Unlike other biplane fighters of its day, the Airco D.H.5 featured an unusual wing configuration. By positioning the upper wing toward the rear of the cockpit, designer Geoffrey de Havilland was able to improve the pilot's field of vision. Despite this improvement, at high altitude the D.H.5 was a poor performer due to its underpowered engine. By the end of 1917, it was removed from combat and used as a trainer.
The Armstrong-Whitworth F.K.10 was a two-seat quadruplane built for fighting and bombing. Like its predecessor, the F.K.9, it was a poor performer with serious design flaws. Of the fifty aircraft ordered by the Royal Naval Air Service, only eight were delivered.
The Avro 528 was an unsuccessful large span single engined biplane built to an Admiralty contract in 1916. It carried a crew of two; only one was built.
Very little is known about the Avro 528 apart from a photograph and a general arrangement diagram. It was a two seat single engined biplane ordered by the Admiralty in 1915, and not even the task for which it was intended is recorded. It had some similarities with the Avro 519 (a single seater intended for the RFC) and the twin seat 519A, built for the RNAS, though neither of these were armed and both had 150 hp Sunbeam Nubian engines rather than the 225 hp Sunbeam of the 528. Both the 519s and the 528 had some shared features with the Naval Avro 504.
It was a large three bay biplane with unswept, unstaggered and constant chord wings of unequal span, the lower plane having a span 10 feet 0 inches (3.05 m) less than the upper. Ailerons were carried on the upper wings; both wings folded for storage. The fuselage had similarities with the Naval 504s though the overall length of the 528 was greater by about 4 feet (1.2 m): both had a generous fixed fin in contrast to the all moving, comma shaped rudder of the RFC's 504s. The vertical stabiliser was also close in size to that of the 504, but the rather rectangular horizontal tail was nearly 60% greater in span. Like the 519s, the top of the fuselage carried a raised decking that provided deeper cockpits for the pilot, placed under the trailing edge of the wing and the observer/gunner, in a separate cockpit close behind equipped with a ring mounted gun. The fixed single axle undercarriage had no central skid.
The Sunbeam engine drove a four bladed propeller and had a single, central and near vertical exhaust pipe. There were two radiators, mounted edge on (longitudinally) between the wings, rather than the single but similarly mounted radiators of the Avro 519s and the Avro 527. Two tank-like features are shown in both image and diagram on the lower wings just inboard of the innermost interplane struts; they may be fuel tanks.
The first flight was on 19 December 1916 at Avro's Hamble factory. The aircraft remained troublesome, with a variety of propellers being tried but the Admiralty lost interest and the 528 last flew in April 1917.
The Blackburn Triplane was a single-engine pusher single-seater, designed specifically to attack Zeppelins. It flew in 1917, but was not successful.
The Triplane was the third unsuccessful attempt at an anti-Zeppelin fighter that involved Blackburn. The first was Blackburn's own Twin Blackburn and the second the AD Scout, Blackburn building two of the four machines of this type to an Air Department of the Admiralty design. In 1916, the Scout's designer, Harris Booth moved to Blackburn where he created a heavily-revised aircraft, the Triplane.
The layout of both Scout and Triplane was determined largely by the Admiralty requirement to carry a quick-firing, recoilless Davis gun that used 2 lb (1 kg) shells. At the time, there was no way of synchronising such a weapon with the propeller, or of mounting it elsewhere than the fuselage, so a pusher configuration was necessary, the pilot sitting in a nacelle with the gun in its nose.
In order to make the aircraft more manoeuvrable and in particular to increase its roll rate, a triplane configuration was chosen. This provided about the same total wing area as that of the biplane Scout with a lower moment of inertia about the roll axis. The Triplane had single-bay wings with heavy stagger and carrying six ailerons. The lower wing was close to the ground so two underwing skids were added below the interplane struts. The mid-line of the nacelle, with the engine at its rear, was on the centre plane, giving the pilot a slightly less good view than from the Scout.
