P.Lewis The British Fighter since 1912 (Putnam)

During the final months of the 1914-18 War a number of new single-seat fighters were completed or were in the final stages to meet the requirements of the R.A.F. Type 1 Specification issued in 1918. Several prominent firms tendered to it and, among them, Sopwith produced three interesting prototypes.
   May, 1918, saw the appearance of the Sopwith 8F.1 Snail Mk.I, of particular note for its finely-conceived wooden monocoque fuselage. The Mk.I was completed after its sister Snail with a conventional fuselage structure covered with fabric, which had been rolled out during the previous month. Both machines used the temperamental 170 h.p. A.B.C. Wasp 1 as power but the Snail Mk.II differed from the Mk.I in having its wings set with a small amount of negative stagger as opposed to the other machine’s positive stagger.

F.Mason The British Fighter since 1912 (Putnam)

Sopwith 8F.1 Snail

   Origins of the Sopwith Snail go back to October 1917 when Herbert Smith was managing the design of a small fighter, to be powered by the new ABC Wasp radial engine and intended for submission to meet the Air Board Specification A.1A. As originally designed, this aeroplane, the 8F.1, was to be constructed on strictly conventional lines, that is wooden box-girder fuselage, faired to oval section, although Smith called on a number of successful features from recent Sopwith designs - concentration of principal masses in the nose of the Camel, the benefits of back-staggered wings and forward location of the cockpit prominent among them. Indeed the 8F.1 was smaller than the Camel, though not strictly a light fighter in the accepted sense.
   Six 8F.1 prototypes, C4284-C4289, were ordered on 31 October, but on 23 November the Air Board asked that the last two aircraft be designed around a monocoque fuselage. As the first of the monocoque aircraft began to take shape early in 1918, it earned the company nickname Snail, presumably on account of its shell-like fuselage, and this name was adopted officially when the new regulations regarding the naming of aircraft were issued. Thus the monocoque aircraft logically became the Snail Mark I, and the fabric-covered prototype the Mark II.
   It was the Mk II which appeared first in April, being easily identifiable by the back stagger on the wings; the top wing was so rigged as to lie directly over the cockpit with the result that a large cutout was necessary in order for the pilot’s head to protrude above the upper surface. The Mark I was completed before the end of the same month and featured normal forward-staggered wings which resulted in the cockpit being below the wing’s trailing edge, which was also cut away.
   Both aircraft featured an exceptionally neat installation of the two Vickers guns low in the sides of the nose and almost totally enclosed within the fuselage. The monocoque fuselage was built up with ply skin over circular formers with wooden stringers.
   Although the aircraft both returned fairly good performance figures, their handling was severely criticised as demonstrating the vicissitudes of the Camel to an extreme, but with added difficulties at low speeds. Be that as it may, once again the general unreliability of the Wasp engine brought about the end of Snail development, and only one example of each version was completed.


   Type: Single-engine, single-seat, single-bay biplane fighter.
   Manufacturer: The Sopwith Aviation Co Ltd, Kingston-upon-Thames and Brooklands, Surrey.
   Air Board Specification: A.1A of 1917.
   Powerplant: One 170hp ABC Wasp seven-cylinder radial engine.
   Structure: Mk I. Wooden monocoque fuselage. Mk II. Wooden box-girder fuselage with fabric covering.
   Dimensions: Span, 25ft 9in; length, 18ft 8in; height, 8ft 3in; wing area, 250 sq ft.
   Weight: All-up, 1,478lb.
   Performance: Max speed, 127 mph at sea level; climb to 10,000ft, 7 min 58 sec.
   Armament: Two synchronized 0.303in Vickers machine guns in the sides of the nose.
   Prototypes: Six ordered, C4284-C4289; only C4284 (Mk II, first flown, April 1918) and C4288 (Mk I, first flown, May 1918) completed; the other aircraft cancelled. No production.

W.Green, G.Swanborough The Complete Book of Fighters

SOPWITH 8F.1 SNAIL UK

   In October 1917, the A.B.C. Wasp seven-cylinder radial air-cooled engine was considered to offer much promise, and on the 31st of that month Sopwith was invited by the Air Board to tender designs for a single-seat fighter utilising that power plant. Four prototypes were ordered, these being of conventional construction, and, on 23 November, the company was asked to build two additional prototypes with plywood monocoque fuselages. In view of its intended function adoption of the name Snail for the new single-seater was bizarre, this being approved on 16 February 1918. Powered by a 170 hp Wasp I, the first prototype Snail was completed in April 1918, this having negative wing stagger and fabric skinning for its circular-section fuselage. Intended armament comprised two synchronised 0.303-in (7,7-mm) machine guns, a third weapon of similar calibre being mounted above the wing centre section, to starboard of the cut-out. The remaining three prototypes of conventional construction were not completed, the next Snail to fly being the first of the two with plywood monocoque fuselages and positive wing stagger. On 9 May, the monocoque Snail was sent to Martlesham Heath for official trials, the reports being less than complimentary about its manoeuvrability and low-speed control. When, in October 1918, it was decided to abandon the Wasp engine, further work on the Snail was terminated, the second monocoque prototype being discontinued before completion. The following data relate to the monocoque Snail.

