Whilst
Mitchell was busy with his first medium-sized, slow-flying designs (the
Commercial Amphibian and, later, the Seal/Seagull II development), his firm was
still interested in the possibility of selling the concept of a small naval
“scout” to the Navy and Mitchell was involved with the various modifications to
this fast seaplane type.
The
company’s interest in the fast interceptor had begun with an Air Ministry
requirement, N.1B, for a fast manœuvrable single-seat seaplane or flying-boat
fighter with a speed of 95 kt at 10,000 ft and a ceiling of at least 20,000
feet. The resultant Baby had been designed by F. J. Hargreaves, who was in
charge of the drawing and technical offices at Pemberton Billing 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 but the Baby was, in other respects, a
more ‘in house’ response to the ambitious N.1B specification.
 |
| N.1B |
However,
this machine did not go into production because of the ending of World War I
but, as Mitchell had joined the firm in 1916 and had then been involved at
least with the Nighthawk (see my Blogpost: 'What was R.J. Mitchell's First Design?'), it is entirely
likely that he had had some design input in the three N.IB airframes that were
built: by the time of the Armistice, N59 (see photo above) 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 design) the one bought back from the Air Ministry for
entry in the 1919 Schneider Trophy competition, in the hope thereby to gain
some very useful publicity. The modifications were such that it was
re-named the Sea Lion I.
Sea Lion I.
 |
| Sea Lion I |
The
particular configuration of this aircraft suggests that the modifications to
the Baby design were largely Hargreaves’. The fin and rudder were enlarged in a
shaping not followed later by Mitchell (see fin sketches below); likewise, the
base of the latter was used as a water rudder, the interplane struts were splayed
outwards, and the wings had balanced ailerons on the top wing only and 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:
 |
| Sea King I (see later) Sea Lion I Sea Lion II |
In
appearance, the aircraft suggested that the man with overall responsibility for
this aircraft seemed to have favoured rugged seaworthiness rather than speed
through the air; as such, it was the Royal Aero Club’s choice over the slightly
faster Avro 539A, for the third entry to the 1919 Schneider Cup competition –
possibly hedging their bets because of the already proven sea-going qualities
of Supermarine machines. 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.
However, the
“non-event” of the 1919 Schneider Trophy contest was of no help to Supermarine’s
hopes for this type but the company persisted with their fighter flying-boat
concept with their next two fast flying-boats, the Sea Kings.
Sea King I.
As
Mitchell’s design inputs began in 1916, it is more than likely that he had also
been involved with the Sea King modifications to the original N.1B Baby design;
however, little is known about his involvement in the N60 version, also bought
back from the Air Ministry, and which, it seems likely, became the Sea King I.
This
aircraft appeared, largely unmodified, at the 1920 Olympia Aero Show, after
Mitchell’s appointment as Chief Designer, but how long it had been in
existence in this guise before this date is unknown; certainly the direct
repetition of the earlier, apparently inadequate tail configuration looks
backwards rather than to the future:
 |
N.1B Baby and Sea King I Sea Lion I Sea King II
(see below)
|
One
speculates that, at this time, the profitable modifications to the A. D. Boats
had so pre-occupied Supermarine that a relatively unmodified N60 Baby was sent
to the Olympia Aero Show essentially as a marker for the company’s continuing
interest in the naval fighter scout concept. There is no record of the aircraft
having flown, thus adding to the speculation surrounding the Sea King I. The
following publicity for this aircraft, apparently re-engined, would seem to
imply that control might not be quite adequate; it also reveals that the
company was hoping to sell to the many private flyers that World War I 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 160 h.p. 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 and so takes rather more flying on the part of the pilot than does the bigger machine.
Had there
been any sales, perhaps Mitchell might have wished to modify the tail surfaces but, unfortunately, neither the military nor the ‘single or unhappily married
man’ came along to buy one and 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 modification of the Baby/Sea King I machine:
‘designed 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 [boat] of equal size’
(Supermarine publicity). 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 above) – and it would appear from the Supermarine publicity
quoted below that this had a noticeably beneficial effect). As with his Seal (see my
Blogpost: 'Precursors of R.J. Mitchell’s Walrus'), the tailplane was now placed
almost midway on the fin and the retracting gear of the Seal was again
utilized. At the same time, Mitchell also devised a very simple method for the
removal of the undercarriage system and a Seal type combined tailskid and sea
rudder was also employed.
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 – whose reversed camber
(“of the depressing kind” continued the Baby tradition. The
aerodynamically balanced ailerons and rudder of the Sea King I were again
abandoned in favour of the Baby configuration; the more streamlined Baby/Sea
King I hull was retained.
The
Supermarine description of this version of the single-seat flying boat fighter
type also 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 manœuvrability 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 300 h.p. 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 [is] 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.
The Sea King
II was designed and built in six months and made its first flight at the end of
1921 but, once more, no orders were received; however, there was some further
development in 1922 and 1923 – see my Blogpost concerning Sea Lions II and III.
* * * * *
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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