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).
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.
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).
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.