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Armstrong Whitworth Ara

Страна: Великобритания

Год: 1919


Armstrong Whitworth - F.M.4 Armadillo - 1918 - Великобритания<– –>Armstrong Whitworth (Siddeley) - S.R.2 Siskin - 1919 - Великобритания

O.Tapper Armstrong Whitworth Aircraft since 1913 (Putnam)


  In 1917 a new engine had emerged which promised to give decisive air superiority to future British fighters: this was the A.B.C. Dragonfly radial engine which was supposed to give 320 hp for a weight of only 600 lb. Murphy, like many other designers, was quick to appreciate what might he accomplished with a powerplant of this calibre, and early in April 1918 Armstrong Whitworth asked the Air Ministry for blue prints of the Dragonfly; in reply, the Assistant Controller, Design, suggested that the company should not embark on a new design until the Armadillo had been tested, and that it would be advisable to have discussions with the Assistant Controller about which type of aircraft should next he undertaken. But Armstrong Whitworth had their own ideas on the subject and, in spite of the official advice, Murphy went ahead with the design of a Dragonfly-engined fighter. At some stage in the proceedings the official policy must have changed, for three examples of the new fighter, later to he named the Ara, were ordered. The Ara should logically have borne an F.M. number, presumably F.M.5, but it never seems to have carried this designation.
  This second Armstrong Whitworth single-seat fighter retained the two-bay type of wing structure and the same type of slab-sided fuselage which characterized the Armadillo, but this time the top wing was raised a short distance above the fuselage, although the gap was still somewhat narrow. The wings were of equal span, but the chord of the lower wing was less than that of the top wing. The tailplane was conventional, with the fin and rudder, like those of the Armadillo, rather on the small side. The Dragonfly engine was neatly installed in a cowling that faired smoothly into a pointed spinner on the propeller boss. Comparative figures, if they are to be believed, show that the Ara, like the Armadillo, had an unusually low structure weight; both aircraft were of roughly the same size, but the Dragonfly engine weighed some 150 lb more than the B.R.2 rotary; nevertheless, the Ara was only about 70 lb heavier than the Armadillo and both had approximately the same useful load.
  Like its numerous contemporaries, the Ara had no chance of survival because the Dragonfly engine failed completely to fulfil its initial promise. It had been designed by Granville Bradshaw whose object was to produce a light, high-powered radial which would be easy to build on a large scale. Unfortunately, the authorities were too easily persuaded by Bradshaw's optimism, and the engine was put into production before adequate testing had taken place. In the event, the Dragonfly, on which the nation's biggest production effort was to be concentrated, not only failed to develop the power expected, but suffered, among other troubles, from a species of high-frequency vibration which led to the wrecking of the engine after a few hours' running. At that time there was no known cure for this trouble and the whole engine production programme had eventually to be abandoned. Fortunately the war ended before the full impact of this debacle could have its effect.
  The first Ara, F4971, was completed during the summer of 1918, but no engine was immediately available. By the time the first engine was delivered to Armstrong Whitworth in December, it had already been decided that the Ara would not be put into production; the war was over, and by now the Dragonfly's troubles were beginning to become apparent. Nevertheless, two of the three aircraft ordered were completed, the second aircraft, F4972, having a larger gap with the lower wing running below the fuselage. Work on the third airframe was discontinued at a late stage of construction. Because of engine unreliability, no systematic trials were carried out with the Ara, but such figures as are available indicate that, when the engine worked, the aircraft had a good performance, with a top speed of about 150 mph at sea level, and the ability to climb to 10,000 ft in 4 1/2 min. The ultimate fate of the two aircraft is not known, but doubtless they soon found their way on to the scrap heap. The Ara was the last of the Armstrong Whitworth designs to be built at Gosforth and, as recorded elsewhere, the company's aeroplane department was closed down at the end of 1919.


  Dimensions: Span 27 ft 5 in (8.36 m); length 20 ft 3 in (6.17 m); height 7 ft 10 in (2.39 m); wing area 257 sq ft (23.88 sq m).

   320 hp A.B.C. Dragonfly
Max weight: 1,930 lb (875 kg)
Empty weight: 1,320 Ib (599 kg)
Max speed
  Sea level: 150 mph (241 km/hr)
  10,000 ft (3,048 m): 145 mph (233 km/hr)
  to 10,000ft (3,048m) 4.5 min
Service ceiling: 28,000 ft (8,534 m)
Endurance: 3 1/2 hr

P.Lewis The British Fighter since 1912 (Putnam)

Two further single-seat fighters were planned under the R.A.F. Type 1 conditions. These were the Armstrong Whitworth Ara and the Nieuport Nighthawk but neither machine was ready before the beginning of 1919.
  Designed by F. Murphy, the Ara shared the same unhappy type of engine as the Nighthawk - the 320 h.p. A.B.C. Dragonfly 1 - and retained the same two-bay wing layout as Murphy’s earlier Armadillo. The fuselage was unusually deep-sided towards the rear where it would normally have been expected to have tapered steadily in elevation. In F4971, the first prototype, the fuselage rested on the lower wings but F4972 introduced greater gap between the mainplanes, resulting in the lower wings passing beneath the fuselage. The fore-part of the fuselage housed two Vickers guns and the Ara turned in the useful top speed at ground level of 150 m.p.h. The Ara was typical of the trend of the final generation of fighters which made their debut at the end of the War and this styling was shared by the Nieuport Company’s Nighthawk.

