General Aircraft Hamilcar

The General Aircraft Limited GAL. 49 Hamilcar or Hamilcar Mark I was a large British military glider produced during the Second World War, which was designed to carry heavy cargo, such as the Tetrarch or M22 Locust light tank. When the British airborne establishment was formed in 1940 by the order of Prime Minister Winston Churchill it was decided to develop a large glider which would be able to transport heavy equipment in support of airborne troops. General Aircraft Limited were chosen in January 1941 to develop this glider, which they designated the GAL. 49 'Hamilcar'. It was designed to transport a light tank or two Universal Carriers. A number of problems, which included vacillation by the War Office on the number of gliders it wanted and poor management by GAL, led to delays in the production of the Hamilcar and it was not until mid-1943 that the first production glider was assembled. These problems were only partially solved and production of the glider continued to be slow, hampered by difficulties in finding suitable locations to store and construct them once their parts were produced. A total of 344 Hamilcars had been built when production ended in 1946.

Hamilcars were used on three occasions,and only in support of British airborne forces. They first saw action in June 1944, when approximately thirty were used to carry Ordnance QF 17 pounder anti-tank guns, transport vehicles and Tetrarch light tanks into Normandy in support of British airborne forces during Operation Tonga. In September 1944 a similar number of Hamilcars were used to transport anti-tank guns, transport vehicles and supplies for airborne troops as part of Operation Market Garden. They were used a third and final time in March 1945 during Operation Varsity when they transported M22 Locust light tanks and other supplies. The gliders proved to be successful in all three operations, although their slow speed and large size made them easy targets for anti-aircraft fire, which resulted in a number of gliders being damaged or destroyed. A powered variant of the Hamilcar was produced, the Hamilcar Mark X, to extend the range of the Hamilcar so it could serve in the Pacific War; the conflict in the Pacific ended before the design could see combat.

Development

Background

The British airborne establishment was formed in June 1940 under the orders of the Prime Minister, Winston Churchill, in response to the German use of airborne forces during the Battle of France. When the equipment to be used by the airborne forces was being developed, it had been decided by officials at the War Office that gliders would be an integral component of such a force; these would be used to transport troops and heavy equipment, which by 1941 had been expanded to include artillery and some form of tank. By the beginning of 1941, the War Office had issued four specifications for military gliders to be used by the airborne forces. The first was Air Ministry specification X.10/40, which called for an eight-seater glider similar to the German DFS 230, which eventually became the General Aircraft Hotspur I; the second was specification X.25/40 which became the Slingsby Hengist, a fifteen-seat glider; the third was specification X.26/40, the 25-seater Airspeed Horsa; and the last, X.27/40 was for a glider that could carry a light tank or other heavy loads.Flint 2006, p. 35. The number of aeronautical firms able to design and produce gliders was limited, especially since several were already committed to producing other prop-driven aircraft for the government; as such, contracts for the gliders were allocated to firms as the government saw fit, rather than through any competitive process. Slingsby was chosen to develop ''X.25/40'' because it was believed to be too small to build larger gliders, and Airspeed would eventually build the Horsa. Because it had already developed the Hotspur, which first flew in November 1940, and was considered to have a sufficiently developed production capacity capable of producing a larger glider, General Aircraft Limited were chosen to develop X.27/40.

Before being selected, the company had already been in the process of developing designs for a glider which would carry a single Mk VII 'Tetrarch' light tank. The design was a low-wing aircraft designed so that the tank driver also functioned as the glider pilot, and flew the glider from his seat in the tank through a series of internal modifications to the tank. The idea behind the design was to save on specially-trained glider pilots and allow the tank to be brought into action as soon as the glider landed; surviving illustrations of the design show the tank encased in the glider's fuselage but with the turret outside the airframe, possibly so that it could engage targets as it landed.Flint 2006, p. 38. However, the design was considered to be impractical, both by the company and the War Office, and a more conventional design was finally arrived at in a joint meeting between the two in January 1941. It called for a glider which would be constructed primarily out of wood capable of carrying a Tetrarch light tank or two Universal Carriers with a combined maximum weight of approximately ; a surviving requisition form from the Air Ministry to GAL confirms a cost of £50,000 per glider. By early February 1941 the basic design for the glider had been completed by the company's chief designer, and had been designated the GAL. 49 with the service name 'Hamilcar'; the name came from the Carthaginian general Hamilcar Barca.

