From Nighthawk to Spitfire Page 5

  The pilot’s cockpit is in the nose of the boat and gives an almost unobstructed view in every direction. The equipment consists of a complete set of instruments, anchor and cable, bilge pump, towing fairleads and make-fast cleats, boathook, engine and cockpit covers, towing bridle and lifting slings, ‘Pyrene’ fire-extinguisher, Lewis gun and six double trays of ammunition.

  The Sea King II was designed and built in six months and made its first flight at the end of 1921. Flight repeated the Supermarine claims that it had a degree of manoeuvrability equal to that of any contemporary conventional fighter and that it was inherently stable, allowing hands-off flight in reasonable weather conditions.

  One interesting feature of the design was a vertical tube through the fuselage which conducted air from the slipstream down to just behind the rear planing surface, in order to prevent a vacuum forming behind the step when accelerating for take-off. This form of ducting had been employed earlier by water speed enthusiasts. However, as there are no other reports of Supermarine again using this approach to the problem of efficient ‘unsticking’ from water, it must be assumed that no advantages were found to this device.

  Once more, no orders were received, but there was some further development in 1922 and 1923 in respect of Sea Lions II and III.

  MITCHELL’S SEA LIONS

  In 1922, the Air Ministry issued a specification for a single-seat fighter capable of operation from aircraft carriers or as a floatplane, but the Sea King II, being a flying boat, was not in the reckoning in spite of a potentially competitive performance. The winner of the Air Ministry contract was the Fairey Flycatcher with, eventually, a profitable 196 machines being built. It had a slightly higher top speed over the Sea King (133mph compared with 125mph) and it was just as aerobatic. Additionally, its short span allowed it to be struck down to aircraft carrier hangers without folding wing arrangements, and its extensive aileron-cum-flap arrangements produced very low minimum take-off and landing speeds.

  With hindsight, it might be seen that the days of a flying boat fighter were numbered, but the managing director of Supermarine was still determined to continue with the type and decided again to seek publicity for it by entering another version of the aircraft in the 1922 Schneider Trophy contest. Another, more patriotic, reason might have been to prevent the Italians from winning the trophy outright, which, according to the rules of the contest, they could do in the forthcoming competition: it may be recalled that, after the inconclusive Bournemouth event of 1919, the Italians had had fly-overs in the following two years.

  Meanwhile, with France winning the Gordon Bennett Cup for land planes for the third consecutive time, permanent possession of this trophy had gone to the winning country and thus, importantly for Mitchell, brought to an end the main international prestige race for land planes. Thus, despite the poor attendances and even worse performances in the Italian fourth and fifth events, the Schneider Trophy contest had ended up as the main international speed competition remaining. This would obviously suit Supermarine very well because of their concentration on seaplanes and, in particular, on flying boats. The recent contests had set the trend for entering this type of machine rather than the improvised land plane.

  In addition, the rules had been changed in 1920 to encourage a more practical type of aircraft, rather than an out-and-out racer. 300kg of ballast had to be carried, and this had favoured flying boat designs. Although the ballast requirement was dropped the next year, it was replaced by a watertightness test in which the aircraft had to remain afloat, fully loaded, for six hours. Again, this rule tended to suggest the continuing suitability of the flying boat for the trophy contests, and it must have been noted that the recent Italian designs of this type which had failed in the previous two competitions had actually only done so because of over-ambitious power upratings.

  Sea Lion II

  Despite the omens favouring flying boats, any such Supermarine entry was unlikely to have any financial backing from its government, unlike the firms from Italy. The uncertain financial outlook of the Supermarine Company at this time was such that when its managing director entered an aircraft, he had obtained the loan of a Lion engine from the manufacturers, a high-speed propeller, petrol and oil from other companies, and had negotiated a reduction in insurance rates.

  Scott-Paine also negotiated with the Royal Aero Club for the payment of the competition entry fee and, shortly afterwards, a payment of £100 towards the company’s costs. Nor was the company intending to incur the cost of designing and building an entirely new airframe. The fuselage of the salvaged Sea Lion I was with the Science Museum at South Kensington and so the fuselage of their Sea King II (which, in any case, was aerodynamically cleaner) was utilised.

