D.James Westland aircraft since 1915 (Putnam)
Although the Royal Air Force had not been founded until 1 April, 1918, during the last few months of the 1914-18 War a number of new single-seat fighters designed to meet the RAF Type I Specification were nearing completion. Among those companies producing prototypes was Westland whose small design team, led by Robert Bruce and Arthur Davenport, had been considering the design of a small fighter during the latter half of 1917. One of the requirements of the outline Type I Specification for a light fighter was that it should have an engine delivering 50 hp more than the 130 hp Clerget rotary engine in the Sopwith Camel. This increase in power, plus the smaller size implicit in the 'light fighter' description, was aimed at producing a performance which would exceed that of the Camel, both in terms of maximum speed and rate of climb, with improved handling characteristics.
At about the time when this specification was issued the Air Board was examining a recently-introduced experimental seven-cylinder air-cooled radial engine. Designed by Granville Bradshaw who had founded ABC Motors, the successor to ABEC (All British Engine Company), it weighed 290 lb, was of 657 cu in capacity and produced 170 hp. Named Wasp, it was engineered throughout for easy production; however, one of its design features, which was the use of copper-plated steel cooling fins on the cylinders, was to contribute to its future unreliability. It was this engine which the Westland design team had in mind for possible use in its private venture light fighter, provisionally known as the Hornet, and which was to power it when built as the Wagtail.
Of conventional external appearance and construction, the Wagtail had a wooden girder type fuselage. rectangular in section for most of its length, with light wood fairings to provide shape. Spruce longerons of square-section were employed with staggered vertical and horizontal spacer struts tapering to fit into square cups in light steel fittings bolted to the longerons. These fittings also carried attachment lugs for the swaged rods which braced each bay of the fuselage structure. The braced tailplane and fin were of similar wooden construction while the elevators and rudder were of metal. The rear fuselage aft of the cockpit, which was located under the upper wing trailing-edge, was fabric covered and removable fabric covered panels enclosed the cockpit and the forward fuselage, wire-braced engine mounting ring with four attachment plates was carried on inwardly curved extensions of the longerons with the entire nose and engine having removable metal top and side panel and a metal cowling through which the Wasp's seven cylinders protruded. Inverted-V main undercarriage legs of spruce carried a cross-axle with bungee rubber shock absorbers and a curved tailskid was mounted below the tailplane leading-edge. The main spars of the constant-chord single-bay wings were of ash with cross-braced drag struts and the spruce ribs of RAF 15 aerofoil section were built up from three-ply webs with spruce capping strips.
The Type I Specification stressed the need for a good all-round view for the pilot; thus the flat wide-span upper centre-section - a feature to minimise the spar bending moment - had a large trailing-edge semi-circular cut-out above the cockpit, and was supported on two pairs of outwardly-canted struts. Constant-chord wide-span ailerons were carried on both the upper and lower wings which, in the prototype Wagtail, C4291 , had the same 2 1/2 deg dihedral and were wire-braced. The wings and tail unit were fabric-covered. In this aircraft too the fin had a long dorsal extension well in front of the tailplane leading-edge. Control wires to the ailerons and rudder ran inside the wings and fuselage but were carried externally to the elevator. Fuel was carried in a 26 gal fuselage-mounted tank in front of the cockpit, two synchronised Vickers .303 in guns were mounted on top of the fuselage and oxygen equipment was located in the cockpit.
Originally six Wagtails were ordered by the Air Board and allocated the serials C4290-96 but the contract was later reduced to three aircraft, C4291-93. Construction of the first Wagtail airframe was completed by the end of February 1918 with production of two more, C4292 and 4293, well in hand; however C4291's Wasp engine was still awaited from the manufacturer. During this period Capt F Alexander, Royal Flying Corps, was attached to Westland Aircraft Works to fly the Wagtail. With operational experience he believed that the cut-out in the prototype's centre-section should be larger. Because a modification at that stage would have delayed the first flight, a re-designed centre-section was first fitted, as a trial installation, to the incompleted third aircraft. The three central rib aft of the front spar and the centre-section trailing-edge were removed leaving a wide aperture spanned only by the nosing and the rear spar. This new centre-section was mounted six inches lower than on the prototype and in order to use the same length faired tubular steel interplane struts and bracing wire, the lower wings were re-rigged flat and the upper wings given 5 deg dihedral. While the modified centre-section improved the pilot's view, what was not quantifiable or immediately recognisable was the effect the loss of wing area had upon wing lift and air flow disturbance.
The first flight date of 4291 has not been established; however, it is known that it took place early one morning in April 1918, and that the Wagtail's handling characteristics were such that they inspired apt Alexander to execute a loop. This test flight also suggested that there was insufficient rudder area to counteract the nose-down effect of the fin in a side-slip; in order to minimise the time and cost involved in building a larger rudder, it was decided to cut back the fin to about half of its length. Meanwhile, work on fitting the modified centre-section and fin to the second and third aircraft was in progress.
