Practice rig for pilot of model helicopter has four vertical posts supporting horizontal rods guiding arms attached to hub sliding vertically on rod with cardan joint

摘要

The vertical posts (5) are fastened to a firm foundation and there are pairs of horizontal rods or tubes (2,3) stretched between them. The arms (1a-1d) attached to the central hub (4) slide between the upper and lower rods fastened to the posts. A rod with a stop on one end passes through the central bore in the hub and the other end is held on a cardan joint.