A few airships have been Schwarz's first aluminum rigid airship of 1893 collapsed, while his second flew; the nonrigid ZMC-2 built for the US Navy flew from 1929 to 1941 when it was scrapped as too small for operational use on anti-submarine patrols; while the 1929 nonrigid Slate Aircraft Corporation " City of Glendale " collapsed on its first flight attempt.
22.
A few airships have been Schwarz's first aluminum rigid airship of 1893 collapsed, while his second flew; the nonrigid ZMC-2 built for the US Navy flew from 1929 to 1941 when it was scrapped as too small for operational use on anti-submarine patrols; while the 1929 nonrigid Slate Aircraft Corporation " City of Glendale " collapsed on its first flight attempt.
23.
In this approach the symmetry groups are known as " Schr�dinger supergroups " and consist of two types of operations ( and their combinations ) : ( 1 ) the geometric symmetry operations ( rotations, reflections, inversions ) of rigid molecules, and ( 2 ) " isodynamic operations ", which take a nonrigid molecule into an energetically equivalent form by a physically reasonable process such as rotation about a single bond ( as in ethane ) or a molecular inversion ( as in ammonia ).
