Segmented back-up bar Patent
A 1966 United States patent filing by W. J. Franklin and N. C. Martin, held in NASA's technical reports collection, describing a segmented back-up bar for welding the seams of large cylindrical tanks and rocket structures. The plates are hard-line engineering drawings: tall ribbed cylinders in perspective with clamp fixtures ranged around their rims, plus exploded and sectioned close-ups of brackets, bolts and coolant tubes, all tagged with leader lines and reference numerals useful as clean technical linework.
