Airco DH.5

The Airco DH.5 was a British First World War single-seat biplane fighter aircraft. It was designed and manufactured at British aviation company Airco. Development was led by the aircraft designer Geoffrey de Havilland as a replacement for the obsolete Airco DH.2.

"DH5" redirects here. For other uses, see DH5 (disambiguation).
Airco DH.5
A production DH.5
Role fighter
Manufacturer Aircraft Manufacturing Company (Airco)
Designer Geoffrey de Havilland
First flight August 1916
Introduction May 1917
Primary user Royal Flying Corps (RFC)
Number built 550[1]

The DH.5 was one of the first British fighter designs to include the improved Constantinesco gun synchronizer, which allowed a forward-firing machine gun to fire through the propeller faster and more reliably than the older mechanical gears. It was also one of the earliest biplanes to feature a marked "back-stagger" of its wings. Despite these advances, by the time the DH.5 was fielded, it was already notedly inferior to other fighters that had entered into production and thus proved to be both unpopular and unsatisfactory amongst the pilots of the Royal Flying Corps (RFC). As such, the type was quickly withdrawn from service as soon as supplies of the Royal Aircraft Factory S.E.5 permitted.

Design and development

Origins

Shortly after completing work upon the twin-seat Airco DH.4 light bomber, Captain Geoffrey de Havilland commenced work on a new single-seat fighter aircraft to replace the obsolete Airco DH.2 fighter, which was designated at the DH.5.[2] The design sought to combine the superior performance of a tractor biplane with the excellent forward visibility of a pusher type. The resultant aircraft was a relatively compact single-bay biplane, while the construction was that of a conventional tractor biplane, the mainplanes were given 27 inches of backward stagger, so that the lower wing was positioned forward of the upper wing.[3] This configuration enabled the pilot to be positioned underneath the leading edge of the wing, providing uninterrupted forward and upward views; aviation author J.M Bruce refers to this approach as having been radical for the era.[2]

The first prototype emerged during late 1916, and underwent manufacturer's trials at Hendon Aerodrome in the hands of test pilot B.C. Hucks.[2] It was powered by a single Le Rhône 9Ja rotary engine, capable of providing up to 110hp of thrust, which drove a twin-bladed propeller. The fuselage had flat sides aft of the wings and featured relatively short fairings either side of the circular engine cowling; towards the rear of the airframe, the fuselage tapered to the tail, which comprised a small fin and horn-balanced rudder arrangement.[2] The equal-span single-bay wings were outfitted with atypically large ailerons on both the upper and lower mainplanes, a rubber bungee cord attached to the upper ailerons to return them to their standard position. At one early stage, it was known that the prototype was outfitted with a small hemispherical spinner.[2] As the pilot was seated forward of the centre of gravity, the main fuel tank was necessarily behind the cockpit, below the oil tank. An auxiliary gravity fuel tank was fitted over the top mainplane, offset to the right.

Into flight

Initial test flights with the prototype determined that it lacked sufficient directional control, a finding which led to a revised and enlarged fin and rudder combination being adopted.[2] Early on, the first prototype had been flown in an unarmed state. Around the same time as the revised tail unit was installed, it was also decided to arm the aircraft in preparation for official trials.[2] Upon being armed, the prototype armament installation comprised a single forward-firing .303 in (7.7 mm) Vickers machine gun, which was either fixed to fire upward at an angle or possibly mounted so that its elevation could be adjusted in flight; in the production installation the gun was given a more conventional fixed mounting on top of the cowl, offset to the left, to fire in the line of flight.[4][5] Bruce notes that it appeared that the DH.5 was designed with the intention of typically attacking enemy planes from below, a decision that he described as ironic considering its limited operational ceiling in comparison to its contemporaries.[2]

