Copyright (C) 2004-2005 dondalah@ripco.com (Dondalah)
The following image shows one type of design for a dome hub based on a frustum with flanges.
Most hubs have six struts. Some have five struts. Hubs at ground level have four struts. The angle of the cone in the hub depends on the type of polyhedron and the frequency of the dome. You can get a general idea of the cone angle by using the dihedral angle of triangles at the equator. The dihedral angles in the center of a pentagon are slightly higher than they are elsewhere on the dome.
The hub should be mass produced to keep its cost to a minimum. It should be strong enough to withstand tornados, earth quakes, extreme temperatures, and water damage. It should stabilize the struts without buckling under weight or stress.
The length of each strut should include the size of the hub as part of its length. The length of each strut in the strlen program is end-to-end. It does not assume a hub of a certain size as part of its length. Therefore you will have to include hub sizes in your calculations if you use the strlen program to design a dome.