Supermarine Walrus, part four

The prototype of the Supermarine Walrus, was flown on 21st June 1933 at the hands of "Mutt" Summers, who was test pilot both for Supermarine and Vickers. Five days later, on 26th June, it made an appearance at the SBAC (Society of British Aircraft Constructors) show, at Hendon, in London, where Summers startled the spectators by looping the Walrus. Those acrobatics were possible because the aircraft was stressed for catapult launching. Later, on 29th July, Supermarine handed over the aircraft to the Marine Aircraft Experimental Establishment, located in Felixstowe, in Suffolk. During the next months extensive trials were performed, including some seaborne ones aboard the HMS Repulse (34) battlecruiser or HMS Valiant (02) battleship, carried out on behalf of the Royal Australian Navy and catapult trials were also carried out by the Royal Aircraft Establishment in Farnborough, located also, in London. That way the Walrus became the first amphibious aircraft in the world to be launched by catapult with a full military load, piloted by Flight Lieutenant Sydney R. Ubee.
The strength of the Walrus was shown in 1935 when the prototype was assigned to the HMS Nelson (28) battleship, at Portland Harbour, in Dorset. With the commander-in-chief of the Home Fleet on board, Admiral Roger Backhouse, the pilot tried to perform a water touch-down, forgetting that the undercarriage was deployed. Therefore, the Walrus was flipped over but the occupants had just minor injuries and the aircraft was later repaired and returned to active service. Afterwards, every production model (and the prototype too) was fitted with an undercarriage position indicator in the pannel, becoming one of the first aircraft in history to have one. Later was stated by test pilot Alexander Henshaw that the Walrus was strong enough to make a wheels-up landing on grass without sustaining too much damage.
When it was flying from a warship, it could be recovered by touching-down alongside, then lifted from the sea by a ship's crane. Its lifting-gear was kept in a compartment in a section of wing directly above the engine. A crew member would climb-up to the upper wing and attach this to the crane hook. Landing and recovery were easy tasks in calm water, but it could be very difficult in rough conditions. The usual procedure was for the ship to turn through around 20º just before the aircraft touched down, creating a 'slick' to the lee side of the ship, where the Walrus could alight, being followed by a quick taxi up to the ship before the 'slick' dissipated.
The Royal Australian Air Force ordered 24 examples of the Seagull V in 1933, with deliveries starting in 1935. Production aircrafts differed from the prototype in having Handley-Page slots fitted to the upper wings. The first order for the Royal Air Force of 12 aircraft was placed in May 1935, and the first production aircraft flew on 16th March 1936. Serving with the RAF the type was called Walrus. Initial production aircrafts were powered by a Bristol Pegasus II M2, but from 1937 onwards a Bristol Pegasus VI was fitted which yielded a power of 750hp. Production aircraft differed from the prototype in minor details only. The transition between upper decking and the aircraft sides was rounded off, the three struts bracing the tailplane were reduced to just two, the trailind edges of the lower wing were hinged to fold 90º upwards rather than 180º downwards and the external oil cooler was skipped.
In total 743 examples were built in three variants, Seagull V, Walrus Mk.I and Walrus Mk.II.
Of the Mk.Is, 283 machines were manufactured by Supermarine Aviation Works (Vickers) at their plant in Woolston and 270 of them were manufactured by Saunders-Roe at their plant in East Cowes.
Of the Mk.II variant which were manufactured all of them by Saunders-Roe, a total of 190 machines were built from May 1940 until January 1944 when production ceased as the aircraft was already showing its age. The Mk.II variant had a heavier wooden hull, but made with more economic materials nonetheless as it didn't employ light alloys.

Sources:
1. https://en.wikipedia.org/wiki/Supermarine_Walrus
2. https://www.valka.cz/Supermarine-Walrus-t60340