,,the ,,development ,,of                
,armor-piercing ,shells  7,with         
,suggestions for their ,improvement7    
,by  ,,carlos ,,de ,,zafra1 ,m4,e4      
,faculty ,lecturer1 ,new ,york          
,university    #aiae     ,historical    
,the manufacture of projectiles to meet 
the requirements of the modern science  
of warfare has been brought to its      
present high stage of development       
through a long series of experiments    
based1 at first1 more upon theory than  
perhaps any other branch of engineering4
  ,in the days of wooden vessels very   
little thought was given to the actual  
physical properties of the then cast    
iron spherical mass4 ,the gun was the   
agent upon which depended the ability of
 the projectile to penetrate4 ,the      
projectile1 being confronted by so      
slight a resisting material as wood1 was
 distorted or physically affected to    
practically no degree by the resisting  
medium4 ,when fighting yard-arm to      
yard-arm the power of the gun was       

sufficient to fully penetrate the enemy1
 while at long ranges considerable      
damage would be executed without in the 
least impairing1 by the shock of impact 
7which was inconsiderable as compared   
with modern conditions7 the physical    
condition of the shot4  ,in the days of 
the all-wood vessel the guns were of the
 smooth-bore class divided into various 
types with nomenclature according to the
 size or weight of the shot1 very much  
as they are today1 i4e41 #c-pounder1    
#f-pounder1 #d-;inch1 #aj-;inch1 etc4   
,a general review of the gradual        
development of projectiles will be found
 beneficial and helpful to a more       
complete understanding of the           
complexities involved in overcoming the 
present day difficulties4  ,in the      
smooth-bore gun spherical shot was used4
 ,this was by no means a tight fitting  
device4 ,upon firing the gun            
considerable powder pressure was lost   
through the rapid escape of the gases   
past the shot between it and the bore of

 the gun4 ,this would most naturally be 
expected since at best the surface of   
contact between the shot and the bore   
would be only a circular line quickly   
eliminated or worn away through friction
 under the high temperature of the      
burning gases behind the shot4 ,the most
 obvious way to eliminate that wearing  
away of the bearing surface was to      
increase it1 in doing which the escape  
of gas past the projectile would be     
greatly checked1 and the gas pressure   
behind the projectile increased         
7exerting1 thereby1 a greater propelling
 force7 and imparting to the projectile 
greater velocity1 increased momentum1   
and consequent increased penetration4   
,but an increase in the bearing surface 
of the shot necessitated an alteration  
in its shape introducing difficulties   
affecting the accuracy of its passage   
through the air4  ,it was not an        
appreciation of any ineffectiveness in  
the early shot that first brought about 
a realization of the importance of      

obtaining the highest possible results  
from the material at hand1 for no       
difficulty was experienced in           
penetrating the early wooden barriers4  
,but with the introduction of rail-road 
and boiler iron and anchor chains along 
the sides of the vessels of war as a    
protection it was demonstrated that the 
old round shot previously most effective
 at the same range was now of little    
consequence4 ,armored vessels1 though   
crude as was their armor1 could with    
impunity run up along side a wooden     
enemy and demand immediate surrender    
with immediate destruction as the       
penalty for non-compliance4 ,it is only 
necessary to refer to the ,naval        
,history of the ,civil ,war of the      
,united ,states for the most convincing 
proof that this was so4  ,thus began one
 of the greatest industrial wars of the 
,world--the ,battle of ,guns and ,armor1
 which has been constantly waged through
 years of international peace and       
prosperity1 and is destined to continue 

indefinitely or until the ,utopian days 
of ,universal ,disarmament and          
everlasting peace arrive4     ,early    
,developments   ,with the change from   
the spherical to the longitudinal       
projectile1 difficulties in securing    
accuracy of flight arose not previously 
existing4 ,it was found that the        
elongated projectile would tumble or    
revolve about its transverse axis during
 its flight1 also wobble or describe a  
cork screw or spiral trajectory--capital
 defects requiring immediate attention4 
,the principle of the gyroscope to the  
effect that a body would maintain any   
desired position while revolving at a   
high rate about the proper axis was     
known and it was found desirable to     
adopt this principle in some practical  
manner to the development and           
improvement of the projectile4 ,it was  
believed that were it possible to give a
 high rotative speed to the projectile  
about its major axis the desired object 
of keeping that axis co-incident with   