  Mitchell, no doubt having taken note of the sleek Savoia S.13 at Bournemouth, aimed for increased speed by making the entry of the fuselage, which was originally shaped to house a gun (see drawing on p.35), somewhat smoother, and his simplified method for the removal of the undercarriage system also enabled the hull to be easily stripped of the extra weight and drag of this item. Also, as the Napier replacement developed 150hp more than the Hispano-Suiza engine that had originally been fitted, he was able to decrease the area, and therefore the drag, of the wings by reducing their width.

  Another modification, probably mentioned to Cozens by his neighbour, Biard, was necessitated by the pilot’s refusing to test fly the aircraft until the rear fuselage had been stiffened up (see extract below). Again, in response to the extra power of the engine, an additional increase in fin area was called for. Mitchell achieved this with the least expenditure of time and money by merely modifying the vertical surfaces above the tailplane. The leading edge of the fin was given a pronounced forward curvature which proved to be effective but certainly won no prizes for elegance.

  Although Supermarine’s finished entry was very much based on Mitchell’s Sea King, it was named the ‘Sea Lion’, thus drawing attention to the name of the loaned engine. It was also designated a Mark II, to distinguish it from Hargreaves’ earlier design but, as a result, it has misleadingly suggested that it was a direct development from it, contrary to its actual pedigree described earlier.

  There have been many accounts of the 1922 Supermarine win, and so the following relatively unknown contemporary Cozens’ extract is given:

  The price for such an engine was beyond the means of such a small firm as Supermarine but on the other hand they offered an ideal opportunity to test its capabilities, so Montague Napier loaned it, knowing that if the Sea Lion won the publicity would repay him. It was a water-cooled twelve cylinder with three banks of four cylinders in arrow formation, short and sturdy for its power output. Each cylinder barrel was a separate casting but the cylinder heads were in a single casting for each block so that the whole block bolted together into a well-designed and efficient unit, sturdy and reliable. Each cylinder had its own copper water jacket. The tall Mr Pickett was responsible for the engine fitting and his skill and experience served Supermarine well for many years.

  When the new racer was taken out on to the quay and the powerful Napier was run up Captain Biard took one look at the vibrating tail and said he would never fly that aeroplane, but, with typical press-on spirit the riggers wrapped doped fabric round the fuselage and made the whole unit stiffer. The next crisis was when the Italians advanced the date of the race by fourteen days and bad weather cut down Captain Biard’s chances of getting used to the Sea Lion, and this was further jeopardised by a forced landing which began with the engine cutting out over the Dock. However, when he had had a few more flights he was satisfied and the speed and handling proved very good, indeed it was faster than any flying boat or seaplane of that time. Then, with the limited time available, it was doubtful if they could get the Sea Lion to Naples in time but the General Steam Navigation Co. agreed to take it and it was hurriedly dismantled, put into a crate and on to a lighter, and one of Ray’s tugs took it down to the Solent and the freighter Philomel lifted it on
board and took it to Naples.

  The Sea Lion II. (Courtesy of E.B. Morgan)

  Pre-race spying and counter-spying on both sides was all part of the event. This atmosphere continued throughout the whole series and it was the policy of each competitor to arrive at the start of a competition with a machine that was ahead of its rivals by virtue of some secret and outstanding advantage which was not revealed until it was too late for anyone to copy. In the case of the Sea Lion this meant that the wingspan was cut down to an absolute minimum and as the trials at Woolston had been curtailed even Captain Biard was not too well practised as to the machine’s behaviour.

  He kept his speed down in the practice flights but was quietly getting used to the course and conditions, and his engine fitter, Mr Pickett, tuned up the engine to the higher temperature of the Bay of Naples, so that when the race started Biard was reasonably prepared …

  When Captain Biard and his victorious team came to the Floating Bridge with the great prize held above their heads no one bothered whether it was a cup or a trophy – everyone called it a cup, certainly Scott-Paine. I had parked my bicycle outside the Woolston Picture House and I saw the Supermarine workers run down to meet them. They had taken the two swivel chairs from the office and fixed them to poles and they lifted Captain Biard and Scott-Paine in the chairs shoulder high and carried them round the works.

