M.Goodall, A.Tagg British Aircraft before the Great War (Schiffer)
Deleted by request of (c)Schiffer Publishing
SOPWITH Bat Boat hydro-biplane
It was inevitable, with his marine interests, that Tom Sopwith should consider operating aircraft from water. His first experience was to fly a Donnet-Leveque flying boat from the Seine near Paris, when it was reported that he flew over and under the bridge at Juvisy on 2 June 1912. This machine was a small side by side flying boat, with retractable land undercarriage and a pusher propeller, driven by a 50 or 80hp Gnome engine.
This was, no doubt, practice for his later attempt to fly a similar machine of his own construction, seen at Brooklands and briefly described in The Aeroplane of 1 August 1912 (p. 110), of which no further reports were published. However a vague report in The Aeroplane of 5 September 1912 (p.244), referred to an Evening News headline ' Waterplane Turns Turtle'. Could this have been the end of the first Sopwith Bat Boat?
The hull of the machine was built by S.E. Saunders Ltd. of Cowes, using two layers of spruce with a waterproof fabric interlayer, sewn together with copper wire by the 'Consuta' method, patented by Saunders. The hull had a flat top and sides and at least one step on the planing bottom, which curved down from the broad prow, but was otherwise flat, as it tapered in width to a point aft. The pilot was seated behind the wings with the passenger in front between the lower wings. The wings were attached to the top of the hull and were of unequal span, with a single bay and with warping for lateral control. Cylindrical stabilizing floats with pointed nose and tail were hung under the lower wing tips. The Gnome engine, with fuel and oil tanks behind it, was placed on the front of the center section struts and drove a tractor propeller. This position resulted in a high thrust line and undoubtedly contributed to the machine's demise.
Note. The photographs of this machine only came to light in 1991 in Sir Thomas's personal possessions and show the machine at the Saunders works at East Cowes. In retrospect, the machine would appear to have had poor water handling characteristics and whatever happened on test was sufficient to discontinue further work and no mention was made of it subsequently.
Power: 70hp (probably) Gnome seven-cylinder air-cooled rotary.
Span top 30ft approx.
Weight of hull 130lb.
Span bottom 22ft approx.
SOPWITH Bat Boats (Type.l) Nos.BB1, 2 and 3
The earlier attempt to make a flying boat was relegated to the past and soon forgotten. This next design evolved in the latter part of 1912 and appeared as the first machine on the floor of the Rink at Kingston in January 1913. Work on it proceeded rapidly, with the object of showing it at the Aero Show, opening at Olympia on 12 February 1913. This was achieved, and the Bat Boat shared the stand with the new three-seater Tractor. The machine was much admired for its workmanship, which included the attractive Saunders-built hull, designed by Sydney 'Joe' Porter. The Admiralty selected it as one of the number of machines, which were ordered at the Show. Contract CP32098/13X2399 was issued as cover on 20 February 1913 at an agreed price of .1,500.
After the show closed on 22 February 1913, the Bat Boat was taken to Kingston and then on to Cowes, where it was housed in the Folly Sheds at Whippingham, and Sopwith and Hawker began testing. During March a number of attempts, by both, to lift the machine off the water were made without success. Sopwith eventually reached a height of a few feet but the Bat Boat dropped back onto the water, severely damaging the hull. The machine was left out overnight and further damage was caused by rough weather, the extent of which was such that Sopwith immediately instructed that a replacement be put in hand to satisfy the Admiralty contract. This was ordered on the works on 1 April 1913 and known as BB2. It was made together with a further machine, known as BB3, an amphibious version intended to compete for the Mortimer Singer Prize. This latter machine was seemingly a rebuild, but how much of BB1 was salvaged is not clear.
Although all three machines were of the same basic design, a number of variations took place during the course of their development. The type number is used here to distinguish these machines from the larger machine which came later; it was not in use at the time.
SOPWITH Bat Boat (Type 1) No.BB1
The hull was twenty-one feet long with a vee entry and a single thirty-four inch deep step at twelve feet from the sternpost. The crew were seated side-by-side with the pilot on the port side. A hull of 'Consuta' construction of cedar ply was made by S.E. Saunders Ltd. for this first machine. The ply was applied in strips fifty-six inches wide lengthwise, caravel fashion, with a waterproof fabric layer between the plies.
The two bay wings were of equal span and parallel chord, mounted on short struts above the hull, immediately behind the cockpit. Cutouts in the trailing edges provided clearance for the propeller. The bottom center section was open and consisted of the two main spars only. The original bracing wires to the forward part of the hull were soon replaced by substantial struts to the engine mounting structure. Wing warping control was employed.
Twin strut and wire braced booms, of three bays, extended aft from the inboard interplane struts to a single sternpost. No fin was fitted and the single parallel chord rudder with curved top and bottom ends protruded above, and below, the booms. A parallel chord tailplane with divided elevators was mounted on the top booms. An additional elevator was fitted above the nose of the hull. The wing tip floats were of cylindrical form with conical ends and were made of light gauge copper sheet. Bicycle valves were provided to permit inflation for the removal of dents occurring in use.
The coolant radiators were of spiral tube manufacture and were mounted on either side of the engine between the wings. A handle for hand starting from the cockpit operated on the front end of the crankshaft. Fuel was carried in a cylindrical tank on the port side below the top center section.
Power: 90hp Austro-Daimler six-cylinder inline water-cooled driving a two-bladed pusher Levasseur propeller.
Chord 5ft 6in
Gap 5ft 6in
Area 400 sq. ft
Length 30ft 4in
Span tailplane 9ft
Span front elevator 8ft
Hull length 21ft
Hull beam 4ft
Weight of hull 180lb.
Weight allup 1,650lb.
Max speed 60-65 mph
SOPWITH Bat Boat (Type 1) No.BB2
This machine was assembled at the Salterns Yard of Hamble River, Luke & Co. and was delivered to the Navy at Calshot on 8 June 1913 to meet Contract CP32098/13, placed as a consequence of the 1913 Olympia Show. The aircraft was given Serial No.38 and served until September 1914.
After the first machine was damaged at Cowes in March, a number of improvements were made to the second Bat Boat. The twin strut and wire braced booms now had four bays and tapered to a single sternpost. The rudder was of a new type, aerodynamically balanced by extensions forward of the hinge line at both top and bottom and operated between a divided elevator. No fin was fitted and the front mounted elevator was discarded. The wings incorporated ailerons and there was a small increase in area and dihedral angle. The machine was rebuilt after severe damage, caused by heavy seas, while moored overnight at Brighton on 23 August 1913. A triangular fin was fitted together with an oval shaped rudder during the rebuild.
The hull was similar to that used on the previous machine except that it was built by Sopwiths at Kingston, using cedar ply skins and was not fabricated by the Consuta method.
Power: 90hp Austro-Daimler six-cylinder inline watercooled.
Data Similar to BB1 except for following:
Area 428 sq. Ft
SOPWITH Bat Boat (Type 1) No.BB3
The machine numbered BB3 in the Order Book was to be used by Hawker to contest the Mortimer Singer Prize, in which he was successful on 9 July 1913. It is not clear which parts of BB1 were used in this aircraft. The hull may have been repaired and reused. However, apart from this the differences from, and damage to the first machine, were such that probably mainly minor items were used.
An undercarriage was necessary for the contest, the main element being a tubular member across the hull mounted in bearings on each side. The wheels were carried in forks on the outboard ends of the tube and were designed to be raised by a lever in the cockpit and to fall under their own weight. The wheels were fitted with tires, two feet in diameter and four inches wide, and were unsprung. The hull was supported at the rear by a tail skid, when on the ground.