the vertical plane of the trajectory    
would be accomplished4  ,among the first
 steps towards the development of the   
modern rifled artillery and elongated   
projectile we find certain improvements 
to have originated in the small arms    
pieces4 ,in his ,report on the ,art of  
,war in ,europe in #ahed1 #ahee1 and    
#ahef ,colonel ,r4 ,delafield1          
,u4,s4,a41 gives the first reference of 
immediate importance to the subject in  
question4 ,the small arms bullet was of 
lead which readily adapted itself to    
such configuration as was desired4      
,great contrariety of opinion existed as
 to the best form of ball and principle1
 even1 by which it was caused to partake
 of the rifle twist of the gun barrel4  
,the following are some of the first    
forms and methods adopted and are worthy
 of consideration3  ,illustration3 ,fig4
 #a  ,among the ,french and some others 
the tige principle was employed4 ,it    
consisted in forcing the base of the    
ball open so as to fit the bore and     

rifle grooves by driving it on a        
projecting spike in the bottom of the   
gun attached to the breech1 and rising  
through the charge of powder1 as in     
,fig4 #a4 ,for this purpose a           
countersunk rammer head to fit over the 
head of the ball had to be used4        
,illustration3 ,fig4 #b  ,fig4 #c  ,fig4
 #d  ,fig4 #e  ,fig4 #f  ,fig4 #g  ,in  
the ,english ,enfield rifle a form of   
ball was used consisting of a hollow cup
 or cone in the bored-out base of the   
ball 7,figs4 #b and #c7 the action of   
the powder driving this cup into the    
ball causing it to expand and take the  
rifling4 ,iron cups were used in the    
,crimea but because of occasionally     
cutting off and leaving in the bore a   
ring of lead were discarded for solid   
wood or papier mache cups 7,fig4 #d74   
,figs4 #e and #f show forms of hollow   
base balls used by the ,french and      
,russians1 in which the direct action of
 the powder on the base caused the      
sought for expansion into the rifling4  

,the ,russians at ,sebastopol employed  
also a fourth principle consisting of   
two short projections or lugs on the    
cylindrical part of the solid ball to   
engage in two grooves cut in the bore of
 the gun4 ,its proportions are          
illustrated by ,fig4 #g4  ,illustration3
 ,fig4 #h  ,fig4 #i  ,fig4 #aj  ,fig4   
#aa  ,fig4 #ab  ,fig4 #ac  ,the         
modifications of the preceding forms1   
shown in ,figs4 #h and #i were used in  
the ,crimea by the ,sardinian army which
 also used a smoothbore musket with     
solid ball as per ,fig4 #aj4 ,the       
,french army ,zouaves used a solid      
cylindro-conical grooved ball1 as in    
,fig4 #aa1 in a tige rifle4  ,the #ahef 
,austrian rifle used a solid            
cylindro-conical ball1 with two deep    
grooves cut in the cylindrical part such
 that the parts between the grooves are 
forced together and outwards1 or upset  
by the explosion of the powder1 to fill 
the bore and the rifle grooves1 as in   
,fig4 #ab4 ,fig4 #ac illustrates the    

same principle as used by the ,saxon    
army4  ,illustration3 ,fig4 #ad  ,fig4  
#ae  ,fig4 #af  ,fig4 #ag  ,fig4 #ah    
,other forms used at the time by the    
various ,powers are illustrated in      
,figs4 #ad1 #ae1 #af1 #ag1 and #ah4 ,but
 it was an open question as to which was
 the best form1 no ,power being fully   
satisfied4  ,it may be noted here that  
as the breech-loading rifle had not up  
to this time been sufficiently          
perfected1 all the above bullets were   
for muzzle loading rifles4              
,breech-loading arms had been known for 
over two centuries but were as yet      
unreliable1 clumsy1 and generally       
imperfect4  ,illustration3 ,fig4 #ai4   
,the ,lancaster ,gun4  ,the early       
methods adopted in the construction of  
cannon to impart to the projectile the  
desired rotary motion are as interesting
 as the early methods adopted in the    
construction of the projectile4 ,heavy  
rifled artillery was introduced in #ahef
 against ,cronstadt4 ,the ,english      

