Downloaded from https://www.everyspec.com AMCP 706-210 tank (HEAT) rounds to develop a characteristic sense the location of the target, or indeperdent jet that is particularly effective in defeating commands may artificially cause target sensing. armor. Extremely rapid fuze action (20 u see) When operating properly, the missile guidance is required to achieve the proper stand-off dis- system compensates for changes in target posi. tjnce. This can be achieved as follows: a piezo- tion. Once the missile has come into target electric trrnsducer is placed in the nose that will range, it will then sense the target's exact posi- tion by another means to initiate fuze action.
initiate an electric detonator in the base, or an explosive element is placed in the nose with 3-2.3 PRESETTING provisions for its detonation products to be "spit back" through a tube in the base. The The third type of sensing is achieved by a time second process is used for slow rounds (1500 fps fuze. Time is estimated arid preset before firing or less) and when the spit distance is short or launching the ammunition. Time fuzed ammu- (30 mm weapons). nition may be designed to function: (1) against moving targets, (2) some distance from a fired 3-2.2 INFLUENCE SENSING target or above ground, or (3) at the target during subsequent events.
This type of fuzing results in detonation of A range of a few seconds to two minutes is the bursting charge n the vicinity of the target. common for time fuzes fired to explode against th busting chargefu in he vni of ttcale moving targets or near targets. The decision as S\ich sensing is useful in a number of tactical to when the fuze shall function is based on in- situations: to rain fragments on ground troops formation regarding wind velocity, target range, from the air or to fill the air around an aircraft position of the target when the missile is due to with fragments; Since a direct hit is not neces- reach it, and other pertinent details.
On this sary, the net effect is that of an enlarged target. basis, the fuze is set to detonate at the estimated The leading example of this type of influence most effective time after launching, and the in- sensing is the proximity fuze of the radio type. terval of time is measured during flight by ap- Originally, such fuzes were called "VT" but the propriate means, usually a clockwork mechanism term proximity is now preferred. or an electric timing circuit carried in the fuze. A simple proximity fuze of the radio type Time fuzed ammunition may also be dropped or placed at a target and then required to func- connan a ctiuous-wave tanmitte, a s a tion a long time (several days) after arrival.
Such tenna, and a receiver. When the emitted waves action would, for example, permit friendly strike a target, some of the energy is reflected troops to leave the area. These long intervals are back to the antenna. Because of the relative achieved by means of clockworks or chemical motion between fuze and target, the reflected- delays. wave frequency differs from the original emitted frequency and the difference frequency (known 3-2.4 COMMAND as the Doppler or beat-note frequency) is gen- Command fuzes initiate their munition on im- erated in the antenna and amplified in the re- pulses received after launching. This is usually ceiver.
When the signal reaches a certain value, done by triggering the fuze with a radio signal an electric detonator is initiated that in turn when observation indicates that the fuze should functions the explosive train, function. This point can be determined and the Proximity fuzes are the subject of other Engi- command sent automatically by use of radar neering Design Handbooks P t. Some further dis. and other electronic equipment. cussion is given in par. 12-5.3. 3-2.5 COMBINATIONS AND SELF-DESTRUCTION Refinements of influence sensing become es- pecially important for surface-to-air guided mis- siles.
The missile must sense the target both to It is often desired that a fuze be able to sense follow it and to initiate the fuze action. Several the target in more than one way so as to in- methods are in use to do this: detectors sense the crease its effectiveness. It is possible, for ex- target's heat or noise, transmitted radio waves ample, that a time fuze, set incorrectly, might 3-2