The increased length tail booms were fitted, but were opened out to double stern posts to carry twin rudders, of a new shape, and providing more clearance of the propeller tips. A new tailplane, with curved leading edge, carried a one piece elevator. No fins were originally fitted, but small triangular fins were added when the machine was in Naval service in about May 1914.
To comply with the rules of the contest, a British-made Green engine was used, which was removed later, as was the undercarriage, when the machine was transferred to the Navy in February 1914. As No.118 it served until February 1915.
100hp Green six-cylinder inline water-cooled driving a 9ft diameter pusher propeller.
90hp Austro-Daimler six-cylinder inline water-cooled.
A report that a 120hp version of this type was fitted at first was probably incorrect.
Data Basically as for BB2 although an increase in the allup weight of the amphibious version to 1,950/2,000 lb. could be expected. The undercarriage track was 4ft 8in.
SOPWITH Bat Boat (1915 Project)
The small Bat Boat was used extensively by the naval personnel at Calshot, and during the various trials it was inevitable that improvements and other applications were suggested. Flight Commander J.L. Travers, an experienced pilot with design experience prewar at Shorts, earned out much of the flying. He proposed a redesigned version based on No. 118, powered by a 100hp Gnome engine and capable of carrying a machine gun or 150 lb. of bombs. To comply with this proposal, R.J. Ashfield produced a general arrangement drawing No.839, dated 27 January 1915, with tandem seating and a gun mounted forward of the front cockpit. Travers was interested also in a gun mounted on the upper center section, firing above and behind, and suggested that the pilot and passenger positions should be reversed. His request to carry out trials with a gun fitted to No. 118 was not approved within the Admiralty and neither was the redesigned Bat Boat, which remained only a project. Details are in Air 1.349.15/227/4. PRO report dated 12 January 1915.
SOPWITH Bat Boats (Type 2) BBS
The Order Book shows, on 17 November 1913, two separate orders for Bat Boats of an enlarged version with the more powerful Salmson (Canton-Unne) engine. The first order was placed by Capt. von Pustau, acting as agent for the German Navy, and the second by the British Admiralty on Contract CP57461/13X18411.
The first appearance of the larger Bat Boat was in March 1914 at the Aero Show at Olympia, when the machine for Germany appeared on the Sopwith stand. After the show it was assembled at Woolston and was flying there in May. Although one source reported that the machine was flown away by Herr Hillman, the firm received in March, an order for packing cases to transport the machine to Germany, which is almost certainly the way in which it was delivered. The aircraft received serial No.44 in the German Naval Air Arm and was based at Kiel-Holtenau for training purposes.
The machine for the Admiralty was flying over Southampton Water in April and early May, when it was taken to Calshot by Howard Pixton. The aircraft was identified as No. 127, but it was not well received by the Navy and was passed on to Vice-Admiral Kerr for .3,000 for use by the Greek Naval Air Corps.
A third machine of the type, but with a Sunbeam engine was ordered on 5 March 1914, to be flown by Pixton as No.3 in The Daily Mail Seaplane Circuit of Britain, to be held in August, but which was abandoned at the outbreak of war. The aircraft was delivered to Calshot on 9 August 1914 by Pixton and it was taken over by the Navy as No.879 for .2,800. It remained mainly unserviceable, due to engine trouble and damage, until November, when it was suggested that two 100hp Gnome Monosoupape engines should be fitted. The engine change did not take place and No.879 was dismantled in the sheds at the Salterns at Hamble Spit in April, although the machine was still on Admiralty lists in September 1915.
SOPWITH Bat Boat (Type 2) German and Greek aircraft
This enlarged version had double the power of the earlier Bat Boats, but the basic design was generally similar. The hull was covered in mahogany, it was 20ft long and was broader and deeper. Anew feature were the external ducts, which fed air to the single step to break the suction on take off. The crew were seated side-by-side with the pilot to starboard.
The three-bay wings were of unequal span, and greater in both span and chord than the earlier Bat Boats. The lower wings were mounted direct to the gunwale with three degrees of dihedral, and with 1ft 6in of stagger. Box shaped wing tip floats were mounted on four short struts. The tail booms contained four bays and tapered to a single vertical sternpost. There was no fin and a single oval shaped balanced rudder was fitted. The tailplane with divided elevators was mounted on the top booms and braced to the bottom booms by cables. Sketches in Flight, made prior to the Aero Show, showed three bays and a parallel chord unbalanced rudder, with clearance for a one piece elevator, but these features were not incorporated in the machine as exhibited.
The engine was mounted high up on the rear center section struts on cross mountings, with a radiator in front mounted across the two forward struts. A small gravity tank was fed by a wind pump from the main fuel tank in the rear of the hull, giving a total fuel capacity of seventy gallons. The engine was started by compressed air supplied by a system housed in the front of the hull. The machine supplied as No. 127 to the RN was fitted with a wireless telegraphy set, ahead of the passenger, and this was powered by a generator driven by a single-cylinder Motosacoche engine.
Power: 200hp Salmson (Canton-Unne) 2M7. fourteen-cylinder water-cooled radial driving a two-bladed Integrale propeller direct.
Span top 54ft
Span bottom 44ft 6in
Chord 6ft 9in
Gap inboard 6ft
Stagger 1ft 6in
Dihedral 3 deg
Area 600 sq. ft
Length 36ft 6in
Hull 20 ft long 4ft 4in beam 3ft 6in deep
Weight 2,300 lb.
Weight allup 3,1201b.
Speed range 40-70 mph
Endurance 4 l/2hr (180 mile radius)
Rate of climb 500ft per min
SOPWITH Bat Boat (Type 2) Circuit of Britain version
A few changes were necessitated by the fitment of the Sunbeam engine in this machine, which was impressed by the Admiralty as No.879 at the outbreak of war. The main change was to raise the wings on four short struts above the hull to provide clearance for a larger propeller, leaving an open center section across the hull. The engine was mounted on beams running fore and aft between the center section struts. The tail unit was the same as on previous machines but with struts bracing the tailplane to the lower booms. Later a triangular fin and unbalanced rudder were fitted. The wingtip floats originally fitted were cylindrical but these later reverted to floats of box shape.
Power: 225hp Sunbeam twelve-cylinder water-cooled vee driving a two-bladed Integrale propeller later changed to a four-bladed propeller in Naval service.
Data As before except for the following:
Span top 55ft
Span bottom 45ft
Weight allup 3,180lb.
Speed range 48-75 mph
P.Lewis British Aircraft 1809-1914 (Putnam)
Sopwith Bat Boat 1 and 1a
Alongside their Three-seater at the 1913 Olympia Aero Show, the Sopwith company exhibited another advanced design, the Bat Boat, significant as the first successful British flying-boat. When it first appeared the machine was fitted with a 90 h.p. Austro-Daimler engine turning an 8 ft. 6 ins. Levasseur propeller. The elegantly-proportioned hull was planked with cedar, and was the product of S. E. Saunders & Co., of East Cowes. The cockpit was just ahead of the lower wings, and it seated two in side-by-side seats. The remainder of the airframe was built in the Sopwith works at Kingston-on-Thames, where the complete Bat Boat was assembled. The unstaggered two-bay wings were mounted above the hull, and attached to it by two pairs of struts. Lateral control was by wing-warping, and a single rudder was fitted. In addition to the normal rear tailplane and elevators, an auxiliary elevator was mounted at first on the extreme nose of the hull.
