Handley Page HP.38: Ұлыбританиялық түнгі бомбалаушысы

{|Infobox aircraft type
|type = Heavy night bomber
|manufacturer = Handley Page
|national origin=United Kingdom
|designer = George Volkert
|first flight = 12 June 1930
|introduced = 1934
|retired = 1941 In response, the Air Ministry issued Specification B.19/27, which sought a heavy bomber for nighttime operations to replace the Vickers Virginia. The requirements listed included the use of a twin engine arrangement, positive stability, ease of maintenance, good manoeuvrability, avoidance of excessive pilot fatigue, an adequate self defense capability, sufficient carrying capacity for up to 1,546 lb (700 kg) of bombs, and to traverse a distance of 920 miles at a speed of at least 115 mph (185 km/h). The release of the specification was met with a large number of proposals from various companies across the British aircraft industry. Specifically, designs were submitted by Fairey (the Fairey Hendon) and Vickers (the Type 150 and Type 163 being built) in addition to Handley Page's own proposal. The responsibility for producing Handley Page's design was given to the company's lead designer G. R. Volkert. According to aviation author C. H. Barnes, while Handley Page was satisfied with the qualities of wooden construction, it was the Air Ministry's insistence that all future production aircraft use metal construction that compelled the firm to change. Further changes to the proposed design were made over the following months, often involving its propulsion in particular. Multiple engines, including the Napier Lion, Rolls Royce Kestrel inline engines and Bristol Jupiter radial engines, were considered by Handley Page, before it was determined that the Kestrel was superior. The prototype was completed during May 1930; it was powered by a pair of Rolls Royce Kestrel II engines, each capable of producing up to 525 hp (390 kW), that drove a set of two bladed propellers. On 12 June 1930, this prototype performed its maiden flight from Handley Page's factory at Radlett. Handley Page were under pressure to proceed rapidly, partially due to competition from the Vickers Type 150 and the Fairey Long range Monoplane; the prototypes of both these rivals suffered separate accidents, which gave extra time to refine the HP.38. Revisions around this time largely focused on increasing the workspace for crewmembers and the clearance for groundcrews to arm the aircraft. On 11 April 1932, revisions to the prototype's monocoque fuselage to incorporate all of the recommended improvements were authorised. As a consequence of the talk at the League of Nations of abolishing bombing, military planners opted to delay the awarding of a production contract; at one point, Handley Page was considering laying off numerous staff involved with the HP.38 over this uncertainty. However, the Japanese invasion of Manchuria and a lack of consensus among the Geneva Disarmament Committee led to the Air Ministry issuing instructions to proceed with an initial batch of five aircraft, designated "HP.50 Heyford". During March 1933, production contract 25498/33 was issued to Handley Page, ordering 15 HP.50s. The first of these aircraft was assembled by hand, partially due to the need for it as a prototype after the loss of the HP.38 in an accident. The production aircraft differed somewhat from the earlier prototype, the Heyford I was fitted with 575 hp (429 kW) Kestrel III engines and retained the two blade propellers, while the improved Heyford IA had four blade propellers. Engine variations were primary differences for both the Mk II and III variants; the former being equipped with 640 hp (480 kW) Kestrel IVs, supercharged to 695 hp (518 kW) in the Heyford III.

The Handley Page Heyford was a twin engine biplane bomber designed for nighttime operations. It featured a relatively novel configuration in which the fuselage was attached to the upper wing – somewhat resembling the 1914 designed German Gotha G. I. This arrangement provided a favourable field of fire for its defensive weapons, which were positioned on the nose and dorsal sections, along with the ventral retractable "dustbin" turret, each of which were armed with a single .303 in (7.7 mm) Lewis light machine gun. while the fuselage consisted of an aluminium monocoque forward section with a fabric covered frame to the rear. It was operated by a crew of four, typically consisting of a pilot, a bomb aimer/navigator/gunner, a radio operator and a dorsal/ventral gunner. Open positions were provided for the pilot and both the nose and dorsal gunners. As part of the RAF's expansion plan, follow on orders were placed for 70 Heyford IIIs during 1936, which were equipped with steam condenser cooled Rolls Royce Kestrel VI engines. The delivery of these aircraft enabled the RAF to have nine operational squadrons equipped with Heyfords by the end of 1936. During the late 1930s, these Heyford squadrons comprised a significant proportion of Bomber Command's night bomber strength. Accordingly, Heyfords commonly flew lengthy nighttime exercises, sometimes conducting mock attacks against targets in France. On 12 December 1936, disaster struck one of these long range exercises; a flight of seven Heyfords of No. 102 Squadron, returning for Northern Ireland encountered fog and icy weather conditions on their approach to RAF Finningley, Yorkshire. Of these seven aircraft, four crashed and two had to make forced landings, resulting in the deaths of three crewmen and a further three sustaining injuries. During 1937, the replacement of the Heyford commenced, coinciding with the arrival into service of the Armstrong Whitworth Whitley and Vickers Wellesley. The last examples were withdrawn from frontline service during 1939. Several Heyfords continued to be used for secondary duties, being commonly used as bombing and gunnery trainers, into the 1940s, although the Heyford had been officially declared to be obsolete during July 1939. A pair were still being used as glider tugs until April 1941. There are at least three fatalities associated with the Heyford in the Second World War, these occurring due to a mid air collision between two aircraft on 4 April 1940. At least two examples found experimental use; one for airborne radar and the other for aerial refuelling, and it is reported that a single Heyford was still in storage as late as 1944. No. 7 Squadron
No. 9 Squadron
No. 10 Squadron
No. 38 Squadron
No. 58 Squadron
No. 78 Squadron
No. 97 Squadron
No. 99 Squadron
No. 102 Squadron
No. 148 Squadron
No. 149 Squadron
No. 166 Squadron

No intact Heyfords, or significant portions from a single one, have survived through to preservation. The Royal Air Force Museum has several components of the Heyford on display; these include a pair of main wheels, two blades of a Heyford propeller and tailplane parts of Heyford III K6875 of No. 166 Squadron, recovered from its crash site in the Peak District.