Such a large glider had never been constructed before by the British military, and to test the design, a half-scale prototype model was first designed; designated GAL. 50 it still required an Armstrong Whitworth Whitley medium bomber to act as a tug to get it airborne, and was first flown in September 1941.Flint 2006, p. 40. However, it only flew once; the test pilot approached the landing area too low, attempted to raise the flaps for extra glide, and instead crashed the prototype and wrecked it. However, the trial was considered to be a success and the first full-scale prototype model was finished at GAL's works in Hanworth, Middlesex in March 1942. The Hamilcar was transported to RAF Snaith in Yorkshire, as GAL's airfield at Hanworth was too short for the glider to take off from; moving the glider to a secure military airfield would also ensure that it remained secret. Its first flight was conducted on 27 March 1942, towed by a Handley Page Halifax bomber. A second prototype was completed in June 1942, and further testing and development took place at a number of different airfields, including the Airborne Forces Experimental Establishment at RAF Beaulieu; all flight trials appear to have been successful, and there were few differences between the prototypes and the production models.Flint 2006, p. 41.

Production problems

The number of Hamilcars that the War Office required frequently fluctuated. In May 1942 the War Office asked GAL for 360 Hamilcars to be used in two major airborne operations, but this was found to be unrealistic; not only was the production rate for the glider far too slow to accommodate this large number, the same number of tugs needed to tow the gliders could not be found.Weeks, p. 128. In November 1943 the War Office issued another report in which it increased the number of required gliders to 800, an even more unrealistic number; by the time production of the Hamilcar ended, a total of 344 had been built. GAL produced an initial run of 22 Hamilcars, which included the two prototype models and ten pre-production aircraft required for evaluation trials. Subsequent production of parts was assigned to a series of sub-contractors called the 'Hamilcar Production Group', which included the Birmingham Railway Carriage and Wagon Company, the Co-operative Wholesale Society and AC Cars. Production for the glider was targeted to begin in late 1941 with approximately 40–50 to be completed by the end of that year; in reality this was overoptimistic, with the planned 40–50 only being completed by June 1944.Flint 2006, p. 44.

The slow rate of production for the Hamilcar appears to be the result of a combination of factors. There was a great demand on the specific types of wood required to build the glider, and difficulty in finding suitably large airfields with enough skilled personnel where the gliders could be constructed and stored; it also appears that a lack of official priority and poor management at GAL also impeded production. Between March and August 1942 GAL had promised eighteen Hamilcars would be built and delivered, but by September only one had actually appeared; this slow rate of production so concerned the Ministry of Aircraft Production that it appointed an 'Industrial Panel' of three senior industrial experts to visit GAL and detail the causes of the problems. The panel visited GAL in early September 1942 and issued a report on 24 September which stated that the root of the problems was that GAL appeared to have taken a bigger workload than it could handle, which was exacerbated by poor organisation and management skills. There were also conflicts between GAL and the Hamilcar Production Group which hurt production; the Group had been formed by the Ministry on 28 July in an attempt to speed up production, but senior GAL managers resented this and failed to co-operate fully with the Group. The panel also identified a 'piecemeal method of ordering' by the Ministry of Aircraft Production as a cause of further delays. Ultimately several senior managers and staff at GAL were replaced on the recommendation of the panel in an attempt to decrease internal conflicts and speed up production.