To enable it to compete for the Mortimer Singer £500 prize for amphibians, the Bat Boat was re-engined with a 100 h.p. Green to bring it into the all-British category, and a pair of forward-retracting wheels allowed it to operate as a landplane. The propeller diameter was increased to 11 ft. to absorb the extra power, and twin rudders were fitted in association with a one-piece elevator. A pair of strong struts from the engine-mounting to the fore-hull replaced the earlier wire bracing between these points, and the hull was faired into the lower wings around its attachment struts. A further refinement was the provision of cable-connected ailerons on upper and lower surfaces. On 8th July, 1918, H. G. Hawker flew the machine successfully to win the Mortimer Singer award, and the Bat Boat was then delivered to the Admiralty.
The 90 h.p. Austro-Daimler engine was put back into the Bat Boat, and the wheeled undercarriage was removed; other modifications included the addition of small triangular fins in front of the rudders, and the installation of a powerful electric searchlight in the bows.
This Bat Boat was used by the R.N.A.S. at Calshot, and numbered 118. It took part in the July, 1914, Spithead Naval Review, and after the outbreak of war was flown on patrol from Scapa Flow from 24th August until it was wrecked by a gale on 21st November, 1914.
A second Bat Boat, supplied to the R.N.A.S. as number 38, retained the original design of empennage with divided elevators and single rudder, the only modification being the addition of a triangular fin underneath the tailplane.
Description: Two-seat pusher hydro-biplane. Wooden structure, fabric covered.
Manufacturers: Sopwith Aviation Co. Ltd., Kingston-on-Thames, Surrey.
Power Plant: 90 h.p. Austro-Daimler. 100 h.p. Green.
Dimensions: Span, 41 ft. Length, 30 ft. 4 ins. Wing area, 428 sq. ft.
Weights: Empty, 1.200 lb. Loaded, 1,700 lb.
Performance: Maximum speed, 65 m.p.h. Endurance, 4-5 hrs.
Sopwith Bat Boat 2
Ready in time for the 1914 Aero Show at Olympia was an enlarged and improved version of the 1913 Bat Boat. Engine power was doubled by the use of a fourteen-cylinder 200 h.p. Salmson, which was cooled through a large rectangular radiator mounted in front between the centre-section struts. The same general arrangement as that of the earlier machine was retained, with an overall increase in size.
An extra half-bay was added to the wings, together with strut-braced upper wing-tip extensions, which increased the span by 14 ft. to 51 ft. Slight stagger was also introduced into the new wings, and the original type of cylindrical wing floats were replaced by a pair of rectangular section. The upper wings which carried ailerons were straight, while the lower pair were set with dihedral. The wings of the new Bat Boat were mounted on to the revised and strengthened hull, which was built in the Sopwith factory together with the rest of the airframe, the whole being of the best construction and finish. A further refinement was the installation in the cockpit of a compressed-air starter for the engine.
For the 1914 Daily Mail Circuit of Britain contest, Sopwith produced yet another version of the Bat Boat. C. Howard Pixton was named as the pilot of the new machine, which was powered with a 225 h.p. Sunbeam engine. The Circuit Bat Boat reverted to the former practice of mounting the wings above the hull, and increased tankage gave an endurance of 5 hrs. War prevented the Daily Mail race from taking place; before the start of hostilities, one Bat Boat fitted with the 200 h.p. Salmson engine was delivered to Germany and used later in the Baltic.
Description: Two-seat pusher hydro-biplane. Wooden structure, fabric covered.
Manufacturers: Sopwith Aviation Co. Ltd., Kingston-on-Thames, Surrey.
Power Plant: 200 h.p. Salmson, 225 h.p. Sunbeam.
Dimensions: Span, 55 ft. Length, 36 ft. Wing area, 600 sq. ft.
Weights: Empty, 2,300 lb. Loaded, 3,180 lb.
Performance: Maximum speed, 70 m.p.h. (200 h.p. Salmson). Maximum speed, 75 m.p.h. (225 h.p. Sunbeam). Endurance, 4.5 hrs. (200 h.p. Salmson). Endurance, 5 hrs. (225 h.p. Sunbeam).
H.King Sopwith Aircraft 1912-1920 (Putnam)
The principal authors who inspired some of Britain's aircraft pioneers - Tom Sopwith by no means least among these latter were Jules Verne, H. G. Wells and Rudyard Kipling. And here one might add that C. G. Grey, as editor of The Aeroplane continued these writers' work ('For their work continueth", as Kipling declared in Stalky & Co) if only because so many of his compositions were fanciful (or fictitious) as well as being breezy (or blustering). So greatly influenced was Grey himself by Kipling that 'R.K.' was quite often quoted as 'C.G.G.'; but indubitably it was Kipling's story With the Night Mail - published as a separate title in the USA, with special illustrations, though familiar on both sides of the Atlantic as a component of the book Actions and Reactions - which provided the name for Britain's first successful flying-boat and the title for the present chapter of this book.
The true nature of Kipling's fictitious 'Bat-Boats' is conveyed in a page from Actions and Reactions, which calls for no comment here, except to re-emphasise Tom Sopwith's love of motor-boat racing. But, just as the bibliography of Kipling's tale can prove confusing, so is it important at this early point to make it clear that there were two distinct forms of the Sopwith Bat Boat flying-boat, and that, following marine practice, these were called by Sopwith Bat Boat I and II respectively. The Navy (in the manner wherein they styled the 'rig of the day') sometimes referred to them as No.1 and No.2.
Just us the Hawker Hart and Hornet caused a buzzing at the Olympia Aero Show of 1929, so did the joint appearance of the Sopwith Three-seater and Bat Boat (retrospectively called Bat Boat I) at the corresponding show of February 1913.
As first exhibited at Olympia the Bat Boat I (for so we shall call it) was an altogether trimmer craft than its successor, which, nevertheless was a far nearer approach to the big, successful and multi-engined British flying-boats that followed it from other works.
In truth, the Bat Boat I itself was not a wholly Sopwith product, for the hull was built by Saunders of Cowes a name that was to be sustained in the RAF by the sturdy Saunders-Roe London of 1934. As Harald Penrose (a boat-builder himself, as well as a gifted author and eminent test-pilot) remarks in Vol I of his splendid Putnam trilogy British Aviation; The Pioneer Years 1903-1914:
'The sea had long been the passion of Sopwith and Sigrist, and since they had just sold their first aeroplane to the Admiralty, it was natural that they thought in terms of marine aircraft as the opening venture of the new Sopwith aeroplane company, which was rumoured to be backed by the millionaire Barnato Joel, who had married one of Sopwith's sisters. Not only had Tom Sopwith raced speed-boats, but he was a client of the redoubtable boat-builder Sammy Saunders, of the neatly trimmed white beard and powerful personality. Grandson of the founder, he had transferred the family business in 1901 from Goring-on-Thames to Cowes, establishing the "Saunders Patent Launch Building Syndicate", and registered it in 1908 as S. E. Saunders, Ltd., to exploit his patented system of Consuta laminated-strip planking cross-sewn with copper wire to give far greater strength for weight than hitherto available. In developing high-powered racing boats, the new company had experimented with many hull forms, plain and stepped, as well as a sidewall vessel some 35 ft. in length with air-lubricated bottom. Recently Curtiss in the United States had developed his simple single-pontoon biplane into a more capacious hull in which pilot and passenger were seated. The idea attracted Tommy Sopwith, and he discussed it with Sammy Saunders' hull designer Sydney E. Porter, who had started with him in 1903. Already he had evolved for Sopwith the very successful Maple Leaf stepped hydroplane, and he saw no difficulty in designing a similar Consuta-sewn single-stepped cedar hull. 21 ft. long, with V entry, and side-by-side seating immediately above the step.'
