Downloaded from https://www.everyspec.com AMCP 706-210 ,ienuaturely by any actitlit .d setiuLtvce or kniown and reproducible. Keep m mind that Lthe events which mitay ovcutr at any tilwa between tie average value for a paranleter may bit -0: iii start of its fabrication id its approach to te iportant for design purposes than the extreme target. values. Reliability is the probability that naterial (d) As far as possible, design itens in f;ueh a will perform its intended function for a speci. manner that defects which affect reliability and fied period under stated conditions'. It is de- safety can be detected by means of nonds.struc- fined in statistical terms.
We say that a system tive tests or inspection. has a refiability of, say, 99 ptrcent and we make Multiple fuzing refers to the combination of this statement with a confidence of, say, 95 fuzes or their componentU into a network to percent' . obtain improved performance over single-.fuze While safety is also defined statistically, the systems. The duplication may involve the deto- approach to safety is somewhal different from nator, a circuit element, the sufing and arming that applied to reliability. The keystone of this device, or the entire fuze. Redundant compo- approach is the fail-safe principle.
Essentialy, nents are used to improve the overall j,.;ability this principle states that any sequence of events of the system. For example, a multichannel fuze other than that to which a round is subjected in of 99% reliability can be built from individual normal operation shall result in failure rather fuze channels having a reliability of only 90%. than detonation of the round. Compliance with Fig. 2-1 illustrates a fuze circuit having three the fail-safe principle is usually accomplished switches so arranged that closure of any two of mechanically, and is the reason most ordnance the three double-pole switches assures circuit devices must be considered as mechanisms, continuity.
The subject of multiple fuzing iF In terms of added bulk, weight, and com. covered in detail in classified handbooks'. plexity-which can be translated into terms of reliability, effectiveness, and logistics--safety is expensive. Hence, the problem of safety is a POWER ELECTRIC double one. The designer must be certain that his device is safe enough and yet impose the least impairment of functioning. A number of policies, rules, and safety codes that apply to various types of materiel have been promulgated. In view of the variety of these code3, it is well for a designer to examine in ad- vance the safety criteria that will be applicable to his design.
Note the safety requirements for fuzes in Figure 2.1. Possible Multiple Fuzing Circuit par. 9-2.2. See also the several safety tests that have been developed (par. 15-3). The design techniques that will help protect the weapon 2-4 STANDARDIZATION system against radio frequency energy, static electricity, and lightning are covered in a sepa- 2-4.1 USE OF STANDARD COMPONENTS rate publication 6 . The following rles can serve for general The decision as to whether to dapt a system guidance in the design of safe and reliable fuzes:
design to the use of a standardized component or (a) Whenever possible, use standard compo- to design a new component especially adapted nents with established quality level and other to a system is often one of the most difficult a reliability criteria at least as high as that required designer has to make. On the one hand, a new by the application. item has often been developed because, in the (b) Wherever possible, particularly in more layout stage of design, it took less effort to complex and expensive material, use multiple sketch in something that fit the dimensions than fuzing (see below), to find out what was available.
On the other (c) Specify materials for which the proper- hand, the hard and fast resolution to use only ties of importance to your application are well shelf items has resulted in systems which are 2-3