The Lioré et Olivier Leo H-15 was a French twelve-seat civil flying boat, flown in a national contest in 1926. It did not win but set two load carrying records, one a world record.

Design and development

In 1926 the French government offered large prizes in a contest to produce new, multi-engined commercial

seaplane A seaplane is a powered fixed-wing aircraft capable of taking off and landing (alighting) on water.Gunston, "The Cambridge Aerospace Dictionary", 2009. Seaplanes are usually divided into two categories based on their technological characteri ...

s. Compared with similar landplane competitions, few manufacturers offered a candidate; at the trials, held in July and August only the Lioré et Olivier LeO H-15 and the SPCA Météore 63 took part. The LeO H-15 was a three-engined biplane with high aspect ratio, thin section wings of unequal span. The shorter span lower wing, with slight dihedral, was built into the hull and the upper wing was mounted on it without stagger or dihedral. The

interplane struts In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of strut, which act in ...

were in parallel pairs, two outward leaning and two vertical outboard, and an interconnected central complex which both braced the wings and mounted two of its three Gnome & Rhône 9Ab 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 ...

s close inboard between the wings. The other was mounted on the upper wing over the hull. Its hull had two steps, one under the wing

trailing edge The trailing edge of an aerodynamic surface such as a wing is its rear edge, where the airflow separated by the leading edge meets.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 521. Aviation Supplies & Academics, 199 ...

and the second further aft. The underside had a rounded, rather than V, section and was wider than its upper part. The pilot was positioned in an open cockpit just ahead of the

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, ...

of the wing and a "luxurious" passenger cabin, accommodating twelve, was accessed via a hatch in the nose. On each side a stabilizing float was mounted below the lower wing on extensions of the outer interplane struts, strengthened with another, inward pair. The LeO H-15's

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 ...

was part of the hull and was roughly triangular in profile. It carried a vertical-edged, balanced rudder which extended to the lower fuselage. A rectangular 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 gyropla ...

was mounted on the fin a little way above the fuselage, braced on each side with a parallel pair of struts to the lower fuselage and wires from the upper fin; like the rudder, the

elevator An elevator or lift is a cable-assisted, hydraulic cylinder-assisted, or roller-track assisted machine that vertically transports people or freight between floors, levels, or decks of a building, vessel, or other structure. They a ...

s were balanced.

Operational history

The LeO H-15 first flew on 10 June 1926, less than six weeks before the start of the trials on July 19 at Saint-Raphaël. It was required to achieve its Certificate of Airworthiness two days before the trials to take part. Its trials pilot was Lt. de Vaisseau Benoit. The Météore out-performed the LeO in the commercial flight tests and was judged safer and more comfortable for the passengers, though its take-offs took longer, it climbed more slowly and was less seaworthy. As a result, the Météore received the first prize of 100,000 francs and the LeO the 20,000 francs second prize. During the trials the LeO H-15 set two records, both for aircraft carrying a load of . The first was a world duration record of 4 h 32 min 11 s and the second a French speed record over at .

Specifications

References

{{Lioré et Olivier aircraft Flying boats Trimotors 1920s French airliners H-15 Biplanes