Here, then, we have the essence of the Sopwith Bat Boats' history, related with multi-professional authority; and it remains to add the aeronautical appurtenances.
Mounted amidships on two pairs of struts, somewhat above the hull (which, in its bare form, weighed a mere 180 lb) was a two-bay, equal-span unstaggered wing cellule; and set high between the wings was a 90 hp Austro-Daimler six-cylinder inline water-cooled engine driving a pusher propeller. The hull being short - only 21 ft (6.4 m) overall - the tailplane and elevator, together with a deep single rudder, were carried clear of the water on converging tail-booms; but in addition to the rear tailplane and elevator already mentioned there was an auxiliary elevator, strut-mounted over the bow of the hull. Wing-warping was used for lateral control.
'The wing-tip floats' (declared one enthusiast) 'are constructed of copper plate, corrugated in order to give additional strength. A really most original point in their construction is the fact that each is equipped with a bicycle-valve in order that, should they become dented in any way, they can be blown back to their original shape by means of the ordinary pump! This is really worthy of a patent.'
For use by the Naval Wing of the RFC the Admiralty bought a specimen of the type described and used it for experimental work at Calshot, early modifications including the removal of the bow elevator. (No self-respecting sailor would put to sea with such an appendage just where the figurehead should be -or so it was said), and hardly less noticeable was the replacement of the original deep, unbalanced rudder by a larger surface, horn-balanced at each end. Later this gave place to a rudder of roughly oval form.
To render the Bat Boat 'all-British', and thus allow it to compete for the Mortimer Singer ?500 prize for the first such aircraft of amphibious form, the engine-bearers were modified to accept a 100 hp Green water-cooled unit and - of greater technical significance - two wheels were fitted, one on each side of the hull and capable of being raised clear of the water as required. On land, the hull sat tail-down. To absorb the extra power of the Green engine, the propeller diameter was increased to 11 ft (3.3 m) and twin rudders, below a new one-piece elevator, were associated with a modified tail-boom assembly. Instead of the earlier bracing cables, a pair of sturdy struts ran down to the hull from the new engine-mounting, and a further improvement was the fairing-in of the bottom-wing/hull junction round the supporting struts. The wing-warping system now gave place to ailerons, but the original pattern of wing-tip stabilising floats (cylindrical, with pointed ends) remained unchanged.
The demands imposed by the Mortimer Singer prize performance were very stringent and somewhat bewildering; but on 8 July, 1913, carrying Lieut Spenser Grey as official observer, Harry Hawker completed the specified tests in 3 hr 25 min, thus winning the ?500 prize and an important place in British aircraft history. In securing these distinctions Spenser Grey did not lend a hand, as might have been expected of a sailor (even though an official observer) but a foot to kick the wheels down for each landing at Hamble, the reason being that after take-offs from the Solent they had failed to drop into position when released.
Thus, although it bore a general resemblance to the slightly larger Supermarine Walrus of the Second World War, the Bat Boat was far more deserving of the description ‘primitive' that has been too frequently applied to the 'Shagbat', or Walrus - which had, in any case, a full-length hull.
Slill, the original Sopwith Bat Boat represented a truly significant accession to the development of British Naval flying. That Naval pilots flew the machine with and without the bow elevator seems certain; and, in his book already referred to, Harald Penrose has shown a photograph of it upside down on land and with the elevator prominent, though much the worse for wear following an incident which Mr Penrose records as follows: 'It was wrecked at the end of August ' - the Austro-Daimler engine having by that time been re-installed, and the wheels removed - 'after it had been moored for the night, because the sea was too rough to beach the machine at Calshot. Next morning heavy seas were breaking over the boat, eventually filling it, aided by the wash from passing steamers. Coastguards attempted to get the craft ashore, but in the process it struck a submerged groyne and was holed and turned over. The Admiralty ordered a replacement.'
This mishap notwithstanding, the Bat Boat which bore the Service number 118, and which was generally regarded as the 'original', though clearly much rebuilt, was sent to Scapa Flow when war broke out for Fleet-patrol work (after being present at the Spithead Naval Review in July 1914) - and though it suffered gale-damage on 21 November, 1914, it was not officially written off until March of the following year.
That this pioneering Bat Boat I was a proud possession of the Royal Navy (if sometimes fractious and fractured) is clear, not only from its presence at the 1914 Spithead Naval Review, but from its use for experiments involving a little searchlight in the bows (searchlights by that time having become as much a part of a warship's equipment as were guns) - and also by some semblance of armament itself. As I recorded in my Armament of British Aircraft 1909-1939: 'The first flying-boat of this type was used for armament experiments with which the names of Lieut A. W. Bigsworth and Sub-Lieut J. L. Travers are particularly associated. The dropping of darts and practice bombs was preceded by the discharge of potatoes, Naval ratings observed the fall of shot. Data on bomb-aiming were thus accumulated.'
Even so, I feel that the Bat Boat's significance in armament development may have been much overplayed by reason of the delightful circumstances attending this episode, for by 1914 - contrary to widely held opinion - a great deal of experimental, as well as theoretical, work had been done in Britain with a variety of weapons and gear bombs and bombsights included.
The second and seemingly separate - example of the Bat Boat supplied for British Naval service was No.38, which, at one stage at least, was distinguished by a triangular fin ahead of a single ellipsoidal rudder. But such was the extent of modification and rebuilding, and so great the perils of confusion that existed in those times (and have since been multiplied) that firm identities are exceedingly difficult to establish. In any case, the Sopwith Bat Boat II - as we shall call it for consideration now - was a very different aircraft, and was used not only by the British, but by the German Naval Air Service.
The fact just stated, though doubtless already known to many readers, has never, in the present writer's view, been accorded due prominence; for if ever the heartcry that has echoed down the years and through the wars - 'Whose side are we on, anyway?' - clamoured for renewed expression it is surely here. Indeed, the instance of the German Bat Boat II must rank almost equally with 'Kestrels for German prototypes' in the 1930s and 'Nenes for Russia' in the later years. True, the aircraft itself probably had little influence on German design or policy; true likewise that such anomalies recurred, as the present writer can attest with warm personal feeling. Yet, whatever the facts of such matters, and the pretexts advanced in extenuation (notably continuance of business contacts until a few weeks before the 1914 war) there is something clammy in any transaction whereby a threatening Power can acquire, on the very eve of conflict, a prime example of a prospective opponent's technical potential.
In essence, the Bal Boat II was not only a larger and more powerful development, but differed quite strongly in appearance from its precursor. This was immediately evident on the first public showing - at Olympia in March 1914, less than five months before Britain declared war on Germany. The differences, moreover, were more than superficial, for the new and stronger hull had been made not by Saunders on their patented system at Cowes, but by Sopwith themselves at Kingston-on-Thames. The entire hull-structure was deeper, and suggestive of the sturdiness that was in fact conferred by a double skinning of mahogany on a framework of ash stringers. As on the earlier boat, there was a single step, though the planing bottom was flatter, and, for better water-clearance, the bottom wing (which was staggered appreciably behind the top one) had quite a sharp dihedral. The outboard stabilising floats were of a new design, with a rectangular instead of a circular section, and similar to those of the Type C torpedo-dropping floatplane.
