A NEW APPROACH IN DESIGNING OF STRATOSPHERIC PLATFORMS AIMED AT MULTI-USER LDB FLIGHTS

Thanks to the high latitude of the location the new scenario of the Svalbard Islands as well as that of the already operative Swedish launch base is very close to becoming a principal launching site for Long Duration Ballooning (LDB) arctic campaigns. LDB flights, rather than mid latitude flights that last several hours have become a suitable framework for all efforts to create low cost campaigns. The scientific world, which uses balloons to record measurements beyond the atmosphere, needs both frequently scheduled campaigns and an optimized organization capable of reducing flight costs. It is obvious that a reducing of general costs means keeping in mind, during all design phases, versatility and the standardization of common facilities such as gondola frame as well as the protection of the solar panels upon landing etc. The multi-user payload is certainly the first step for reducing launch costs. Each balloon is launched as much as possible when its payload hosts a number of experiments that weight just a little less than its maximum lifting capacity, apart from the necessary their mutual compatibility. A second step, concerns the optimization of the gondola frame design. It must manufacture gondolas easy to assemble, transport and as well as be easy to modify in shape in order to host a different combination of a given number of experiments, once these have been selected by a scientific authority for the same balloon. The new concept in designing platform which takes advantage of special mechanical elements that are capable both of jointing different beam lengths and of distributing tensile or compression stress only is proposed. The gondola can be assembled simply by only cutting structural aluminum beams into different lengths. Differences between traditional rigid structures and the new concept of construction are pointed out, as a reduction in the total weight and as an easy way to balance the gondola almost without adding extra weight. An example of how the new mechanical joint works and how its behavior closely approximates to the theoretical one is also demonstrated. The study is devoted to design the platform of one of the next balloon experiments funded by ASI): The Large Scale Polarization Explorer (LSPE).