A Strain-Sonde Technique for the Measurement of Mechanical Time-Delay Fuze Function Times and Performance
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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A technique has been developed for an in-flight measurement of function time and the clock rate of the M577 mechanical time-delay fuze. A full- bridge, semiconductor strain gage is bonded to the projectile ogive in the vicinity of the fuze well. The output of the strain-gage bridge is conditioned by a high-gain, wide frequency bandwidth amplifier and telemetered to a ground receiving station using an FMFM telemetry package aboard the projectile. The stain-sonde is sensitive enough to respond to the escapement mechanism in the timer of the M577 fuze. The response is in the form of a train of high-frequency pulses from strain-sonde. The repetitive rate of the pulse train corresponds to the tick-toc or clock rate of the fuze. The frequency content of each pulse depends upon projectile and fuze configuration but, generally, frequency components of approximately 1Khz, 4Khz, and up to 8Khz have been measured in conjunction with an M509 projectile. The signal-to-noise ratio of the voltage signal from the strain-sonde varies from 21 to 41 but is sufficient to obtain an accurate measurement of the M577s clock rate. The strain-sonde also detects other mechanical events or operations associated with the fuze. For example, with the M577 fuze, the arming mechanism is detected, the motion of the rotor in the safe-sensing device is detected, and the operation of the firing pin is detected. The ability to detect all of these events with the fuze strain-sonde allows the complete operational sequence of the fuze to be monitored and measured under real flight conditions. Clock rates, arming times, and function times can be checked.
- Ammunition and Explosives
- Solid State Physics