Device for retaining a tank in an aircraft

1. A supporting and holding device for a tank of a cylindrical or conical overall shape and of a main axis X in a vehicle, comprising:

two pairs of first tank-retaining means for retaining the tank along an axis Z perpendicular to the main axis X, one of the two pairs of first tank-retaining means being joined to the tank at a first end of the tank and another of the two pairs of first tank-retaining means being joined to the tank at a second end of the tank,

a second tank-retaining means for retaining the tank along an axis Y perpendicular to the main axis X and to the axis Z at the first end of the tank, and

a third tank-retaining means designed to retain the tank along the axis X and the axis Y and connected to the second end of the tank,

wherein the two pairs of first tank-retaining mans provide a degree of freedom to the tank in the X and Y axis, the second tank-retaining means provide a degree of freedom to the tank in the X and Z axis and the third tank-retaining means provide a degree of freedom to the tank in the Z axis.

2. The supporting and holding device as claimed in claim 1 , further comprising at least one further second means for retaining said tank along the axis Y at the first end of the tank so as to constitute a redundant safety retaining means.

3. The supporting and holding device as claimed in claim 2 , wherein said at least one further second tank-retaining means along the axis Y consist of link rods fixed to the tank by means of pins free to rotate and arranged in such a way as to allow the tank to expand or contract freely.

4. The supporting and holding device as claimed in claim 2 , wherein at the first end of the tank the pair of first tank-retaining means, the second tank-retaining means and the further second tank-retaining means are made of link rods and provide four fixing points distributed at a top, a bottom, and two sides of the first end of the tank, said first end of the tank being fixed by the respective pair of first tank-retaining means, the second tank-retaining means, and the further second tank-retaining means alone.

5. The supporting and holding device as claimed in claim 1 , wherein said two pairs of first tank-retaining means and said second tank-retaining means consist of link rods fixed to the tank by means of pins which are free to rotate and arranged in such a way as to allow the tank to expand or contract freely.

6. The supporting and holding device as claimed in claim 5 , wherein, at the first end of the tank the two pairs of first tank-retaining means and the second tank-retaining means made of link rods provide three fixing points distributed at a top or bottom and two sides of the first end of the tank, said first end remaining free of other fixing points.

7. The supporting and holding device as claimed in claim 5 , wherein said link rods are positioned in such a way as to work tangentially to the skin of the tank.

8. The support and holding device as claimed in claim 5 , wherein at the second end of the tank the pair of first tank-retaining means are made of link rods distributed at two sides of the second end of the tank while the third tank-retaining means provide an additional fixing point at a bottom of said second end, said first end of the tank being fixed by the respective pair of first tank-retaining means and the second tank-retaining means alone.

9. The supporting and holding device as claimed in claim 8 , wherein at the first end of the tank the pair of first tank-retaining means and the second tank-retaining means made of link rods provide three fixing points distributed at a top and two sides of the first end of the tank, said first end of the tank being fixed by the respective pair of first tank-retaining means and the second tank-retaining means alone.

10. The supporting and holding device as claimed in claim 1 , wherein said two pairs of first tank-retaining means at each respective first and second end of the tank are made of four link rods arranged symmetrically with respect to planes of symmetry ZY and ZX of the tank and oriented along said axis Z in order to withstand tank accelerations on said axis Z.

11. The supporting and holding device as claimed in claim 10 , wherein the fixing points of said four link rods on the tank are located in a plane of symmetry XY of the tank.

12. The supporting and holding device as claimed in claim 1 , wherein said second tank-retaining means consists of a link rod at the first end of the tank, positioned in the axis Y and withstanding forces along the axis Y transverse to the main axis X of the tank.

13. The supporting and holding device as claimed in claim 12 ,

wherein said two pairs of first tank-retaining means at each respective one of the first and the second end of the tank are made of four link rods, arranged symmetrically with respect to planes of symmetry ZY and ZX of the tank and oriented along said axis Z, provide all retaining means the Z axis, and

wherein the link rod positioned in the axis Y and the link rods oriented along said axis Z, are positioned such a way as to allow the tank deformations along the axis X while at the same time allowing radial travel of the tank so as not to generate stress caused by radial thermal deformations of the tank.

14. The supporting and holding device as claimed in claim 12 , wherein a fixing point on the tank of said link rod in the Y axis is in the plane of symmetry XZ of the tank.

15. An aircraft comprising a tank and a tank supporting and holding device as claimed in claim 1 , wherein

said main axis X is a substantially horizontal axis substantially parallel to the aircraft axis,

said axis Y is a horizontal axis transverse to the aircraft, and

said axis Z is a vertical axis,

said two pairs of first tank-retaining means and said second tank-retaining means being held on frames of a fuselage of the aircraft.

16. The aircraft as claimed in claim 15 , wherein the said tank is suspended from said two pairs of first tank-retaining means.

17. The aircraft as claimed in claim 15 , wherein said two pairs of first tank-retaining means and said second tank-retaining means are link rods fixed by ball-joints to attachments of the tank and attachments on said frames of the aircraft, or to shock-absorbing webs between said frames.

18. The aircraft as claimed in claim 15 ,

wherein said third tank-retaining means comprises a vertical fixing rod fixed to a structure of the aircraft and fitted into a sliding joint surrounded by a ball-joint at an end of a skirt secured to said tank,

wherein said structure transmits forces from the rod to the fuselage of the aircraft, and

wherein said sliding joint withstands forces along the axes X and Y while at the same time being entirely free to rotate and free to effect a translational movement about the rod along the vertical axis Z.

19. The aircraft as claimed in claim 18 , comprising a safety redundancy of the third tank-retaining means.

20. The aircraft as claimed in claim 19 , wherein said safety redundancy is achieved by a peg clearance hole device situated on the skirt, between the vertical fixing rod and the tank, and on a support fixed to the fuselage so as to restrain the tank in X and in Y in case of breakage of the vertical pin or of the skirt on the tank side.

21. The aircraft as claimed in claim 18 , wherein said structure comprises a double flange.

22. The aircraft as claimed in claim 15 , wherein said aircraft is a vehicle that operates as an aircraft in air and as a spacecraft in space and said tank is a cryogenic feed tank for a rocket engine of such vehicle, the first, second, and third tank-retaining means being configured to provide degrees of freedom suited to avoiding thermomechanical stresses under the effect of differential thermal deformations of the tank in the longitudinal and radial directions.