C.Andrews, E.Morgan Supermarine Aircraft since 1914 (Putnam)

Sea King

  A project for a single-seat fighter flying-boat similar to the Baby was started on 29 October, 1919, under Supermarine job number 1169, when hull lines were drawn. With the cessation of hostilities the original N.1B requirement expired as did the use of the Baby. Supermarine decided to pursue the concept and various schemes were considered. Of these, in July 1919 a master drawing was finalized of a seaplane with a Napier Lion engine which became the Sea Lion I and was entered for the 1919 Schneider Trophy contest. After the race at Bournemouth, in which the Sea Lion sank, the fighter flying-boat concept was continued in an overall configuration similar to the Sea Lion. When this machine was completed it was named the Sea King I, powered with a 160 hp Beardmore engine. One modification was the deletion of the horn balances of the control surfaces. It was flown early in 1920 but there is no record of the exact date or the identity of the pilot.
  How long the Sea King I remained in its original form is uncertain as so little was published and when it appeared at Olympia in July 1920, where it attracted much attention as the only single-seat seaplane fighter, the wing structure had been altered to that of an equal-span single-bay biplane. The hull and the T-type tail were the same but with the addition of a small triangular fin above the horizontal stabilizer. Another version is believed to have been flown with a Siddeley Puma engine which would have improved performance. This scheme also improved on the Baby’s machine-gun mounting which had been right in the middle of the pilot’s view, and was now moved to a lower position in the hull nose. Directional stability must have remained a problem as the rudder still appeared too small for adequate control. Other schemes were considered at the same time as the Puma installation. One of these projects was for a two-seat fighter with a Lewis gun on a Scarff ring in the front cockpit giving more than 180 degrees of fire, and with provision for two parachutes and a fog horn, the latter introduced no doubt as a consequence of experience in the Schneider race in 1919 at Bournemouth, which had been fogbound. The deciding factor in choice of design was probably the issue by the Air Ministry in June 1921 of basic requirements for a D of R type 6 single-seat fighter for shipboard use, which could be satisfied by an amphibian but in the event was filled by the Fairey Flycatcher of conventional landplane fighter design. The scheme eventually chosen and constructed was that of 7 July which reverted to the single-seat amphibian layout with either a Lion or the larger Hispano engine. Meanwhile one design quite unlike any other at that time was for a tractor amphibian with either a Jaguar or a Jupiter air-cooled radial engine, shades of things to come in the Walrus and Sea Otter era.
  The Sea King II was completed with the 300 hp Hispano-Suiza at the end of December 1921 and flew shortly afterwards, six months from design to first flight. Like the modified Mk I shown at Olympia, it was an equal-span single-bay biplane with a much modified tail reflecting the influence of Mitchell in the overall design. The horizontal stabilizer had been lowered in position and the enlarged fin and rudder consequently extended above, thus dropping the T form of the Mk Il’s predecessors. The hull was developed on Linton Hope principles with mahogany planking attached to the rock elm timbers and frames by non-ferrous fixings and rivets with a covering of special pigmented doped fabric. The two steps were attached as separate components to the planing bottom and could be easily renewed in event of damage. An unusual feature was an attempt to avoid cavitation by inserting a tube running through the hull supplying ventilating air to the rear step. The idea was to facilitate ‘unsticking’ from the water by removing any vacuum behind the step during the acceleration build-up of speed for take off. No report exists of this system being used in any other Supermarine design so apparently the results were inconclusive.
  Another innovation was that the pilot’s back rest could be lowered to form a step for easy access to the starting magneto on one side of the engine and the filler cap of the petrol tank on the other. The undercarriage struts were so arranged that the landing shocks were not transmitted through the hull and were of the bent axle type with retraction upwards and outwards. The tailskid-cum-water rudder was substantial and was steerable from a wheel in the cockpit. The engine mounting structure was independent of the wing cellule enabling the outer planes to be removed without disturbing the power unit. In fact the whole wing structure plus the power unit could be removed by withdrawing eight bolts and the undercarriage by removing ten bolts. This facility was indicative of the ease of maintenance and interchangeability introduced into the design of the Sea King II. This latter characteristic was inspired largely by the policy of most aircraft firms of the time to make do and mend by using components and parts from other designs which had become obsolescent, such as the Supermarine-built Baby and the Sea Lion I.
  Pilots who flew the Sea King II claimed that it had an unusual degree of manoeuvrability in that its aerobatic capability was the equal of any contemporary landplane fighter and was inherently stable. It was free from any change of trim, engine on or off, and could be flown hands off in reasonable weather conditions. There was no tendency to porpoise on the water as on some previous types. It was the first complete design over which Mitchell had full authority as chief designer and this extended to the modifications necessary when the Sea King was considered, largely on a suggestion by the editor of Flight, as an entry for the 1922 Schneider Trophy contest. It was renamed the Sea Lion II and achieved a notable success for Britain, although not a single customer could be found for it as the Sea King II amphibian fighter.


