The Denhaut Hy.479 was a French

flying boat A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in that a flying boat's fuselage is purpose-designed for floatation and contains a hull, while floatplanes rely on fusela ...

flown in 1926 and intended to be suitable for commercial or military applications. Only one, in military configuration, was built and was sometimes known as the France-Aviation Denhaut.

Design and development

The Hy.479 was an unequal span, single bay biplane with thick section wings. The longer upper wing was in three parts, with a short, almost rectangular centre section and trapezoidal outer panels. The lower wings were attached to the upper hull and were swept with constant

chord Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * Chord ( ...

, then straight-tapered to the squared tips. The top surface of the upper wing was flat but deceasing thickness provided some dihedral; the lower wing carried dihedral on both surfaces. Ailerons, which covered over half the span. were only fitted on the upper wing. Structurally the wings were wooden, with two spars 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 ...

-covered

leading edge The leading edge of an airfoil surface such as a wing is its foremost edge and is therefore the part which first meets the oncoming air.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, ...

s; elsewhere the covering was

fabric Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not the ...

. The wings were braced together on each side by a pair of parallel, outward-leaning interplane struts. Below these, steeply angled stabilizing floats were attached close to the lower wing underside with short struts. To minimise hangar space, the outer wings could be folded back alongside the hull. The Hy.479 was powered by a pair of Gnome & Rhône 9A Jupiter nine-cylinder

radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...

s strut-mounted midway between the wings immediately below the end of the upper centre-section, placing them as close together as the

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

s allowed. The engines were uncowled, though their accessories were placed behind them under conical fairings. Its hull was deep, with steep sides and a shallow V-section bottom without steps. It was compartmented, double- and triple-planked below the waterline and

covered above. The pilots sat side by side in an open

cockpit A cockpit or flight deck is the area, usually near the front of an aircraft or spacecraft, from which a Pilot in command, pilot controls the aircraft. The cockpit of an aircraft contains flight instruments on an instrument panel, and the ...

ahead of the propellers, protected by a generous windscreen. In the military configured first and only prototype there were

machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) a ...

ners positions in the rounded nose and midway between the wings and tail. The Denhaut had a large, triangular

fin 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 a deep, curved,

balanced rudder Balanced rudders are used by both ships and aircraft. Both may indicate a portion of the rudder surface ahead of the hinge, placed to lower the control loads needed to turn the rudder. For aircraft the method can also be applied to elevators and ...

. Its delta plan

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 mounted halfway up the fin, braced on each side with a single strut to the lower hull, and carried 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, ...

s with a cut-out for rudder movement. The Hy.479 could be easily configured as an

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

, with mainwheels on V-struts hinged on extensions of the engine struts and inner V-struts braced to the lower hull. With the inner struts disconnected, the wheels could be raised outwards to the wing underside. The date of the Hy.479's first flight is not known but trials were under way in early December 1926, flown from

Étang de Berre The Étang de Berre (in Provençal Occitan: ''estanh de Bèrra / mar de Bèrra'' according to classical orthography, ''estang de Berro / mar de Berro'' according to Mistralian orthography) is a brackish water lagoon on the Mediterranean coast of ...

. Flight characteristics, including single-engined performance, were reported to be good; allowing the aircraft to go to Saint Raphaël for official tests in January 1927. After a minor accident when a crane cable failed, development was stopped as Denhaut withdrew from the project, possibly due to Aeronavale's preference for tandem engines (reducing problems of asymmetric thrust during engine failure / differential throttle settings). The proposed passenger version with an internal cabin was not built.

Specifications (Hy.479)

References

{{reflist, refs= {{cite journal , last=Serryer , first=J. , date=8 December 1926, title=L'hydravion France-Aviation Denhaut, journal=Les Ailes, issue=286 , pages=5, url=http://gallica.bnf.fr/ark:/12148/bpt6k65683188/f5 {{cite journal , date=6 January 1927, title=(left column), journal=Les Ailes, issue=290 , pages=6, url=http://gallica.bnf.fr/ark:/12148/bpt6k65683225/f6 {{cite journal , date=28 July 1927, title=Moteurs latéraux ou moteurs en tandem, journal=Les Ailes, issue=319, pages=2, url=http://gallica.bnf.fr/ark:/12148/bpt6k6568351w/f2 {{cite journal , date=January 1927 , title=L'industrie aéronutique, journal=L'Aéronautique, volume=1927 , issue=92 , pages=29, url=http://gallica.bnf.fr/ark:/12148/bpt6k65680187/f57 Flying boats 1920s French military aircraft Aircraft first flown in 1926 Biplanes Twin-engined tractor aircraft