601 



ANALYSIS OF THE SPRAY DOME 

 G. W, Walker 



tUne Design Department, 

 Admiralty 



1^19 



Objec 



The object of this research is to oroviOe sufficient data from which it will ce possible 

 to form an accurate estimate of tne amount and otstrlbution of cxolosive material required to 

 oroouce destruction of a given structure at a jiven range of distance. 



The res&'^rch might ercceed on entirely emoirtcal linos, Acert from the enormous cost' of 

 niaterlal ana time invDlved, such a methco is n:t in acccraance with scientific mc'th:^d, which aims 

 at cc-ordinating infcrmatijn in such a way that ^ reasinabls estimate may be fcmeo of the effect 

 cf varyino ^.ny oarticular s?t .f circumstances. 



Thus the research *in follcw two main lines:- 



{ l) Full scale sea exoerimsnts in which the damage done on certain known structures 



by ^i'wHn exolcsions is quantitatively Octcrniined, 



(2) The determinat ion of these ohysical quantities in an exolosion which determine 

 damage, 



A shio is damaged as the r-^^sult of the pressures ^xerted on it, and which are orccagatea 

 through tne water as a result of tno ?xcl:sion. Thus a c-molete kn:w1e3ge of the time aeveloomsnt 

 of oressure in the water at any distance from a given mine is a vital link in the chain which 

 conn='Ct5 the exolosion with the damage done. 



It will orobably be some time beforo an accurate soluti:;n of this difficult problem is 

 obtained, sc that meanwhile wc crocked to an account of an investigation of oart of the oroblem 

 which has been carried out in Mining School during tne oast year, and which has thrown considerable 

 1 Ight on the matter. 



The exolosion of a nin: in water, is followed by an joheaval of water, j-;S ^.nd stones. 

 Gen-^rai Aooct "Suc-arine Min?5" oiscjj-es thf ^u^^^stion of a study c' tne in-nc^en.^ is a frv.'ans 

 of quantitative measurement. His view, excressea cage U2, is that the ohenomena are too variable 

 to give results of great value. 



Now the Ohenomena ubserv 'd occur in distinct chases of which there are two or cossibly 

 three deosnoing on circumstancf:s, it aojears that General Aooot is thinking aoout the very fine 

 spectacular effect of the discharge cf gas etc*, and that he had not observed or had not 

 crnslder3d tne remarkably sharp scray phenomenon phase ( l) which almost immeoiattly follows tn-r 

 firing of the mint: and creceoes tho upheaval of gas, etc. 



This scray risis almost instantaneously in the form of e. dome 5S shewn in °late 1. The 

 outir edge i= vry sh:,roly divided from the still w^ter surface ano ^very o^rt cf the aome seems 

 to rise vertically. 



Numerous exoerin-ents havs De'.n made and shew that the soray chenomenon is a definite one 

 ana that it Icaos to important conclusions as tc th^. nature cf tie .xolcsive wave propagated 

 from the mine, 



Assumctions have to be m^.oe before we can interpret the sprsy phenomenon and the 

 justif icatirn for the assumptions consists in the manner in which the conclusions r-.gree with the 

 experiments. 



