Helicopter Kit

A kit (1, 1’) is described that comprises a device (15, 15’) adapted to dampen the vibrations transmitted by the rotor (4) to the fuselage (2); the device (15) comprises two first elements (21a, 21b; 20a, 20b) movable along a first axis (B); two second elements (20a, 20b;21a, 21b) rotatable about the first axis (B); a first inerter (16) with a first female screw (21a), a first screw (20a), and first rollers (22a) rotatable about respective second axes (C) and around the first axis (B) with respect to the first female screw and first screw (21a, 20a); a second inerter (17) with a second female screw (21b), a second screw (20b) operatively connected to the second female screw (21b); and a plurality of second rollers (22b) rotatable about second axes (C) and around the first axis (B) with respect to the second female screw and second screw (21b, 20b); the first and second female screws (21a, 21b) defining the first threaded elements (21a, 21b;20a, 20b), and the first and second screws (20b, 20a) defining the second threaded elements (20a, 20b; 21a,21b); or the first and second screws (20b, 20a) defining the first threaded elements (21a, 21b; 20a, 20b) and the first and second female screws (21a, 21b) defining the second threaded elements (20a, 20b; 21a, 21b).