artillery at ,sebastopol used the       
,lancaster ,gun1 illustrated in ,fig4   
#ai4 ,the form of the bore section of   
this gun was that of an ellipse of #h   
and #h-e_/h diameters1 the bore being   
generated by the section of such an     
elipse making a revolution of about     
one-quarter turn in the length of the   
bore1 the center of the section always  
co-incident with the longitudinal axis  
of the gun1 forming thereby a continuous
 elliptical cylinder1 the greater axis  
at the muzzle lying in the vertical     
plane and gradually becoming horizontal 
at the breech section1 or in other      
words1 the whole length and section of  
the bore was a rifle twist of one       
quarter of a turn in its length4  ,the  
projectile was a wrought iron shell of  
the form and size indicated in ,fig4    
#bj1 as ascertained by measurement of   
one found in the trenches at            
,sebastopol4  ,illustration3 ,fig4 #bj  
,the use of these guns in the siege was 
by no means satisfactory1 giving neither

 precision of fire nor extraordinary    
range1 while the gun more often failed  
by bursting than other types4 ,the      
principle1 however1 met with favor and  
was studied and improved upon4  ,another
 method of applying the rifle principle 
to heavy guns consisted in casting a    
segment of a sphere 7nearly7 on the side
 of the cylinder part of the shot with  
corresponding grooves in the bore of the
 gun1 making about one turn in twenty   
feet4 ,it is somewhat like the principle
 of the solid musket ball1 ,fig4 #g with
 a difference in the shape of the       
projections1 as shown in the annexed    
,fig4 #ba1 giving the form and size     
7nearly7 of the shot4  ,guns of this    
pattern were adopted for many of the    
gunboats fitted out by ,france for      
operations in the ,baltic in #ahef1 some
 with four and others with two guns     
each4  ,illustration3 ,fig4 #ba         
,illustration3 ,fig4 #bb  ,the bore of  
the gun had a circular section of       
#f-a_/b diameter with two grooves cut in

 it1 as shown in ,fig4 #bb1 which in the
 length of the bore had a twist equal to
 one turn in six meters4  ,figures #bc  
and #bd represent cast iron shot of very
 peculiar shape1 intended apparently1 as
 a substitute for the rifle groove4     
,they were cylinders of about four      
inches diameter1 with a flattened       
spherical head from which three spiral  
openings communicate with the open      
interior of the cylinder4 ,the          
cylindrical part was formed with        
grooves4444  ,illustration3 ,fig4 #bc   
,illustration3 ,fig4 #bd     ,the       
,modern ,type of ,gun   ,from these     
earliest examples the development of    
artillery has been gradual until the    
present day of the built-up gun with an 
energy and range undreamed of in the    
earlier days4 ,the built-up gun of today
 has attained to a calibre of #af       
inches1 a length of nearly #ej feet1 a  
weight of #abd tons1 and an extreme     
range at #db deg4 elevation of #bj4i    
miles with a maximum height of          

trajectory of over #e-c_/d miles4 ,the  
projectile1 too1 has increased in size  
from a few pounds to the one ton or     
#b1bdj-pound mass used in the above gun4
 ,the energy imparted to it at the      
muzzle amounts to #f1djh-;foot tons     
assuring a penetration at the muzzle of 
#cc4h inches of steel1 or at #c1ejj     
yards of #bg4e inches1 the muzzle       
velocity being #a1ige-;foot-seconds and 
powder charge #fdj pounds of smokeless4 
,the maximum pressure in the powder     
chamber allowed is #cg1jjj pounds per   
square inch4  ,briefly the modern gun is
 a built-up piece1 constructed by       
fitting or shrinking super-imposed hoops
 or cylinders one over the other in size
 and number as diagramatically explained
 in ,fig4 #be1 sufficient to re-inforce 
the bore to withstand the varied        
pressures4  ,illustration3 ,fig4 #be4   
#ac-;inch ,b4,l4,r4 7,total ,length1 #dj
 feet47  ,illustration3 ,fig4 #bf  ,the 
twist or rotary motion is imparted to   
the projectile by means of the rifling  

