The Alpaero Choucas (English:

Jackdaw Jackdaws are two species of bird in the genus ''Coloeus'' closely related to, but generally smaller than, the crows and ravens (''Corvus''). ''Coloeus'' is sometimes treated as a subgenus of ''Corvus'', including by the IUCN.Madge & Burn (1994) ...

) is a French two seat, single engine tailless kit-built

ultralight Ultralight aviation (called microlight aviation in some countries) is the flying of lightweight, 1- or 2-seat fixed-wing aircraft. Some countries differentiate between weight-shift control and conventional three-axis control aircraft with aile ...

motor glider A motor glider is a fixed-wing aircraft that can be flown with or without engine power. The FAI Gliding Commission Sporting Code definition is: a fixed-wing aerodyne equipped with a means of propulsion (MoP), capable of sustained soaring flight ...

. At least 12 are flying, with more under construction.

Design and development

The Choucas is the fourth design by Claude Noin and is sometimes referred to as the Noin Choucas. It is an ultralight, initially produced in kit form for home assembly, though since 2005 flight-ready aircraft have been an option. It is a single-engine tailless aircraft of similar layout to the Fauvel AV.22: short, with fin and rudder but no horizontal stabiliser and a mid-mounted wing with mild forward sweep at mid-chord, carrying 4° of dihedral. The

aerofoil An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine. ...

has reflex camber and a thickness/chord ratio of 17%. The wing leading edge is straight and unswept, and the centre section has almost constant chord, but outboard the trailing edge has marked forward sweep. The main spar is

carbon fibre Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers (Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon compo ...

, supporting glass fibre-reinforced

styrofoam Styrofoam is a trademarked brand of closed-cell extruded polystyrene foam (XPS), commonly called "Blue Board", manufactured as foam continuous building insulation board used in walls, roofs, and foundations as thermal insulation and water barrie ...

ribs with a plywood-covered D-section box at the leading edge. The rest of the wing is

Dacron Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in fibres for clothing, containers for liquids and foo ...

-covered. An option extends the span by 0.65 m to 15 m and includes

winglets Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft' ...

. Outboard

ailerons An aileron (French for "little wing" or "fin") is a hinged flight control surface usually forming part of the trailing edge of each wing of a fixed-wing aircraft. Ailerons are used in pairs to control the aircraft in roll (or movement around ...

provide lateral control and centre section moulded carbon fibre

elevators 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 are ...

, assisted by

trim tab Trim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilise the boat or aircraft in a pa ...

s, control pitch. Spoilers, at about mid-chord on the wing upper surface and just outboard of the centre section, also act as airbrakes. The standard fuselage is formed from two carbon fibre half shells, though glass fibre may be used as a heavier alternative. Seating is side by side under a one-piece, upward-hinging canopy. The rudder is large but not balanced or tabbed. The Choucas has a

tailwheel undercarriage Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail.Crane, Dale: ''Dictionary of Aeronautical Term ...

with outward-curving faired main legs cantilevered from the lower fuselage, carrying spatted wheels. The Choucas is powered by a 37 kW (50 hp)

Rotax 503 The Rotax 503 is a , inline 2-cylinder, two-stroke aircraft engine, built by BRP-Rotax GmbH & Co. KG of Austria for use in ultralight aircraft.Raisner, William: ''LEAF catlog'', pages 6-105. Leading Edge Airfoils, 1995. As of 2011 the Rot ...

Hirth Hirth Engines GmbH is an engine manufacturer based in Benningen, Germany. It is currently a part of the UMS Aero Group. Hirth began manufacturing aero engines in the 1920s, was taken over by Heinkel in WWII to develop the Heinkel-Hirth jet en ...

two-stroke A two-stroke (or two-stroke cycle) engine is a type of internal combustion engine that completes a power cycle with two strokes (up and down movements) of the piston during one power cycle, this power cycle being completed in one revolution of ...

powerplant or a 60 hp (45 kW)

HKS 700E The HKS 700E is a twin-cylinder, horizontally opposed, four stroke, carburetted aircraft engine, designed for use on ultralight aircraft, powered parachutes and ultralight trikes. The engine is manufactured by HKS, a Japanese company noted f ...

four-stroke piston engine, driving a two-bladed carbon fibre propeller. A folding propeller, with parked blades parallel and pointing forwards, is available for better unpowered gliding. The second prototype, which incorporates this feature, also has detachable winglets and a rudder, deepened to below the lower fuselage line, which incorporates the tail wheel.

Operational history

The Choucas first flew in February 1996, followed by a second aircraft in 2004. By 2007 two further Choucas were being built. In 2011 twelve powered by the HKS 700E were reported flying.

Specifications

References

{{Alpaero aircraft 1990s French sport aircraft Motor gliders Mid-wing aircraft Aircraft first flown in 1996