Fore and Aft Fuzing System

The present invention relates to a fore and aft fuzing system and more particularly to a fore and aft fuzing system which effects the detonating of a warhead in the lethal burst position regardless of size of the target.

In known fixed angle microwave fuze systems, the warhead burst position is determined by the following sequence of operations: (a) A delayed time is computed on the basis of closing velocity information, (b) The delayed time begins when the fuze detects any part of the target at a fixed angle from the missile axis, and (c) The warhead is detonated at the end of the delayed time. In the known systems, the delay computed for any particular closing velocity is necessarily a compromise between the delays required for targets of radically different sizes and for widely different directions of missile approach to the target. The shortest delay that will burst the warhead in a lethal position for a large target frequency exceeds the longest delay that will yield a lethal burst against a small target at a comparable closing velocity. The best compromise delay is thus relatively ineffective against one or both classes of targets.

This invention utilizes the loss of signal occurring when the conical beam of the guard channel detection pattern has swept over the target and enters the region of free space. The loss of signal occurring at this instant is used to over-ride the computed delay, and to terminate the delay, detonating the warhead at this instant. In fuzes incorporating this invention the time delay computer could be designed to instrument longer delays than would be appropriate for the compromise used in the old systems, and these longer delays would be more effective against large targets, yet the fuze system would also be effective against small targets by the action of the target signal dropout time delay terminator. Thus the fuze would be effective against targets of all sizes.

Accordingly, an object of the present invention is to provide a fuzing system which will be effective regardless of the size or type of target encountered.

Another object is to provide a fuzing system which will detonate the warhead in the event a target is acquired and then lost prior to a predetermined time delay based on information from time of acquisition and closing velocity between the missile and target.

Other objects and many of the attendant advantages of this invention will become readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a block diagram of a preferred embodiment of the invention.

FIGS. 2 and 3 are graphs used in conjunction with the explanation of the invention.

FIG. 4 shows a modification of the embodiment of FIG. 1.

FIG. 5 is a representative showing of the conical patterns utilized in the embodiment of FIG. 1.

FIG. 6 is a block diagram of a further modification of FIG. 1.

Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a simplified block diagram of the parts of the fuze system that pertains to an illustrative embodiment of the invention. In the embodiment shown in FIG. 1 there are two channels 10 and 11 for receiving signals from targets. Conical beam 12 of the fuze detection pattern is associated with channel 10 while conical beam 13 is associated with channel 11 (FIG. 5). Channel 10 comprises an amplifier limiter 14, a time delay circuit 16, and a differentiator limiter 17, while channel 11 comprises an amplifier limiter 18, phase inverter 19 and differentiator limiter 21. The outputs of both channels are fed into a firing circuit 22. Channel 10 is the fuzing channel and assuming the target is of sufficient size a detected target signal is received first in channel 11 and then in channel 10. Channel 10 produces a firing pulse at the end of a predetermined time delay as shown in the graph of FIG. 2. Detected target signal 23 is received and fed through amplifier 14 to produce the output waveform 24, which is fed into time delay circuit 16. Closing velocity information which may be obtained from the guidance and control system of the missile is also fed into time delay circuit 16 for determining the proper delay time. Output waveform 26 from time delay circuit 16 is fed into differentiator limiter 17 to produce firing pulse 27 at the end of the time delay, i.e., at the beginning of waveform 26. Channel 11 produces a firing pulse at the loss of signal as shown in FIG. 3. Waveform 29 may represent a small target or it may represent a large target under certain intercept conditions. The detected signal 29 from a small target is fed into amplifier 18 to produce waveform 31 which is inverted in phase inverter 19 to produce waveform 32. Waveform 32 is differentiated in differentiator limiter 21 to produce firing pulse 33. Therefore, if a large target is detected by conical beam 13 and then detected by conical beam 12 which starts the time delay and the target signal is not lost in channel 11 before the expiration of the time delay in channel 10 then the fuze will be fired at the end of the predetermined time delay by fire pulse 27. However, if the target is first detected by channel 11 and then detected by channel 10 which starts the time delay; but the signal is lost by channel 11 before the expiration of the time delay, then a firing pulse 33 is generated by channel 11 to fire the fuze.

Referring now to FIG. 4 there is shown a modification of the embodiment of FIG. 1 which uses only one conical beam detection pattern. The received signal is fed through amplifier limiter 40 in the same manner as 14 of FIG. 1 to produce waveform 24 or 31 depending on the size of the target. The output from amplifier limiter 40 is simultaneously fed through time delay circuit 41 and phase inverter 42 to produce waveforms 26 and 32 respectively. If the received target signal is of sufficient duration then the output of time delay circuit 41 is fed into differentiator limiter 43 and produces a firing pulse 27 at the end of the time delay. If the received signal is from a small target and is lost, waveform 32 is differentiated in differentiator limiter 44 to produce firing pulse 33.

FIG. 1 may be further modified as shown in FIG. 6 by feeding the outputs of amplifier limiters 14 and 18 into a decision circuit 15 which will not allow any signal to pass to phase inverter 19 until a signal from amplifier limiter 14 is detected. If a signal is detected from amplifier limiter 14 and no signal has yet been received from amplifier limiter 18 then a firing pulse will be fed directly to firing circuit 22. Thus, the time delay will be overidden and cause the fuze to fire immediately.

This system is not limited to microwave or fixed angle fuzing, but may be used with fixed angle optical fuzes or variable angle fuzes.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.