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).

J.Bruce British Aeroplanes 1914-1918 (Putnam)

A.D. Scout, the Sparrow

  THE A.D. Scout, or Sparrow, was designed in 1915 by Harris Booth and was intended to be an anti-Zeppelin fighter. The armament was to have been a Davis recoilless quick-firing gun, a weapon in which the Admiralty were then interested.
  The Sparrow was a single-engined pusher biplane of unusual appearance. Sketches of a wind-tunnel model depict a two-bay biplane of fairly large gap, with the nacelle attached to the upper wing: it appeared that the spars of the wing were attached to the underside of the upper longerons of the nacelle. An enormously tall undercarriage was necessary, but the track of the wheels was absurdly narrow. Presumably it was hoped that the widely separated twin tail-skids would provide sufficient ground stability.
  The tail-booms were parallel in plan and elevation, and supported a single tailplane of great span. There were two fins and rudders.
  The nacelle was an ugly, angular affair which had obviously been designed round the gun: the weapon was mounted on the floor of the nacelle, and the barrel protruded two feet in front. The engine was an 80 h.p. Gnome rotary mounted at the rear of the nacelle. The pilot sat well forward of the wings and must have had an excellent all-round view from his cockpit.
  Four A.D. Scouts were ordered - two from the Blackburn company and two from Hewlett & Blondeau. It is uncertain whether all were built, but at least one was completed and was flown at Chingford. The Sparrow turned out to be considerably overweight, and on test it proved to be unsatisfactory and tricky to fly. It was quickly abandoned.


SPECIFICATION
  Manufacturing Contractors: The Blackburn Aeroplane and Motor Co., Olympia, Leeds, Yorkshire. Hewlett & Blondeau, Ltd., Leagrave, Bedfordshire.
  Power: 80 h.p. Gnome.
  Approximate Dimensions: (Derived from drawings of a wind-tunnel model.) Span: upper 32 ft 4 in., lower 33 ft 5 in. Length: 22 ft 9 in., 24 ft 9 in. over gun. Height: 10 ft 3 in. Chord: 4 ft 6 in. Gap: 5 ft 9 1/2 in. Stagger: 1 ft 7 in. Dihedral: 3 30'. Span of tail: 21 ft. Wheel track: 2 ft 7 in. Track of tail-skids: 11 ft 2 in. Airscrew diameter: 9 ft.
  Serial Numbers: 1452-1453: ordered from Hewlett & Blondeau under Contract No. 38552/15. 1536-1537: ordered from Blackburn.

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

C.Owers British Aircraft of WWI. Vol.7: Experimental Fighters Part 3 (A Centennial Perspective on Great War Airplanes 81)

The A.D. Sparrow Scout

  The Admiralty was responsible for the aerial defence of the United Kingdom when war broke out in 1914. The air raids by German airships led to the Admiralty’s Air Department proposing in 1915 a fighter capable of operating in the anti-airship role. The Air Department’s “D” Section - the “D” standing for Drawing Office Section, but more accurately would be Design Section, as the office, under Harris Booth, produced its own designs and then contracted private firms to build them. Booth’s anti-zeppelin design, named Sparrow, was an unusual single bay biplane powered by a 100-hp Gnome Monosoupape rotary engine in pusher configuration at the rear of the nacelle.
  In order to save on materials that were in short supply, Booth made use of ordinary mild steel for all fittings, even designing special turnbuckles for the machine. The A.D. Scout was unorthodox in having a nacelle situated high with the upper wing spars meeting the top longerons of the nacelle. Strut connected ailerons were fitted to both wings. The pilot had an excellent field of vision; however, the wheel track was only 2 1/2 feet, and even with the skids incorporated into the landing gear, the high thrust line of the engine with the narrow track could only have resulted in gross unwieldiness in take-off, landing and taxiing.
  The tailplane spanned approximately 63% of the span. The tailplane was set high on the tail booms that were parallel in plan and elevation. Twin fins and rudders were fitted. The late Jack Bruce commented on the type: - What astonishes me most is the absence of any transverse connexion between the lower ends of the fins. What sublime faith they must have had in cables.
  Two machines were ordered from Hewlett & Blondeau of Leagrave, Bedfordshire, under Contract No. CP38552/16, (serial Nos. 1452 - 1453), and two from Blackburn Aeroplane & Motor Co Ltd of Leeds, (Nos. 1536 and 1537).
  The report of “Y” Section for the W/E 22 July 1915, recorded for Blackburn C.P.76201. Firm unable to tender for two Sparrow Biplanes - ask tender held over for present. Construction at Blackburn still went ahead, their tender being officially accepted nearly eight months later in the W/E 24 March 1916, their contract being No. CP104662/16.
  “D” Section was intimately involved with the manufacturers, and for the W/E 20 August 1915, reported that During the week a number of questions of approvals of design have been dealt with, notably in the case of the Hewlett & Blondeau Sparrows, the 150 H.P single seater Avro and the Handley Page machines. Hewlett & Blondeau were concerned about the narrow undercarriage and they designed and built an alternative undercarriage that had a wider track but this was rejected and the original had to be adhered to.
  The following reports for the next two weeks noted that during the week Messrs. Hewlett & Blondeau and Messrs. Blackburn have been visited in connection with the completion of the Sparrow Machines. Delivery of this is fixed to take place at Chingford, the trial flight being carried out by an Admiralty Pilot.
  During the W/E 25 Sept 1915, “D” Section personnel paid a visit to Chingford regarding the erection of the Sparrows. This would have been No. 1536 that was being erected there by the makers from the 23rd.
  The last report to mention the Scout was that of “K” Section. Lt Hardstaff visited Chingford on Monday 6 February 1916, re the A.D. Scouts. With regard to modifications to be carried out on the aileron control nothing has so far been done. No. 1536 had completed its tests by then, and was dismantled by 17 March. No. 1537 was tested at Chingford, then sent to the Central Supply Depot, White City.
  The Hewlett & Blondeau constructed machines were both tested at Chingford. No. 1452 being delivered on 15 November 1915, and tested on 2 December.
  Nos. 1452 and 1536 were reported on 1 April 1916 as - Sparrows dismantled at Chingford.
  Both Hewlett & Blondeau machines were sent to White City, and all four Sparrows were deleted on 7 June 1916. However, the Daily Reports noted that at the Central Supply Depot the list of aircraft in store included four A.D. Scouts unpacked. It seems that, as usual, the paperwork and the activity on the ground were not in sequence, although the machines were officially deleted, they were not destroyed on that date.
  The machines are believed to have been heavier than estimated and to have had unfavorable flight characteristics. It was soon apparent that ordinary aircraft could undertake the task of anti-zeppelin fighters and that the A.D. Scout was a dead end. The Davis recoilless gun has been presented as the proposed armament for the A.D. Scout, however the near impossibility of mounting that weapon in the airframe rules this out, even if it was considered. Reports only mention the Lewis gun as the armament.
  

A.D. Sparrow Scout Specifications
Span 33 ft 5 in
Length 22 ft 9 in
Height 10 ft 3 in
Speed Max 84 mph
Climb to 3,000 ft 5 min
Climb to 6,500 ft 12 min
Climb to 10,000 ft 25 min
Endurance 216 hrs
Source: J.M. Bruce data.