Structure

A sabot is used to enclose a payload for launch, and - in Raziel - consists of two main sub-assemblies: the foamboard sabot shell and the inner metal enclosure.

Sabot shell halves in closed configuration.                                                                                                              Rover enclosure in open configuration.

The sabot shell, in its complete form, resembles a cylindrical piece of foam with a centered square cut. For our purposes, the shell is split into two halves, with each rectangular face fitted with PEM broaching nuts to interface with each face of the enclosure.

The square enclosure fits into the sabot shell to create a housing for the rover, ideally robust enough to withstand a rough landing.

The flight competition required the enclosure be made to resemble a Cube-Sat of designation 2U.

Deployment Mechanism

Upon landing, the sabot is able to automatically deploy its rover. Torsion spring hinges were installed along one edge of the enclosure connecting its two halves, allowing the energy in the springs to be stored while the sabot is in closed configuration. To remain in closed configuration, the sabot assembly was held together by one loop of (dimension) rope, placed within a notch cut into the sabot shell.

Deployment is achieved when a team-built PRC (Pyrotechnic Rope Cutter) installed onto the loop of rope activates and cuts the rope, releasing the energy in the torsion spring hinges and allowing the sabot halves to separate.

See the sabot assembly in its open configuration below:

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Materials and Preparation

Stiff foamboard was used to fabricate the sabot shell in the aim of absorbing lots of impact upon landing. The foam was cut on the Hot Wire Foam Cutter in the Gelb Lab (basement of Building 33).

The following shapes were modeled with simple Cartesian points, which were fed in Excel files to the Hot Wire Foam Cutter computer to make the cuts.

Lessons Learned

Lesson #1: To inhibit rotational freedom on a bar fastened down at both ends, consider adding extra bolts (one would probably suffice) to block the motion of the bar in the desired direction.

Lesson #2: Make doubly sure that the materials you plan to order (be it from McMaster-Carr or another vendor) are the ones you require. If you are not sure, do not hesitate to contact your vendor.

Lesson #3: Never give up.