Structural module for fixed or rotary wing, comprising: a leading edge structure comprising a first connecting member , a second connecting member and at least one spar section interposed between the first connecting member and the second connecting member and integral with said first connecting member and second connecting member ; wherein each of said first connecting member and second connecting member is configured to engage with a respective adjacent structure; a torsional actuator mounted on the leading edge structure and comprising a torsion bar and actuating devices operatively coupled to the torsion bar ; wherein the torsion bar has a first end connected to the first connecting member and a second end opposite the first end and connected to the second connecting member ; wherein the torsion bar is mounted or mountable on the leading edge structure with a preload torsion, so as to give the structural module a respective predefined twist wherein, with respect to a rest condition of the leading edge structure , the first connecting member is rotated with respect to the second connecting member ; wherein the actuating devices are configured to vary a torsional stiffness of the torsion bar and/or an angular geometry of the torsion bar , so as to vary the twist of the structural module with respect to the predefined twist; wherein the first connecting member has a first seat configured to accommodate the first end of the torsion bar while preventing rotation thereof, and the second connecting member has a circular through-seat configured to accommodate the second end of the torsion bar and allow rotation of the second end relative to the first end to impart to the torsion bar said preload torsion; locking devices being interposed between the second end and the circular through-seat to lock said second end in a plurality of preload positions each corresponding to a preload torsion of the torsion bar . a leading edge structure comprising a first connecting member , a second connecting member and at least one spar section interposed between the first connecting member and the second connecting member and integral with said first connecting member and second connecting member ; wherein each of said first connecting member and second connecting member is configured to engage with a respective adjacent structure; a torsional actuator mounted on the leading edge structure and comprising a torsion bar and actuating devices operatively coupled to the torsion bar ; wherein the torsion bar has a first end connected to the first connecting member and a second end opposite the first end and connected to the second connecting member ; wherein the torsion bar is mounted or mountable on the leading edge structure with a preload torsion, so as to give the structural module a respective predefined twist wherein, with respect to a rest condition of the leading edge structure , the first connecting member is rotated with respect to the second connecting member ; wherein the actuating devices are configured to vary a torsional stiffness of the torsion bar and/or an angular geometry of the torsion bar , so as to vary the twist of the structural module with respect to the predefined twist; wherein the first connecting member has a first seat configured to accommodate the first end of the torsion bar while preventing rotation thereof, and the second connecting member has a circular through-seat configured to accommodate the second end of the torsion bar and allow rotation of the second end relative to the first end to impart to the torsion bar said preload torsion; locking devices being interposed between the second end and the circular through-seat to lock said second end in a plurality of preload positions each corresponding to a preload torsion of the torsion bar . <EOS>