The I.S.T. XL-15 Tagak (Swan in English) was a single-engine, twin-boom,

high-wing A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

monoplane A monoplane is a fixed-wing aircraft configuration with a single mainplane, in contrast to a biplane or other types of multiplanes, which have multiple planes. A monoplane has inherently the highest efficiency and lowest drag of any wing confi ...

designed after the I.S.T. XL-14 Maya and built in the

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

in the mid-1950s. The result of a collaboration between a Government research institute and the

Philippine Air Force The Philippine Air Force (PAF) ( tgl, Hukbong Himpapawid ng Pilipinas, , Army of the Air of the Philippines) ( es, Ejército Aérea del Filipinas, , Ejército de la Aérea de la Filipinas) is the aerial warfare service branch of the Armed Forc ...

, it was designed as a utility, liaison or ambulance aircraft and as a test bed for the use of local materials in aviation.

Design and development

In the early 1950s in the Philippines, the Institute of Science and Technology (I.S.T., previously known as the Bureau of Science) designed at least three different prototypes, both to investigate the scope for local aircraft design and production and to examine the use of indigenous materials in their construction. One such material of interest was ''Wobex'' (Woven bamboo experimental), a reinforced woven

bamboo Bamboos are a diverse group of evergreen perennial flowering plants making up the subfamily Bambusoideae of the grass family Poaceae. Giant bamboos are the largest members of the grass family. The origin of the word "bamboo" is uncertain, bu ...

. The XL-15 Tagak was the second of these prototypes, developed in collaboration with the

. It was a single-engine,

with a

twin-boom A twin-boom aircraft is characterised by two longitudinal booms (extended nacelle-like bodies). The booms may contain ancillary items such as fuel tanks and/or provide a supporting structure for other items. Typically, twin tailbooms support ...

layout and

tricycle undercarriage Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', arranged in a tricycle fashion. The tricycle arrangement has a single nose wheel in the front, and two or more main wheels slightly aft of the center of gravity. Tricycle ge ...

to enable easy access to the fuselage pod via rear doors. The inner wing sections, fitted with slotted flaps on the trailing edges had constant chord but further out the wings tapered, with slotted

ailerons An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in Flight dynamics, roll (or ...

. There was a single lift

strut A strut is a structural component commonly found in engineering, aeronautics, architecture and anatomy. Struts generally work by resisting longitudinal compression, but they may also serve in tension. Human anatomy Part of the functionality o ...

on each side between wing and lower fuselage, with an airfoil profile to add to the lift from the wings. The

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

of the Tagak was a wood and

plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...

framed semi-monocoque skinned with Wobex and ply. Its cabin, behind the 185 hp Lycoming flat six engine, was 3.26 m (10 ft 6 in) long to the rear of the pod. There were two front seats under the wing leading edge, two more behind and room for one or two (stacked) stretcher cases. The cabin had two windows on each side and the rear part of the pod, which projected behind the wing trailing edge, was also extensively glazed. The two tail booms, of all ply construction, were integral with the wing centre section. The

fins A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. Fin ...

, with long chord underside fillets, were integral with the booms. The

tailplane A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplane ...

was rectangular and extended beyond the fins, carrying a horn balanced

elevator An elevator or lift is a wire rope, cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or deck (building), decks of a building, watercraft, ...

. The fixed surfaces were of wood and ply construction, with Wobex covering; control surfaces were fabric covered. Flight testing of the Tagak began in October 1954. By 1956 some small modifications had been made: rudder area was increased and a shimmy-damper added to the nosewheel leg. Only one was built.

Specifications

References

{{reflist, refs= {{cite book , title= Jane's All the World's Aircraft 1956-57, last= Bridgman , first= Leonard , year=1956, publisher= Jane's All the World's Aircraft Publishing Co. Ltd, location= London, page=192 XL-15 Twin-boom aircraft High-wing aircraft Single-engined tractor aircraft Aircraft first flown in 1954 1950s civil utility aircraft

Design and development

Specifications

See also

References