From Nighthawk to Spitfire
Page 4
Cozens’ account of the AD Boat conversion and of the early, spartan Supermarine passenger services deserves recording:
The conversion from wartime use to peacetime was fairly basic and consisted of taking out the engine and fitting a more economical Beardmore 160hp which caused the machines already prone to porpoising, to be even worse. The rest of the preparation was to paint out the RAF roundels, but not the red, white, and blue colours on the twin rudders, and SUPERMARINE was painted on each side of the bow.
When the pilot and his mechanic got to Bournemouth, or Brighton, or Bognor or elsewhere they planned to operate they anchored and relied on the local boatmen to ferry out the passengers and help with the refuelling. This enterprise started in July and continued through August and September …
Towards the end of September they were modified to carry three passengers and began flying to Le Havre and so became the world’s first international flying boat service.
The experience gained in September and October 1919 by flying passengers across 114 miles to Le Havre led Supermarine to plan further efforts for 1920 and they built more machines with a higher bow to give the passengers more protection against wind and sea. They were known as Channel IIs but the passengers still had an uncomfortable ride on many occasions and I remember seeing a Channel come up to a buoy just below the Floating Bridge [at Woolston] and although the three people were wearing flying coats and helmets they looked wet and miserable as they got into a boat that was rowed out to meet them …
Captain Biard was yet another of the colour[ful] personalities that Supermarine seemed to attract and he was an extremely good pilot, indeed he flew every kind of aircraft as it was produced, be it single or twin engine, light or heavy, on land or sea. One of the little known but important things he did was to train pilots for flying boats, something that even experienced land pilots found difficult, and it was a common sight to see a Channel taxying up and down Southampton Water trying to take off, or landing with a series of bounces.
Four of the AD Boats had gone to an embryo Norwegian Air Service and Mitchell was obviously also involved with the company’s further purchase of another six AD Boats. Some were converted to a three-seat trainer version and some were bought by the Norwegian Government for use with their Naval Air Services. There then followed a Mark II conversion with a more powerful engine, and three such aircraft went to the West Indies in 1920; two more were modified for photographic reconnaissance and used for surveys of the Orinoco Delta in Venezuela. Other Channels were also delivered to the New Zealand Flying School, the Royal Swedish Navy, Chilean Naval Air Service and the Imperial Japanese Navy (the visiting Japanese officials were reported to have been particularly impressed by the handling of the Channel in strong winds and heavy seas by Henry Biard, who in 1919 had now joined the company as test pilot).
A Channel II ‘on the step’. (Courtesy of Solent Sky Museum)
Meanwhile, a separate Air Ministry had been created, the RAF Staff College had been established at Cranfield and a marine training section and aerial navigation school had been set up at Calshot, only a few miles from the Supermarine factory. Thus, although Supermarine’s order book was soon not always to be so healthy, the newly married Mitchell, with the optimism of youth, could see signs of an expanding new transport system and of government support, particularly for its military aspect, and he could look forward to his company taking a full part in these developments.
Looking out over the River Itchen, down to Southampton Water and then, in his mind’s eye, to the destinations of the recent Supermarine aircraft – Europe, Japan, South America, or New Zealand – the industrial smog of Stoke-on-Trent must have seemed a long way away, particularly as in 1919 he had just been appointed chief designer, at the age of 24. Other quite young designers must have had similar dreams: Chadwick, at A.V. Roe, was 26 and Pierson, at Vickers, was 27. Sopwith, Fairey, Handley Page, Folland and Blackburn were all in their early 30s, leaving Oswald Short at 36 and De Havilland at 37, as the old men of the group.