  One suspects that Mitchell’s relatively recent arrival in the firm at the time, as well as his temperamental self-effacement, account for there being no mention of him in the celebrations.

  Mitchell’s machine not only won the Schneider Trophy race for Britain at an average speed of 145.7mph, but it also gained the first Fédération Aéronautique Internationale (FAI) world records for seaplanes:

  (i) Duration – 1hr 34min 51.6sec

  (ii) Distance flown – 230 miles

  (iii) Fastest time for 100km closed circuit – 28min 41.4sec (130mph)

  (iv) Fastest time for 200km closed circuit – 57min 37.4sec (129.4mph)

  Although city dignitaries had turned out in full ceremonial dress in recognition of Supermarine’s international success, subsequent lack of military interest in the Sea Lion type must have been a disappointment to the company. Also, its designer would have been only too aware that the Savoia S51 which was beaten in this last competition would, in all probability, have been the winner had it not been for the handicap of a damaged propeller. In fact, it was powered by an engine only two-thirds as powerful as the Napier Lion and, on 22 December of that year, it captured the world speed record for seaplanes at a speed of 174.08mph.

  The Sea Lion III

  As the next Schneider Trophy contest was to be held in England, it was to be expected that Supermarine would be only too happy to capitalise on their 1922 publicity by competing, successfully it was hoped, without the cost of overseas travel and accommodation. Indeed, the new venue decided on was to be Cowes, less than 20 miles from the Supermarine works at Woolston.

  While the order for a second batch of five Seagulls in February 1923 was to be welcomed (see Chapter 3), it was still only a part of the government’s minimal financial lifeline to the ailing aircraft industry, and only with the large-scale production of the Southampton, which began two years later, might Supermarine have felt justified in the cost of designing and building a one-off specialist racer. As the top speed of the Sea Lion II was significantly less than the record-breaking S51, the company did not immediately respond to the challenge.

  When Scott-Paine was persuaded to submit an entry, he confined himself to asking his chief designer to do his best with the Sea Lion II airframe. Mitchell designed new wing-tip floats, which offered less frontal area, mounted them on streamlined struts and added fairings around the main strut attachment points. Because an extra 75hp was available from the new Lion engine, the rudder and fin were increased in area, with the resultant redesign looking somewhat like an extension of his early Sea King II outline, and certainly less improvised than that of the Sea Lion II.

  The Sea Lion III.

  Mitchell fitted the uprated Napier Lion III engine and radiator into a more streamlined nacelle, and the more powerful engine also allowed for a reduction in the wingspan by 4ft; he also had fairings made behind the two hull steps – which might have inhibited the ability of the aircraft to take off, had it not been for the extra power now available.

  Mitchell’s changes could hardly prevent the Supermarine machine from showing its, by now venerable, pedigree – as did the other two eventual British contenders. The Blackburn Pellet was, like the Sea Lion, based on a hull built for the 1918 N1B contract, and the third British entry, from Hawker, was to be a further uprated version of the Sopwith Schneider machine of 1919.

  One feels that the rather whimsical sea lion motif painted on the nose and floats of the Supermarine entry (see photograph on p.46) was almost a self-deprecating gesture in the face of the expected serious opposition from overseas: in 1921, the US Navy had contracted with the Curtiss Aeroplane & Motor Co. for the development of a pursuit (fighter) plane, the CR-1, which was soon to be tested in the newly established Pulitzer Trophy Race for land planes; it won, at an average speed of 176.6mph. The US Army then took over the development of the Curtiss racers which, in 1922, were fitted with one of the great aero engines in aviation history, the Curtiss D-12, whose frontal area was about 50 per cent less than that of the rival Napier Lion. The winning of the 1922 Pulitzer race was also due to the incorporation of radiators flush-mounted on the wings, and to the use of metal propellers (the usual, thicker, wooden blades were beginning to prove inadequate for the newer engines which were producing tip speeds approaching the speed of sound).

