Downloaded from https://www.everyspec.com AMCP 706W210 7 CHAPTER 3 PRINCIPLES OF FUZE INITIATION 3-1 GENERAL munition and target, (2) influence sensing with no contact between munition and target, and A fuze is a device used to cause functioning of (3) presetting in which the functioning delay of a munition at a desired time or under specific the fuze is set before launching or implacement. circumstances.
To accomplish this task, the fuze must become armed, determine a time interval, 3-2.1 SENSING BY CONTACT sense a target, or recognize some specific cir- cumstance, and then initiate the desired action, Fuzes which are initiated by contact with the including any delays or other specialized actions target are the simplest and afford the most direct that might be required. Commonly, the desired solution of fuzing problems. All functioning ac- action is to start the propagation of an explo- tions start when some part of the munition sion. These actions are divided into two main tuches the target.
When properly designed, this parts, arming and functioning system can be used to produce a detonation oi Arming concerns the shift in the status of a the bursting charge anywhere from a short dis- fuze from a safe condition to tiat in which the fuze can function. It is discussed extensively in tance in front of the target to several feet within Part TWO. the target. Fuze functioning is the succession of normal The electrical or mechanical action of such actions from initiation of the first element to de- fuzes is usually activated by some mechanical livery of an impulse from the last element of the action resulting from contacting the target, for explosive train.
First, the fuze must sense the example, by moving a firing pin, by closing a target. When the proper target stimulus is re- switch, or by stressing a piezoelectric transducer. ceived, the fuze mechanism is then ready to go Contact sensing satisfies a wide range of prob- through the steps that will lead to initiation of lems and results in positive action. On the other the first element of the explosive train. These hand, a direct hit is required. Other sensing steps differ depending on whether the fuze is features are needed, particularly for antiaircraft mechanical or electrical. use, to function the fuze in case of near misses.
3-2 TARGET SENSING Contact sensing is applied in a variety of ways. (1) On the target surface. The most straight. Different munitions are assigned specific tasks. forward use of contact sensing occurs when it is Some are designed to detonate as they approach desired to have a munition detonate on the front their targets, others are expected to detonate up- surface of the target. When the fuze touches the on impacting the target, and still others are ex- target, action starts at once and detonation pected to detonate only after penetrating the occurs as a direct consequence of the sensing. target. In some cases, it is desired that the fuze (2) Behind the target.
A typical example is a provide for optional actions. Some fuzes are re- munition designed to detonate within the struc- quired to destroy the munition if no target is ture of an aircraft. Methods of extending func- sensed within a given time interval or flight dis. tioning time or delaying detonation of the tance. Some items, such as mines, are expected bursting charge after first contact are discussed to lie dormant for indefinite periods and then to function when a suitable target moves into their effective range. In every instance, the fuze must (3) In front of target.
Another example is first sense the target at the proper time or dis- that of detonating the bursting charge some dis- tance so that its subsequ'ent actions may be ini- tance in front of target. This distance in front of tiated. This problem is usually solved in one of the target, known as the stand-off distance, per- these ways: (1) sensing by contact between mits the shaped charge of high exp!osive, anti 3.1