On 9 December 1916, the first DH.5 prototype commenced its service trials at the Central Flying School.[2] The official report compiled from the observations of its pilots was largely favourable, stating that it possessed satisfactory stability and controllability, its favourable qualities for reconnaissance and agility, but also observed a poor view to the rear.[6] The type's speed was a significant advance over its DH.2 predecessor, but it was also recognised that some existing fighters were already capable of exceeding its capabilities, especially its climbing abilities. It has been speculated that performance may have been negatively impacted via the adoption of an alternative four-bladed propeller during testing.[7]

Production

By the time that trials had commenced in France, superior types such as the Sopwith Camel and the Royal Aircraft Factory S.E.5 were not far behind. The performance of the new fighter was also inferior in most respects to the earlier Sopwith Pup. The provision of a single machine gun at a time when most fighters carried two also meant the aircraft was considered to be somewhat under-armed for operations in 1917. Nevertheless, on 15 January 1917, the DH.5 was ordered in quantity production in the form of two contracts for a combined 400 aircraft.[7] A total of four manufacturers were involved in producing the type: Airco (200), British Caudron (50), Darracq (200) and March, Jones & Cribb (100).[8]

The design of the DH.5 was subject to extensive changes prior to entering mass production.[7] A substitute fuel system was adopted, which included an additional five-gallon gravity tank mounted above the upper wing and a pressured main tank directly behind the pilot's seat. The appearance of the aircraft was drastically changed via the revised fuselage, which now had an octagonal cross section and featured additional stringers around the area of the engine cowling.[7] Directional control was also altered, introducing a rudder that lacked a horn balance. Unusually, some of these changes made the aircraft more complex to manufacture.[7]

In terms of its construction, the main fuselage structure was produced in two sections that were butt-joined at an attachment point upon the rear-section struts.[7] Extensive use was made of plywood across the structure, while the remainder used conventional wire-braced wooden box-girden. While some DH.5s were built with the original rubber bungee return springs on the ailerons, later-built examples used a system of pulleys and balance cables.[9] A major positive feature of the aircraft was its great structural strength, which was revealed during April 1917 in destructive testing.[10]

Operational history

The introduction of the DH.5 to squadron service with the Royal Flying Corps (RFC) was protracted; according to Bruce, these delays, which had been mainly generated as a result of Airco's focus having been centered upon the more successful DH.4, had greatly hindered the type's prospects.[11] On 1 May 1917, the first DH.5 arrived with No. 24 Squadron of the RFC; deliveries were slow, as the squadron had only a handful of the type by 7 June. The DH.5 was not well regarded by the squadron, and this negative attitude would not be a unique outlook.[12]

Soon after entering service, the DH.5 quickly proved to be most unpopular amongst the RFC. Its unconventional appearance led to rumours (that were largely unfounded) of handling difficulties.[12] There were also claims that the DH.5 had gone into service against the wishes of its designers.[13] What was true was that the DH.5's performance would rapidly drop off at altitudes in excess of 10,000 ft (3,000 m) and that while it was very manoeuvrable, it tended to lose altitude quickly in combat.[5] The unusual position of the upper mainplane resulted in an unfortunate blind spot above and to the rear (which was the very direction from which a single-seater would generally be attacked from).[6]

A DH.5 serving with the Australian Flying Corps in September 1917

The robust construction, good performance at low altitude and the pilot's good forward field of view made the aircraft a useful ground-attack aircraft. In this capacity, the type served with distinction in the Battle of Cambrai.[1] During the battle, the DH.5 had, in conjunction with Sopwith Camels, provided airborne mobile machine gun coverage to friendly troops on the ground, strafing enemy trenches and leading to extensive losses. However, the process of replacing the type had already commenced beforehand, and the meritorious performance at Cambrai did little to halt this withdrawal.[14]

