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The Supermarine Walrus was a British single-engine amphibious biplane reconnaissance aircraft designed by R. J. Mitchell and first flown in 1933. It was operated by the Fleet Air Arm (FAA) and also served with the Royal Air Force (RAF), Royal Australian Air Force (RAAF), Royal New Zealand Navy (RNZN) and Royal New Zealand Air Force (RNZAF). It was the first British squadron-service aircraft to incorporate a fully retractable main undercarriage, completely enclosed crew accommodation, and an all-metal fuselage in one airframe.〔Brown 1972, p. 25.〕 Designed for use as a fleet spotter to be catapult launched from cruisers or battleships, the Walrus was later employed in a variety of other roles, most notably as a rescue aircraft for downed aircrew. It continued in service throughout the Second World War. ==Development== The Walrus was initially developed as a private venture in response to a 1929 Royal Australian Air Force (RAAF) requirement for an aircraft to be catapult-launched from cruisers, and was originally called the Seagull V, although it only resembled the earlier Supermarine Seagull III in general layout. Construction was started in 1930 but owing to Supermarine's other commitments it was not completed until 1933. The single-step hull was constructed from aluminium alloy, with stainless-steel forgings for the catapult spools and mountings. Metal construction was used because experience had shown that wooden structures deteriorated rapidly under tropical conditions.〔Brown 1972, p.28.〕 The wings, which were slightly swept back, had stainless–steel spars and wooden ribs and were covered in fabric.〔Flight (1934), p.299〕 The lower wings were set in the shoulder position with a stabilising float mounted under each one. The horizontal tail-surfaces were positioned high on the tail-fin and braced on either side by N stuts. The wings could be folded on ship, giving a stowage width of . The single Pegasus II M2 radial engine was housed at the rear of a nacelle mounted on four struts above the lower wing and braced by four shorter struts to the centre-section of the upper wing. This powered a four-bladed wooden propeller in pusher configuration. The engine nacelle contained the oil tank, arranged around the air intake at the front of the nacelle to act as an oil cooler, and electrical equipment and had a number of access panels for maintenance. A supplementary oil cooler was mounted on the starboard side.〔 Fuel was carried in two tanks in the upper wings.〔 The pusher configuration had the advantages of keeping the engine and propeller further out of the way of spray when operating on water and reducing the noise level inside the aircraft. Also, the moving propeller was safely away from any crew standing on the front deck, which would be done when picking up a mooring line.〔Flight (1934), p.298〕 The engine was offset by three degrees to starboard to counter any tendency of the aircraft to yaw due to unequal forces on the rudder caused by the vortex from the propeller. A solid aluminium tailwheel was enclosed within a small water-rudder, which could be coupled to the main rudder for taxiing or disengaged for takeoff and landing. Although the aircraft typically flew with one pilot, there were positions for two. The left-hand position was the main one, with the instrument panel and a fixed seat, while the right-hand seat could be folded away to allow access to the nose gun-position via a crawl-way.〔(【引用サイトリンク】title= Supermarine Walrus Manual )〕 An unusual feature was that the control column was not a fixed fitting in the usual way, but could be unplugged from either of two sockets at floor level. It became a habit for only one column to be in use; and when control was passed from the pilot to co-pilot or vice versa, the control column would simply be unplugged and handed over. Behind the cockpit, there was a small cabin with work stations for the navigator and radio operator.〔 Armament usually consisted of two .303 in (7.7 mm) Vickers K machine guns, one in each of the open positions in the nose and rear fuselage; with provision for carrying bombs or depth charges mounted beneath the lower wings. Like other flying boats, the Walrus carried marine equipment for use on the water, including an anchor, towing and mooring cables, drogues and a boat-hook.〔 The prototype was first flown by "Mutt" Summers on 21 June 1933; five days later it made an appearance at the SBAC show at Hendon, where Summers startled the spectators (R. J. Mitchell among them) by looping the aircraft.