Turboprop with a variable-pitch propeller

1. A turboprop comprising at least one propeller formed by a set of blades secured to a first annular rotary support mounted to rotate about an engine axis X-X and adjacent to an outer stationary casing housing a turbine having a rotor driving said first rotary support, each blade of said set being mounted on a pin to swivel relative to said first rotary support, each blade pin carrying a gearwheel meshing with a first actuator annulus forming a toothed wheel and mounted to be capable of rotating about said engine axis on said rotary support, and the actuator annulus being coupled to a first external control annulus coaxial about said first rotary support, via a first epicyclic mechanism carried by said first rotary support, wherein said first epicyclic mechanism carries a planet-carrier ring mounted to be capable of rotating on said first rotary support, and wherein said ring carries two groups of planet gearwheels, the gearwheels of the first group being interposed between a toothed ring of the first rotary support and a toothed ring of the stationary casing, and the gearwheels of a second group being interposed between a toothed ring of said first actuator annulus and a toothed ring of said first control annulus.

2. A turboprop according to claim 1 , including a second annular rotary support rotatable in the opposite direction to said first rotary support and carrying a second set of blades, each blade being swivel-mounted on said second rotary support, wherein each blade pin carried by said second rotary support is engaged by meshing with a second actuator annulus forming a toothed wheel mounted to be capable of rotating on said second rotary support, and wherein said second actuator annulus is coupled to a second control annulus coaxial about said second rotary support via a second epicyclic mechanism carried by said second rotary support.

3. A turboprop according to claim 2 , wherein said second control annulus comprises a toothed ring meshing with gearwheels of blades carried by said first rotary support.

4. A turboprop according to claim 2 , wherein said second epicyclic mechanism comprises a planet-carrier ring mounted to be capable of rotating on said second rotary support and carrying two groups of planet gearwheels, the planet gearwheels of a first group being interposed between a toothed ring of said second rotary support and a toothed ring of said first rotary support, and the planet gearwheels of a second group being interposed between a toothed ring of said second actuator annulus and a toothed ring of said second control annulus.