Aircraft such as the Airspeed AS.51 "Horsa" rarely receive their due in the grand scope of World War 2 - a conflict littered with excellent fighter and bomber types as well as the eccentric design or two. The Horsa was a simple glider design intended to haul man and machine to places far beyond fighting fronts, landing often times behind enemy lines. Observing the success that the German airborne elements had in the early stages of the war, the British followed suit and set up their own airborne contingent and, to this, was realized that specialized hardware would be required for their light-armed infantry. The Horsa proved a success in its subtle ways, ferrying dozens of troops, light artillery pieces or light vehicles to war and production eventually yielded between 3,500 and 5,000 units by war's end (sources vary). The Americans also took on stocks of Horsa numbering several hundred while other nations fielded much limited numbers.
Early development of British military gliders yielded limited results. Specification X.26.40 was eventually fleshed out for a dimensionally larger airframe which could ferry 25 infantry while being towed by a "host" aircraft. The charge fell to the Airspeed Company which - in just eleven months - returned with the AS.51 "Horsa". At Fairey Aircraft's Great West Aerodrome, prototypes were evaluated with an Armstrong Whitworth Whitley bomber as the host and five additional vehicles were commissioned to serve in loading trials. In February of 1941, authorities contracted for 400 of the glider and a first flight was recorded on September 12th in that same year. Production examples were expected to be delivered for the following summer.
With a structure made largely of wood, and requiring the facilities of British furniture factories, the plans for the aircraft were specially drawn up to serve established furniture-making business practices. Since most furniture builders lacked the space required for completed aircraft, the gliders saw their final assembly at the hands of Royal Air Force (RAF) personnel offsite. Manufacture of the gliders fell to Harris Lebus and the Austin Motor Company.
The initial Horsa Mk I was given a portside hinged door that doubled as a loading ramp. It was towed through a Y-cable arrangement which ran from the host aircraft to points on the Horsa's wings. As designed, the Horsa was essentially an aircraft sans its engines for the chosen configuration was conventional with a centralized fuselage and forward-set cockpit, high-mounted monoplane wings and a traditional single-finned tail with low-set horizontal planes. The cockpit was heavily glazed and offered excellent vision. A crew of two sat in a side-by-side arrangement with a dual-control scheme so either member could control the aircraft. A simplified instrument panel was set on a pedestal between the two positions as was a low console. Beyond that, the cockpit remained spartan and devoid of unnecessary clutter. Aft of the cockpit was the hold which included exposed framework and seating for up to 25 infantry along side wall benches. The aircraft was towed during take-off atop a jettisonable tricycle undercarriage arrangement and a nose wheel/belly skid combination was used for landing. Strong handling qualities made her a favorable aircraft to control and a "quick-dive" capability allowed pilots some pin-point accuracy.
Dimensions included a length of 67 feet, a wingspan of 88 feet and a height of 19.5 feet. Empty weight was listed at 8,370lbs with a loaded weight topping 15,500lbs. Due to its towed existence, the Horsa was limited in its performance specifications. Top speeds reached up to 150 miles per hour with gliding speeds near 100 miles per hour or less.
In practice, the Horsa was assisted in large part by a host aircraft which was powered. The glider was attached by way of strong cables joining the two aircraft from take-off to flight. From there, glider pilots attempted to keep their aircraft in tune with the host until near the drop zone. Once detached, the glider crew managed the aircraft down to the best of their abilities - sometimes under clear unassuming skies and other times under direct enemy gunfire.
Production of the AS.51 began in earnest during 1942 which resulted in over 2,300 units being made available by the target delivery month. During testing, the gliders initially showcased structural faults when attempting to haul more than just personnel and these were rectified as quickly as possible, adding the much-needed capability of carrying light artillery systems and even 4x4 vehicles. Early use saw the types in action over North Africa and, in November of 1942, during the Norway campaign with mixed results. Regardless, the aircraft soldiered on in the British inventory and saw additional service in such key operations as Operation Husky, the Normandy Invasion and Operation Market Garden. Market Garden alone utilized over 1,200 glider aircraft in General Montgomery's famous multi-pronged assault intended to end the war by Christmas 1944. The British military fielded the AS.51 across its Glider Pilot Regiment of the Army Air Corps and No. 670 Squadron of the Royal Air Force (RAF).
Four major designations were ultimately tied to the Horsa legacy including the initial Mk I models. The AS.58 Mk II was a modified form with a hinged nose for easier loading/unloading and its tow cables now connected at the two-wheeled nose leg. The AS.52 was a proposed "bomber" form with provision for ordnance but was never furthered. Similarly, the AS.53 fell by the wayside and was intended as a more evolved Mk I.