e A116 ® This is aacther statement of general “principle of least preesures” vaich hae been apparent for some tine in blast hyirodynamice, Mare fully, this statement is tnt, in a hytrodynasic process which mightiavolve a susber of possibie paths by which @ blast wave could change from one ecnfiguration to snocther, a gmeral property of these hydrodynamics exists by vhich the blast wave will follow that pattern, which results in the smallest possible peak pressures, Based on this principle, it may not seem 20 surprising that the ideal pressures alyays soen to be approached and seldom realised in TUB Parring 8 umjor reversal of the preliminery data, some tentative con- clusions to be dream from Ivy ere? (1) the baste blast yattern from nuclear explosioas now aypears to be éetablished ca quite firm theoretical and empirical grounds, in a self-consistent theory beginming vith the grovth of the fireball, and extenting to pressures less then 1 rei. (2) Large scale atncsyharic immomogenisties mrkedly affect the blast variables at the long distances in the region of interest for large scale veepons in the magnates reage, In particular, under the conditions of wormad lapse rate of temperature vith altitude, as in MIKE shot, the peak preseure at long distances are markedly reduced, (3) the general theory of surface loss, as explained in LA-1406, are again ecafivued, here, vith regard to the behavior expected over ideal surfuces, BEST AVAILABLE COPY ee Ce a sik tre actual measurenmt,