The SNCAC NC.2001 Abeille ( en, Bee) was a single engine, twin intermeshing rotor

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 ...

designed and built in

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

in the late 1940s. Three were completed but only one flew, development ending when

SNCAC SNCAC (the ', sometimes known as ) was a French aircraft manufacturer created by the nationalisation of the Farman Aviation Works and Hanriot firms in 1936. It was liquidated in 1949, with assets distributed between SNCAN, SNCASO, and SNECMA, a ...

was closed.

Design and development

The design of the Abeille was directed by René Dorand at the helicopter division of SNCAC. An intermeshing rotor layout was chosen instead of a

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 ...

design, following the examples of the 1939

Flettner Fl 265 The Flettner Fl 265 was an experimental helicopter designed by Anton Flettner. Design and development This helicopter, developed in 1938 with the support of Nazi Germany's ''Kriegsmarine'', made it possible, for the first time, to transition from ...

and the Kellet XR-8 of 1944. Its twin, two blade rotors were driven by shafts which leaned out of 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 ...

side-by-side. The rotor blades, which began some way from the hub, tapered strongly. Pitch and

roll Roll or Rolls may refer to: Movement about the longitudinal axis * Roll angle (or roll rotation), one of the 3 angular degrees of freedom of any stiff body (for example a vehicle), describing motion about the longitudinal axis ** Roll (aviation), ...

were adjusted from the control column by altering

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 ...

via a pair of

swashplate A swashplate, also known as slant disk, was invented by Anthony Michell in 1917. It is a mechanical engineering device used to translate the motion of a rotating shaft into reciprocating motion, or vice versa. The working principle is similar to c ...

s and yaw by changing the relative

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 ...

of the two rotors with the pedals. Forward tilt of the rotor shafts was automatically linked to forward speed. A single lever controlled both the collective pitch and the

throttle A throttle is the mechanism by which fluid flow is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases (by the use of a throttle), but usually decreased. The term ''throttle'' ...

through an electrical link. The Abeille was powered by a

Renault 12S Monument Municipal Airport is a public airport located 1 mile (1.6 km) northwest of Monument, in Grant County, Oregon, United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or ...

, an inverted, air-cooled

V-12 engine A V12 engine is a twelve-cylinder piston engine where two banks of six cylinders are arranged in a V configuration around a common crankshaft. V12 engines are more common than V10 engines. However, they are less common than V8 engines. The fir ...

. The Abeille had a pod and boom, all-metal

. The nose was fully glazed with two side by side crew seats ahead of a cabin with a bench seat for three passengers. The engine and gearboxes were behind them. Aft, a high mounted boom carried the

empennage The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third ed ...

, which on the first prototype consisted of a tall

T-tail A T-tail is an empennage configuration in which the tailplane is mounted to the top of the fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs from the standard configuration in which the tailplane is ...

with a narrow

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 ...

. On the second machine the tailplane was lowered to the top of the fuselage and had a pair of fins at its extremities, each roughly elliptical and mounted from its top. The tails was wooden, with fabric covered. The Abeille's fixed main

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

had two wheels on a single axle positioned a little behind the rotor shafts and mounted on broad, single

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 ...

s to the mid-upper fuselage, together with a smaller nose wheel. Three examples of the Abeille were built. The first was destroyed by fire before it had flown. The second made its first flight on 28 June 1949, piloted by Claude Dellys. SNCAC was closed in that month, its assets distributed between three remaining state owned firms and as a result the Abeille programme was abandoned; the second machine did not fly again and the third never flew.

Specifications

References

{{SNCAC aircraft

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1940s French helicopters Aircraft first flown in 1949 Single-engined piston helicopters Synchropters

Design and development

Specifications

See also

References