Max speed, 115 mph (185 km/h) at sea level.
Time to 6,000 ft (1830 m), 6.25 min.
Empty weight, 1,390 lb (630 kg).
Loaded weight, 1,920 lb (871 kg).
Span, 25 ft 4 in (7,72 m).
Length, 19 ft 0 in (5,79 m).
Height, 7 ft 10 in (2,39 m).
Wing area, 228.6 sqft (21,24 m2).

J.Bruce British Aeroplanes 1914-1918 (Putnam)

Sopwith 8F. 1 Snail

  NEXT after the Snipe in the line of Sopwith single-seat fighters was the 8F.1 which - oddly, in view of its designed function - was named Snail. It was one of the first aeroplanes to be named in accordance with the official system of nomenclature defined in T.D.I. 506, as amended by T.D.I. 506A*; and its name was, in one sense at least, apposite, because the basic design of the Snail employed a monocoque fuselage which could be likened to a snail’s shell.
* The initials T.D.I. signified Technical Department Instruction.
  The fuselage of the Sopwith Snail was of circular cross-section, and consisted of a plywood skin applied to a structure of circular formers and wooden stringers. The lines of the fuselage were good, and the complete aircraft was of pleasing appearance. The single-bay wings had positive stagger, and the pilot sat in line with the trailing edge of the upper mainplane. Ailerons were fitted to upper and lower wings.
  The monocoque Snail appeared in May, 1918, when its structure was regarded as unusual in Britain. This typically conservative attitude towards a breakaway from conventional British methods of fuselage construction was probably responsible for the existence of a second and quite different version of the design.
  The second Snail was designated Snail Mark II in order to distinguish it from the monocoque Snail Mk. I. In point of time the Mk. II preceded the Mk. I, for it appeared in April, 1918. That fact may have been attributable to the simpler construction of its fuselage, which was a fabric-covered structure of conventional design. The basic wire-braced wooden-box girder was faired out to a rounded cross-section.
  The difference between the two Snails was accentuated by the rigging of the wings of the Mk. II. The pilot was accommodated in a manner reminiscent of the Dolphin: he sat high up with his head in the central aperture of the centre-section. As on the Dolphin, the mainplanes had a slight backwards stagger.
  Both Snails had the same wings and tail-unit. The fin and horn-balanced rudder were of similar form to those of the second Snipe prototype.
  Neither version of the Snail was adopted for Service use. No doubt the waywardness of the A.B.C. Wasp engine contributed to the abandonment of the design.


SPECIFICATION
  Manufacturers: The Sopwith Aviation Company, Ltd., Canbury Park Road, Kingston-on-Thames.
  Power: 170 h.p. A.B.C. Wasp I.
  Dimensions: Span: 25 ft 9 in. Length: 18 ft 9 in. Height: 8 ft 3 in.
  Areas: Wings: 250 sq ft.
  Weights: Loaded: 1,478 lb.
  Performance: Maximum speed: 127 m.p.h. Climb to 10,000 ft: 7 min 58 sec.
  Armament: Two fixed, forward-firing Vickers machine-guns, one either side of the cockpit, synchronised to fire through the airscrew.
  Serial Numbers: C.4284-C.4289.

H.King Armament of British Aircraft (Putnam)

Snail. The Snail Mk.II single-seat fighter, which appeared in 1918 earlier than the Mk.I version (monocoque fuselage), carried its two Vickers guns in an extremely neat installation. The relatively large fuselage diameter enabled the guns to be mounted in the sides of the cockpit, the only external evidence of their presence being the extreme muzzle ends projecting into short troughs and the separate case and link chutes in the flanks of the cockpit. A Lew is gun was mounted above the starboard edge of the centre-section cut-out, the rear end picking up a fitting seen in the photograph. In firing position, the gun was parallel with the centre line, but a pivoted arm attached to the rear face of the front spar allowed the gun to be swung inboard for reloading. This was, in effect, a reversal of the system used on the Snipe. The windscreen was perforated for an Aldis sight. The Snail Mk.I does not appear to have carried its intended armament of two Vickers guns.