The ten pre-production gliders were eventually delivered by the end of 1942, and the first production glider was put together between March and April 1943. Production of parts and the building of complete gliders continued throughout 1943, but production schedules continued to fall behind, particularly when the United States Army Air Forces became interested in the glider, requiring a significant number to be completed for Operation Overlord, the airborne landings in Normandy, and a number of others to be used in the Far East. This placed further pressure on GAL and the Hamilcar Production Group, as the USAAF demands would require further production and new flight trials to see if the glider would operate effectively in a tropical climate. In late 1943 the USAAF required 140 Hamilcars, which would be used to transport bulldozers and other construction equipment for airfield building, and in November it was agreed that 50 would be supplied to them by June 1944. However, the continued slow production of the gliders so concerned the USAAF that it cancelled its requirement in February 1944; this meant that American personnel who had been helping with the production of the gliders were withdrawn and production times were further delayed. It also meant that only British airborne forces would use the Hamilcar.Flint 2006, p. 47. By January 1944 only 27 Hamilcars had been erected and were ready for use; a total of 53 had been produced, but the rest were in storage awaiting parts to complete them or to be erected. Finding personnel to erect the gliders, and airfields to store them, continued to be a problem. By June, however, eighty of the gliders had been manufactured and erected and were ready for use in airborne operations, in time for a small number to be used during Operation Tonga, the British airborne landings in Normandy.Otway 1990, p. 176. Production continued throughout the conflict and finally ended in 1946, with a total of 344 being produced.Flint 2006, p. 48.

Design

The Hamilcar was constructed primarily from wood, mainly birch and spruce, with fabric-covered plywood forming the skin, and high grade steel reinforcement beams in critical areas. It had a wingspan of , a length of and a height of to the top of the fin with the tail down.Dank 1977, p. 47. It weighed when empty, and could transport a military load of to give a total weight of .Weeks, p. 127. The whole aircraft was broken down into smaller sections for transport.''Flight'' 14 December 1944, p. 636. It was so large and heavy that it required the largest and most powerful aircraft to pull it off the airfield and subsequently tow it; four-engined bombers were used, most frequently the Handley Page Halifax.Otway 1990, p. 393. Both wing and cockpit were set above the fuselage to provide the greatest amount of room for the cargo compartment, and to ensure that they did not interfere with the loading of vehicles; the compartment measured approximately , inches wide and between and inches in height.Mondey 1994, p. 109. The nose of the glider was hinged and opened to the side for ease of loading vehicles and cargo, and the crew of two pilots were seated in tandem in a cockpit on the top of the fuselage, which was accessed via an internal ladder and was fifteen feet above ground; they were eventually protected by a bullet-proof windscreen and a plate of armour behind the second pilot. An intercom was also added to provide communication between the pilots and the personnel below them. An initial design feature, which was eventually removed prior to full-scale production, was the installation of an under-fuselage hatch which would allow the prone firing of a Bren light machine gun as the glider approached the landing zone.

The ratio between length and wingspan was practically the same as that of an Avro Lancaster bomber, which had a wingspan of and a length of , in contrast to modern sport gliders which possess a particularly large wingspan to enhance gliding performance.Flint 2006, p. 39. This was the result of a decision taken by the War Office in early 1940 on how military gliders would be used; the idea was for the glider to be released at a low altitude close to the landing zone and conduct a steep descent to reduce time in the air and exposure to enemy fire. The glider also possessed large flaps which assisted in a steep and rapid descent, and through adjustments of their angle during landing a precise control over descent rate and point of landing could be achieved; they also allowed a slower touchdown speed to be attained. They were operated through a small bottle of compressed air large enough only for a single landing; a small bottle not only saved weight, but gave a smaller chance of it being hit by enemy fire, thereby exploding and damaging the glider. Standard approach speed for the Hamilcar was , although for shorter landings this could be slowed to , and stalling speeds were with flaps up or with flaps deployed. The Hamilcar was fitted with tailwheel landing gear, with oleo-pneumatic shock absorbers that could be deflated to bring the fuselage nose down for loading or unloading purposes.Lloyd 1982, p. 65. A jettisonable undercarriage was initially designed for the glider, as it was discovered that it travelled for a shorter distance when it landed only on its skids. However, this was eventually replaced with a fixed undercarriage – the same as had been designed for ferrying operations – as pilots found that they preferred to land on wheels because of the extra control it gave them and the ability to avoid other gliders and potential collisions in the landing area. The wheeled undercarriage was not fitted until after the glider had been loaded; two 15-ton jacks were used to lift the aircraft for the fitting.''Flight'' 14 December 1944 pp. 635–6.