  As it turned out, no Italian competitors were sent to the competition and, on the day of the race itself, one of the French machines which had survived the flight to England, collided with a yacht and the damage to its hull put it out of the contest. Another was unable to compete because of engine trouble. Also, the Blackburn Pellet had sunk after serious porpoising on take-off. Then the surviving French CAMS withdrew on the second lap of the flying section, because of engine trouble and damage to its right elevator on take-off. So, perhaps the obsolescent Supermarine aircraft might have some success, after all. It all depended upon the quality and seaworthiness of the less robust American floatplanes.

  Of the three machines that finished the competition, the Curtiss CR-3 floatplanes came first, with an average speed of 177.3mph, and second, with an average of 173.46mph. Despite 75hp more, Supermarine’s flying boat could only manage an average of 157.17mph and a poor third placing. Clearly, the usual European formula of an engine mounted above a flying boat hull was no longer likely to be the best configuration. The American approach, despite the drag of floats, allowed for an engine to be neatly cowled so as to merge into the streamlines of the fuselage. There was also a formidable engine and propeller combination and flush-fitted wing radiators to take account of. The Curtiss CR-3 design also limited the number of other drag-inducing items to sixteen struts, with twenty wires, despite the extra penalty of float attachments and bracings, whereas the Sea King/Sea Lion I designs Mitchell had inherited required thirty-three struts and forty-two wires.

  The Supermarine Sea Lion III at Cowes, 1923, with test pilot Biard in the cockpit. (Courtesy of Solent Sky Museum)

  At the end of the race, Biard made a consolatory gesture by pulling up to a considerable height and then descending in a series of tight spirals before alighting in front of the disappointed British crowd. Afterwards, Scott-Paine praised the Napier engine ‘that would have gone on for ever’ but said that he needed ‘to apologise to Captain Biard because we did not give him a good enough machine’.

  The Sea Lion was returned as N170 to the Marine Aircraft Experimental Establishment at Felixstowe with its undercarriage and sea rudder/skid now replaced, but its career was short-lived, owing to its extremely lively take-off performance. As Biard had said, ‘It was an interesting sensation; you switched on the eng
ine, and before you could count 1,2,3,4 fast – she was flying.’

  Unfortunately when a service pilot, Flying Officer E. Paul-Smith, took the Sea Lion over, he apparently did not take sufficient notice of the warning that the machine tended to lift off before flying speed had been reached. As a result, he took off, dropped back onto the water, rose to about 40ft, stalled again and dived in. Paul-Smith was killed – a sad precursor to Lieutenant G.L. Brinton’s death in the S6A eight years later (see Chapter 5). The Sea Lion was too extensively damaged to be considered worth repairing.

  This incident, on 25 June 1924, marked the end of Supermarine’s attempts to interest the Air Ministry in the seaplane scout concept but, importantly, it also led to Mitchell’s later searches for a design specifically dedicated to the Schneider Trophy competition.

  MITCHELL’S FIRST FULL DESIGN

  Although he had contributed to the Nighthawk of 1916, assisted chief designer Hargreaves until he left in 1919 and was involved with various conversions of Admiralty-inspired aircraft, R.J. Mitchell was first responsible for an overall design with the ‘Commercial Amphibian’ of 1920. It is surely worth considering this design in some detail, not only because it represents the beginning of an illustrious career, but also because it showed immediate promise.

  The first aircraft involved in commercial flying after the end of the First World War were conversions of military machines – like the Channels, which we saw earlier were by no means well suited to their new roles. And so it was in March 1920 that the newly formed Department of Civil Aviation at the Air Ministry announced two competitions for commercial designs ‘of British Empire origin’ to promote ‘safety, comfort and security’ in air travel. With a view to developing international travel (bearing in mind the few airfields available, compared with large stretches of water worldwide) one of these competitions was specifically for amphibian seaplanes, with a first prize of £10,000 and a second one of £4,000.