in the bore4 ,fig4 #bf shows the        
cross-section of an #h-;inch gun with   
the dimensions of the rifling1 which is 
composed of two elements1 the groove or 
spiral cut made in the bore and the land
 or space between two adjacent grooves4 
,to take these grooves rotating bands of
 soft metal1 generally copper1 are      
fitted to the projectile as will be     
explained under ,manufacture of         
,projectiles4     ,classification of    
,projectiles   ,projectiles are         
classified according to their calibre1  
type of gun for which they are intended1
 material of which they are made1 etc41 
as per the following scheme used in the 
,u4,s4 ,army for marking cases of       
projectiles3                      ,cast 
steel     ,inch   ,rifle   ,cast iron   
,mortar  ,common steel    ,shot         
,armor piercing  ,shell                 
,rendable ,a4,p4           ,weight      
empty--,lbs4           ,capped or       
uncapped                or              
,capped and grooved for base cover      

or           ,uncapped and grooved for  
base cover           ,base   ,fuze      
,point      ,manufacture of ,projectiles
   ,while a high state of development   
has been attained in the manufacture of 
armor-piercing shells attention will be 
confined to their manufacture in so much
 as the methods for improvement         
hereinafter suggested are intended to   
affect the physical and not the chemical
 properties of the material1 and are1   
therefore1 applicable to all projectiles
 in which the stresses to be resisted   
exceed the resisting powers of the      
projectiles as at present manufactured4 
,the function to be performed by an     
armor-piercing shell is that of fully   
penetrating1 without disruption to      
itself1 an armor plate in thickness     
equal to1 at least1 the calibre of the  
shell in question1 and then be in       
condition for effective bursting4  ,the 
following extracts from the ,army and   
,navy specifications pertain to3        
,,material ,,and ,,workmanship  7,art   

#bj1 ,o4 ,d41 ,u4,s4,a47  ,the          
projectiles must be of forged steel1    
sound1 and free from cracks1 seams1 and 
other defects#a4        #a ,italics are 
those of the author and refer to defects
 which       it is the object of his    
design and method of manufacture to     
remedy4  ,the base plugs must be of     
forged steel1 annealed after forging or 
tempering1 free from seams1 cracks1 and 
other defects1 and have the following   
physical properties3      ,elastic limit
          #ej1jjj to  #fj1jjj pounds    
,tensile strength       #ij1jjj to      
#ajj1jjj        ,elongation             
#ah per cent4     ,contraction          
#be       ,the projectiles shall be     
machine-finished1 before treatment1 as  
close to the prescribed dimensions as   
may be consistent with that operation1  
and must1 if necessary1 be finally      
finished to the prescribed dimensions   
within the allowed variations4          
,cylindrical tensile-test specimens with
 diameter of stem of #j4eje inch will be

 used in all cases when the piece is    
sufficiently thick to finish the stem to
 that dimension2 when not1 the          
inspectors will determine the exact form
 or diameter of the specimens to be     
used1 the largest practicable being     
used1 considering the piece under test4 
,a length of stem between gauge marks of
 #b inches will be used in all cases    
where the elongation is to be taken4    
,,capping  7,art4 #ba1 ,o4 ,d41         
,u4,s4,a47  ,all steel projectiles shall
 be fitted1 when required1 with a cap of
 soft steel placed upon the point1#b the
 caps to be of the dimensions shown on  
the approved drawings and secured in a  
manner satisfactory to the ,chief of    
,ordnance by means of a groove1 to be   
turned on the head of the projectile    
prior to tempering4        #b ,see      
,frontispiece4  ,the steel for the cap  
must show a tensile strength not to     
exceed #fj1jjj pounds per square inch1  
an elongation after rupture of not less 
than #cj per cent1 and a reduction in   