Four parallel tail booms ran aft, two from the mid-span of the upper wing and the others from the lower wing. These four members carried the tail. The tailplane, mounted on the upper booms and bearing a full-width elevator, had a span of 18 ft 10 in (5.74 m), no less than 78% of the wingspan. A pair of fin and rudders joined the upper and lower booms, a height of about 7 ft 6 in (2.3 m). The "reversed" undercarriage of the Scout was abandoned and the main wheels were mounted on a single axle supported by two pairs of struts to the nacelle. Though photographs show the gun port, the gun itself was probably never fitted.
The Triplane first flew with a 110 hp (80 kW) Clerget rotary engine driving a four-blade, 8 ft (2.46 m) diameter airscrew, then later with a 100 hp (75 kW) Gnome with a two-blade propeller.
Only one was built. It was accepted by the Admiralty on 20 February 1917, but was rapidly found wanting like the Scout before it. It was struck off charge just a month later, the only Blackburn triplane and the last of their attempts to build an anti-Zeppelin fighter.
The creation of C.J.H. MacKenzie-Kennedy, the Kennedy Giant biplane bomber was aptly named. A huge aircraft for its time, it was also a giant design failure. Manufactured in Hayes, England by the Gramophone Company, Ltd., it was constructed out in the open because none of the Northolt Aerodrome hangars were large enough to contain it. Despite its four engines, the Kennedy Giant was so underpowered that once airborne it could do little more than fly in a straight line.
The R.E. 7 has been called the most useless airplane ever made, and for some good reasons. Between it's top speed and the speed at which it stalled and spun out of control there was a margin of only twenty miles an hour. It was intended to have a top speed of 80 mph, but it usually managed only 60, and it's stall speed was 48 mph. This made take-offs, landings and manoeuvring in the air very difficult. It came armed with a forward firing machine gun mounted oblique to the aircraft to avoid the propeller. This made it very difficult to hit anything, as the aircraft had to be crabbed to one side when aiming at another plane. The observer could not stand, or turn around like in later aircraft, so a machine gun in the back was nearly ineffective as the observer had to aim it by leaning back and swivelling the gun while looking over his shoulder.
The Sopwith Long Range Tractor Triplane (L.R.T.Tr) was a prototype British long-range three seat triplane escort fighter of the First World War. Of unusual layout, with a small gunner's nacelle mounted on the upper wing to give an all-round field of fire. Only a single example was built, other, smaller, fighters proving more practicable.
In early 1916, the British War Office drew up a specification for a multi-seat escort fighter to be powered by one of the new Rolls-Royce Eagle engines, intended to protect formations of bombers from German fighters, with an additional role of destroying enemy airships. While the specification did not require high speed, a good field of fire for its guns was essential, while the secondary anti-Zeppelin role demanded an endurance of at least seven hours.
Orders were placed for prototypes from Armstrong Whitworth (the F.K.6), Sopwith and Vickers (the F.B.11). All three designs were driven by the need to provide wide fields of fire in the absence of effective synchronisation gear that would allow safe firing of guns through the propeller disc.
The Sopwith proposal was modified from an existing design for a two-seat triplane, with a nacelle for a gunner added to the upper wing. It had three-bay, narrow chord wings, with the streamlined nacelle housing the upper gunner who was armed with a 0.303 in (7.7 mm) Lewis gun built around the center section of the upper wing. Ailerons were fitted to all wings, with air brakes fitted to the lower wing. The deep fuselage housed the pilot and a second gunner armed with a 0.303 in (7.7 mm) Lewis gun to guard the aircraft's tail. Power was provided by a 250hp Rolls-Royce Mk I (Eagle I) 12-cylinder water-cooled engine. Balancing wheels were fitted well ahead of the aircraft's mainwheels in order to prevent the aircraft overturning, as the upper gunner would be extremely vulnerable if this occurred.
The prototype, which was nicknamed "Egg-Box" flew late in 1916. It was not developed further, with smaller fighters fitted with synchronisation gear such as Sopwith's own 1½ Strutter now available, with all of the proposed three-seat escort fighters abandoned.
Overweight and clumsy, the Sopwith Bulldog two-seater biplane was heavily armed with two forward firing machine guns and two independently mounted machine guns in the rear. Only two of them were built during World War I.