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Airspeed Horsa

Page Created
June 1st, 2024
Last Updated
July 13th, 2024
Great Britain
British Flag
Length
20.40 metres
Wide
26.80 metres
Height
5.90 metres
Weight
3,855 kilograms
Loaded Weight
6,900 kilograms
Propulsion
Armour
Armament
History
Airspeed AS.51, Horsa

The glider, demonstrated by the Luftwaffe at the Belgian fort of Eben Emael in 1940, has a significant attraction: like modern troop-lift helicopters, it can land a formed group, usually a platoon, on a compact landing zone. The British require their glider pilots not only to deliver men and equipment safely into battle but also to join the fight as infantry after landing. Paratroops, while less vulnerable, can be scattered by wind or the speed of their exit from the aircraft, delaying their formation into an effective fighting force.

The Air Ministry issues Specification X.26/40, calling for a large glider aircraft capable of accommodating up to thirty fully equipped paratroopers for operations in Northern France. One key requirement is the use of wood as the main construction material to conserve critical supplies of metals.

Airspeed Limited receives this specification and begins producing initial designs at Hatfield under the leadership of A. Hessell-Tiltman. With the war effort in full swing, the parent company, de Havilland Aircraft Company, which has recently acquired a controlling interest in Airspeed, provides support. However, the team works in the classrooms of the de Havilland Technical School, which is not ideal due to the constant threat of air raids. Consequently, the Airspeed team relocates to Salisbury Hall in nearby London Colney. Salisbury Hall also houses the DH98 Mosquito design team, led by Ralph Hare and Ron Bishop. The Mosquito, later dubbed ‘The Wooden Wonder,’ benefits from the synergy between the two projects.

The final design for the new glider is completed in just 11 months, an extraordinary achievement given that Britain is at the height of its conflict with Germany and the Battle of Britain is being fought in the skies of southern England.

With the designs complete, the first two prototypes are built at Salisbury Hall before being transported to the Fairey Aviation Works at Hayes, near the Great West Aerodrome. The first prototype, DG597, is first flown on September 12th, 1940, by George Errington. It is towed into the skies over West London and Berkshire by an Armstrong Whitworth Whitley, then released and landed with very little difficulty. Allocated the Airspeed designation AS.51, the type is christened Horsa, after the legendary fifth-century conqueror of southern Britain. Five additional prototypes are quickly assembled and test flown at the Airspeed Works in Christchurch, Dorset.

As soon as production begins, expert subcontractors, some with decades of experience in wooden furniture, suggest a number of improvements and refinements. These enhancements result in the AS.58 Airspeed Horsa II.

This modified design features a reinforced floor and a hinged nose section to accommodate military vehicles for both transport and combat roles. Another significant upgrade includes the installation of a stronger twin nose-wheel and a modified tow attachment. These modifications increase the all-up weight to 7,140 kilograms. It is worth noting that although Airspeed Limited is responsible for most aspects of the Horsa II, they never manufacture or assemble any of this model.

Design and Features of the Horsa Glider

The Horsa is a high-wing cantilever monoplane with wooden wings and a wooden semi-monocoque fuselage. The fuselage consists of three bolted sections: the pilot’s compartment and main freight-loading door at the front, accommodation for troops or freight in the centre, and the tail unit at the rear. Airspeed subcontracts construction to Austin Motors, and furniture manufacturers like Harris Lebus also contribute, given the significant use of wood in the airframe.

One of the Horsa’s pioneering features is its tricycle undercarriage, which can be jettisoned after take-off for landings on a sprung skid under the fuselage. The wings have large ‘barn door’ flaps allowing for steep, controlled descents into confined landing zones. The glider has dual controls and side-by-side seats for two pilots. A hinged cargo-loading door on the port side doubles as a ramp, and the main compartment can accommodate thirty soldiers on bench seats. Soldiers can also enter and exit through a smaller starboard side door. Rapid unloading is facilitated by breaking the fuselage joint at the rear of the main section. The Horsa can carry six Central Landing Establishment (CLE) containers under the wings.

