Thursday, 23 March 2017

Mitchell’s Amphibian Bomber and an Enigma; The Scarab and the Sheldrake.

Supermarine Sheldrake
Supermarine Scarabs
(from paintings by the author)

The Scarab, which first flew on 21 May, 1924, was a powerful fighting machine for its period and was the only Mitchell design sold exclusively outside the British Empire;  the other Supermarine amphibian at this time, the Sheldrake, was an enigma. 

The result of the criticisms of the Supermarine Seagull [see my Blogpost: 'Precursors of R.J. Mitchell's Walrus'] was that, in 1923, an Air Ministry order was placed for an improved version. The resultant aircraft was the Sheldrake whose flying surfaces were virtually identical to those of the Seagull but which had a more efficient boat-like hull very similar to that of the Sea Eagle . It is surprising that the noisy stabilising screens on either side of the engine were still retained, as was the separation of the pilot from the rest of the crew – which already had been addressed in the Seagull II [see my Blogpost: 'Pre cursors of R.J. Mitchell's Walrus'].
   Even more surprising was the apparent inactivity around the Sheldrake – perhaps the first flights of the Sea Eagle and of the Sea Lion III, the first production batch of the Seagull IIs, and consideration of the larger flying-boats, the Scylla and the Swan, were important factors here – but, for whatever reasons, its only known public appearance is recorded as late as 1927, at the Hamble Air Pageant, where it could be seen to be an obsolescent type.

Meanwhile, a year after the Sheldrake was ordered, the second of our aircraft made its maiden flight – the first of a Spanish order for twelve aircraft. There was no prototype for this aircraft – as it was in a great many respects similar to the Sheldrake, the Air Ministry order for the Sheldrake provided most of the design work.

King Alfonso of Spain was a regular visitor to the Hendon RAF Air Shows and must have had an early appreciation of the new British ‘control without occupation’ tactics whereby air power, not ground forces, was used to control insurgent tribes in areas of the British Empire or in areas mandated to Britain by the League of Nations. As a result, the Spanish Royal Naval Air Service asked Supermarine for an amphibian to be produced, capable of carrying a bomb load of 454 kilos, as it had been noticed the passenger carrying capacity of the Sea Eagle promised a suitable basis for a design.
   In the new, Scarab, version, the engine was returned to the more familiar pusher configuration as the crew were all now, more conveniently, grouped together in front of the wings – with the navigator/bomb-aimer also having a position in the hull immediately behind and below his cockpit position.  The fuel tanks were now removed from the hull and placed above the middle section of the top wing. The space not now required in the fuselage was used for twelve 50 lb. bombs which could be dropped via a sealable aperture in the bottom of the hull. Four 100 lb. bombs were also carried under the wings and the total weight of bombs carried amounted to the equivalent of six men. The Scarab also had a crew of three and had to carry a machine-gun, ammunition and a considerable amount of fuel – thus making it an attractive powerful fighting machine for its period, given its single engine.
   The first Scarab made its maiden flight on 21 May, 1924, but whether all the twelve that were ordered actually saw service is unclear. One was damaged on acceptance trials when its Spanish pilot hit the side of a Union Castle liner when taking off; and they had to survive a severe Bay of Biscay storm stowed under tarpaulins as deck cargo. Nevertheless, Scarabs were seen above Barcelona at the 1925 Royal Review of the Spanish forces by King Alfonso and they equipped a seaplane carrier, the Dédalo, a converted merchant vessel – being lowered into the water or raised from it by crane.
    They were based at Carageno from whence they took part in actions against Riff and Jibala insurgents in the Spanish Moroccan campaign, including bombing raids in support of an amphibian  landing at Al Hoceima.
    The Moroccan conflict ended soon afterwards in 1926 and so Supermarine publicity ran as follows: "A large number of these machines have been bought by the Spanish Government, and these have been in operation for the past year in Morocco with the most satisfactory results [my italics]."

No Scarabs were ordered by the British Government but the Spanish order for the twelve machines was, at that time, quite substantial, especially coming soon after the order for 25 Seagull II aircraft and the three Sea Eagles.

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For reference sources, see my Blogpost: “Source Material and References" – an extended bibliography is included in my R.J.Mitchell at Supermarine; Schneider Trophy to Spitfire  which also provides material for wider reading, grouped according to specific areas of interest. 

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