Isotoxal figure 2-dimensional tessellation constructed from regular polygons is isotoxal. For instance, the truncated icosahedron (the familiar soccerball) has two types of edges: hexagon-hexagon and hexagon-pentagon, and it is not possible for a symmetry of the solid to move a hexagon-hexagon edge onto a hexagon-pentagon edge. An isotoxal polyhedron has the same dihedral angle for all edges. There are nine convex isotoxal polyhedra formed from the Platonic solids, 8 formed by the Kepler–Poinsot polyhedra, and six more as quasiregular (3 | p q) star polyhedra and their duals. There are at least 5 polygonal tilings of the Euclidean plane that are isotoxal,
A Plane Is Born training at Staverton Airport in Gloucestershire with instructor Carl Bowen. - Building Begins Mark learns that before he starts to build his aeroplane he must attend a workshop on composite building techniques. His crash course is instructed by expert Neville Eyre. In part 2, back at the workshop, he begins work on his kit plane, starting with the Rudder. Some respite from plastics is provided at Gloucester airport where his flying training continues apace. In a regular feature, Dudley Pattison shows us the Isaac's Fury biplane he took fifteen years to build. - Wings Filming in the workshop, work begins