Lioré et Olivier LeO H-27

The LeO H-27 was built in response to a French government call for a postal aircraft able to cover the South Atlantic routes. It was in competition with the Latécoère 300 and the Blériot 5190.[1]

The design of the LeO H-27 was assisted by Lioré at Olivier's experience with the LeO H-180 and LeO H-240 flying boats, the first single-engined and the second with one push-pull pair. It was a high wing cantilever monoplane with an all-metal wing in two parts, each with a thick airfoil, rectangular plan centre section and a trapezoidal outer panel with a rounded tip. The outer panel tapered in thickness outwards and carried 11.80 m (38.7 ft) span ailerons which, like the rear control surfaces, were balanced. The wing was built around two duralumin spars joined into a central box to which the leading and trailing edges were attached; all were dural covered.[1][2]

Four 480 kW (650 hp) Hispano-Suiza 12Nbr water-cooled V-12 engines, each driving a three blade propeller, were mounted in two push-pull pairs, each pair mounted above the central panel on N-form, broad, faired struts assisted by two forward diagonal thrust struts and a near vertical pair aft.[1][2]

The LeO H-27 had a two step hull; its concave V reinforced underside had a central angle of 144°. It was a flat sided structure built around longerons and frames. There was a mooring compartment in the extreme nose and in a second section the pilots' multiply-windowed cabin was also well forward and in front of the propeller discs. It had side-by-side seats with dual controls and was high up, with a navigator's cabin and radio equipment underneath, lit by portholes just forward of the port side crew entry door. The engineer's compartment was immediately behind the pilots. The mail was stored in a third, 8 m³ (280 cu ft), section of the hull and the fourth housed equipment and four hammocks.[2]

At the rear a tall, straight edged fin mounted a narrow rectangular balanced rudder and also the high aspect ratio, parallel chord tailplane, positioned about halfway up the fin to keep it out of the spray and braced with a single strut on each side to the top of the hull. It had separate, narrow chord elevators.[1][2]

Lateral stability on the water was provided by two wing-mounted floats, with single step, V-form undersides. These were mounted below the central-outer wing panel junctions at only about one-quarter span on a combination of faired-in vertical and inward leaning struts.[2]

Though the hull of the LeO H-27 was first seen in public at the 12th Paris Aéro Salon in November 1930,[1] it did not fly until 30 December 1933, piloted by Bourdin.[3] Only one was built and Air France's South Atlantic routes were flown instead by the Latécoère 300; the LeO H-27 did make at least one Atlantic crossing when Bourdin flew it to the Antilles towards the end of 1934.[4]

Data from Les Ailes February 1934[2]

General characteristics

• Crew: Four
• Length: 21.45 m (70 ft 4 in)
• Wingspan: 36.80 m (120 ft 9 in)
• Height: 7.13 m (23 ft 5 in)
• Wing area: 180 m² (1,900 sq ft)
• Empty weight: 9,330 kg (20,569 lb)
• Gross weight: 18,200 kg (40,124 lb)
• Fuel capacity: 9,460 L (2,080 imp gal; 2,500 US gal)
• Powerplant: 4 × Hispano-Suiza 12Nbr water-cooled geared V-12, 480 kW (650 hp) each
• Propellers: 3-bladed metal

Performance

• Maximum speed: 245 km/h (152 mph, 132 kn) at 1,500 m (4,900 ft)
• Range: 3,500 km (2,200 mi, 1,900 nmi) with 600 kg (1,300 lb) of mail and a 50 km/h (31 mph) head wind
• Service ceiling: 4,300 m (14,100 ft) theoretical
• Time to altitude: 15 min 30 sec to 2,000 m (6,600 ft)