The uppermost of the three-bay staggered wings had strut-braced extensions (again, as on the Type C) and - unlike the lower wing - carried ailerons. The interplane struts were of spruce, and spruce was also used for the wholly new tail-boom structure, the side-struts of which were raked to conform with the staggering of the wings. Atop the convergence of the upper booms was a tailplane/elevator assembly of very deep chord (far more so than formerly) with raked tips matching those of the mainplanes. There was no fin, and the rudder was ellipsoidal.
One especially remarkable feature of the new, Sopwith-built, hull was the 'vented step', and hardly less remarkable, the means whereby air was led to it. 'The method of leading air to the step", commented one marine-minded observer, 'is very ingenious. Instead of doing this by leading tubes through the interior of the boat, which necessitates piercing of the bottom, the same results have been obtained by sheet brass channels screwed to the sides of the boat."
Much of the interest in the new Sopwith flying-boat was nevertheless concentrated in the powerplant. which resembled the earlier scheme only in driving a pusher propeller and in being associated with forward-running struts between the engine-bearers and the hull. The engine itself was a 200 hp Canton-Unne (Salmson) water-cooled two-row radial - a form somewhat difficult to comprehend these days - with a broad frontal radiator instead of the earlier side-mounted layout. For this impressive engine (concerning which more will be said in connection with the Type C) a compressed-air starter was provided in the side-by-side two-seat cockpit. To deliver power for a wireless transmitter (note how Sopwith were meeting, and even anticipating, Service demands, though there was no provision for armament) a Motosacoche motor-cycle engine could be installed forward of the passenger's seat, and put in gear by hand.
In addition to the German Bat Boat II, which was actually being flown over the Baltic by German Naval pilots before war came, a similar flying-boat (understandably known as the 'Circuit Bat Boat') was constructed for the 1914 Daily Mail “Round Britain" contest, this machine being chiefly distinguished by a 200 hp Sunbeam engine; by the mounting of the bottom wings a little above the hull, instead of being directly attached; and by an increase in petrol tankage to give an endurance of 5 hours. C. Howard Pixton would have been the pilot, but the war caused cancellation of the contest. It was reckoned that the Sunbeam-powered machine was about 5 mph (8 km/h) faster than the Canton-Unne version.
Bat Boat I
(90 hp Austro-Daimler or 100 hp Green) Span 41 ft (12.5 m); length 32 ft (9.7 m); wing area 422 sq ft (39.2 sq m). Empty weight 1.200 lb (544 kg): maximum weight 1.700 lb (770 kg). Maximum speed 65 mph (104 km/h).
Bat Boat II
(200 hp Canton-Unne) Span 55 ft (16.8 m); length 36 ft (11 m). Empty weight 2,300 lb (1,043 kg); maximum weight 3.180 lb (1.443 kg). Maximum speed 70 mph (112 km/h).
G.Duval British Flying-Boats and Amphibians 1909-1952 (Putnam)
Sopwith Bat Boat No. 1 (1912)
Europe’s first successful flying-boat, and the world’s first practical amphibian, the Bat Boat was truly a flying-boat in every sense, for its designer, wishing to combine the sports of flying and motor boat racing, simply mounted a pusher-engined biplane upon the hull of a racing hydroplane boat. Its name was derived from an advertisement for a mythical flying machine featured in Rudyard Kipling’s book With the Night Mail.
The aircraft structure was built at Kingston on Thames by T. O. M. Sopwith and Fred Sigrist in late 1912, the work being carried out in a disused skating rink leased by Sopwith for the construction of earlier machines. Of conventional layout for the time, the machine was a pusher biplane, with the tailplane and single oval rudder carried aft on tail booms. The engine, a 90 h.p. Austro-Daimler, was mounted in mid-gap at the centre section, being braced to the hull by the long forward struts, with a gravity-feed fuel tank positioned above the engine bay. Cylindrical wing-tip floats were strut-mounted below the lower wing-tips. The hydroplane hull, built by Saunders of Cowes, had a single step, a two-seat side-by-side cockpit, with the outer skin formed of ‘ Consuta ’ copper-sewn plywood. External scoops were fitted to the hull sides for the purpose of admitting air to the hull step. An auxiliary elevator was mounted on the bows, but later removed. The controls were normal, column and handwheel for elevator and ailerons, with a pivoted foot bar for the rudder.
The flight trials, completed by Harry Hawker at the beginning of 1913, proved to be entirely satisfactory, and on 16 February, 1913, the Bat Boat was exhibited at the Olympia Aero Show, where it attracted much interest, notably that of Mr Winston Churchill, First Lord of the Admiralty. Shortly afterwards, the machine was purchased for the Naval Wing of the Royal Flying Corps, and consigned to the Experimental Station at Calshot. There, it became the favourite mount of the chief test pilot, Lieut. A. W. Bigsworth, who soon had some distinguished passengers in the persons of Mr Churchill and fellow M.P.s, visiting Calshot during week-ends spent aboard the Admiralty yacht Enchantress.
In the spring of 1913, the American sewing machine magnate, Mortimer Singer, put up a prize of £500 for British amphibian aircraft. The stipulated course consisted of six out-and-back flights from land to a water touch-down point five miles distant, and a five-hour time-limit was imposed. With the Naval Wing’s consent, Sopwith entered the Bat Boat for the prize. The Austro-Daimler engine was replaced by a 100 h.p. Green, to make the machine all-British, and a pair of retractable wheels was attached to either end of a stout tube running across the hull. Twin rudders were also fitted. On 8 July 1913, the machine took off from a field near Hamble, piloted by Hawker, with the Officer Commanding Calshot, Lieut. Spenser Grey, aboard as official observer. The water touch-downs were made in the Solent, and 3 hr 25 min later the prize was won. The only difficulty experienced was a reluctance of the undercarriage to lower, overcome by well-placed kicks from the boot of Spenser Grey. The Bat Boat, re-engined with the original Austro-Daimler, but retaining the twin rudders, was then returned to Calshot. There, it provided a great deal of research information, and a wealth of data on bomb aiming became available through the efforts of Sub-Lieut. J. L. Travers, who would fly with Bigsworth in the machine, armed with a bag of potatoes, a detail of naval ratings observing the fall of ‘shot’. Later, special darts and practice bombs replaced the vegetable missiles.
In July 1914, the Bat Boat was slightly modified by fitting a triangular fin in front of each rudder, and on the 16th of that month made the world’s first off-water night flight with Travers at the controls. Illumination was provided by a car headlight mounted in the bows, powered by accumulators. The following day, it took part in a flypast by machines of the newly constituted Royal Naval Air Service at the Spithead Naval Review. At the end of July, the Bat Boat took up its War Station at Scapa Flow, being employed on patrol work, and on 21 November, 1914, was destroyed there by a gale.
Prototype - One 90 h.p. Austro-Daimler engine
Mortimer Singer - One 100 h.p. Green
Span: 41 feet
Length: O.A. 32 feet
Weight Loaded: 1,700 pounds
Total area: 422 square feet
Max. Speed: 65 m.p.h.
Endurance: 5 hours
Armament: Light bombs only
Sopwith Bat Boat No. 2 (1914)
In the summer of 1913, the Daily Mail offered a prize of £5,000 for the winner of a Round Britain Race by marine aircraft. Four machines were entered, but the Cody had already crashed, killing its illustrious sponsor, and the Radley-England and Short entries were scratched. This left the Sopwith Tractor seaplane piloted by Hawker, who crashed after a gallant attempt to complete the course. Hawker received a consolation award, and the main prize was carried over to the next year. With this in mind, and fully aware of Bat Boat No. 1’s success, Sopwith set about building two improved Bat Boats, one for the 1914 Race, and one to be offered for sale.
