I have good news! Two weeks ago I told you that we were looking for some new reinforcement for the Upper Hemisphere (Link). Today we finally assembled the first of those reinforcements to one of the FFU and we tested the deployment system of the parachute. So far it is working very well and we are really happy about this!
Here you can find some CAD model of the reinforcement and some pictures that we took today while we were gluing the reinforcement and a metal ring to the Hemispheres.v
The parachute will be housed, for the entire flight, under the upper hemisphere of the FFU.
Calculations of the terminal velocity has been made and the Top Flight ThinMill 30″ X-shape has preliminary been chosen. This parachute will be sufficient to achieve a landing speed of around 10 m/s for the preliminary mass estimate of the FFUs. Drop and deployment tests will be made, similar to previous KTH REXUS teams, which will determine the final parachute size.
An extra precaution has been made regarding the packed volume of the parachute. Volume estimates of a few parachutes has been made (including cords) and the ThinMill 30″ packs well inside the upper hemisphere and weighs only 28g/m2 (!). Folding tests were made with fabric of the same density and size as the ThinMill 30″ and the results were implemented the volume estimates. More folding experiments will be performed with the parachute and the ropes to find the most efficient and reliable packing method.
The connection between the parachute and the FFU will be through a long rope to ensure that the parachute ropes do not entangle during the descent. Tests will be done to determine that the parachute can withstand the shock force when deployed.