The Airspeed AS.51 Horsa was a sizable troop carrying glider .
It was capable of transporting a maximum of 30 seated fully equipped troops, it also had the flexibility to carry a Jeep or an Ordnance QF 6-pounder anti-tank gun.
The Horsa Mark I had a wingspan of 88 feet (27 m) and a length of 67 feet (20 m), and when fully loaded weighed 15,250 pounds (6,920 kg).
The later AS 58 Horsa II featured an increased fully loaded weight of 15,750 pounds (7,140 kg) along with a hinged nose section, reinforced floor and double nose wheels to support the extra weight of vehicles.
The tow cable was attached to the nose wheel strut, rather than the dual wing points of the Horsa I.
It was considered to be sturdy and very manoeuvrable for a glider.
The design of the Horsa adopted a high-wing cantilever monoplane configuration, being equipped with wooden wings and a wooden semi-monocoque fuselage.
The fuselage was built in three sections bolted together, the front section held the pilot’s compartment and main freight loading door, the middle section was accommodation for troops or freight, the rear section supported the tail unit.
The fuselage joint at the rear end of the main section could be broken on landing to facilitate the rapid unloading of troops and equipment, for which ramps were provided.
Initially the tail was severed by detonating a ring of Cordtex around the rear fuselage.
But this was thought to be hazardous, especially if detonated prematurely by enemy fire.
In early 1944, a method of detaching the tail was devised that used eight quick-release bolts, and wire-cutters to sever the control cables.
The wing carried large barn door flaps which, when lowered, made a steep, high rate-of-descent landing possible—this performance would allow the pilots to land in constricted spaces.
By employing a combination of the flaps and pneumatic brakes, the glider could be brought to a stop within relatively short distances.
The Horsa was equipped with a fixed tricycle landing gear and it was one of the first gliders equipped with a tricycle undercarriage for take off.
On operational flights, the main gear could be jettisoned and landing was then made on the castoring nose wheel and a sprung skid set on the underside of the fuselage.
The pilot’s compartment had two side-by-side seats and dual controls, all of which being contained within a large Plexiglas nose section.
Initially, the cockpit would be outfitted with internal telephone systems that allowed for communication between the pilots of the glider and tug aircraft while connected, however, this was replaced on later-built models by radio sets instead, which had the advantage of being able to maintain contact after detaching.
Aft of the pilot’s compartment was the freight loading door on the port side, the hinged door could also be used as a loading ramp.
The main compartment could accommodate 15 troops on benches along the sides with another access door on the starboard side.
Supply containers could also be fitted under the centre-section of the wing, three on each side.
During March 1942, the Airborne Forces Experimental Establishment and 1st Air landing Brigade commenced loading trials using several of the prototypes, but immediately ran into problems.
During an attempt to load a jeep into a prototype, Airspeed personnel present informed the evaluation staff that to do so would break the glider’s loading ramp, as it had been designed to hold only a single motorbike.
With this lesson learnt, 1st Air landing Brigade subsequently began sending samples of all equipment required to go into Horsa’s to Airspeed, and a number of weeks were spent ascertaining the methods and modifications required to fit the equipment into a Horsa.
Even so, the loading ramp continued to be considered to be fragile and prone to damage, which would ground the glider if sustained during loading.
28 troops / 2x ¼ton trucks / 1x M3A1 Howitzer + ¼ton truck with ammunition and crew
(20–25 troops was the “standard” Mark I load)
67 ft 0 in (20.42 m)
88 ft 0 in (26.82 m)
19 ft 6 in (5.94 m)
1,104 sq ft (102.6 m2)
Root: NACA 4419R 3.1
Tip: NACA 4415R 3.1
8,370 lb (3,797 kg)
15,750 lb (7,144 kg)
100 mph (160 km/h, 87 kn) normal operational gliding speed