A.Jackson Blackburn Aircraft since 1909 (Putnam)
Designs to an Admiralty requirement for a single-seat fleet escort bomber to replace the Blackburn-built Sopwith Baby seaplane, made known in 1916 as category N.1B, were prepared by the Blackburn Aeroplane and Motor Co Ltd at Leeds, the Supermarine Aviation Works Ltd at Southampton, and the Westland Aircraft Works at Yeovil. Contracts were placed for eight prototypes, three by Blackburn, three by Supermarine and two by Westland. All were known as N.1B, but whereas the Westland machines N16 and N17 were twin-float seaplanes somewhat similar to the Sopwith Baby, the three Supermarines, N59, N60 and N61, were small pusher flying-boats.
The Blackburn N.1B design resembled Supermarine's concept of the requirement in that it too was a pusher flying-boat employing a hull of Linton Hope design. This was built to a system created by Lt Linton Hope, RN, and consisted of circular wooden formers spaced by stringers and planked diagonally with narrow mahogany strips one-eighth of an inch in thickness, in two laminations so that the layers crossed each other at 90 degrees. There the resemblance ended, for the Supermarine boat was constructed on strictly utilitarian lines and had a monoplane tail while the Blackburn N.1B was a sesquiplane of inspired design using a hull of refined and delicate aerodynamic form. Armament was to have been a single Lewis gun mounted on the nose in front of the pilot.
The hand of Harris Booth, who had joined Blackburns from the Air Department of the Admiralty in 1915, can be detected in the design of Blackburn's Machine, not only through general similarity of layout to the early A.D. Flying-Boats (of which the Supermarine N.1B was a descendant), but in minor design features such as the shape of the wing tip floats and the retention of a biplane tail using an inverted RAF14 aerofoil section on the upper tailplane to hold the tail down with engine on if nose heavy and automatically take up a correct gliding angle if the engine failed.
The mainplanes were built round rectangular box spars with two-ply spruce webs and spruce flanges. They were designed to fold to a mean width of 11 ft 2 in, and it is probable that it was intended to have jettisonable wheels for taking-off from the decks of naval vessels.
The two-step hull swept gracefully upwards at the rear, but even so the lower tailplane would have been awash when the aircraft was taxying. It is probable therefore, in the absence of precise details, that this was to have been a watertight plywood structure as on the A.D. Flying-Boats. The ends of all aerofoil surfaces were elliptical, directional control was by twin rudders, and ailerons were fitted to all four wings. Power was supplied by a 200 hp Hispano-Suiza engine, mounted high up under the top centre section, driving a two-bladed, fabric-covered, mahogany airscrew and cooled by a circular radiator mounted in front. Fuel was carried at the C.G. in a midships tank.
Supermarines and Westlands built and flew their prototypes during 1917-18, but successful deck operations by the Sopwith Pup and a promise of an even better performance by its successor the Camel, led to a cancellation of the N.1B contracts in November 1918. Non-availability of the engine slowed down the work of construction at Leeds and, when work ceased, Blackburns had completed only the hull of their first machine N56, and the other two, N57 and N58, existed merely as a number of sub-assemblies.
The completed hull of N56 was put into storage, but was taken out in 1923 and used in the construction of Blackburn's Schneider Trophy entry, the Pellet.
SPECIFICATION AND DATA
Manufacturers: The Blackburn Aeroplane and Motor Co Ltd, Olympia Works, Roundhay Road, Leeds, and Brough Aerodrome, East Yorks.
Power Plant: One 200 hp Hispano-Suiza
Span (upper) 34 ft 10 in (lower) 29 ft 4 in
Length 28 ft 3 1/2 in Wing area 314 sq It
Weights: Tare weight 1,721 lb All-up weight 2,390 lb
Maximum speed 114 mph Climb to 5,000 ft 7 min
Ceiling 16,000 ft Range 340 miles
Production: Hull of N56 only; N57 and N58 incomplete.
Flight, December 11, 1919.
THE BLACKBURN MACHINES.
The "N1b" Flying Boat
The next machine to be laid down was a seaplane of the flying boat type, known as the "N1b." Owing to certain changes in Service requirements this machine was not actually completed, although we understand that both design and construction were nearly finished. It will therefore be understood that the figures of performance, etc., are estimated ones. The "N1b" was intended to act as escort to our large bombing flying boats.