British twin-engine medium bomber
The Handley Page HP.52 Hampden is a British twin-engine medium bomber that was operated by the Royal Air Force (RAF). It was part of the trio of large twin-engine bombers procured for the RAF, joining the Armstrong Whitworth Whitley and Vickers Wellington. The Hampden was powered by Bristol Pegasus radial engines but a variant known as the Handley Page Hereford had in-line Napier Daggers.
The Hampden served in the early stages of the Second World War, bearing the brunt of the early bombing war over Europe, taking part in the first night raid on Berlin and the first 1,000-bomber raid on Cologne. When it became obsolete, after a period of mainly operating at night, it was retired from RAF Bomber Command service in late 1942. By 1943, the rest of the trio were being superseded by the larger four-engined heavy bombers such as the Avro Lancaster.
Development.
Origins.
In 1932, the Air Ministry issued Specification B.9/32 seeking a twin-engined day bomber with higher performance than any preceding bomber aircraft. Handley Page and Vickers both designed aircraft to meet this specification, the Vickers design became the Wellington. The Handley Page design team, led by George Volkert, drafted a radical aircraft, initially centering upon the politically favoured Rolls-Royce Goshawk engine. By mid-1934 development of the Goshawk looked less promising and the Air Ministry relaxed the tare weight (unloaded weight) requirement of the specification, allowing for the use of heavier and more powerful radial engines such as the Bristol Perseus and Bristol Pegasus. According to aviation author Philip J.R. Moyes, the Handley Page design soon found support with the Air Ministry in part because it was judged to represent a fair compromise between range, payload, and speed.
During early 1936, the first prototype, designated as the HP.52 and given the serial number "K4240", was completed. On seeing the narrow-yet-deep fuselage, which was only 3 ft wide, C. G. Grey, founder of "The Aeroplane" magazine, remarked "it looks like a flying suitcase", a nickname that stuck with the aircraft for its lifetime. On 21 June 1936, the prototype, powered by a pair of Bristol Pegasus P.E.5S(A) engines, conducted its maiden flight from Radlett Aerodrome, Hertfordshire, piloted by Handley-Page chief test pilot Major James Cordes. In late June 1936, the prototype was put on public display in the New Types Park, Hendon Air Show, London. In August 1936, in response to the successful flight trials performed by "K4240", the Air Ministry issued an initial production order for the type, ordering 180 production aircraft to be manufactured to meet Specification B.30/36; concurrently, a second order for 100 aircraft powered by the Napier Dagger was issued to Belfast-based Short &amp; Harland.
In early 1937, a second prototype, which received the serial number "L7271", was completed; this second prototype had several differences from the first, including the pitot tube being repositioned below the fuselage, a more rounded ventral defensive gun position, and a slightly modified nose. "L7271" later received a pair of Dagger engines and was accordingly re-designated as the "HP.53"; on 1 July 1937, it performed its first flight after having received the new engines. Another prototype, "L4032", was produced to serve as the production-standard prototype; on 24 June 1938, the third prototype conducted its maiden flight. "L4032" differed from the previous two prototypes in that it was powered by a pair of Pegasus XVIII engines, the nose incorporated an optically flat bomb-aiming panel, as well as the ventral and dorsal gun positions being revised.
On 24 June 1938, "L4032" was officially christened by Lady Katharine Mary Montagu-Douglas-Scott, Viscountess Hampden, at a ceremony held in Radlett Aerodrome, the same day on which its first flight took place. Viscountess Hampden's speech invoked "the spirit of John Hampden, the defender of civil liberties" to inspire future crews of his namesake aircraft. "L4032" and "L4033", which was the second production-standard Hampden to be produced, would be later assigned to the Aeroplane and Armament Experimental Establishment at RAF Martlesham Heath, Suffolk. On 20 September 1938, the third production Hampden, designated "L4034", following the completion of handling trials conducted by the Central Flying School at Upavon Aerodrome, Wiltshire, become the first aircraft to enter RAF squadron service, being delivered to No. 49 Squadron.
Production.
By late 1938, the mass manufacturing plans for the Hampden had been formalised. In addition to Handley-Page's own production line, the type was to be built under subcontract by English Electric at its factory in Preston, Lancashire; on 6 August 1938, English Electric was awarded an initial contract to manufacture 75 Hampdens. In addition, Canadian interest in domestic production of the type had resulted in the establishment of the joint Anglo-Canadian Canadian Associated Aircraft company, which promptly received an initial order from the RAF for 80 Hampdens to be completed in Canada; this facility would effectively act as a shadow factory during wartime. On 1 September 1938, in response to interest expressed by the Royal Swedish Air Force (RSAF) in the Hampden, including in a potential licence production arrangement for 70 aircraft to be built in Sweden, a single production Hampden was supplied to Sweden. Designated "P.5" by the RSAF, it was operated by the service until November 1945, after which it was sold to Svenska Aeroplan AB (SAAB) to serve as a flying testbed before being retired in late 1947.
On 22 February 1940, the first Preston-built Hampden, "P2062", conducted its maiden flight. English Electric would go on to manufacture a total of 770 Hampdens, more than any other company, before delivering its final aircraft on 15 March 1942. In July 1940, Handley-Page terminated its own production line for the Hampden upon the completion of its 500th aircraft. On 9 August 1940, the first Canadian-built Hampden, "P5298", made its debut flight; by October 1940, Canadian production had risen to 15 aircraft per month. A total of 160 Hampdens were completed by Canadian Associated Aircraft, many of which were ferried to the United Kingdom for wartime service. The final Canadian-built aircraft was delivered in late 1941.
Design.
