A tail sitter aircraft (1', 1"") comprising: a wing with a closed front section; a fuselage, from which said wing extends; said fuselage extending parallel to a first axis; said wing being a non-planar wing closed in on itself and without free ends; said front section being defined by the projection of said wing on a plane orthogonal to said first axis; said wing comprising: - a first portion projecting from said fuselage; - a second portion spaced from said first portion; and - a first and a second connecting section, which are interposed between respective ends (8, 9) of said first portion and of said second portion; said first portion and said second portion being parallel to one another and extending parallel to a second axis orthogonal to said first axis; said first axis being arranged, in use, vertically in a take-off/landing position and inclined with respect to the vertical direction in a cruising position; said first and a second connecting section extend parallel to a third axis orthogonal to said second axis and to said first axis; characterized in that said wing with a closed front section comprising a third portion arranged on the opposite side of said first portion with respect to said second portion and connected to said first portion at their respective ends (32, 8) by first sections extending parallel to said third axis; said first portion, second portion and third portion being provided with landing members; a centre section of said third portion being connected to said fuselage by a second section interposed between first sections along said second axis; said second section extending parallel to said third axis. a fuselage, from which said wing extends; said fuselage extending parallel to a first axis; said wing being a non-planar wing closed in on itself and without free ends; said front section being defined by the projection of said wing on a plane orthogonal to said first axis; said wing comprising: - a first portion projecting from said fuselage; - a second portion spaced from said first portion; and - a first and a second connecting section, which are interposed between respective ends (8, 9) of said first portion and of said second portion; - a first portion projecting from said fuselage; - a second portion spaced from said first portion; and - a first and a second connecting section, which are interposed between respective ends (8, 9) of said first portion and of said second portion; said first portion and said second portion being parallel to one another and extending parallel to a second axis orthogonal to said first axis; said first axis being arranged, in use, vertically in a take-off/landing position and inclined with respect to the vertical direction in a cruising position; said first and a second connecting section extend parallel to a third axis orthogonal to said second axis and to said first axis; characterized in that said wing with a closed front section comprising a third portion arranged on the opposite side of said first portion with respect to said second portion and connected to said first portion at their respective ends (32, 8) by first sections extending parallel to said third axis; said first portion, second portion and third portion being provided with landing members; a centre section of said third portion being connected to said fuselage by a second section interposed between first sections along said second axis; said second section extending parallel to said third axis.