World War Photos

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The Hamilcar stood as the largest wooden aircraft constructed during World War II. To effectively bear the heavy loads it needed to carry, both structurally and aerodynamically, a wing loading much higher than any previously contemplated for a glider was chosen, resulting in a wing loading of 21.7 lb per square foot (105.8 kg per square meter). This high-wing, cantilever monoplane boasted a remarkable wing span of 110 feet (33.5 meters) and a wing area of 1,657 square feet (153.9 square meters), crafted from wood. The wing comprised a center section and two tapering outer sections. Internally, the structure featured two box spars with laminated plywood booms and plywood webs, strengthened further with ribs. A thin plywood sheet formed the outer covering of the wing, while a fabric cover was added on top of it. The fuselage was rectangular and made of wood, divided into two main sections that could be separated for easier ground transportation to assembly points. The ingenious construction enabled the plywood surface of the body to carry a significant portion of the stresses from various sources. For loading purposes, the bulbous nose was hinged on the starboard side, allowing it to swing open. The impressive capabilities of the glider were evident in its capacity to carry diverse loads, such as a Tetrarch Mark IV tank or a Locust tank, two Bren-gun universal carriers or two armored scout cars, a 25-pound gun with tractor, and similar weights. With an ‘all-up’ weight reaching 36,000 pounds (16,329 kilograms), the Hamilcar required an immensely powerful aircraft to tow it. Initially, early tests involved a Halifax with enhanced engines, but as the Halifax bomber underwent modifications to boost its engine power, a standard Halifax became the designated tug for the Hamilcar. On occasion, the Lancaster and Stirling four-engined bombers were also employed as tugs.

The first full-sized prototype took flight on 27th March 1942, and throughout the war, a total of 412 Hamilcars were produced. These gliders played a vital role in various critical operations, demonstrating their worth in Normandy, at Wesel, and during the Arnhem campaign. In fact, one Hamilcar was acquired by the U.S. Army Air Forces for testing and evaluation at the Air Force Materiel Command located at Wright Army Air Force Field near Dayton, Ohio. Additionally, design studies were conducted to explore the possibility of operating the Hamilcar in a ‘pick-a-back’ system, in conjunction with the P-38 Lightning. A later British advancement included the Mk X, a two-engined powered version of the glider. This modification proved to be remarkably successful and capable.

Type

High-wing cantilever monoplane designed for transporting military equipment.

Wings

• Section: RAF .34 modified.
• Aspect Ratio: 11.5.
• Structure:
  • Centre-section with two tapering outer sections.
  • Two box spars with laminated booms and plywood webs.
  • Built-up former ribs and plywood skin covered with fabric.
  • Outer wings attached to the centre-section via two fore-and-aft pin-joints per spar.
  • Flaps: Pneumatically-operated slotted flaps between ailerons and fuselage, made of wood with a single box spar, diaphragm ribs, and plywood skin.
  • Ailerons: Dynamically-balanced slotted ailerons with a single spar, former ribs, plywood leading-edge, and fabric covering. Trim-tab in the starboard aileron.

Fuselage

• Structure: Rectangular all-wood semi-monocoque in two main sections (separable for transport).
  • Series of vertical square frames, four corner longerons, and fabric-covered plywood skin with intercostal stringers.
  • Two massive frames reinforced with high-tensile steel gusset plates for transmitting lift loads.
  • Keel beam acts as main load anchorage.
  • Nose: Hinges to open to starboard for loading.
  • Flight Compartment: Located in the roof of the forward fuselage, ahead of the rear centre-section spar. Supported on three transverse trusses with a transparent canopy.
  • Rear Fuselage: Terminates in two heavy frames supporting the fin, tailplane, and tail-wheel.

Tail Unit

• Type: Cantilever monoplane.
• Structure: Two-spar structures with a plywood skin.
• Control Surfaces: Elevators and rudder have wood frames and are fabric-covered. Trim-tabs present in elevators and rudder.

Landing Gear

• Type: Divided.
• Structure: Two Vees hinged to the lower fuselage longerons with a vertical oleo-pneumatic shock-absorber leg hinged to the centre-section front spar.
  • Vees consist of stainless steel boxes, with the rearmost acting as the axle beam.
  • Universal ball-joint anchorages.
  • For loading/unloading, the shock-absorber struts’ pressure can be released, allowing the aircraft to rest on ash skids.
  • Differentially-operated wheel-brakes.
  • Alternative jettisonable landing gear without shock-absorbers for skid landings.
  • Fully-castoring tail-wheel.

Accommodation

• Flight Compartment:
  • Upper forward fuselage, seating two in tandem with dual controls.
  • Bullet-proof windshield and armor behind the second pilot.
  • Access via a ladder on the inner starboard side, through a roof hatch, and along a walkway on the top of the centre-section.
• Freight Compartment:
  • Dimensions: 25 ft. 6 in. (7.78 m) long, 8 ft. (2.44 m) wide, and 7.5 ft. (2.3 m) high.
  • Capacity: Up to 17,500 lbs. (7,950 kg) of military equipment.
  • Nose hinges to starboard for loading.
  • Cable-operated push-rod assembly for opening the nose, either manually or automatically.
  • Vehicle rails adjustable for different track widths.
  • Central load anchorage on the keel beam.
  • Exhaust extractors for vehicle engine start-up before landing.

Dimensions

• Span: 110 ft. (33.5 m)
• Length: 68 ft. (20.7 m)
• Height: 20 ft. 3 in. (6.2 m) (tail down)
• Wing Area: 1,657.5 sq. ft. (154 sq. m.)

Weights

• Empty: 18,400 lbs. (8,350 kg)
• Military Load: 17,600 lbs. (7,980 kg)
• Loaded: 36,000 lbs. (16,330 kg)
• Wing Loading: 22.37 lbs./sq. ft. (109.2 kg./sq. m.)

Performance (at sea level)

• Maximum Towing Speed: 150 mph (240 km/h)
• Maximum Diving Speed: 187 mph (300 km/h)
• Stalling Speed: 65 mph (105 km/h)