Versions

AS.51 Airspeed Horsa I. Production glider with cable attachment points at upper attachment points of main landing gear.

AS.52 Airspeed Horsa. Bomb-carrying Horsa; project cancelled prior to design/production

AS.53 Airspeed Horsa. Further development of the Horsa not taken up.

AS.58 Airspeed Horsa II. Development of the Horsa I with hinged nose, to allow direct loading and unloading of equipment, reinforced floor, and double nose wheels for extra weight, with the tow attached to the nose-wheel strut instead of the wing points.

By the end of World War II, 3,655 Horsa’s have been built, with about 1,000 available for operations on D-Day.

Operational Use and Lessons Learned

The Horsa’s operational debut is during the landings on Sicily in Operation Husky in July 1943. Pilots undertake a long and hazardous journey under tow from southern England to airfields in North Africa. The operation faces high casualties due to several factors, including some gliders being released too far from the coast and ditching at sea, and friendly fire from Allied anti-aircraft gunners mistaking them for enemy aircraft.

Lessons from Husky are applied by D-Day, with new drills to prevent similar tragedies. A dramatic measure involves painting bold black and white stripes on wings and fuselages, D-Day stripes. Allied anti-aircraft gunners are instructed not to engage any aircraft with these markings, ensuring safer operations for all Allied aircraft over Normandy.

For the six Horsa Gliders used during the Coup de Main to capture the bridges adaptions are made to perform their mission.

The three Horsa’s that would attack the Caen Canal bridge would require specific modifications. Because they are flying right-handed turns, the first pilot is advised to fly on the right-hand side of the glider, contrary to the usual left-side position. Under the perspex front of the cockpit, a second panel is cut and fitted with perspex, allowing an almost vertical view of the ground, and providing an extra window for better visibility.

The command pilot occupies the right-hand seat to maintain a clear view of the bridge during a descent rate of 750 metres per minute at an angle of about forty-five degrees. This positioning allows for better right-hand circuit navigation. The co-pilot uses a small torch to avoid interfering with the pilot’s vision and manages a stopwatch. Additionally, a direction finder (gyro-compass) is installed in the aircraft because the standard compass is not effective at a forty-five degree angle.

It is also recognised that bringing seven tons, the combined weight of three tons of troops and the three and a half-ton glider, down into a small field from 1,800 metres and bringing it to a stop is quite challenging. Although the glider excels in short landings using full flaps, there remains the problem of fitting three gliders, or even one, into that field with the landing run, especially with two more gliders following closely behind. Consequently, the decision is made to install drag chutes. This idea is proposed by Flight Lieutenant Grant, who observed the Americans using them during trials in the United States.

During the night of June 2nd, 1944, a team of Airspeed engineers, equipped with mobile workshops, arrives at Tarrant and begins modifying the six gliders. An arrester parachute is fitted into each tail. To unload the Mk 1 Horsa glider, there is a double bulkhead aft of the trailing edge of the main planes, featuring six quick-release bolts to drop the tail out of the way. This section includes a panel on the lower part of the fuselage that can be lowered to attach a rifle or other weapon for use upon landing.

The parachute, connected to the bulkhead, is placed in a box on this panel and can be operated from the cockpit using toggle switches in the centre of the instrument panel. One switch opens the trap door for the chute to fall out and deploy, while the other operates the release mechanism to discard the parachute. The Glider Pilots are concerned because, with the parachute lying on a loose panel on the floor, turbulence might cause the panel to be sucked out, leading to the parachute deploying while being towed across the Channel. Therefore, it is decided that the Oxf and Bucks or the engineer sitting in the rear seat of the glider will keep the parachute on their lap during the flight over the Channel. Once they have cast off, they will lean over the back of their seat and place the parachute onto the panel, positioning it for deployment.

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Construction and Assembly

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