Handley Page H.P.54 Harrow
|Harrow of No. 115 Squadron|
|Designer||G. V. Lachmann|
|First flight||10 October 1936|
|Primary users||Royal Air Force|
Royal Canadian Air Force
The Handley Page H.P.54 Harrow was a heavy bomber designed and produced by the British aircraft manufacturer Handley Page. It was operated by the Royal Air Force (RAF) and saw use during the Second World War, although it was quickly overshadowed as a bomber by larger and more capable alternatives.
The Harrow was developed during the 1930s as a derivative of the Handley Page H.P.51, an unsuccessful monoplane bomber-transport hybrid. It was a twin-engine, high-wing monoplane with a fixed undercarriage. In 1935, the Air Ministry wrote Specification B.29/35 around the Harrow proposal, seeking a 'stop-gap' heavy bomber to facilitate the expansion of the RAF's bomber squadrons. Handley Page updated the design with new features and along with structural changes to better facilitate its rapid construction. Despite incorporating several modern features, including hydraulically-powered turrets, steam-based cabin heating, and variable-pitch propellers, the Harrow was not as capable of equal performance to contemporary bombers such as the Armstrong Whitworth Whitley.
On 14 August 1936, the Air Ministry ordered one hundred Harrows for the RAF. While the Fleet Air Arm also placed a separate order for one hundred Harrows, Handley Page were unable to spare sufficient capacity to produce these aircraft. On 13 January 1937, the first Harrow was delivered to No. 214 Squadron; by the end of that same year, all one hundred of the RAF-bound units had been delivered. By the end of 1939, the Harrow had been rapidly displaced as a frontline bomber, it was flown as a transport aircraft instead, which included its use as an air ambulance. It participated in several major actions, including an unorthodox defensive role for The Blitz in the winter of 1940–1941 and Operation Market Garden in September 1944. Limited numbers served through to the conclusion of the conflict, the RAF withdrew the Harrow in May 1945.
The H.P. 54 Harrow was the production version of the earlier Handley Page H.P.51 design, itself a monoplane conversion of the three-engined Handley Page H.P.43 biplane. The two monoplanes were both designed by Dr. G.V. Lachmann. The aviation author C. H. Barnes observes that, despite rumours to the contrary, the development of the Harrow had nothing to do with Specification B.9/32, which sought a dedicated medium bomber; several features of the aircraft, such as its fixed undercarriage and general construction, were incompatible with the requirements laid out. Instead, the aircraft had been developed as a response to the Air Ministry's issuing of Specification C.26/31, which sought a new bomber-transport aircraft. Handley Page had intended to offer the preceding H.P.51, before opting for the H.P.54 at the last minute as it was viewed as a superior offering to fulfil the requirement.
Recognising that production of existing bomber platforms, such as the Armstrong Whitworth Whitley, or upcoming projects be reasonably accelerated, the Air Ministry came to recognise that additional types of aircraft would have to be procured if it was to keep pace with political pressures to appropriately equip the Royal Air Force, which was undergoing a period of rapid expansion and modernisation, including the growth of its bomber force, as the situation in Europe continued to deteriorate. Accordingly, in June 1935, Specification B.29/35 was written around the Harrow with the intention of using it as a 'stop-gap' solution; as such it was directed to be suitable for rapid production despite its performance not being equal to front line peers. The use of the aircraft in its bomber role was emphasised by B.29/35 over that of its transport capability, although this was retained as a secondary role.
In order to fulfil the requirements of the specification, which sought the Harrow as a heavy bomber, the design had to be reworked, largely in terms of its structure. Several new features were introductioned, including variable-pitch propellers, heated steam boilers to heat the cabin, and hydraulically-powered turrets. To enable rapid construction of the type, modern construction methods drawn from studies of American automotive factories were adopted, which included a sub-assembly flow system and priority being placed on a high standard of practical training. On 14 August 1936, months before the first Harrow flew, the Air Ministry opted to place a production order for one hundred aircraft. The Fleet Air Arm also placed its own order for one hundred Harrows, but Handley Page found that it lacked the production capacity to supply them. Quantity production of the Harrow commenced shortly after production of the Handley Page Heyford biplane came to an end.
On 10 October 1936, the first Harrow performed the type's maiden flight from Radlett. Service trials of the type commenced at RAF Martlesham Heath twenty days later using this same aircraft. During January 1937, the second Harrow, which differed from the first by its fitting of the improved Bristol Pegasus XX radial engine, along with prototype Habbart-F.N. turrets, arrived for armament trials. In March 1937, following the forced landings of seven Heyfords in bad weather, it was ordered that improved navigator positions be adopted on all bombers wherever feasible, leading to urgent modifications being performed on all Harrows. To speed deliveries, and to allow time to resolve issues with the hydraulically-powered turrets, early production units were delivered to training squadrons without these turrets installed.
