The SNCASE SE-3110 or Sud-Est SE-3110 was a French two seat experimental

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

with unusual twin, angled

tail rotor The tail rotor is a smaller rotor mounted vertically or near-vertically at the tail of a traditional single-rotor helicopter, where it rotates to generate a propeller-like horizontal thrust in the same direction as the main rotor's rotation. The ...

s, first flown in 1950. After brief tests

SNCASE SNCASE (abbreviated from ''Société nationale des constructions aéronautiques du Sud-Est'') or Sud-Est was a French aircraft manufacturer. The company was formed on February 1, 1937, by the nationalization and merger of Lioré et Olivier, Potez ...

decided to concentrate on a closely related but single-tail-rotor design.

Design and development

The SE-3110 drew heavily on the design and development of the 1948 SE-3101, sharing much of the latter's control system and also its unusual twin tail rotors. Externally it was much more refined, with a rounded forward pod for occupants and engine and a slender tail boom. The two crew sat side by side behind a fully glazed nose; structurally the pod was a light

monocoque Monocoque ( ), also called structural skin, is a structural system in which loads are supported by an object's external skin, in a manner similar to an egg shell. The word ''monocoque'' is a French term for "single shell". First used for boats, ...

. A Salmson 9 Nh nine cylinder, air-cooled

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 ...

was mounted horizontally under a transmission box attached to 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 ...

by steel tubes and driving a three-blade

rotor Rotor may refer to: Science and technology Engineering *Rotor (electric), the non-stationary part of an alternator or electric motor, operating with a stationary element so called the stator * Helicopter rotor, the rotary wing(s) of a rotorcraft ...

. Some sources give the engine as a Salmson 9 Nc, which was probably fitted to the first ground test article. The tail rotors were mounted above the end of the boom on shafts at right angles to it and to each other, so that the rotor planes were leaning inwards at 45° to the vertical. At least one image shows the drive shafts within slender fairings but several others show them bare. The SE-3110 landed on small wheels mounted on

cantilever A cantilever is a rigid structural element that extends horizontally and is supported at only one end. Typically it extends from a flat vertical surface such as a wall, to which it must be firmly attached. Like other structural elements, a canti ...

legs on each side and a long, forward-pointing, sprung skid. As on the SE-3101, differential pitch settings of the twin tail rotors compensated main rotor torque; there were mechanical linkages between the

collective pitch A helicopter pilot manipulates the helicopter flight controls to achieve and maintain controlled aerodynamic flight. Changes to the aircraft flight control system transmit mechanically to the rotor, producing aerodynamic effects on the rotor bla ...

, the throttle and the tail pitch control to lower the pilot's workload. Directional control was achieved by altering the tail pitch difference and the tail could be lifted or depressed, giving longitudinal control (aircraft pitch), in the same way. A new feature on the SE-3110 was longitudinal trim control via the main rotor

cyclic pitch A helicopter pilot manipulates the helicopter flight controls to achieve and maintain controlled aerodynamic flight. Changes to the aircraft flight control system transmit mechanically to the rotor, producing aerodynamic effects on the rotor bla ...

. The SE.3110 first flew on 10 June 1950, piloted by Jaques Lacarme. Gaillard states that the first prototype made only two flights at low altitude before being abandoned in favour of the SE-3120 Alouette I. However, other sources say that two SE-3110s were built, appearing on the French civil register initially as F-WFUD and F-WFUE, later transferring to the B list (after gaining their Certificates of Airworthiness) as F-BFUD and F-BFUE. In Liron's account the first prototype was retained for ground durability testing but the first flight of the second prototype on 15 September 1950 rapidly ended with loss of control and a side-on crash, though Lacarme walked away. SNCASE decided the way forward lay with the single tail rotor and with main rotor blades stabilized to prevent excessive

flapping Flapping or tapping, also known as alveolar flapping, intervocalic flapping, or ''t''-voicing, is a phonological process found in many varieties of English, especially North American, Cardiff, Ulster, Australian and New Zealand English, whereby ...

, both features of the SE-3120.

Specifications

References

{{SNCASE aircraft 1950s French helicopters SNCASE aircraft Single-engined piston helicopters Aircraft first flown in 1950