Motivation to Design:
With the LA Metro Regional Connector finally finished, beach trips became much easier! After a few trips with no free beach seats and sand all over my towel, I decided to fix my problem. The REI Co-op Flexlite chair is a lightweight and portable backpacking chair that fits into my daypack, but it has small feet that sink straight into the sand. I remembered a video of a column of sand under compression that didn’t fall apart because of an internal mesh reinforcement keeping the sand from flowing out, and decided to design feet for my chair based on a similar concept.
Design Goals:
Attach to the feet of an existing chair.
Support human body weight over loosely compacted (i.e. sandy) ground.
Portable to the same extent as the existing chair.
Relevant Interfaces:
The top “shoe” area that the chair’s existing feet can slip into. The cutout angle was measured to match the chair’s existing foot angles.
The bottom, stepped cone that defines a roughly conical internal shape and constrains the outside edges of the sand cone. The edge constraint is critical for maintaining compressive strength of the sand, allowing the feet to sit above the sand instead of sinking into it.