Sea King I - One 160 hp Beardmore or one 240 hp Siddeley Puma. Single seat.
   Span (upper) 35 ft 6 in (10-82 m). (lower) 30 ft 5 in (9-27 m); length 27 ft 4 in (8-33 m); height 11 ft 7 in (3-53 m); wing area 339 sq ft (31-49 sq m).
   Loaded weight (Beardmore) 2.500 lb (1.134 kg), (Puma) 2.646 lb (1,200 kg).
   Maximum speed (Beardmore) 110-5 mph (177-8 km/h). (Puma) 121 mph (194-7 km/h). Estimated speed with Napier Lion (as amphibian) 141 mph (226-9 km/h).

Sea King II - One 300 hp Hispano-Suiza. Single seat.
   Span 32 ft (9-75 m); length 26 ft 9 in (8-15 m); height 11 ft 7 in (3-53 m).
   Empty weight 2,115 lb (959 kg); loaded weight 2,850 lb (1.292 kg).
   Maximum speed 125 mph (201-1 km/h) at sea level; climb to 10,000 ft (3,048 m) 12 min; duration 2 hr.

G.Duval British Flying-Boats and Amphibians 1909-1952 (Putnam)

Supermarine Sea King I and II (1919)

   When the First World War ended, the Supermarine Company survived the resultant financial slump due to brilliant leadership and sound business sense, and in the five years following the Armistice produced seven flying-boats and flying-boat amphibians, some of which were conversions of military machines and some new designs. Most of them proved successful, and the few that failed to secure orders initially were soon improved and modified until they, too, proved a financial asset to the Company. The two Sea Kings belonged to the latter category.
   The Sea King I was a development of the Supermarine Baby, now rendered obsolete by Government policy, and was aimed at the civil market which showed increasing interest in amphibian machines. This first Sea King had the same wing span as the Baby, but the power unit was a pusher 160 h.p. Beardmore, and a fin and rudder of large area was fitted, with a combined water rudder/tail-skid at the rear end of the hull. The manually-operated undercarriage was arranged to swing upwards and outwards from the hull to its retracted position for water operation. The hull itself was generally identical to that of the Baby, but the single cockpit was moved slightly aft on a raised turtle-decking, and a padded headrest faired into the decking top. Completed in 1919, the Sea King I had a maximum speed of 109 m.p.h. at an all-up weight of 2,250 pounds, being advertised as a single-seat sporting amphibian. No orders were received, and the machine was retained by the company as a flying test bed, in which capacity it carried out flying tests fitted with the 240 h.p. Siddeley Puma, the eventual power unit of the Supermarine Channel.
   The Sea King II was a development of the Mk. I, and also completed in 1919, powered by a 300 h.p. Hispano-Suiza engine. Built as an amphibian, this version had its wing span increased to 32 feet, retaining the Mk. I tail surfaces, and at an all-up weight of 2,850 pounds attained a speed of 125 m.p.h. Registered as G-EBAH, the Sea King II was fitted out as a military amphibian fighting scout. In 1921, when it was certain that no orders were forthcoming, the machine was rebuilt with wings of reduced chord, retaining the original span, and re-engined with a 450 h.p. Napier Lion engine, with the amphibian undercarriage removed. Thus modified, G-EBAH was renamed Sea Lion II, and subsequently won the 1922 Schneider Trophy Race.

SPECIFICATION

   Power Plant:
   Mk.I - One 160 h.p. Beardmore or one 240 h.p. Siddeley Puma
   Mk.II - One 300 h.p. Hispano-Suiza.
   Span:
   Mk.I - 30 feet 6 inches
   Mk.II - 32 feet
   Length:
   Mk.I - 26 feet 4 inches,
   Mk.II - 24 feet 9 inches
   Weight Loaded:
   Mk.I - 2,250 pounds
   Mk.II - 2,850 pounds
   Total Area:
   Mk.I - 309 square feet.
   Mk.II - 352 square feet
   Max. Speed:
   Mk.I - 109 m.p.h.
   Mk.II - 125 m.p.h.
   Endurance: Both Marks - 3 hours
   Armament: Mk. II - single .303-inch Lewis gun, provision for light bombs