Within a week or so the first of many engine snags, which were to plague the Wasp, were encountered and it was removed from C4291 for return to the manufacturer. Much of the trouble stemmed from valve and cylinder design and cooling. When C4291 's engine was returned to Yeovil it was fitted to the second Wagtail, C4292, which had the modified centre-section and wings and was nearer completion than the third airframe. With this engine test flying was resumed on 29 April; but soon afterwards this Wagtail was badly damaged while in a canvas Bessoneaux hangar at Yeovil which had caught fire when an employee had been endeavouring to prove that he could extinguish a lighted cigarette in a can of petrol!
With the arrival of two more Wasp engines the third Wagtail was quickly completed, enabling it to fly early in March, and work on modifying the prototype's centre-section and fin was pressed forward. On 8 May C4293 was flown to the Aircraft Experimental Establishment at Martlesham Heath for 'fighter trials' with a number of different propellers. Unfortunately, after a badly executed landing on 18 May, the Wagtail nosed over on rough ground damaging the engine and undercarriage. After repairs this aircraft was transferred to the Royal Aircraft Factory at Farnborough on 27 May, only a few days before it was renamed Royal Aircraft Establishment, a name it was to retain for the ensuing 70 years. There it was used by the RAE and ABC to investigate the source of the Wasp's problems; but the programme was short-lived for two weeks later all trials of Wasp-powered aircraft - which included the Sopwith Snail and the BAT Bantam - were halted. However, it is recorded that, in July 1918, C4293 was at Martlesham Heath for 'motor trials' but for how long is not known.
The prototype Wagtail, meanwhile, had been re-engined and the airframe modifications had been embodied. It flew again at about the same time that Wasp investigations ceased; nevertheless it went to the RAE thereafter and is recorded as having been at Martlesham Heath during August for evaluation against other fighters, presumably the Camel, Snail and Bantam. Then, on 6 November it went to the Aircraft Armament and Gunnery Experimental Establishment at Orfordness for gun firing trials. By this time not only was the War finished but all flying trials with Wasp-powered light fighters had been terminated and production of this engine been cancelled. Nevertheless, like Charles II, the Wagtail/Wasp combination was 'an unconscionable time dying' and on 29 January, 1919, the rebuilt airframe of the second aircraft, C4292, arrived by road at Martlesham Heath where it was to remain at least until 1920.
In spite of numerous problems with the Wasp, ABC continued to develop this engine and one of the Wagtails is reported to have flown with a 200 hp Wasp II. But this was not the end of Wagtail production for in 1920 two more Wagtails were ordered, powered by the new 150 hp Armstrong Siddeley Lynx seven-cylinder air-cooled radial engine. Serialled J6581 and J6582, airframe modifications included shortening the fuselage by removing the metal-panelled bay aft of the engine to maintain the centre of gravity with the heavier Lynx, changing the shape of fin and rudder to a 'comma' shape and fitting a stronger main undercarriage to suit the increased all-up weight. These two aircraft were flown at the RAE and at Martlesham Heath until about 1922, some record indicating that at least one, J6582, having also been powered by a Wasp II.
Description: Single-seat light biplane fighter. Wood/metal construction with fabric and metal covering.
Accommodation: Pilot in open cockpit.
Powerplant: One 170 hp ABC Wasp seven-cylinder air-cooled normally-aspirated radial engine driving a two-blade 7 ft 4 in diameter wooden propeller.
Armament: Two fixed synchronised Vickers .303 in machine-guns mounted on top of the fuselage, with 1,000 rounds of ammunition.
Dimensions: Span 23 ft 2 in: length 18 ft 11 in; height 8 ft 0 in; wing area 190 sq ft.
Weights: Empty 746 lb; loaded 1,330 lb.
Performance: Maximum speed at 10,000 ft 125 mph; landing speed 50 mph; climb to 5,000 ft in 3.5 min, to 17,000 ft in 17 min; service ceiling 20,000 ft.
Production: Five Wagtail built by Westland Aircraft Work, Yeovil, Somerset, during 1917-20.
H.King Armament of British Aircraft (Putnam)
Wagtail. A light single-seat lighter of 1918, the Wagtail earned its two Vickers guns externally immediately forward of the cockpit sides. The case chutes were very low in the fuselage in metal panels let in to the fabric covering and were canted down at an angle of about 45 degrees to the line of flight. The windscreen had a hole on the starboard side to receive the eyepiece of the Aldis sight. On the centre line was a ring-and-bead sight, with the bead immediately ahead of the windscreen. Westland gave the weight of' 'two guns, gear and 1,000 rounds' as 160 lb.
