Theoretical and Semi-Empirical Methods of Designing Ribbon Unwinders.

The objective of this program has been to develop theoretical and semi-empirical methods to enable engineers to design ribbon unwinders with reasonable accuracy and a minimum of development effort. This basic objective has been fulfilled, despite the fact that the degree of predictive accuracy depends to some extent on the design details of the fuze containing the ribbon unwinder. Some of the conclusions are that 1 Ribbon materials had to be in a dead soft condition to be suitable for unwinder application. Aluminum, brass, copper and lead were found to work well, but steel and titanium could not be annealed sufficiently to remain wound in a coil without external restraint. 2 Ribbon material properties and thickness had no definite effect on unwinding time. 3 Winding tightness had no definite effect on unwinding time. 4 Unwinding time was found to be proportional to ribbon length divided by spin rate-times-cavity radius, and 5 For all the empirical data gathered in this air spinner test program, the standard deviation was 39 of the man unwidning time. This is not considered excessive variation for an arming delay system.