The hulls of these machines were of stouter construction, covered by two diagonally opposed skins of mahogany. Positioned behind the two crew seats, a 70-gallon fuel tank fed a gravity tank over the engine by wind-driven pump, while beneath the seats lay two compressed air starters for the engine. Under the foredeck, a small motor cycle engine generated power for a wireless transmitter. One machine was powered by a 200 h.p. Salmson Canton-Unne pusher engine, and had the lower wing resting on the hull gunwales. The other, intended for the Round Britain Race, had a pusher Sunbeam engine of 225 h.p., with the lower wing supported above the hull on short struts, as in Bat Boat No. 1. Both machines featured a large balanced rudder of oval shape. The Sunbeam version had the original cylindrical wing-tip floats, but the Salmson machine was equipped with tip-floats profiled as miniature hulls, without steps. In both cases, the machines proved to be remarkably stable, and capable of level flight for long periods without the pilot touching the controls.
On 16 March, 1914, the Salmson-engined Bat Boat was exhibited at the Olympia Aero Show, being acquired for the German Navy by Von Pustau, their aircraft purchasing agent. In the light of subsequent events, this transaction may seem strange, but it should be remembered that little deterioration of business or diplomatic contact occurred between this country and Germany until a few weeks before a state of war existed. The German machine was delivered in June 1914, and put into service in the Baltic. It later appeared as the subject of a wartime propaganda photograph, titled ‘A captured British flying-boat’. The Sunbeam-engined Bat Boat, entered as Number 3 for the Round Britain Race, with C. Howard Pixton nominated as pilot, was, in the event, purchased for the R.N.A.S., and delivered to Calshot in May 1914, the race having been cancelled. With the R.N.A.S., it carried out experimental and training duties, being eventually written-off in 1915 due to unknown causes.
R.N.A.S. - One 225 h.p. Vee-type Sunbeam
German - One 200 h.p. Salmson Canton-Unne
Span: 55 feet (both machines)
Length: 35 feet (both machines)
R.N.A.S. - 3,120 pounds
German - 3,180 pounds
Total Area: 600 square feet (both machines)
Max. Speed: 78 m.p.h. (both machines)
R.N.A.S. - 5 hours
German - 4-5 hours
Armament: Nil, or light bombs only
O.Thetford British Naval Aircraft since 1912 (Putnam)
SOPWITH BAT BOAT
The Bat Boat, which first appeared in 1913, was the first flying-boat to be built in Great Britain. It entered service with the Naval Wing (No.38) and a second (No.118) took part in the Royal Naval Review of July 1914. On the outbreak of war it was used on sea patrols from Scapa Flow until November 1914. One 100 hp Green engine as illustrated. Later fitted with a 90 hp Austro-Daimler engine. Loaded weight, 1,700 lb. Maximum speed, 65 mph. Span, 41 ft. Length, 32 ft.
H.King Armament of British Aircraft (Putnam)
Bat Boat. The first flying-boat of this type was bought by the Admiralty in 1913 and was used for armament experiments with which the names of Lieut A. W. Bigsworth and Sub-Lieut J. L. Travers are particularly associated. The dropping of darts and practice bombs was preceded by the discharge of potatoes. Naval ratings observed the fall of shot. Data on bomb aiming were thus accumulated.
Pusher Seaplane Gun-carrier No. 127. The identity and significance of this historic aircraft is apparently now established for the first time, the significance being that it was armed with the 1 1/2-pdr Vickers gun before that weapon was transferred to Short S.81 No. 126. First, there is the testimony of Sir Arthur Longmore that 'one of our Sopwith pusher seaplanes' (at Calshot before the 1914 war) carried a 1 1/2-pdr gun weighing 265 lb, with which Lieut R. H. Clark-Hall conducted many successful tests. Second, it was stated on the occasion of the Naval Review in July 1914 that a 'Sopwith Gun Carrier' with 200-hp Salmson (Canton-Unne) engine was unable to fly because of tail alterations. On this same occasion the Short S.81 No. 126 was present carrying a 1 1/2-pdr gun and it was remarked:
'The gun on the Short is the biggest weapon yet used in aircraft. It was first used on the Sopwith, and later was used to test the Short's ability to stand the recoil.'
Aircraft No.127 is on record as being a Sopwith with 200-hp Canton-Unne engine, and it may be supposed that this and the Short machine were ordered as a pair for trials with heavy guns. That No.127 was of the well-known Greek Gun Bus type (see below) is certainly open to question, having regard to the fact that this was a much smaller machine than the Short No. 126, the respective wing spans being 50 ft and 67 ft; and there can be little doubt that No. 127 was the Hydro Biplane Type S of 80 ft span, already associated by J. M. Bruce with a quick-firing gun. Thus No. 127 must take its place in history, not only on account of its big gun, but as the largest British aeroplane of its time.
One Sopwith seaplane with 120-hp Austro-Daimler engine has also been recorded as having a gun. This was probably No.93.
Jane's All The World Aircraft 1913
SOPWITH. Sopwith Aviation Co. Works: Canbury Park Road, Kingston-on-Thames. School: at Brooklands. Established by T.O.M. Sopwith, the well-known aviator at Brooklands, Autumn of 1911, where during 1912, a 70 h.p. tractor biplane and a 40 h.p. biplane was turned out.
Floor area of the Kingston works in March, 1913, was 30,000 sq. ft. with electric power plant. Works manager: F. Sigrist. General manager: R.O. Cary. Output capacity: at full pressure about 50 machines a year.
1913. 1913. 1913. 1913.
Bat boat Tractor School Armoured
hydro biplane biplane. warplane.
Length......feet(m.) 30-1/3 (9.20) 29 (8.85) 9 (8.85) 29' 7?" (9)
Span........feet(m.) 41 (12.50) 40 (12.20) 40 (12.20) 50 (15.25)
Area.....sq.ft (m?.) 422 (39) 365 (34) 400 (37) 552 (51)
total...lbs.(kgs.) 1700 (771) 1750 (794) 1200 (544) 2000 (907)
useful..lbs.(kgs.) 500 (227) 750 (340) 400 (181) 800 (362)
Motor......... h.p. 90 Austro- 80 Gnome 50 Gnome 90 Austro-
max...m.p.h.(km.) 65 (105) 74 (125) 48 (78) 65 (105)
min.. m.p.h.(km.) 42 (68) 40 (65) 35 (60) 38 (61)
Endurance........hrs. ... ... ... ...
Notes.--Wood construction. Carriage wheels and skids. Control: balanced ailerons.
Flight, February 8, 1913.
WHAT THERE WILL BE TO SEE AT OLYMPIA.
The Sopwith Aviation Co.
Here, on Stand No. 22, will be shown two biplanes, one a water flyer and the other a land machine. Let us take the hydro-biplane first. It is, at the moment, receiving its finishing touches at the firm's works at Kingston, and, as soon as the Show is over, Mr. T. O. M. Sopwith proposes to take it out to Monaco to compete in the hydro-aeroplane meet there in April. It is driven by a 90-h. p. Austro-Daimler mounted on exceedingly strong ash and hickory supports, midway between the main planes. The main planes are arranged at a slight dihedral angle to one another. The machine's alighting gear consists of a double-skinned hydroplane hull built by Messrs. Saunders, the well-known yacht builders of Cowes. Tremendously strong, the hull only weighs 180 lbs., and it is wide enough abeam to seat pilot and passenger side by side. The tail is supported by tapering Farman-type outriggers, and an auxiliary elevator is arranged in front, over the bow of the hydroplane hull.
