ON RESONANCE PHENOMENA AND SHORT RANGES IN MORTAR FIRE

The occurrence of occasionr-l short ranges in mortar fire has long plagued the designers of ordnance materiel and impaired the utility of mortars in combat. Despite the existence of a well-developed tneory of motion and the availability o-f mians for reliable raeasurement of the principal aerodynamic proper"cic3 of new shell, bporadic s.iort rounds continue to occur with contemporary designs. ' The principal purpose of this paper is to review the American effort toward elucidation of the causes of short ranges in mortar fire, and to present the author's conclusions as to hew sporadic shorts may be eliminated by suitable de; ■';•'■; and quality control precautions. It is apparent that full understanding of the non-linear phenomena which presumably operate when a round becomes a "short" Iß not necessary. "Shorts" may be eliminated by satisfying four conditions, conditions which serve to guarantee that the flight is describable by linearized aerodynamic theory. The extent to which current knowledge permits detailed satisfactior of all conditions is discussed and the need for further reliable measurements is pointed out.