The problems caused by large-volume aerostatic balloons capable of withstanding high overpressures while remaining of a relatively moderate weight, are presently being solved. Such balloons, for instance those described in French patent application No. 84.18798 by the same applicant, comprise of at least one inner envelope containing helium and one outer envelope containing both the inner envelopes and air which imparts its generally cylindrical shape to the balloon. The capability of the outer envelope to withstand high overpressures makes it possible to use such balloons as high-load transports, with the lifting of the load and the aerostatic vertical control being implemented by merely ballasting the air.
For operations where lifting is predominant, one application comprises an aerostatic lift device associated with a horizontal mechanical winch means. This device involves a captive balloon tethered to the ground at three fixed or automotive points. It may comprise a simple aerostatic balloon devoid of any means of its own for displacement, or it may also include, for lifting more substantial loads, an aerostatic machine comprising the combination of several balloons secured to external structures. Such an application moves large loads over short distances but is restricted in operations by the presence of cables and the need for a clear field.
This situtation may be improved by implementing the horizontal winching of the device by the use of a separate aircraft that can be reduced to a point (helicopter or blimp). However these two applications require large tractions in order to achieve the horizontal winching by the balloons(s). These transverse forces are transmitted by the coupling means to the pole pieces of the balloons. Considering the small size of these pole pieces and the inertia of the assembly, the stresses applied to the envelope at the pole pieces, therefore, are quite high and may bring about the degradation and even the rupture of the connection between this envelope and the pole piece. The devices coupling the envelope and the horizontal winch means for an isolated balloon or the envelope and the external structure therefore must be carefully designed to permit transmitting high transverse forces.
Beyond those two applications, more ambitious projects combine aerostatic balloons into airships equipped with sets of horizontal propulsion plants and all means required to move bulky and high loads over long distances. Such airships require an aerodynamic design reducing the drag of the assembled balloons. This drag reduction may be achieved in significant manner by rotating these balloons about their longitudinal axis. This rotation also allows setting up artificial gravity. Considering the inertia of these balloons, rotation demands coupling them to external structures by means of devices allowing to transmission of large couples.
The object of the present invention is to provide a solution for the above discussed problems and to create a device coupling an envelope and an external element and allowing to transmit large forces to the envelope.
To that end, the main object of the invention is to have all or a great part of the envelope absorb the point stresses or torques transmitted in the vicinity of the pole of the envelope.
Another object of the invention is to create a coupling member which can act as damper between an envelope and an external element.
Still another object is to provide a coupling member capable of adapting itself to the differences in shape of an envelope subjected to variation in its inner overpressure.