1963 US Army Vietnam War Armor Operations ... - Survival Books

WWW.SURVIVALEBOOKS.COMSection II. FIELD EXPEDIENT METHODS FOR ESTIMATION OFNUCLEAR BURST YIELDzontal plane and the top of the mush-room cloud, measured at approximately10 minutes after the burst.4. Description of Terms At this time the cloud has stabilized3. General and reported to assist higher headquarters inlocating ground zero of the burst, by means ofAfter a nuclear burst certain measurementsmust be observed and reported to provide ameans of determining location of ground zero d. Cloud Angles.and estimating the yield. Units in the vicinity (1) Cloudtop angle is the vertical angleof the burst, but outside the zone of primaryin mils or degrees subtended by horieffects,will measure and report to their nexthigher headquarters burst observations.a. Flash-to-Bang Time. This is the time in height (fig. 84).interval in seconds between the "chalkwhite (2) Cloudbottom angle is the vertical angleflash" of the detonation and the arrival of thein mils or degrees subtended by asound of the explosion at the position of thehorizontal plane and the point ofobserver. This measurement establishes theintersection of the mushroom clouddistance from the observer to ground zero. Theand the stem, measured at approxishockwave (sound of the explosion) travels atmately 10 minutes after the burstan average velocity of 350 meters per second. (fig. 84).To determine the distance in meters from the e. Height of Burst. This is the position ofobserver to ground zero (GZ), multiply the the explosion relative to the surface (earth orflash-to-bang time in seconds by 350 meters. water). The exact, height of burst of enemyb.Width of the Fireball. This is the angle in delivered weapons is desirable to know, butmills subtended by the fireball and measured may be virtually impossible to ascertain withby an observer immediately after the passage present observational techniques. The trainedof the shock wave,observer can, however, discriminate betweenthe obvious airburst and the contact surface(1) In the field, this measurement is made burst, leaving the transition zone as an area ofby the observer taking cover on noting doubt to be resolved by other means, such asthe flash, and counting the secondsthe presence or the absence of a crater.until the explosion is heard (flash-tobangtime); he then measures the fire- f. Cloud Diameter. There may be instancesball width by available means. At where it is not possible to distinguish clearlythis time there is no danger to the the cloudtop height or cloudbottom height. Ineyes from the fireball luminescense. such cases, if a clear measurement of cloudIt is important that the measurement diameter is possible at time of stabilizationbe made immediately after the pass- (H+ 10 minutes) this measurement, in milsage of the shock wave, because the or degrees together with the observer location,rapid expansion of the fireball would should be reported through command channelscause a late reading to be in error. to the CBRE for use in yield determination (fig.(2) The fireball will vary in appearance,depending on the yield and the distanceof the observer f rom GZ. Theg. Ground Zero. This is the point on theground at or above which the nuclear explosionoccurs. The location of GZ can be determinedeither by intersecting azimuths (e above), orradiant ball of fire at early times, to by flash-to-bang time (a above).a barely luminous, generally sphericalcloud at later times.5. Nuclear Burst Informationc. Azimuth Measurement. Azimuth from the a. There are certain requirements for obobserverto the mushroom stem is measured served data on nuclear bursts.AGO 9139A 357