A.Jackson Blackburn Aircraft since 1909 (Putnam)

Blackburn Triplane

  While the batch of T.B. seaplanes was going through the Blackburn works, the firm was also engaged in the construction under contract of two examples of another anti-Zeppelin fighter, the A.D. Scout (later known as the Sparrow), designed by Harris Booth of the Air Department of the Admiralty. This aircraft was a heavily-staggered, single-bay biplane of extremely unorthodox appearance, built to meet an Admiralty requirement for a fighter built from commercially obtainable materials and which could be armed with the Davis two-pounder quick-fire recoilless gun. This lay in the bottom of a short, single-seat nacelle, the top longerons of which were bolted directly to the main spars of the upper wing. With the 100 hp Gnome Monosoupape rotary driving a 9-ft pusher airscrew behind his back, the pilot had a superlative view in nearly every direction.
  The aircraft's extraordinary appearance stemmed from the fact that the abnormally large mainplane gap was below instead of above the nacelle, and because the twin fins and rudders, no less than 11 ft apart, were mounted on two pairs of parallel outriggers and supported a vast tailplane of 21-ft span. A suitably bizarre undercarriage reversed the usual pattern, the three points of contact with terra firma being widely spaced skids under the fins and a pair of small wheels mounted close together centrally under the lower mainplane. In this respect it was similar to the Armstrong Whitworth F.K.12 triplane and the projected Bristol F.3A escort and anti-Zeppelin fighters, for it seems that Harris Booth believed in the 'pogo stick' type of landing gear as a means of simplifying cross-wind landings at night.
  Four prototype aircraft only were ordered, 1452 and 1453 from Hewlett and Blondeau Ltd of Leagrave, Beds., and two others, 1536 and 1537, from Blackburns. They were all delivered to RNAS Chingford, but being considerably above their estimated all-up weight and difficult to handle in the air, were scrapped.

SPECIFICATION AND DATA
  Manufacturers: The Blackburn Aeroplane and Motor Co Ltd, Olympia Works, Roundhay Road, Leeds, Yorks.
  Power Plant: One 100 hp Gnome Monosoupape
  Dimensions:
   Span 33 ft 5 in Length 22 ft 9 in
   Height 10 ft 3 in
  Performance: No confirmed details
  Production:
   Four aircraft only, 1452 and 1453 by Hewlett and Blondeau Ltd; 1536 and 1537 by Blackburn, to Contract 38552 15

H.King Armament of British Aircraft (Putnam)

A.D. Scout (Sparrow). This aeroplane must be considered a curiosity not only in respect of design and construction but of armament and propulsion also: for if, as stated on the best authority, the intended weapon was a Davis recoilless gun, and if this was to lie on the floor of the nacelle, as indicated by drawings, then the engine and airscrew must have been of singular construction to withstand the blast of the rearward charge, even if this propelled a dose of Epsom salts, as it is known to have done on one occasion at least, in any case, the A.D. Scout is a notable machine in aeronautical history, for even if the gun was a Lewis machine-gun, as suggested by one drawing, and if this was fixed, as indicated by other evidence, the 'Admiralty Scout' (designed 1915) may well have been Britain's first fixed-gun fighter. Whether armament of any kind was actually installed is not known, but there is photographic and other proof of a sturdy pillar at the front of the nacelle, the tip of the pillar lying at the level of the pilot's eyes. This pillar may well have been associated with a sight

P.Lewis The British Fighter since 1912 (Putnam)

Among the single-seat fighters designed during 1915, as weapons to deal with the marauding Zeppelins, was the A.D. Scout, known also as the Sparrow, Harris Booth of the Air Department of the Admiralty being the man responsible for the design. The machine was intended to bear aloft the Davis recoilless gun and this was to be housed in the lower part of the pusher biplane’s nacelle.
  A comparatively large gap separated the two pairs of wings, and the nacelle was attached to the underside of the upper pairs of planes. Parallel struts were incorporated in the undercarriage, their length resulting in the cockpit being at an inordinate height above ground level. Extremely large tailplane and elevator surfaces, short-coupled, were carried by the four tail-booms, in between which revolved the pusher propeller and its 80 h.p. Gnome engine. The very narrow track of the wheels combined with the high centre of gravity of the machine, could have resulted only in gross unwieldiness and instability while taxiing and during take-off and landing. Strut-connected ailerons were incorporated on all four of the single-bay wings and twin fins and rudders filled the gap at the rear of the tail booms.
  The whole concept was an unfortunate and unsatisfactory one, about the only point in its favour being the fine view enjoyed by the otherwise hapless pilot. Test flights, soon proved the fallacy of the design, to which two airframes were constructed by Blackburn. An order for a further pair of A.D. Scouts was placed with Hewlett and Blondeau but confirmation of their actual building is lacking.