When the glider was carrying tanks or other vehicles, common practice was that their engines would be started in the air, usually just prior to the glider casting off from the tug; special exhaust ducts were fitted to the glider to expel exhaust fumes. The Tetrarch and M22 Locust light tanks were so large that they barely fit inside the glider, and as such their crews stayed inside the tank for the duration of the flight. Once the glider landed, the anchorages keeping the vehicle stationary would be released by the driver pulling a lanyard within his reach, and the driver would then drive the tank forward, which automatically pulled a line that operated the swing door release.Flint 2006, p. 42. Universal Carriers and other vehicles relied on one of the pilots operating the door line manually. This was achieved by the pilot sliding down the fuselage and then dropping to the ground. They would then go to each undercarriage leg and release the valves there, which would expel hydraulic fluid and allow the shock absorbers struts to deflate, and then enter the glider and operate the door release line. If the swing door was jammed after the glider had landed, it was possible for tanks to break through the unopened forward fuselage and drive straight out of the glider, which occurred in both airborne operations where Hamilcars transported tanks.

Operational history

When the parts for a Hamilcar were completed and the glider was erected, it was flown to RAF North Luffenham in Rutland to have its specific cargo placed on board, and it was then flown to RAF Tarrant Rushton, which had been selected as the Hamilcar training and operational base in November 1943. It was not possible to tow the glider empty, so any empty gliders usually carried Universal Carriers or concrete blocks as ballast. Training with the Hamilcar appears to have taken place primarily at RAF Tarrant Rushton, and began sometime between the end of 1943 and the first months of 1944.Flint 2006, p. 80. Hamilcar training began with dual instruction, where an instructor accompanied the pilots for several hours, and then moved onto flying solo flights. Most of this training consisted of 'circuits and bumps', where the pilots practised controlling the glider as it took off from an airfield under tow, and then landing it after the tow rope was detached; cross-country navigation was also practised. It was common practice for members of airlanded units to be inside the gliders as cargo when training took place, although there is evidence that tank crews only acted as cargo for one or two flights, probably due to the risk of accidents which might cost the lives of specialised troops and equipment. Those flights that tank crews did experience usually consisted of gliders landing on carefully marked airfields instead of the open countryside to minimise the risks involved, and also make recovery of the glider easier. Accidents do not seem to have been a common occurrence. During training by 'C' Squadron of the Glider Pilot Regiment, part of the Army Air Corps, which specialised in flying Hamilcars, over 2800 lifts were made with an average of 50 lifts per crew. Only three incidents resulted in fatalities or injuries, with seven pilots killed during the training.

Operation Tonga

Operation Tonga originated in the planning of Operation Overlord, the plan for the eventual invasion of France and the opening of a Second Front in North-Western Europe. Planning for the invasion of Europe by the Allies had begun in May 1943 when President of the United States Franklin Delano Roosevelt and Churchill had met at the Washington Conference.Otway 1990, p. 156. The two Allied leaders decided that all available Allied forces in the theatre should be concentrated in Great Britain, and that planning for the invasion of North-Western Europe should begin. A provisional target date of May 1944 was set, the code-name Overlord decided upon, and a joint Anglo-American planning staff created under Lieutenant-General Frederick E. Morgan, who was given the title of Chief of Staff to the Supreme Allied Commander (COSSAC). The plan eventually agreed upon called for the British 6th Airborne Division and the American 82nd and 101st Airborne Divisions to land either side of the landing areas to secure their flanks and protect the landing troops from counterattack.Buckingham, p. 27. The British airborne forces were to land in the east and the American airborne forces to land to the west of Bayeux in support of the infantry and armoured units advancing from the beachheads. The operation began on the night of 5 June, with the deployment of 6th Airborne Division to eastern Normandy. It was tasked with protecting the eastern flank of the Allied seaborne landings, securing strategically important areas east of Caen

HOME


Content is Copyleft
Website design, code, and AI is Copyrighted (c) 2014-2017 by Stephen Payne


Consider donating to Wikimedia



As an Amazon Associate I earn from qualifying purchases