〔Mitchell, 2006, p.135〕 Such aerobatics were possible because the aircraft had been stressed for catapult launching. On 29 July Supermarine handed the aircraft over to the Marine Aircraft Experimental Establishment at Felixstowe. Over the following months extensive trials were carried out, including shipborne trials aboard ''Repulse'' and ''Valiant'' carried out on behalf of the Royal Australian Navy and catapult trials carried out by the Royal Aircraft Establishment at Farnborough, becoming the first amphibious aircraft in the world to be launched by catapult with a full military load,〔Kightly and Wallsgrove 2004, p. 10.〕 piloted by Flight Lieutenant Sydney Richard Ubee.〔Later, the commander of experimental flying at Farnborough and an Air Vice Marshal〕 The strength of the aircraft was demonstrated in 1935, when the prototype was attached to the battleship ''Nelson'' at Portland.〔Nicholl 1966 p.26.〕 With the commander-in-chief of the Home Fleet, Admiral Roger Backhouse, on board the pilot attempted a water touch-down, forgetting that the undercarriage was in the down position.〔Backhouse was being flown back from a conference in London: cloud cover forced the flight to be made at a low altitude, and then-current regulations required the undercarriage to be lowered when flying at less than 2,000 ft〕 The Walrus was immediately flipped over but the occupants only had minor injuries; the machine was later repaired and returned to service. Soon afterwards, the Walrus became one of the first aircraft to be fitted with an undercarriage position indicator on the instrument panel.〔Mitchell, 2006, p.136〕 Test pilot Alex Henshaw later stated that the Walrus was strong enough to make a wheels-up landing on grass without much damage (he also commented that it was "the noisiest, coldest and most uncomfortable" aircraft he had ever flown). When flying from a warship, the Walrus would be recovered by touching-down alongside, then lifted from the sea by a ship's crane. The aircraft's lifting-gear was kept in a compartment in the section of wing directly above the engine – one of the Walrus' crew would climb onto the top wing and attach this to the crane hook. Landing and recovery was a straightforward procedure in calm waters, but could be very difficult if the conditions were rough. The usual procedure was for the parent ship to turn through around 20° just before the aircraft touched down, thus creating a 'slick' to the lee side of ship on which the Walrus could alight, this being followed by a fast taxi up to the ship before the 'slick' dissipated.〔Nicholls 1966, p.48.〕 The RAAF ordered 24 examples of the Seagull V in 1933, these being delivered from 1935. These aircraft differed from the prototype and the aircraft flown by the RAF in having Handley-Page slots fitted to the upper wings.〔Nicholls 1966, p.29.〕 This was followed by the first order for 12 aircraft from the RAF, placed in May 1935 〔Thetford 1982 p.321.〕 with the first production aircraft, serial number ''K5772'', flying on 16 March 1936. In RAF service the type was named the Walrus. Initial production aircraft were powered by the Pegasus II M2: from 1937 the Pegasus VI was fitted. Production aircraft differed in minor details from the prototype. The transition between the upper decking and the aircraft sides was rounded off, the three struts bracing the tailplane were reduced to two, and the trailing edges of the lower wing were hinged to fold 90° upwards rather than 180° downwards when the wings were folded, and the external oil cooler was omitted.〔Nicholls 1966 p.29.〕 A total of 740 Walruses were built in three major variants: the Seagull V, Walrus I, and the Walrus II. The Mark IIs were all constructed by Saunders-Roe and the prototype first flew in May 1940. This aircraft had a wooden hull, which was heavier but had the advantage of using less of the precious wartime stockpiles of light metal alloys.〔London 2003, p. 179.〕 Saunders-Roe would go on to build under license 270 metal Mark Is and 191 wooden-hulled Mark IIs.〔 The successor to the Walrus was the Supermarine Sea Otter – a similar but more powerful design. Sea Otters never completely replaced the Walruses, and served alongside them in the air-sea rescue role during the latter part of the war. A post-war replacement for both aircraft, the Supermarine Seagull, was cancelled in 1952, with only prototypes being constructed. By that time, helicopters were taking over from small flying-boats in the air-sea rescue role.〔London 2003, p. 232.〕 The Walrus was affectionately known as the "Shagbat" or sometimes "Steam-pigeon"; the latter name coming from the steam produced by water striking the hot Pegasus engine. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Supermarine Walrus」の詳細全文を読む スポンサード リンク
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