The total dominance of land plane travel nowadays ought not to disguise the fact that, to Pemberton-Billing, to Scott-Paine or to Mitchell, the marine side of aviation would have been seen as the most natural of developments, not the minority, specialist aspect of the business that it is today. With motor travel in its infancy and with Britain being surrounded by sea, flying boats represented the most obvious next step in the development of long-distance travel. Trade depended on boats and they were essential to serving the far-flung outposts of the British Empire. Britain also had numerous reasonably sheltered stretches of water offering generous expanses for machines which, as we have seen, might be erratic in behaviour and need a considerable area for take-off.
Although the original Pemberton-Billing firm had diversified into land planes as part of the war effort, the original intention of the enterprise was best signified by its telegraphic address ‘Supermarine’. The owner’s original goal had been to produce ‘boats which fly and not aeroplanes which float’, and when the new company was formed the new managing director chose for the company name ‘Supermarine’ (literally, the opposite of the more familiar ‘submarine’) to indicate where his hopes for future aircraft also lay.
Reginald Mitchell at the time of his marriage, 1918. (Courtesy of Solent Sky Museum)
But despite the foresightedness of Jacques Schneider in 1912, and despite the fact that the First World War had given a more than considerable boost to aircraft and engine design, the marine side of British aviation had not profited so well – with the large Felixstowe reconnaissance flying boat being something of an exception. Unfortunately, the Felixstowe had not been a Supermarine product, and dwindling new orders, especially for marine aircraft, were beginning to suggest a less prosperous future for the company that Mitchell had joined.
As we shall see, the third Schneider Trophy competition offered the chance of good publicity for marine products, including Supermarine’s, but the entries showed what little progress had been made in this area of aero design at the time that Mitchell became chief designer.
EARLY DAYS AT SUPERMARINE
The Supermarine Sea Lion II. (From a painting by the author)
MITCHELL’S EARLY MODIFICATIONS
The early Pemberton-Billing/Supermarine interests had ranged from the very large Nighthawk land plane to a small naval ‘scout’ for the navy, and Mitchell’s early design experience was closely involved with this latter fast seaplane type and its various transformations.
The company’s interest in the naval interceptor type had begun with an Air Ministry requirement, N1B, for a fast manoeuvrable single-seat seaplane or flying boat fighter, with a speed of about 100mph at 10,000ft and a ceiling of at least 20,000ft. It was required particularly to combat the German Brandenburg fighter seaplanes which had been operating over the North Sea.
The resultant ‘Baby’ had been designed by F.J. Hargreaves, who was in charge of the drawing and technical offices at Pemberton-Billing when Mitchell joined the company and who continued for a little while after the company became ‘Supermarine’.
Hargreaves’ close liaison with the Admiralty Air Department produced an aircraft with what appeared to be a dangerously small fin and rudder, typical of aircraft drawn up by this design team (presumably in response to accidents caused by over-ruddering which could lead to spinning in) but the Baby was, in other respects, a more ‘in-house’ response to the ambitious N1B specification.
This machine did not go into production because the First World War ended, but, as Mitchell had joined the firm in 1916 and had then been involved at least with the Nighthawk, it is entirely likely that he had had some design input in the three N1B airframes that were going through the works. By the time of the Armistice, N59 (see photograph opposite) had been completed and was being evaluated by the navy and N60 was largely complete. The third, N61, was under construction, and was most probably (in view of its extensive departures from the N59 Baby design) the one modified for
entry in the 1919 Schneider Trophy competition – in the hope to gain some very useful publicity from an event to be staged by Great Britain, the winner of the previous event in 1914. The modifications were such that it was renamed the Sea Lion I.
The N1B Baby. (Courtesy of E.B. Morgan)
Sea Lion I
The particular configuration of this aircraft suggests that the modifications to the original Baby design were largely those of Hargreaves. The fin and rudder were enlarged in a shaping not followed later by Mitchell. Likewise, the base of the latter was used as a water rudder, the inter-plane struts were splayed outwards and the balanced ailerons on the top wing had an inverse taper. Also, the hull was decked to keep down spray, and so the front of the fuselage was far less sleek than Mitchell’s later Sea Lion II and Sea King II.