Jane's All The World Aircraft 1919
The Westland "Wagtail" was designed in answer to a general demand for a fast, quick-climbing, general utility single-seater fighter.
It conforms in general arrangement with most other machines of this type.
The pilot's view is very good both upward and downward, more than half the centre section being left open. Main planes of equal span are fitted, the upper plane having a dihedral of 5 degrees, whereas the lower plane is flat, i.e., no dihedral.
THE WESTLAND "WAGTAIL."
Type of machine Single-seater Tractor Scout.
Name and type No. of machine Westland "Wagtail."
Purpose for which Intended High altitude fighting.
Span 23 ft. 2 in.
Gap maximum At outer strut 4 ft. 6 in.
minimum Centre section 4 ft.
Overall length 18 ft. 11 In.
Maximum height 8 ft.
Chord 4 ft 6 in.
Total surface of wings 190 sq. ft.
Span of tail 7 ft. 10 3/4 In.
Total area of tall, incldg. elevators 25 sq. ft.
Area of elevators 9.5 sq. ft.
Area of rudder 4.4 sq. ft.
Area of fin. 2.1 sq. ft.
Area of each aileron 6 sq. ft.
Total area of ailerons 24 sq. ft.
Maximum cross section of body 7.1 sq. ft.
Horizontal area of body 29.3 sq. ft.
Vertical area of body 36.5 sq. ft.
Engine type and h.p. 170 b.h.p."Wasp" Fixed Radial.
Airscrew, diam., pitch and revs. Pitch 2070 m/m., diam. 2590 m/., revs. 1,900.
Weight of machine empty 965 lbs. (Including 219 lbs. for fuel and oil).
Weight of machine empty 746 lbs. (without fuel and oil)
Load per sq. ft Fully loaded 7 lbs.
Weight per h.p. 7.7 lbs.
Tank capacity In hours 2 1/2 hours at 15,000 feet.
Tank capacity In gallons Petrol 26 galls.; oil 3 galls.
Speed at 10,000 feet 125 m.p.h
Landing speed 50 m.p.h.
To 5,000 feet 3 1/2 minutes.
To 10,000 feet 7 1/2 minutes.
To 17,000 feet 17 minutes.
Disposable load apart from fuel 365 lbs
Pilot 180 lbs
Two guns, gear & 1,000 rounds 160
Total weight of machine loaded 1,330 lbs.
W.Green, G.Swanborough The Complete Book of Fighters
WESTLAND WAGTAIL UK
A contemporary of the Sopwith Snail and the BAT Bantam, the Wagtail was similarly designed to comply with the A.1(a) Specification drawn up by the Air Board in 1917 to define its requirements for a single-seat fighter. Emphasis was to be placed upon manoeuvrability and climb, with the ability to achieve 135 mph (217 km/h) at 15,0 ft (4 570 m) when carrying oxygen equipment and three machine guns. Like its competitors, the Wagtail was powered by the 170 hp ABC Wasp I seven-cylinder radial, an engine that eventually thwarted further development of all three A.1(a) types. A well-proportioned, diminutive single-bay biplane, the Wagtail gained a contract for three prototypes late in 1917, and the first was flown in April 1918. Construction was of fabric-covered wood, with metal-framed rudder and elevators, and two synchronised 0.303-in (7,7-mm) Vickers guns were fitted. An overwing Lewis gun was planned, but not fitted to the prototypes. Whereas the first Wagtail to fly had equal dihedral (2 deg 30 min) on upper and lower wings, the second and third were completed (and the first later modified) to have a larger cutout in the upper wing centre section with 5 deg of dihedral on the outer panels of the upper wing and a flat lower wing. Destroyed in a fire at Yeovil soon after its first flight on 29 April 1918, the second Wagtail had to be replaced later that year; the third went to Martlesham Heath on 8 May, but problems with the Wasp limited flying. In October 1918, the engine was officially abandoned, and with it any plans to produce Wasp-engined aircraft. Two more Wagtails were ordered from Westland in 1919, to serve as test-beds for the 160 hp Armstrong-Siddeley Lynx seven-cylinder radial engine. Unarmed, these two aircraft were delivered to the RAE in September/October 1921. The following data for the Wasp-engined Wagtail include performance estimates.
Max speed, 125 mph (201 km/h) at 10,000 ft (3 050 m).
Time to 5,000 ft (1 525 m), 3.5 min.
Endurance, 2.5 hrs.
Empty weight, 746 lb (338 kg).
Loaded weight, 1,330 lb (603 kg).
Span, 23 ft 2 in (7,06 m).
Length, 18 ft 11 in (5,77 m).
Height, 8 ft 0 in (2,44 m).
Wing area, 190 sq ft (17,65 m2).