The Hampden Mk I had a pilot, navigator/bomb aimer, radio operator and rear gunner. Conceived as a fast, manoeuvrable "fighting bomber", the Hampden had a fixed forward-firing .303 in (7.7 mm) Browning machine gun in the upper part of the fuselage nose. To avoid the weight penalties of powered turrets, the Hampden had a curved Perspex nose fitted with a manual .303 in (7.7 mm) Vickers K machine gun and a .303 in (7.7 mm) Vickers K installation in the rear upper and lower positions. The layout was similar to the all-guns-forward cockpits introduced about the same time in "Luftwaffe" medium bombers, notably the Dornier Do 17. During the Norwegian Campaign, these guns proved to be thoroughly inadequate for self-defence in daylight; the single guns were replaced by twin Vickers K guns, a process led by Air Vice Marshal Arthur Harris of No. 5 Group RAF in 1940.
The Hampden had a flush-rivetted stressed skin, reinforced with a mixture of bent and extruded sections in an all-metal monocoque design. A split-assembly construction technique was employed: sections were prefabricated and then joined, to enable rapid and economic manufacture. The fuselage was in three big sections – front, centre and rear – that were built using jigs. The centre and rear sections were made of two halves, which meant that the sections could be fitted out in part under better working conditions prior to assembly. All possible assembly work was performed at the benches prior to installation upon each aircraft.
The wings were made up of three large units: centre section, port outer wing and starboard outer wing, which were also subdivided. Each section was built around a main girder spar, leading edge section and trailing edge section. The wing made use of wingtip slots and hydraulically actuated trailing edge flaps; the flaps and ailerons had stress-bearing "D"-spars. According to Moyes, the configuration of the wing was a key feature of Hampden, being highly tapered and designed to exert low levels of drag; these attributes were responsible for the aircraft's high top speed for the era of while retaining a reasonably low landing speed of .
The Hampden's flying qualities were typically described as being favourable; Moyes described it as being "extraordinarily mobile on the controls". Pilots were provided with a high level of external visibility, assisting the execution of steep turns and other manoeuvres. The control layout required some familiarisation, as some elements such as the hydraulic controls were unobtrusive and unintuitive. Upon introduction, the Hampden exhibited greater speeds and initial climb rates than any of its contemporaries while still retaining favourable handling qualities.
The slim and compact fuselage of the aircraft was quite cramped, being wide enough only for a single person. The navigator sat behind the pilot and access in the cockpit required folding down the seats. Once in place, the crew had almost no room to move and were typically uncomfortable during long missions. Aircrews referred to the Hampden by various nicknames due to this, such as "Flying Suitcase", "Panhandle", and "Flying Tadpole". Wilfred John Lewis wrote:
 ;templatestyles src="Template:Blockquote/styles.css" / ;I did my first flight and first tour on Hampdens. A beautiful aeroplane to fly, terrible to fly in! Cramped, no heat, no facilities where you could relieve yourself. You got in there and you were stuck there. The aeroplane was like a fighter. It was only 3 feet wide on the outside of the fuselage and the pilot was a very busy person. There were 111 items for the pilot to take care of because on the original aircraft he had not only to find the instruments, the engine and all that, but also he had all the bomb switches to hold the bombs.
The newest of the three medium bombers, the Hampden was often referred to by aircrews as the "Flying Suitcase" because of its cramped crew conditions, or more plausibly, because of the unusually thin, deep, slab-sided and rectangular shape of the fuselage was reminiscent of that of a suitcase.
Operational history.
UK service.
In September 1938, No. 49 Squadron received the first Hampdens; by the end of the year, both 49 and 83 Squadrons at RAF Scampton had re-equipped with the type. A total of 226 Hampdens were in service with ten squadrons by the start of the Second World War, with six forming the operational strength of 5 Group of Bomber Command based in Lincolnshire.
With the outbreak of war in 1939, Hampdens were initially used to perform armed aerial reconnaissance missions, observing German naval activity during daylight. However, despite its speed and manoeuvrability, the Hampden proved to be no match for "Luftwaffe" fighters; in December 1939, Bomber Command is claimed to have discarded the belief that aircraft such as the Hampden could realistically operate by day and instead chose to predominantly employ them under the cover of darkness during nighttime operations. During 1940, Hampdens of 5 Group conducted 123 nighttime airborne leaflet propaganda missions, losing only a single aircraft in the process.
On 13 April 1940, days after Germany's invasion of Norway, a large number of Hampdens were dispatched on night-time mine-laying (code-named "gardening") flights in the North Sea in areas deemed unapproachable by British shipping. According to Moyes, this activity proved highly effective, experiencing a low casualty rate of less than 1.9 aircraft per mission. The Hampden also saw a return to its use as a daytime bomber during the Norwegian Campaign, but quickly proved to be under-gunned in the face of German fighters.
On 19 March 1940, Hampdens took part in the first deliberate bombing of German soil in a nighttime raid upon the seaplane hangars and slipways in Hörnum, Sylt. The type continued to operate at night on bombing raids over Germany. Flight Lieutenant Rod Learoyd of 49 Squadron was awarded the Victoria Cross for a low-level attack on the Dortmund-Ems canal on 12 August 1940 where two of five aircraft failed to return. On 25 August 1940, Hampdens from various squadrons participated in the RAF's first bombing raid on Berlin. Sergeant John Hannah was the wireless operator/air gunner of an 83 Squadron Hampden and was awarded the Victoria Cross on 15 September 1940, when he fought the flames of the burning aircraft, allowing the pilot to return it to base.
In April 1942, the Hampden-equipped 144 Squadron and 455 Squadron RAAF were transferred from Bomber Command to Coastal Command to perform the torpedo bomber role. Later that year, detachments from both squadrons were dispatched