From Nighthawk to Spitfire

by John K Shelton

  In sharp contrast, the Australian Seagulls were used more thoroughly, as their survey work extended into 1927 and continued on northwards to include some 10,000 square miles of Papua New Guinea and one staged flight of 13,000 miles. Referred to by the natives as ‘the canoe that goes for up’, it was also pronounced a ‘delightful’ aircraft to fly by one pilot, Commander F.J. Crowther, although in these tropical regions it took more than an hour to reach 8,000ft (but then, a Vickers Victoria transport, at about this time and also in a hot climate, took nearly two hours to reach 10,000ft).

  Traditional Supermarine ruggedness was also evident after the survey work was completed, as the Seagulls were assigned to the newly constructed seaplane tender HMAS Albatross, commissioned in 1929. As they were not easy to deck land, they were lowered and hoisted aboard but they continued in carrier use until 1933, when their vessel was placed in reserve.

  The Seagulls were then transferred to Royal Australian Navy (RAN) cruisers and, in spite of the type’s various limitations, three further engineless RAF Seagulls were acquired at the scrap price of £100 each, intended to be used for spares. However, they were found to be in such excellent condition that they were restored to flying condition and put into service use.

  By this time, the Seagulls had long lost their appeal for the RAF, but the type continued to occupy the minds of Mitchell’s design team even until 1928. Fitting hydro-vanes was considered and various permutations of the hull step position were tried out on N9565 and on N9606.

  One aircraft, N9605, was fitted with Handley Page wing slots and a new tail unit with twin fins and rudders. This aircraft, designated Mark IV, was converted to take five passengers in 1929, as the Supermarine Company was looking forward to a small fleet of this later model resuming the old Sea Eagle Southampton–Channel Islands routes. A pilot service was begun in July by the prototype five-passenger conversion (G-AAIZ), but most of August was void owing to serious damage to the hull caused by its hitting a submerged rock. Then, on 2 September, the short-lived business ceased when the aircraft ran into engine trouble.

  Two other Seagulls, N9653 and N9654, were converted for civilian use. Registered as G-EBXH and G-EBXI respectively, they began a coastal service at Shoreham, but this also failed owing to inadequate public response.

  However, two other modifications of the Seagull were of great significance to Mitchell’s team. One was concerned with equipping a Seagull to initiate the testing of catapults for launching aircraft and the second was the exchanging of the usual water-cooled Napier engine for an air-cooled radial engine in a pusher configuration. As we shall see later, when the Seagull V/Walrus appeared, it was as an aircraft engined in this particular way and stressed for catapult launching

  AN AMPHIBIAN BOMBER AND AN ENIGMA

  While the Mark III Seagull went exclusively to another country, albeit a dominion of the British Empire, one particular design by Mitchell was sold exclusively to a foreign power. This machine was the Scarab, which first flew on 21 May 1924, and was a powerful fighting machine for its period. At this time, there was also a basically similar amphibian, designed for the Admiralty; it was named Sheldrake, and appeared at an air pageant in 1927, but in most respects little is known about it.

  The Sheldrake

  As early as 1923 the criticisms of the Supermarine Seagull led to an Air Ministry order being 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, if the passenger cabin were discounted. As the new hull shape was selected in response to one of the RAF’s criticisms of the Seagull, 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, as we have seen, had already been avoided in the Seagull II.

  Even more surprising was the apparent inactivity around the Sheldrake. Perhaps contributory factors here were the first flights of the Sea Eagle and the Sea Lion III, producing the first batch of the Seagull IIs, and consideration of the larger flying boats, the Scylla and the Swan. But, for whatever reasons, its only known public appearance is recorded as late as 1927, at the Hamble Air Pageant. By this time, it was an obsolete type, as Cozens said:

  The writer especially remembers seeing a Sheldrake at the end of the line of aircraft on show at Hamble. This machine, N180, looked very much like an ‘old gaffer’ … but it did have a certain dignity when it took off and was ‘attacked’ by three Gloster Gamecocks in their silver paint, black and white squares [No. 43 Squadron markings] and RAF roundels.

  No production orders were placed for this enigmatic machine.

  The Scarab

  A year after the Sheldrake prototype was ordered, the second aircraft made its maiden flight – the first of a Spanish requirement for twelve aircraft. There was no prototype for this aircraft and, as it was in a great many respects similar to the Sheldrake, it seems obvious that the Air Ministry order for the earlier aircraft provided most of the design work for the Spanish order – at little extra cost to Supermarine.

  King Alfonso XIII of Spain was a frequent visitor to the annual RAF air shows at Hendon and must have gained an early appreciation of the new British ‘control without occupation’ tactics demonstrated there. Thus it was that, in pursuit of their country’s objectives in North Africa, the Spanish Royal Naval Air Service asked Supermarine to produce an amphibian capable of carrying a bomb load of 454 kilos – it having been noticed that the passenger-carrying capacity of the Sea Eagle promised a suitable basis for a design. Supermarine suggested that the plans being drawn for their new Sheldrake would be a more suitable model for the project, especially as Mitchell had been devising improvements with the naval Seagull II, as we have seen.