F.Mason The British Fighter since 1912 (Putnam)

A.D. Sparrow

  Following the creation of the Naval Wing in 1912, the Admiralty established an Air Department whose purpose was to deal with all matters relating to naval aviation. The popular but eccentric Harris Booth, late of the National Physical Laboratory, was given charge of all technical considerations and, in due course, headed an aircraft design section whose products were to be contracted out for manufacture by private companies.
  One of Booth’s first designs was the A.D. Sparrow, or Scout, of 1915, an extraordinary-looking pusher biplane intended for anti-Zeppelin fighting, and to be armed with a two-pounder Davis recoilless, quick-firing gun; and it was the installation of this weapon that dictated the design of the nacelle. The A.D. Sparrow was a single-bay, heavily-staggered biplane, powered by an 80hp Gnome rotary engine; the tail booms were rigged parallel in plan and elevation and carried an enormous 21ft-span tailplane and elevator with widely-spaced twin fins and rudders. In order to provide ground clearance for the propeller, the nacelle was attached to the upper wings and, with large wing gap, the lower wing was a continuous structure placed five feet below the nacelle. A twin wheel-and-skid undercarriage of exceptionally narrow track was fitted, stability on the ground being achieved by the tail skids at the base of the tail fins.
  Almost certainly owing to the esteem in which Booth was held, four examples of the Sparrow were ordered - two from the Blackburn Aeroplane & Motor Co of Leeds, and two from Hewlett & Blondeau Ltd. It is said that all four were built and delivered to the RNAS at Chingford, Essex, but, being somewhat overweight and underpowered, were found to be difficult to control in the air and were soon abandoned. As far as is known, the Davis gun was never fitted.


  Type: Single pusher engine, single-seat, single-bay biplane scout.
  Manufacturers: The Blackburn Aeroplane & Motor Co Ltd, Leeds; Hewlett & Blondeau Ltd, Leagrave, Bedfordshire.
  Powerplant: One 80hp Gnome rotary engine driving two-blade propeller.
  Structure: Predominantly wood with fabric covering; twin wheel-and-skid undercarriage.
  Dimensions (Approx only,): Span, 33ft 5in; length, 22ft 9in; height, 10ft 3in.
  Weights and Performance: Not known.
  Armament: Intended to be armed with one 2-pdr Davis recoilless, quick-firing gun in the nose of the nacelle.
  Prototypes: Four, Nos 1452-1453 (Hewletts), and 1536-1537 (Blackburn). No production.

W.Green, G.Swanborough The Complete Book of Fighters

A.D. SCOUT (SPARROW) UK

  Designed by Harris Booth of the Air Department of the Admiralty as a single-seat anti-airship fighter, the A.D. Scout - later to become known unofficially as the "Sparrow” - was an extraordinary single-bay staggered biplane intended to carry a Davis two-pounder recoilless gun. The rudders and outsize tailplane were carried by four parallel tailbooms, and the unusual appearance of the A.D. Scout resulted primarily from the fact that the large mainplane gap was below rather than above the nacelle accommodating the pilot. The gun was intended to be mounted in the bottom of the nacelle, to the tail of which was attached a 100 hp nine-cylinder Gnome Monosoupape rotary engine driving a pusher propeller. Construction was of wood with fabric covering, and four prototypes were ordered and built (two by Hewlett & Blondeau and two by Blackburn) in 1915. Delivered to the RNAS, the A.D. Scouts proved seriously overweight and difficult to handle in the air. In consequence, all four aircraft were scrapped.

Max speed, 84 mph (135 km/h).
Endurance, 2.5 hrs.
Span, 33 ft 5 in (10,18 m).
Length, 22 ft 9 in (6,93 m).
Height, 10 ft 3 in (3,12 m).