Rotary wing aircraft with a multiple beam tail
A rotary wing aircraft comprising a fuselage, a cabin volume enclosed by the fuselage, a main rotor arranged above the fuselage, a tail rotor mounted on a tail, the tail being attached to a rear part of the fuselage supporting the tail at its rear end, whereas the tail includes two beam boom elements, one element extending at the port side and the other element extending at the starboard side of the rotary wing aircraft, the front root end of each element being hinged to the corresponding lateral side of the fuselage, and both elements being canted with respect to the longitudinal axis of the rotary wing aircraft so as to be interconnected to each other at the rear portion of the tail.
1. A rotary wing aircraft with a longitudinal axis in x-direction comprising at least:
a fuselage forwardly oriented relative to the longitudinal axis with a port side and a starboard side as lateral sides,
a main rotor arranged above the fuselage,
a tail rotor mounted on a tail, the tail being attached to a rearward oriented part of the fuselage, the tail having a rear end supporting the tail rotor, and
at least one engine for driving at least one of the rotors, the engine being mounted on the fuselage; wherein:
the tail is provided with two beam boom elements extending to the rear end of the fuselage, one of the two beam boom elements extending to the port side and the other beam boom element extending to the starboard side, a front root end of each of the two beam boom elements being respectively attached to the corresponding port or starboard side of the fuselage by a front attachment, the beam boom elements being canted with respect to the longitudinal axis and interconnected to each other at the rear end of the tail; and
at least one of the front attachments is releasable and at least the other of the front attachments is pivotable, so that the tail is pivotable about a z-direction, around at least one of the front attachment.
2. The rotary wing aircraft according to claim 1 , wherein the front attachments are simply supported hinged connections.
3. The rotary wing aircraft according to claim 1 , wherein the cross-section of each of the two beam boom elements has a height-to-width ratio of at least three.
4. The rotary wing aircraft according to claim 2 , wherein the front attachments have securing bolts; a number of securing bolts of each of the two beam boom elements being chosen among: two, three or four securing bolts.
5. The rotary wing aircraft according to claim 1 , wherein the two front attachments are releasable.
6. The rotary wing aircraft according to claim 1 , wherein each of the two beam boom elements is interconnected to the other at its rear end by means of a supported hinged connection.
7. The rotary wing aircraft according to claim 6 , wherein each hinged connection has securing bolts; a number of securing bolts being chosen among: two, three or four securing bolts.
8. The rotary wing aircraft according to claim 6 , wherein one of the beam boom elements is pivotable with respect to another at the rear ends of the two beam boom elements about the hinged connection.
9. The rotary wing aircraft of claim 6 , wherein the beam boom elements each have a neutral line that is straight between the tail boom beam element front root and the rear hinged connection.
10. The rotary wing aircraft of claim 1 , wherein an air gap is transversally provided between the two tail boom beam elements; the air gap having a transverse dimension that is comprised between an upright height dimension in cross section of the tail boom beam elements and five times this upright height dimension.
11. The rotary wing aircraft of claim 1 , wherein at least one beam boom element is completely straight lined from the front attachment to the rear end.
12. The rotary wing aircraft of claim 1 , wherein the cross-section of each of the beam boom elements has an airfoil shape so as to produce an anti-torque lifting force as a result from the down-wash flow from the main rotor.
13. The rotary wing aircraft of claim 1 , the fuselage having a hull, wherein the beam boom elements have outer lateral shapes that are an aerodynamic continuation of the hull of the fuselage.
14. The rotary wing aircraft of claim 1 , wherein the rotary wing aircraft comprises at least an electrically powered rotor drive for an electrically powered tail rotor.