Convertiplane and associated folding method

1. A method of folding a convertiplane ( 1 , 1 ′, 1 ″), said convertiplane ( 1 , 1 ′, 1 ″), in turn, comprising:

a fuselage ( 2 ) having a first longitudinal axis (A);

a pair of wings ( 3 ); and

at least a pair of rotors ( 5 ) arranged on respective mutually opposite sides of the respective said wings ( 3 );

each said rotor ( 5 ) comprising a mast ( 9 ) rotatable about a second axis (B) and a plurality of blades ( 8 a , 8 b ) hinged to said mast ( 9 ) with respect to said second axis (B);

each said wing ( 3 ), in turn, comprising:

a first portion ( 20 ), fixed with respect to said fuselage ( 2 );

a second tip portion ( 21 ) opposite to said first portion ( 20 ); and

a third intermediate portion ( 22 ), which is interposed between the associated said first portion ( 20 ) and the associated said second tip portion ( 21 );

said mast ( 9 ) of each said rotor ( 5 ) being integrally tiltable with said second axis (B) and the associated said second tip portion ( 21 ) about an associated third axis (E) transversal to said second axis (B) and with respect to said fuselage ( 2 ), so as to set said convertiplane ( 1 , 1 ′, 1 ″) between a helicopter configuration and an aeroplane configuration;

each said second axis (B) being, in use, transversal to said first axis (A) of said convertiplane ( 1 , 1 ′, 1 ″) in said helicopter configuration and being, in use, substantially parallel to said first axis (A) in said aeroplane configuration;

said method comprising the steps of:

i) arranging said convertiplane ( 1 , 1 ′, 1 ″) in said helicopter configuration;

ii) rotating an assembly ( 23 ) of each said wing ( 3 ) with respect to said fuselage ( 2 ) and the associated said first portion ( 20 ) about a respective said fourth axis (I, I′, I″), so as to fold said respective said wing ( 3 ) and arrange said convertiplane ( 1 , 1 ′, 1 ″) in a stowage configuration;

each said assembly ( 23 ) being formed by a second tip portion ( 21 ) and by the associated said third intermediate portion ( 22 ); and

iii) folding said assemblies ( 23 ) above said fuselage ( 2 ) and in staggered positions along said first axis (A).

2. The method according to claim 1 , characterized in that step iii) comprises the steps of:

iv) folding the assembly ( 23 ) of one wing ( 3 ) towards a said-tail portion ( 13 ) of said fuselage ( 2 ), starting from an associated said first portion ( 20 ) of the corresponding wing ( 3 ); and

v) folding the assembly ( 23 ) of the other wing ( 3 ) towards a said-nose ( 12 ) of said fuselage ( 2 ), starting from an associated said first portion ( 20 ) of the corresponding wing ( 3 ).

3. A convertiplane ( 1 , 1 ′, 1 ″) comprising:

a fuselage ( 2 ) having a longitudinal first axis (A);

a pair of wings ( 3 ); and

at least a pair of rotors ( 5 ) arranged on respective mutually opposite sides of said wing ( 3 );

each said rotor ( 5 ), in turn, comprising a mast ( 9 ) rotatable about a second axis (B) and a plurality of blades ( 8 ) hinged to said mast ( 9 ) with respect to said second axis (B);

each said wing ( 3 ), in turn, comprising:

a first portion ( 20 ), fixed with respect to said fuselage ( 2 );

a second tip portion ( 21 ); and

a third intermediate portion ( 22 ), which is interposed between the respective said first portion ( 20 ) and the respective said tip portion ( 21 );

said mast ( 9 ) of each said rotor ( 5 ) being integrally tiltable with said second axis (B) and the associated said second tip portion ( 21 ) about an associated third axis (E) transversal to said second axis (B) and with respect to said fuselage ( 2 ), so as to transform said convertiplane ( 1 , 1 ′, 1 ″) between a helicopter configuration and an aeroplane configuration;

each said second axis (B) being, in use, transversal to said first axis (A) of said convertiplane ( 1 , 1 ′, 1 ″) in said helicopter configuration and being, in use, substantially parallel to said first axis (A) in said aeroplane configuration;

wherein said third intermediate portion ( 22 ) of each wing ( 3 ) is hinged to said first portion ( 20 ) of the respective wing ( 3 ) about a respective fourth axis (I, I′, I″), and is movable with respect to said first portion ( 20 ) of the respective wing ( 3 ) to arrange said convertiplane ( 1 ) in a stowage configuration;

wherein each said rotor ( 5 ) comprises a plurality of blades ( 8 a , 8 b ) hinged to said mast ( 9 );

each said blade ( 8 a , 8 b ), in turn, comprising:

a root portion ( 18 ) hinged to said mast ( 9 ); and

a main portion ( 19 ) hinged about the respective root portion ( 18 ) about an associated fifth axis (K) parallel to and offset with respect to said second axis (B);

each said main portion ( 19 ) being movable with respect to the associated said root portion ( 18 ) during the transition of said convertiplane ( 1 ) from said helicopter configuration to said stowage configuration;

wherein said fourth axes (I′) are skew;

a first assembly ( 23 ) being folded towards said tail portion ( 13 ) of said fuselage ( 2 ), starting from an associated said first portion ( 20 ) of the corresponding wing ( 3 ), in said stowage configuration; and

a second assembly ( 23 ) being folded towards said nose ( 12 ) of the said fuselage ( 2 ), starting from an associated said first portion ( 20 ) of the corresponding wing ( 3 ), in said stowage configuration;

said first and second assemblies ( 23 ) being folded above said fuselage ( 2 ) and in staggered positions along said first axis (A), when said convertiplane ( 1 ′) is arranged in said stowage configuration.

4. The convertiplane according to claim 3 , characterized in that each of the first assembly ( 23 ) and the second assembly ( 23 ) is formed by the respective said second tip portion ( 21 ) and respective said third intermediate portion ( 22 ).