Flight, February 15, 1913.
SOPWITH AVIATION CO.
Two biplanes, one a hydro-biplane and the other constructed for land work, represent the Sopwith Co. on Stand 22. Both were designed by, and the construction carried out under the supervision of, Mr. T. O. M. Sopwith and his works manager, Mr. F. Segrits, at the Company's works at Kingston-on-Thames. They are no freak machines, these two biplanes of Sopwith's, a rough glance over them will soon convey to the observer that they are designed by practical men. Of the two, the hydro, is the more interesting since it is the more original.
The 90-h.p. Sopwith Hydro-biplane. - As the silhouette sketch that accompanies this description shows, it has a biplane unit somewhat of Farman type, mounted on a stepped hydroplane hull.
The hull, constructed by the well-known yacht builders, Messrs. Saunders, of East Cowes, I.W., is, roughly, 21 ft. in length, and is sufficiently wide in the beam - 4 ft., to be accurate - to seat pilot and passenger side-by-side. Its light framework is covered with two layers of cedar, laced together, and to the skeleton of the hull, by copper wire, a system of construction that Messrs. Saunders have protected by letters patent, and which they employ in building racing motor-craft. Although the hull is of a considerable size, the writer, when he was privileged to see the machine in course of construction, had no difficulty in lifting it; it only weighed 180 lbs. One of our sketches shows the section of the hull in the neighbourhood of the step, which is between 3 ins. and 4 ins. in depth, and which is placed 12 ft. from the stem post. The bottom of the hull being shaped in this manner, the float is rendered all the more seaworthy for it will not "hammer" to the extent that is noticeable with a flat-bottomed or concave -bottomed hull when "planing" over choppy water.
Supplementary wheeled chassis. - So that the machine may be capable of alighting on land as well as on the water, two wheels are provided, one on either side of the float. They are supported from a common axle member, passing through the hull, by short, hollow struts, beaten and welded up from 14 gauge mild steel. The wheels employed are 24 ins. in diameter, and, apart from the resiliency of the large 4-in. tyres used to shod them, no shock-absorbing devices are fitted. The wheeled chassis may be raised above the level of the bottom of the float, when the machine is being used for overseas work only by rotating the axle which supports it in the manner indicated by one of the sketches.
The plane construction. - Both upper and lower planes of the machine are of the same span, 41 ft., and are placed at a slight dihedral angle. They are separated by 12 struts and cross-braced by stranded steel cable in those bays on the same vertical plane as the main spars, while for front-to-back-bracing piano wire is used. The hollow construction of the main spars and of the struts is interesting. The spars are made from a centre portion, I section, cut from ash, to each side of which are bolted plain spruce faces of rectangular section. This makes a particularly strong yet light spar. The struts are made in a similar fashion, excepting that the central section of ash is of rectangular section to which hollowed out spruce cheeks are applied to give ample cross section and to shape the strut to a good streamline form. Our sketches will make these points clear. The ribs are built up of spruce flanges and cotton-wood webs, a hollow spruce nose strip makes a very satisfactory leading edge, and the trailing edge is kept trim by a piece of steel tubing of streamline section. Cotton-wood, by the way, seems to be an extraordinarily good wood to use for rib construction. It is light, and apparently refuses to split. It is possible to put one end of a Sopwith rib in the vice, and twist the other end through 180 without the rib showing any signs of either splitting or of showing a permanent deformation.
The ends of the planes are shaped with steel tubing. It may be as well to remark here that all metal work that is likely to become wet on the machine and so rust, is first heavily enamelled, then bound with glued tape and finally given a good doping over with fabric varnish.
The motor is a 90-h.p. Austro-Daimler, mounted on hickory bearers, and supported sideways between the planes by solid ash struts. These struts are very strongly cross-braced by the heavy gauge steel wire and by steel tubing, so that it would need a shock considerably more severe than is generally the lot of an aeroplane to experience, to dislodge it from its position and send it tumbling on the heads of the occupants seated in front of it. The motor drives direct a Levasseur propeller, 8 ft. 6 ins. in diameter.
The tail is a flat surface, 22 sq. ft. in area, and approximately rectangular in plan form. Behind it are hinged two flaps by which the elevation of the machine is controlled. It is supported by two spruce outriggers which meet at the rudder bar. The skeletons of all the tail organs are constructed of bent steel tube, with ribs of the same material, oxy-acetylene welded in position. There is a front elevator fitted above the nose of the float. Its area is equal to that of the two rear elevating flaps, that is 15 1/2 sq. ft.
Dual control is fitted and is in the form of a wide swinging bridge on which are mounted two vertical wheels, Deperdussin fashion for warping. Ruddering is done by the conventional form of foot bar.
Weighing 1,200 lbs. light, and designed to carry 450 lbs. of useful load, the machine is expected to show an average flight speed of 65 m.p.h. As soon as the Olympia exhibition closes Mr. T. O. M. Sopwith intends taking the hydro-biplane out to Monaco to compete in the hydro-aeroplane competition there in April next.
Flight, March 14, 1914.
WHAT THERE WILL BE TO SEE AT OLYMPIA.
Sopwith Aviation Co., Ltd. (44.)
OWING to press of work, and, in consequence, their inability to complete the second machine in time for the Show, this firm will only have one machine at Olympia - a two-seater bat boat of the Cusher type; a machine that somewhat resembles in appearance that built by Messrs. Sopwith for the Mortimer Singer Prize, but which is of more advanced design. We should have liked to have seen further examples of their workmanship and design, having in view their excellent record with both their land and sea machines, and we would especially recall the performance of the 100 h.p. Green-Sopwith hydro-aeroplane in the Circuit of Britain Race last August. But what they lack in quantity they have compensated for by quality, as the machine exhibited is one of the finest we have seen, and will be sure to attract considerable attention. The engine is a 200 h.p. 14-cyl. Salmson mounted upon the rear struts between the main planes, the radiator, which is of the honeycomb type, being placed on the front struts.
The whole machine will be of especially substantial construction, the boat being an extremely serviceable craft, and well provided with watertight compartments. The pilot and passenger sit side by side in a well in the centre of the boat. A wireless telegraphy outfit is fitted, driven by a Motosacoche engine, the whole of the apparatus being placed under cover immediately in front of the pilot. The machine is stated to be capable of climbing at the rate of 500 ft. per minute, and weighs 2,300 lbs. when empty, the useful load being about 1,000 lbs.
Flight, March 21, 1914.
THE OLYMPIA EXHIBITION.
SOPWITH (THE SOPWITH AVIATION CO., LTD.). (44.)
THE 200 h.p. machine exhibited on this stand is a development of the bat-boat which won the Mortimer Singer prize, and of the later type which has recently been delivered to the Navy. It is one of the finest examples of workmanship at the Show, and is a thoroughly sound piece of work throughout. The boat itself, as well as the machine, was built at the Sopwith works at Kingston. The boat is built up of two skins of mahogany over ash stringers. It is of the single-stepped type, the hull being of the displacement type in front, gradually flattening out towards the step, where it is perfectly flat. The method of leading air to the step is very ingenious. Instead of doing this by leading tubes through the interior of the boat, which necessitates piercing of the bottom, the same results have been obtained by sheet brass channels screwed to the sides of the boat, as shown in one of the accompanying sketches.
The engine, a 200 h.p. Salmson, is mounted on pressed steel frames on very thick ash bearers, between the rear inner pair of the plane struts, whilst the radiator is mounted between the two front struts. The inter-plane struts are of ample size, and are all made of spruce, with the exception of the inner two rear struts which carry the engine bearers, and which have therefore been made of ash. The whole structure is further strengthened by two oblique struts running down to the forward portion of the boat.