In appearance, the design suggested that the man with overall responsibility for the aircraft seemed to have favoured rugged seaworthiness rather than speed through the air. As such, when it came to selecting the three aircraft to represent Britain in the Schneider Trophy competition, the Sea Lion was the Royal Aero Club’s third choice over the slightly faster Avro 539A, possibly in order to hedge its bets because of the already proven seagoing qualities of Supermarine machines.
Sea Lion I.
Sea Lion II.
Sea King II.
N1B Baby/Sea King I.
Sea Lion I.
Sea King II.
The Sea Lion I at Bournemouth for the 1919 Schneider Trophy Competition. (Courtesy of Solent Sky Museum)
But, by the time of the Schneider contest, Hargreaves had left the company and it was Mitchell who would have assumed last-minute responsibility for this aircraft. He accompanied Scott-Paine, the new managing director of Supermarine, in one of the company’s current Channel flying boats to the event at Bournemouth.
Unfortunately, the 1919 Schneider Trophy contest was an embarrassing non-event because of incompetent organisation and fog, and so was of no help to Supermarine, whose publicity for the Sea Lion I had clearly indicated Supermarine’s hopes of military orders:
This machine, which is said to be the fastest flying boat in the world, is a small, fast, single-seater, designed primarily for war purposes. With the Napier 450hp engine, 2 hours’ supply of fuel, and a load of 140lb of guns and ammunition, the speed is 147 miles per hour. The hull is guaranteed to stand up to practically any weather, and the machine itself may be looped, rolled, spun, or put through any of the manoeuvres demanded by aerial fighting.
The next two Schneider Trophy events took place in Italy, but flyers from other countries apparently did not feel inclined to finance entries to what was not yet a major aeronautical event. Meanwhile, Supermarine persisted with their fighter flying boat concept with the Sea Kings.
Sea King I
Little is known about Mitchell’s involvement in the Baby N60 version, bought back from the Air Ministry, but it seems likely that it became the Sea King I.
This aircraft appeared at the 1920 Olympia Aero Show, and therefore after Mitchell’s appointment as chief designer, but how long it had been in existence in this guise before this date is unknown. Certainly, a photograph from the show reveals a direct repetition of the earlier, apparently inadequate, tail configuration and so represents past practice rather than the future.
Perhaps its original specification, with a Beardmore 160hp engine, was not expected to present directional problems, given that the Baby flew with a 200hp Hispano-Suiza engine, but the proposed fitting of a 240hp Siddeley Puma engine might have produced some design responses from Mitchell, such as the fin and rudder of his later Mark II version (see drawings on p.35).
One speculates that, at this time, the profitable modifications to the AD Boats (also bought back from the Air Ministry) had so preoccupied Supermarine that a N60 Baby, unmodified by Mitchell, was sent to the Olympia Aero Show essentially as a marker for the company’s continuing interest in the naval fighter scout concept.
C.G. Grey has left an interesting memory of this display:
As one stepped onto the stand one had a feeling of confidence that here were people who really knew what they were at in the sea-flying game. Hubert [Scott-Paine] and his two brothers wore yachting caps and double-breasted reefer jackets and looked real sailor men. Their helpers wore jerseys … and in each corner of the stand was a large coil of tarred rope flemished-down in workmanlike seafaring fashion.
Despite the showmanship, there is little information about the aircraft having been flown, although the following publicity for this aircraft would seem to imply that control, even with the original less powerful engine, had not been found to be quite adequate. It also reveals that the company was hoping to sell to the many private flyers that the First World War had produced if military orders could not be achieved:
The ‘Sea King’ is a small fast single-seater which for general purposes follows the structural methods of the ‘Channel Type’ boat. With its 160hp Beardmore engine it puts up a speed of 96 knots, so that it is either a thoroughly sporting little vehicle for the single or unhappily married man, or is a useful small fast patrol machine for naval work along troublesome coasts. Its chief difference in design from the ‘Channel Type’ lies in the fact that it only has a monoplane tail of the depressing kind [inverted camber] and so takes rather more flying on the part of the pilot than does the bigger machine.