The DH.5 has the historical distinction of having formed the initial equipment of No. 2 Squadron Australian Flying Corps, the first Australian fighter squadron. It did not prove satisfactory, incidents in which enemy twin-seater planes were able to escape the single-seat DH.5 were not uncommon.[14] It served mainly in the ground-attack role until December 1917, when the type was replaced by the S.E.5a. By this time, the withdrawal of the type from the Western Front was already almost complete - the last DH.5 squadron receiving the S.E.5a in January 1918.[15] DH.5s issued to training units proved unpopular and the type soon vanished from RFC service.[16] A number of retired aircraft were reused as trials machines, some of these tests included alternative gun mountings, jettisonable fuel tanks and plywood coverings.[17]

No original aircraft has survived but an airworthy full-scale reproduction, built in the United States by John Shiveley, is on display in the Aviation Heritage Centre, Omaka Aerodrome, New Zealand.

Military operators

 Australia

 United Kingdom

Specifications
Replica DH.5 ZK-JOQ at the Classic Fighters 2015 airshow in Blenheim, New Zealand

Data from British Aeroplanes 1914–18[19]

General characteristics

  • Crew: 1
  • Length: 22 ft 0 in (6.71 m)
  • Wingspan: 25 ft 8 in (7.82 m)
  • Height: 9 ft 1 1⁄2 in (2.781 m)
  • Wing area: 212.1 sq ft (19.70 m2)
  • Empty weight: 1,010 lb (458 kg)
  • Gross weight: 1,492 lb (677 kg)
  • Fuel capacity: 26 imp gal (31 US gal; 120 L)
  • Powerplant: 1 × Le Rhône 9J nine-cylinder rotary engine, 110 hp (82 kW)
  • Propellers: 2-bladed, 8 ft 6 in (2.59 m) diameter

Performance

  • Maximum speed: 102 mph (164 km/h, 89 kn) at 10,000 ft (3,050 m)
  • Endurance: 2 hr 45 min
  • Service ceiling: 16,000 ft (4,900 m)
  • Time to altitude:
    • 12 min 25 s to 10,000 ft (3,050 m)
    • 27 min 30 s to 15,000 ft (4,570 m)

Armament

  • Guns: 1 × 0.303 in (7.7 mm) Vickers machine gun
  • Bombs: racks for four 25 lb (10 kg) bombs under fuselage

See also

Aircraft of comparable role, configuration and era

References

Citations
  1. Bruce 1966, p. 12.
  2. Bruce 1966, p. 3.
  3. Jackson 1962, p. 49.
  4. Bruce 1965, p. 129.
  5. Lamberton 1960, p. 42.
  6. Bruce 1966, pp. 3-4.
  7. Bruce 1966, p. 4.
  8. Bruce 1957, p. 185.
  9. Bruce 1966, pp. 4-5.
  10. Bruce 1966, p. 5.
  11. Bruce 1966, pp. 5-6.
  12. Bruce 1966, p. 6.
  13. Bruce 1966, p. 7.
  14. Bruce 1966, p. 8.
  15. Taylor 1969, p. 339.
  16. Jackson 1962, p. 52.
  17. Bruce 1966, p. 9.
  18. Cowan, Brendan (27 August 2014). "AFC Airco D.H.5". adf-serials.com.au. Retrieved 22 December 2016.
  19. Bruce 1957, pp. 185–186.

Bibliography
  • Bruce, J.M. British Aeroplanes 1914–18. London: Putnam, 1957.
  • Bruce, J.M. The de Havilland D.H.5. (Aircraft in Profile number 181). London: Profile Publications, 1966.
  • Bruce, J.M. Warplanes of the First World War, Vol. 1. London: MacDonald, 1965, pp. 128–132.
  • Jackson, A.J. De Havilland Aircraft since 1915. London: Putnam, 1962.
  • Lamberton, W.M. et al. Fighter Aircraft of the 1914-1918 War. Lethworth, Herts, UK: Harleyford, 1960, pp. 42–43.
  • Taylor, John W.R. "D.H.5". Combat Aircraft of the World from 1909 to the Present. New York: G.P. Putnam's Sons, 1969. ISBN 0-425-03633-2.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.