In the next days we will go through the design of the Ribs of the Upper Hemisphere. We want to redesign them since we have had couple of failures during the drop test.
The Ribs are the vertical supports attached to the Upper Hemisphere of the FFU.
The Ribs act as a lateral and rotational constrain and prevent any rotations or movements of the Upper Hemisphere with respect to the Internal Metal Ring. Thanks to the Ribs it is possible to screw together the Upper and the Lower Hemisphere. The Ribs are also crucial for what concern the Deployment System of the Parachute.
During the drop test we had two main problems concerning the Ribs.
First, all the failures have occurred because the Ribs were not well glued to the Hemisphere, this is due to the fact that they were made using PVC. Unfortunately it is not possible to glue properly PVC using Epoxy, and this led to the failures.
Second, since every Rib is glued by hand, the alignment between each Ribs and the Spikes of the Metal Ring were “adjusted” using sanding tools. This solution was good enough for the first prototypes tested in the drop test, but we have to find a better solution.
The new concept design will be based on the idea to add one ring, made by the same material of the sphere, at the border of the Upper Hemisphere. The Ring, that will have all the functions of the Ribs, must be designed in order to fit perfectly inside the hemisphere avoiding all eyebolts and screws.
Since the Ring will be made using the same material of the Hemisphere gluing it with Epoxy will not be as problematic as it was with the PVC. Moreover the ring will be cut using by laser cutting, so the positions of the holes will be precise and the holes will match perfectly with the Spikes.
Pictures of the new Ring will be published soon! Bye!!