  While the navigator and gunner were still situated behind the wings and out of effective communication with the pilot in the Sheldrake, the Scarab version was built with the three-man crew grouped together in front of the wings. In view of this weight redistribution, the engine was now returned to the more familiar pusher configuration. The gunner was now more aggressively forward facing, just behind the pilot, with the navigator/bomb aimer having a cabin in the hull immediately behind and below his cockpit position.

  Mitchell adopted the newer practice of siting the fuel tanks above the fuselage, not only for the benefit of the navigator but also for the stowage of twelve 50lb bombs which could be dropped via a sealable aperture in the bottom of the hull. Four 100lb bombs were also carried under the wings, and the total weight of bombs carried amounted to the equivalent of six men. As the Scarab was designed for a crew of three and had to carry a machine gun, ammunition and a considerable amount of fuel, and as it had the flexibility of an amphibian configuration, it was an attractive single-engined proposition for its buyers.

  The first Scarab made its maiden flight on 21 May 1924, but whether all twelve actually saw service is unclear. One of the Scarabs was damaged in acceptance trials when its Spanish pilot hit the side of a Union Castle liner when taking off; and the ship sent to collect them had a cargo lift 4in too small in one dimension, so the machines 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. This vessel was a converted merchant vessel and lacked a landing deck. The aircraft were lowered into the water or raised from it by crane, like its Seagull predecessor. Based at Carageno and commanded by the king’s nephew, the unit 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 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.’

  The first Scarab for the Spanish Royal Naval Air Service. (Courtesy of P. Jarrett)

  The Supermarine Company was no doubt mindful of the new RAF tactics of ‘control without occupation’, but its publicity did not lead to any British orders. The sole Sheldrake was not heard of again, but at least it had paved the way for the significant order from Spain. And it might be noted in passing that the more successful hull-planing configuration developed for the Sheldrake, and also employed on the Scarab, was an important influence upon the eventual Seagull V/Walrus design.

  All of these machines continued Mitchell’s development of the medium-sized amphibian biplane (of about 46ft in wingspan). Thanks to Mitchell’s original Seal, which first flew in May 1921, the financial position of Supermarine began to improve, as the total of thirty-three Seal/Seagull orders were in addition to the small fleet of Sea Eagle passenger amphibians and the twelve Spanish amphibian bombers. It is clear that its chief designer, R.J. Mitchell, was becoming a valuable asset to the company.

  MITCHELL’S UGLY DUCKLINGS

  During the First World War, Felixstowe F2 and F3 flying boats had been operated successfully on coastal reconnaissance duties despite their various problems, and they were replaced after the Armistice by the F5 from the same makers. However, Flight Lieutenant D’Arcy Greig (later to figure in the Supermarine S5 story) recorded that the latter was no better a performer on water than its predecessors:

  They were grossly underpowered by two Rolls-Royce Eagle VIII engines, and if there happened to be a flat calm at time of take-off, they frequently refused to unstick. On such occasions the pilot had to taxi frenziedly up and down the Solent and around in circles in order to disturb the surface of the water before trying again, but even then they sometimes failed to get airborne.

  These flying boats had slab-sided hulls which were prone to leakage and so the Air Ministry was concerned to see if the Linton Hope type of hull, which they regarded as a success on the Pemberton-Billing AD Boat, could be adopted on aircraft of the Felixstowe size. Specifications N3B and N4 had been issued for this purpose, but the slow process of fulfilling this requirement by various manufacturers around the country lasted until well after the war, by which time Supermarine came into contention with the Scylla.

  The Scylla

  In response to a contract for a five-seat military flying boat, the new machine was conceived in 1923 as a torpedo-carrying triplane with biplane stabilisers, and it was to be powered by two main engines and a much smaller, auxiliary one, sited in the hull to drive a water propeller for taxiing. This last feature seems particularly old-fashioned, looking back to the earlier Pemberton-Billing days of the company and, in particular, the PB 7 (see below).

  Why just the hull of the Scylla was completed is unknown, as was its final fate. At this distance in time, one must accept the view of the authors of Supermarine Aircraft that, after taxiing trials with the hull, ‘the fate of the Scylla design is wrapped in mystery’. Most likely, Mitchell’s rapidly developing confidence as a designer was an important factor. As a new contract was received soon afterwards for a large commercial amphibian, his thoughts could turn from the traditional thinking represented by the Scylla to a more forward-looking aircraft, given the confidence that must have followed from his successful Commercial Amphibian design and the small fleet of passenger-carrying Sea Eagles.

  This new Air Ministry requirement was for a commercial, twin-engined amphibian and it must have had an immediate appeal, as Supermarine believed that it would be the first of its type in the world. Also, as it was required to carry twelve passengers, it would come out at about the same size as the military Scylla and therefore it might be that the first machine was soon relegated to merely providing information for the more exciting new biplane – which Mitchell would have predicted to be a more efficient aircraft. It could also surely have been easily retro-fitted for the military purposes specified for the Scylla. Certainly the earlier machine seems to have been used only for water taxiing trials, and photographic evidence shows a very basic framework erected on the hull to accommodate (perhaps temporarily) the two engines for these purposes.

