Abstract: The tank comprises a bag which has in plan and in the flat condition the shape of a square with rounded corners formed by the assembly of two walls of fabric coated with an elastomer. Two straps also of coated fabric and having equal lengths are each fixed by their respective ends to opposed edges of the bag and have a length slightly greater than the distance between the opposed edges. When the hooking ring disposed in the region of the crossing of the two straps is subjected to a traction by a line carried by a helicopter, each half strap assumes an oblique position so that, when the tank is raised and carried along with the helicopter, the whole of the tank assumes an aerodynamic profile which prevents any pendular or giratory movements in respect of speeds which may exceed 200 km per hour.