To enable the Harrow to better to defend itself, it was typically furnished with several defensive guns, including a powered nose and tail turrets as well as a manually operated dorsal turret. These positions had fixed cupolas that had the guns traverse on a slot; the hydraulic controls were interfaced with the gun sight, while the weight of guns themselves was balanced by the gunner. Bomb-airming was performed using the nose turret, which incorporated a flat optical panel. Early on, both the nose and dorsal turrets were armed with a single Lewis gun, while the tail turret was armed with a pair of Lewis guns. In later service, these guns were typically replaced by Vickers K machine guns. The Harrow could carry a maximum bombload of 3,000 lb (1,400 kg), which was stowed in a bay directly underneath the floor of the cabin; it was also capable of carrying a single 2,000 lb (910 kg) bomb. The majority of Harrows were powered by a pair of Bristol Pegasus XX radial engines, capable of producing up to 925 hp (690 kW).
On 13 January 1937, the first Harrow was delivered to No. 214 Squadron at RAF Scampton. Early examples, powered by the Bristol Pegasus X engine, were designated Harrow Mk.I, while those powered by the more powerful Pegasus XX engine were designed Harrow Mk.II. By the end of 1937, all one hundred aircraft had been delivered to a total of five RAF bomber squadrons. Despite the presence of cabin heating, which used the exhaust head of onboard steam boilers, the Harrow gained a reputation amongst air crews of being a cold and draughty aircraft, which was largely attributed to the design of its turrets.
As the delivery of more modern bombers, such as the Vickers Wellington proceeded, the Harrow was promptly phased out as a frontline bomber by the end of 1939, having never performed any active combat missions in this capacity. Perhaps its most prominent use during this brief period was a series of public formation flights performed over various British cities to mark Empire Air Day in May 1938; the Harrow was also put on full stand-by during the Munich Crisis of 1938.
Although relegated from the night bomber role, the Harrow continued to be operated throughout the Second World War in the transport and trainer roles. On 1 May 1940, No. 271 Squadron was formed with a mixture of Harrows, Bristol Bombays and an assortment of impressed civil aircraft. While the other aircraft equipping 271 Squadron were replaced by Douglas Dakotas, it retained a flight of Harrows (sometimes nicknamed "Sparrows" due to their new nose fairings to give a more streamlined fuselage) as transports and ambulance aircraft until the conflict reached its conclusion in the European theatre.
In its transport capacity, the Harrow was routinely used to convey equipment and personnel between domestic military bases across Britain, as well as to continental airfields prior to the Fall of France. It also occasionally undertook high risk flights between England and Gibraltar; two aircraft were recorded as having being lost on this route. Harrows also operated in support of Allied forces in their advance into north-west Europe, evacuating wounded from the Arnhem operation during September 1944. Seven Harrows were destroyed by a low level attack by Luftwaffe fighters of JG 26 and JG 54 on Evere airfield as part of Unternehmen Bodenplatte, the German attack on Allied airfields in northwest Europe on 1 January 1945, leaving only five Harrows intact. These were eventually retired on 25 May 1945.
The Harrow also served in a novel operational role at the height of The Blitz against Britain in the winter of 1940–1941. Six Harrows equipped No. 420 Flight (later No. 93 Squadron) which used lone Harrows to tow Long Aerial Mines (LAM) into the path of enemy bombers. The LAM had an explosive charge on the end of a long cable and the unorthodox tactic was credited with the destruction of between four and six German bombers. The experiment was judged of poor value and the planned deployment of Douglas Havocs in the LAM role was cancelled. Seven Harrows were also used by 782 Naval Air Squadron of the Fleet Air Arm as transports from June 1941 to July 1943, being used to carry engines and spare parts as well as passengers.
The Harrow was also used as an aerial tanker for in-flight refuelling. During the late 1930s, a total of three Harrows received modifications performed by Flight Refuelling Limited, installing the refuelling apparatus along with additional fuel tanks, after which the company conducted a series of trials. Proving to be sufficiently capable, these aircraft were routinely used to refuel Short Empire Flying boats, enabling them to conduct the long distance flights needed for transatlantic services. For this purpose, two appropriately-equipped Harrows were stationed at Gander, Newfoundland while the third was based at Foynes, Ireland. During 1940, the two aircraft based at Gander were pressed into service with the Royal Canadian Air Force.
- Harrow Mk.I
- Powered by two 830 hp (620 kW) Bristol Pegasus X engines, 19 built.
- Harrow Mk.II
- Powered by two 925 hp (690 kW) Pegasus XX engines, 81 built.
