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Engineering Development of the Fluidic Free-Flight Sensor for Use in Bomb Fuzes

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Final rept. Aug 1971-Dec 1972,

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The objective of this development program was to determine the feasibility of a fluidic free-flight sensor FFFS for use with general purpose and cluster bomb fuzes. The FFFS must establish that the bomb has been safely released, that the velocity of the bomb is 200 ftsec or greater, and that the bomb is in a freefall condition for at least two seconds during the first four seconds after lanyard initiation. These requirements were met by designing an acceleration sensor for sensing free flight and a mechanical arming linkage, both of which are powered by ram air from the bomb slip stream. A ram air pressure regulator was provided so that air pressure used to drive the free- flight sensor and arming linkage remained constant at all velocities above 200 ftsec. The arming linkage was bias loaded so a ram air pressure equivalent to 200 ftsec is required to perform the arming function. One FFFS was fabricated and bench tested by the contractor to determine adequacy of the design and two were delivered for captive flight and drop tests. The two delivered FFFSs were each equipped with two pressure switches and one microswitch to monitor regulator output pressure, sensor function, and arming function during test. A recorder was provided to record the action of the three monitoring switches during drop tests. Flight tests and drop tests have indicated feasibility of the FFFS to determine that the bomb has been safely dropped from the aircraft and is in a free-flight condition.

Subject Categories:

  • Fluidics and Fluerics
  • Ammunition and Explosives

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