H.King Armament of British Aircraft (Putnam)

Ara. Designed in 1918, like its rivals the Snark, Snapper and Siskin, the Ara (completed 1919) had another unusual armament installation, the two Vickers guns (500 rpg) again being internal, but mounted very low in the fuselage. There were two holes in tandem in the fuselage sides in the area where the breech casings of the guns were probably located. Being round rather than rectangular these may have been associated with the ventilation of fumes from the guns rather than ejection.

Jane's All The World Aircraft 1919

The Armstrong-Whitworth "Ara," although it was not produced until early this year, was designed as a single-seater fighter, but can be easily adapted as a sporting machine for one who desires something more than the low-powered, slow-speed machines which are being introduced by many firms at the present time.
  The fuselage is of square   An ordinary vee-type undercarriage is fitted. The upper plane is placed very low over the top of the fuselage thus giving the pilot an excellent view upwards.
Type of machine Single-seater Biplane
Name or type No. of machine "Ara" (1919).
Purpose for which intended Military and Sport.
Span 27 ft. 6 In.
Overall length 20 ft.
Maximum height 7 ft. 10 in.
Engine type and h.p. 320 h.p. A.B.C. "Dragonfly
Weight of machine empty 1,900 lbs.
Tank capacity in hours 3 1/4 hours.
   Speed at 1,000 feet 150 m.p.h.
   Landing speed 55 m.p.h.
   To 10,000 feet in minutes 5 1/2 minutes.

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

  The Ara was designed in 1918 to use the extremely promising ABC Dragonfly nine-cylinder air-cooled radial of 320 hp and three prototypes were ordered. However, delays in delivery of the Dragonfly engine led, in October 1918, to the decision to abandon all plans to produce a Dragonfly-powered fighter in quantity, and those companies with such warplanes under development were each allocated one Dragonfly engine in December 1918 in order to enable them to complete and test one prototype of each of their designs. In the event, the ABC engine proved extremely unreliable when the Ara commenced trials early in 1919. Nevertheless, a second prototype was completed and flown before, late in 1919, Sir W G Armstrong Whitworth & Co Ltd closed its aircraft department. The planned armament of the Ara comprised two 0.303-in (7,7-mm) Vickers guns.

Max speed, 150 mph (241 km/h) at sea level, 145 mph (233 km/h) at 10,000 ft (3 050 m).
Time to 10,000 ft (3 050 m), 4.5 min.
Endurance, 3.25 hrs.
Empty weight, 1,320 lb (599 kg).
Loaded weight, 1,930 lb (875 kg).
Span, 27 ft 5 in (8,35m).
Length, 20 ft 3 in (6,17 m).
Height, 7 ft 10 in (2,39 m).
Wing area, 257 sq ft (23,87 m2).

Журнал Flight

Flight, April 3, 1919.



The A.W. "Ara" Single-seater, 1919

  An improved type of single-seater was contemplated at the time of testing the Armadillo. This was to be fitted with a 320 h.p. Dragonfly engine, but as considerable delay was experienced in the production of this engine, it was not until the last week in December that an engine could be obtained. In the meantime, in the hope of getting this engine, a machine had been built for it. This was the one now known as the "Ara" type. Owing to the delay in obtaining the engine it was not until January, 1919, that the machine was ready for its tests. As will be seen from the table, the performance is very good indeed, both as regards speed and climb. In appearance the "Ara" is somewhat different from the "Armadillo," the top plane being placed some little distance above the fuselage, while the fact that the engine fitted is a radial instead of a rotary has made it possible to provide a better entry for the air in the neighbourhood of the nose of the fuselage. A cone-shaped spinner is fitted over the propeller boss, and only the tops of the cylinders project beyond the cowl. The undercarriage is of the usual simple Vee type.

O.Tapper - Armstrong Whitworth Aircraft since 1913 /Putnam/
The second Murphy-designed fighter, the Ara, first flew after the Armistice in 1918. Its A.B.C. Dragonfly engine was a failure.
Журнал - Flight за 1919 г.
THE A.W. "ARA" SINGLE-SEATER. - The engine fitted is a 320 h.p. A.B.C. "Dragonfly."
Jane's All The World Aircraft 1919 /Jane's/
Front View of the Armstrong-Whitworth "Ara", F4971 (320 h.p. A.B.C. Engine).
W.Green, G.Swanborough - The Complete Book of Fighters
The Ara was designed around the unsuccessful ABC Dragonfly engine, but two prototypes were completed and flown during 1919.
The second Ara, F4972, differed from the first in having an increased gap between the wings.
Журнал - Flight за 1919 г.
Front and side elevations of the Armstrong-Whitworth machines.
Журнал - Flight за 1919 г.
Plan views of the Armstrong-Whitworth machines.
W.Green, G.Swanborough - The Complete Book of Fighters
O.Tapper - Armstrong Whitworth Aircraft since 1913 /Putnam/