  The PB 7.

  The Scylla.

  The Swan

  At least it can be more certainly recorded that when the new machine, to be named the Swan, first appeared in 1924, it was a considerable redesign of the triplane Scylla, being an equal span biplane with a forward-folding wing arrangement like the Sea Eagle of the previous year.

  Indeed the Swan might, in some ways, be regarded as a scaled-up Sea Eagle, although doubling the number of passengers to be carried necessitated accommodating them in the main body of the hull rather than in the forward position which had been approvingly commented upon in the earlier aircraft. Again, the fuel tanks were placed high enough to provide gravity feed to the engines, which were situated between the wings, as well as to provide unusually roomy and fume-free accommodation for the passengers. The fin and rudder outlines also resembled those of the Sea Eagle.

  However, Mitchell’s less complex use of dihedral only on the outer sections of the lower mainplane was new, and the three vertical tail surfaces anticipated his larger designs of the next decade. The single plane stabiliser was also new to larger Supermarine aircraft and was kept well clear of the water by the upward slope of the rear section of the hull. This was very unusual for the time, although not quite an innovation in flying boat design (see the much smaller French Tellier T3 or Latham HB3). Neither was it as graceful as the upward sweep of the future Southampton rear fuselage but, at least, it represented a bold new step in Mitchell hull design, without previous experimentation with smaller hulls.

  The decision to employ three fins had also led to a reversal of the chief designer’s earlier practice, from the Commercial Amphibian onwards, whereby the tailplane had been supported by the fin, with the aid of a complex arrangement of struts. The new feature, with the tailplane supporting the fins, also anticipated most of Mitchell’s later seaplanes and was a more elegant configuration than the backward-looking biplane tail approach proposed for the Scylla.

  The Swan.

  On the other hand, the upswept fuselage and the boat-like prow, which was flared outwards at the top to counteract spray, were features in common with the earlier machine, as they had presumably been proven to be effective by its taxiing trials. The raised cockpit superstructure was also very reminiscent of the unfinished Scylla, and it contributed significantly to the clumsiness of the hull profile. Cozens’ comments are complementary, if not always complimentary:

  The Swan had several features which showed improvements on previous designs, and no doubt these led to its success. The keel had an upward curve towards the tail that enabled it to take off more readily and this feature was noticeable in all later flying boat hulls built throughout the flying boat era, even to the Saunders-Roe Princess of the nineteen fifties …

  An informal moment in the royal visit showing the impressive size of the Swan, including the substantial samson post at the prow. Mitchell is to the right of the Prince of Wales. (Courtesy of The Sentinel, Stoke-on-Trent)

  The struts of the Swan’s centre-section formed large W’s which made for great strength and the large fins and rudders and the considerable spacing between the wings made this aircraft a success from a handling point of view. At any rate, Captain Biard was pleased and so was the Air Ministry, but no one could say that the Swan was a handsome machine with its rounded bow and strange looking cabin and the pilot’s cockpit at the top.

  The ‘strange looking cabin’, which housed a crew of two, sat on the top of the main fuselage so as not to interfere with the passenger space and, as the proposed passenger windows had yet not been fitted, the offending side-view was unrelieved. The same had been true of the Scylla and, while Supermarine had no doubt chosen the latter’s name to suit its proposed military role, it might seem to others that the name reflected its stark appear
ance – according to Ovid, the beautiful Scylla was turned into a thing of terror and, in Homer, Odysseus manages to sail past the monster but not before she catches and devours six of his men. As the new design was to have a more pacific role, the new aircraft was named Swan although, despite its size, ‘ugly duckling’ comes more to mind.

  Be that as it may, the new aircraft was first flown by Biard on 25 March 1924 and, at this time, displayed the triangular cut-outs in the leading edges of the wings to enable them to fold forward. The Swan also had the sort of retracting undercarriage arrangement that Mitchell had designed for his single-engined amphibians, but the much increased size of the new machine necessitated the novelty of some form of servo assistance. Biard described the mechanism as follows:

  It would have been quite impossible to wind down the six-foot wheels and powerful landing-carriage, which had to stand the weight of several tons of aircraft and passengers! So a neat device was fitted to the machine to do the work quickly and efficiently for us. This consisted of a small propeller, which, when not in use, was set sideways to the direction in which we were flying. When we wanted to lower the landing gear, this propeller was swung round to face the direction of our course, and the whirling propeller was connected by cogs to a handle which wound very rapidly round and lowered the wheels into place; by turning the propeller rearward the wheels were wound up out of our way under the wings, and the machine was then able to descend on water. This gear, after one or two adjustments following minor troubles during tests, when the Swan behaved neither like fish, flesh, nor fowl, proved remarkably efficient, and wound the heavy landing gear into place in about half a minute or less.