilitarised and registered to the manufacturers 19.6.19. Flown to Hendon by H. G. Hawker for the Aerial Derby 21.6.19, but participation was forbidden as the Dragonfly engine was still on the Secret List. Scrapped 8.20.
Span, 28 ft. 0 in. Length, 20 ft. 7 in. Tare wt., 1,244 lb. A.U.W., 2,190 lb. Max. speed, 140 m.p.h.
Flight, June 26, 1919.
THE AERIAL DERBY
No. 17. - The Sopwith Biplane, 320 h.p. A.B.C. Dragonfly
When Mr. Hawker on his Sopwith biplane arrived shortly before the start of the Aerial Derby it was thought by many that after all the Air Ministry had withdrawn their prohibition, but this impression was soon dispelled by Mr. Hawker, who, on landing, informed us that he had been unable to obtain the necessary permission, the reason given being, we believe, that the Dragonfly engine was Government property. The disappointment caused by this decision was very keen indeed, as the majority of the visitors had looked forward to seeing Hawker in this famous race. The machine, which was to have carried the official number 17, is a single-seater with one pair of struts on each side. It has the usual arrangement of the centre section struts, which are sloped outwards, and there is a strong family resemblance to previous Sopwith machines, although it would be difficult to state which type she resembles most. The machine is, we believe, known as the Sopwith Snapper.