Had there been any sales, perhaps Mitchell would have wished to modify the tail surfaces but, unfortunately neither the military nor the ‘single or unhappily married man’ came along to buy one, so it had to await the Mark II development by Mitchell two years later.
Sea King II
In response to the continued Air Ministry interest in a fighter design for shipboard use, Mitchell now produced an amphibian version of the Baby/Sea King I machine, designed, as company publicity proclaimed, as:
A high performance fighting scout, specially adapted for getting off gun-turret platforms of capital ships, or getting off and landing on the decks of aircraft carriers. The strength and design of the hull are such that it can operate on and from the water under any weather conditions in which it would be possible to operate any other sea craft [boats] of equal size.
It was produced in 1921 and so its modifications can be attributed entirely to Mitchell and, indeed, it bore distinct evidence of his taking over the design department at Supermarine.
The most obvious revision of the earlier design was the more generous fin and rudder area (see sketches on p.35), as the 160hp Beardmore engine of the Sea King I was now replaced by the much more powerful 300hp Hispano-Suiza engine; and it would appear from the Supermarine publicity quoted on the following page that Mitchell’s redesign had a noticeably beneficial effect.
The Sea King II. (Courtesy of E.B. Morgan)
As with his Seal, which also flew in 1921, the tailplane was now placed almost midway up the fin. The retracting gear of the Seal was again utilised, and a Seal type combined tailskid and sea rudder was also employed. The aerodynamically balanced ailerons and rudder of Hargreaves’ Sea King I were again abandoned, and at the same time Mitchell devised a very simple method for the removal of the undercarriage system which enabled the company to offer the choice of flying boat or amphibian with minimum extra production costs.
In other ways, the Sea King II followed the example of previous Supermarine designs, particularly the Linton Hope hull construction, ‘with built-on steps, which can be replaced in case of damage … divided into watertight compartments, the top side being of single-skin planking, covered with fabric, treated with a tropical doping scheme’. The wing-tip floats were the same full depth type as employed on the Baby, Sea Lion I and Sea King I, and the tailplane outline was similar to that of the Sea Lion I or the Seal II but with the lower position of the latter. Its reversed camber continued the Baby method of counteracting nose-down tendencies at higher engine revs.
The Supermarine description of this version of the single-seat flying boat fighter type a
lso draws attention to its flying qualities as well as to the many practical features now incorporated by the designer (a theme that would become familiar in the Mitchell story):
The manoeuvrability of the ‘Sea King’ Mark II is one of its most important features. It can be looped, rolled, spun, and stunted in every possible way. Longitudinally, the machine is neutral, and flying at any speed throughout its entire range either with engine on, gliding, or climbing, no load is felt on the control stick. This balance has been obtained entirely on the stabilising surfaces, and no mechanical adjustment by the pilot is required …
The engine, a 300hp Hispano-Suiza, is mounted in a streamlined nacelle, which contains oil tank, radiator and shutters, piping, controls, etc. The whole unit is very accessible and the engine can be replaced very easily.
Interchangeability and ease of upkeep and repair have been carefully studied. The complete wing structure, including power unit, can be removed from the hull by withdrawing eight bolts. The wing structure consists of top and bottom centre sections, and top and bottom planes of equal span. One set of struts are carried on either side of the centre-section. The top planes have a dihedral angle of 1° and the bottom planes one of 3°. The engine unit is carried on two sets of inwardly inclined N struts, and can be removed and replaced without interfering with any wing structure member …
The amphibian undercarriage, which can be removed by the undoing of ten bolts in all, folds up under the wings, and when folded is well clear of the water. It is raised and lowered by a worm and bevel gear.