The pilot's and passenger's seats are arranged side-by-side in an extremely roomy cockpit, the pilot occupying the right-hand seat. Control is by wheel on a single tube for ailerons and elevator, whilst the rudder is actuated by a pivoted foot-bar. A very complete set of instruments is mounted on a neat instrument board, in front of the pilot, whilst in the left-hand side of the boat, and in front of the passenger's seat, is mounted the wireless set driven by a motor cycle engine. The main petrol tank, which has a capacity sufficient for four and a half hours' flight, is situated in the boat behind the occupants. Petrol is forced from this tank to a smaller service tank between the engine and the radiator, whence it is fed by gravity to the engine. Under the pilot's and passenger's seats are carried two compressed air self-starters by means of which the engine may be started from the pilot's seat without the necessity of swinging the propeller, a performance which would be extremely difficult, it not actually impossible, on a machine of this type. The four tail booms form a V as seen in plan. These and their struts are made of spruce. The fixed tail plane is flat, and is braced by four steel tubes running from its outer edges to the lower tail boom. The elevator is divided in order to allow of sufficient movement of the rudder, which latter is of the balanced type. There is no vertical tail fin on this machine. It will be noticed that the lower main plane has a very pronounced dihedral angle, in order, no doubt, to allow the machine to roll considerably without fear of the lower planes touching the water, this being further prevented by wing-tip floats of similar construction to that of the boat.
Flight, August 21, 1914.
THE "ROUND BRITAIN" MACHINES.
THE machine which was officially numbered 3 for the Circuit of Britain was
The Sopwith Bat Boat,
to have been piloted by Mr. Pixton. In its general lay out this machine is very similar to the seaplane which was the object of so much admiration at the last Aero Show at Olympia. Several alterations have, however, been effected, as, for instance, the substitution of a 200 h.p. Sunbeam engine for the Salmson Canton-Unne with which the Show machine was fitted.
The wings have also been slightly raised in relation to the hull, so that the lower main plane, instead of resting directly on the gunwales of the boat, as it did in the previous machine, is mounted on short stout struts coming up from the interior of the boat. Joined to these are the four inner inter-plane struts carrying the bearers for the engine - a 200 h.p. Sunbeam of the Vee type - mounted slightly above the centre of the gap between the planes. Of these the upper plane is straight and has a considerable overhang, whilst the lower one is set at a very pronounced dihedral angle, partly, no doubt, to increase the lateral stability of the machine, and partly in order to provide sufficient clearance to allow the machine to roll considerably on the sea without danger of the lower planes touching. The lower planes are further protected by wing tip floats of the cylindrical type.
The inter-plane struts are of ample section, and are made of spruce, with the exception of the inner ones, which, as they take the weight of the engine, have been made of ash. When the machine is in the act of alighting, the weight of the machine is taken by two oblique struts running from the front end of the engine bearers to the forward portion of the boat. As in the Show machine the radiator is mounted between the inner front inter-plane struts.
The tail outrigger, which forms a V, as seen in plan, is made up of four booms of spruce connected vertically and horizontally by struts of the same material. Mounted on top of the upper tail-booms, in such a manner that its angle of incidence can be varied, is the fixed tail-plane, which has a flat under surface and a slightly cambered top. Hinged to the trailing edge of this stabilizing plane is the divided elevator, and pivoted round the rearmost upright strut in the tail outrigger is the rudder, which is of large area and balanced. It will be noticed that no fixed fin is incorporated in the tail unit, all the vertical surface aft being provided by the rudder. Cross-bracing everywhere between the main planes, as well as in the tail outrigger, is effected by means of stout stranded cables, and all control cables are in duplicate.
Interesting as the aeroplane portion of the machine undoubtedly is, the hull or boat is even more so, incorporating as it does all the improvements that long experience with this type of craft has suggested to the designers.
Although following fairly closely on the lines of the boat of the last Olympia Show machine, several details have undergone alteration and improvement, making the Sopwith Bat Boat one of the finest examples of sea worthy flying machines in this or any other country.
In the nose the boat is of the displacement type flattening out gradually towards the step, where it is of hydroplane form. Just behind the step the bottom of the rear portion of the boat is slightly V-shaped, running out to a flat bottom at the stern. Constructionally the boat is built up of two skins of mahogany laid on in opposite directions over a strong framework of ash stringers. The front part is provided with a curved deck, which will quickly shed any water that may wash over it. In front of the occupants' seats the deck is swept upwards to form a wind screen, which also serves to protect pilot and passenger from water spray when getting off or alighting in a rough sea. The high freeboard of the boat further helps to make this an all-weather craft.
One of the numerous difficulties which beset the designer of hulls or floats of the stepped type is that of admitting air to the step. In the Sopwith Bat Boat this difficulty has been overcome in a most ingenious way by fitting external channels or scoops, screwed to the sides of the boat, thus doing away with the necessity of piercing the bottom as in the case of internal air tubes. As to the efficiency of this arrangement, one can only conclude that it has proved to answer its purpose, since after being thoroughly tested in previous machines it has been retained in this latest product of the Sopwith firm.
From the accompanying illustrations a good idea may be formed of the spacious accommodation for pilot and passenger, whose seats are arranged side by side inside the extremely roomy cockpit, the pilot occupying the right-hand seat. Ailerons and elevator are operated by means of a rotatable hand-wheel mounted on a vertical tube which is free to move in a forward and backward direction. The rudder is actuated by a pivoted foot bar. Large petrol and oil tanks, the capacity of which are 70 galls, and 7 galls, respectively, or enough for a flight of five hours' duration without replenishments, are fitted. The weight of the machine empty is 2,300 lbs., and with full load, including pilot, passenger, and fuel for five hours, the weight is 3,120 lbs. As the total area is 600 sq. feet, the loading works out 5 lbs. per sq. foot. A speed range of from 48 m.p.h. to 75 m.p.h. is anticipated, so that with five hours' fuel the radius of action is in the neighbourhood of 180 miles. By fitting larger tanks it should be possible, if desired, to increase this figure considerably.
In the event of the Sopwith Bat Boat being, or having already been, taken over by the Admiralty, there is no doubt that she would not only prove an effective addition to our fleet of seaplanes, but that she would also add considerably to the high reputation of the Sopwith Company.
Flight, February 6, 1919.
THE SOPWITH MACHINES
The Sopwith Bat Boat. (1914)
Although not included in the drawings, the Sopwith Bat Boat merits brief mention here on account of the good work done by this type of machine before the War. Thus it may be remembered that the Sopwith Bat Boat, which was first exhibited at the Olympia Aero Show of 1913 and which had a 100 h.p. Green engine, won the Mortimer Singer Trophy by starting off the sea, coming down on land, and starting from the land alighting on the sea again. This was accomplished by fitting it, in addition to the boat, with a collapsible wheel undercarriage. We are not quite certain but what this was the first flying boat to be built in Great Britain. A later type of bat boat is shown in another photograph. This was fitted with a 200 h.p. Salmson engine and differed from the previous type in various details. Thus, for instance, it had a straight top plane, while the bottom plane had a pronounced dihedral. Also it had a single rudder instead of the twin rudders of the previous model. Also the tail booms were so arranged as to form a Vee when seen in plan view. Boats of this type were ordered by Germany before the War, and from photographs later published in German aviation papers it would appear that the Germans made several copies of this machine, imitating the original down to the smallest details.