- Royal Air Force
- No. 37 Squadron – 1937–1939 at RAF Feltwell
- No. 75 Squadron – 1937–1939 at RAF Driffield and later RAF Honington
- No. 93 Squadron – 1940–1941 at RAF Middle Wallop (aerial mine role)
- No. 115 Squadron – 1937–1939 at RAF Marham
- No. 214 Squadron – 1937–1939 at RAF Scampton later RAF Feltwell
- No. 215 Squadron – 1937–1939 at RAF Driffield and later RAF Honington
- No. 271 Squadron – 1940–1945 at RAF Doncaster later RAF Down Ampney (transport role)
- No. 420 Flight – became 93 Squadron
- No. 1680 Flight – became 271 Squadron
- Fleet Air Arm
- Flight Refuelling Limited
Specifications (Harrow II)
Data from The British Bomber since 1914
- Crew: 5
- Capacity: 20 fully equipped soldiers or 12 stretcher cases (used as transport)
- Length: 82 ft 2 in (25.04 m)
- Wingspan: 88 ft 5 in (26.95 m)
- Height: 19 ft 5 in (5.92 m)
- Wing area: 1,090 sq ft (101 m2)
- Empty weight: 13,600 lb (6,169 kg)
- Gross weight: 23,000 lb (10,433 kg)
- Powerplant: 2 × Bristol Pegasus XX nine-cylinder air-cooled radial piston engines, 925 hp (690 kW) each for take-off
- Propellers: 3-bladed variable-pitch propellers
- Maximum speed: 200 mph (320 km/h, 170 kn)
- Cruise speed: 163 mph (262 km/h, 142 kn)
- Range: 1,260 mi (2,030 km, 1,090 nmi)
- Service ceiling: 22,800 ft (6,900 m)
- Rate of climb: 710 ft/min (3.6 m/s)
- Wing loading: 21.1 lb/sq ft (103 kg/m2)
- Power/mass: 0.0804 hp/lb (0.1322 kW/kg)
- Guns: 4 × 0.303 in (7.7 mm) Lewis Guns
- Bombs: Up to 3,000 lb (1,400 kg) of bombs internally.
- Havoc Mk I (Pandora) intruder – also used for Long Aerial Mine (LAM) operations
Aircraft of comparable role, configuration, and era
- Barnes 1987, pp. 347–351.
- Barnes 1976, p. 372.
- Barnes 1976, pp. 372-373.
- Barnes 1976, p. 373.
- Barnes 1987, p. 372.
- Lewis 1980, pp. 270–271.
- Barnes 1976, p. 374.
- Barnes 1976, pp. 373-374.
- Lumsden and Heffernan Aeroplane Monthly January 1986, pp. 4–7.
- Barnes 1976, pp. 374-375.
- Mason 1994, pp. 301–302.
- Barnes 1976, p. 375.
- Barnes 1976, pp. 378-379.
- Thetford 1957, pp. 248–249.
- Thetford 1957, p. 499.
- Barnes 1976, p. 378.
- Mondey 1994, pp. 125–126.
- Barnes 1976, p. 379.
- Price 1978, pp. 152–153
- Sturtivant and Ballance 1994, pp. 104–105
- Sturtivant and Burrow 1995, p. 292
- Barnes 1976, p. 376.
- Jefford 1988, p. 37.
- Jefford 1988, p. 48.
- Jefford 1988, p. 52.
- Jefford 1988, p. 71.
- Jefford 1988, p. 82.
- Barnes, C. H. Handley Page Aircraft since 1907. London: Putnam, 1976. ISBN 0-370-00030-7.
- Barnes, C. H. Handley Page Aircraft since 1907. London: Putnam Publishing, 1987. ISBN 0-85177-803-8.
- Clayton, Donald C. Handley Page, an Aircraft Album. Shepperton, Surrey, UK: Ian Allan Ltd., 1969. ISBN 0-7110-0094-8.
- Gardner, Brian (1984). "Flight Refuelling... The Wartime Story". Air Enthusiast. No. 25. pp. 34–43, 80. ISSN 0143-5450.
- Jefford, C. G. RAF Squadrons. first edition 1988, Airlife Publishing, UK. ISBN 1 85310 053 6.
- Lewis, Peter. The British Bomber since 1914. London: Putnam Aeronautical Books, 1980. ISBN 0-370-30265-6.
- Lumsden, Alec and Terry Heffernan. "Probe Probare No. 20: Handley Page Harrow". Aeroplane Monthly, Vol. 14, No. 1, January 1986. pp. 4–7. ISSN 0143-7240.
- Mason, Francis K. The British Bomber since 1914. London: Putnam Aeronautical Books, 1994. ISBN 0-85177-861-5.
- Mondey, David. The Hamlyn Concise Guide to British Aircraft of World War II. London: Aerospace Publishing, 1994. ISBN 1-85152-668-4.
- Price, Alfred. "The Long Aerial Mine: Failure or Unrealised Potential?" Air Enthusiast, No. 6, March–June 1978. pp. 151–153.
- Sturtivant, Ray and Ballance, Theo. The Squadrons of the Fleet Air Arm. Tonbridge, Kent, UK: Air Britain (Historians) Ltd., 1994. ISBN 0-85130-223-8.
- Sturtivant, Ray and Burrow, Mick. Fleet Air Arm Aircraft 1939 to 1945. Tunbridge Wells, Kent, UK: Air Britain (Historians) Ltd., 1995. ISBN 0-85130-232-7.
- Thetford, Owen. Aircraft of the Royal Air Force, 1918–57. London: Putnam Aeronautical Books, 1957. OCLC 3875235
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