area of not less than #de per cent on   
standard specimens1 #b inches long      
between measuring points and #j4eje inch
 in diameter4 ,these caps will be       
thoroughly annealed before being placed 
upon the projectiles and will be free   
from cracks and all other defects4      
,,test ,,for ,,detection ,,of ,,holes1  
,,cracks1 ,,etc4  7,art4 #bg1 ,o4 ,d41  
,u4,s4,a47  ,after the submission of a  
lot to the inspector for selection of   
samples for ballistic test1 and before  
final delivery1 the projectiles must be 
subjected to an interior hydraulic      
pressure of #ejj pounds per square inch 
for one minute4 ,all projectiles in     
which holes1 cracks1 or any unsoundness 
are developed by this test will be      
rejected4   ,,tensile ,,test  7,art4    
#bh1 ,o4 ,d41 ,u4,s4,a47  ,after        
forging1 the projectiles shall be       
annealed at a temperature of at least   
#a1bjj deg4 ,f42 and after being        
annealed1 tangential test specimens     
shall be taken from the base or base    

prolonged of #b per cent of the         
projectiles from each lot selected at   
random by the inspector4  ,the tensile  
strength of the projectiles in a lot    
shall not vary more than #bj1jjj pounds 
from the highest to the lowest4         
,,chemical ,,test  7,art4 #cj1 ,o4 ,d41 
,u4,s4,a47  ,a careful and complete     
chemical analysis shall be made of the  
metal of each heat from which the       
projectiles are manufactured under these
 specifications4   ,,tests ,,for ,,the  
,,detection ,,of ,,initial ,,strains    
,,bordering ,,on ,,rupture  7,art4 #ca1 
,o4 ,d41 ,u4,s4,a47  ,after final       
treatment and before acceptance for the 
ballistic test1 all ,a4,p4 shot must be 
cooled to a temperature of about #dj    
deg4 ,f41 and then suddenly heated by   
being plunged into a bath of water at a 
temperature of from #ahj deg4 ,f4 to    
#bab deg4 ,f41 as the ,chief of         
,ordnance may direct4 ,when thoroughly  
heated to this temperature each         
projectile must be plunged1 with its    

axis horizontal1 halfway into a bath of 
water at a temperature not greater than 
#dj deg4 ,f41 and after a brief period  
shall be turned #ahj deg4 for a like    
immersion of the opposite side1 after   
which the projectile shall be removed   
from the bath4  ,this test shall be made
 in the presence of the inspector1 and  
an interval of at least three days must 
elapse between the final treatment and  
the submission of the projectiles to    
this test4 ,this test is not required   
for shell4   ,,ballistic ,,test  7,art4 
#cb1 ,o4 ,d41 ,u4,s4,a47  ,each lot of  
projectiles shall be subjected to the   
following ballistic test3  ,after a     
final treatment and on presentation of  
the entire lot for the ballistic test1  
the inspector shall select three        
projectiles to represent the lot1 which 
shall be finished1 inspected and        
delivered in the same manner as required
 for the rest of the lot4  7a7          
,armor-piercing shot4 ,two capped shot1 
sandloaded to standard weight1 shall be 

fired against a hard-faced ,krupp armor 
plate from #a to #a-a_/b calibres thick1
 secured to a timber backing in a manner
 satisfactory to the ,chief of          
,ordnance1 with about the corresponding 
velocity given by the following table1  
with the requirement that the shot shall
 perforate the plate unbroken and then  
be in condition for effective bursting4 
,if both projectiles fulfill the above  
test1 the lot will be accepted4  ,if1   
one of the shots fails to pass the test 
here prescribed1 a supplementary test   
shall be made by firing the third shot  
under the same conditions as the first  
two shot2 if this passes the test as    
prescribed above1 the lot shall be      
accepted2 if it fails to do this1 the   
lot shall not be accepted4              
----------------------------------------
----------------       ,calibre of      
,weight of    ,thickness of   ,velocity 
for          shot          shot         
plate       penetration                 
----------------------------------------

----------------       #d-;inch         
#ccc        #d-;inch        #a1icj      
#e-;inch        #b1bie                  
#d4g-;inch         #dec         #e-;inch
        #b1bbj                          
#e-;inch           #eh                  
#e-;inch        #b1jje                  
#f-;inch        #b1cbj                  
#f-;inch          #ajf                  
#f-;inch        #a1iej                  
#h-;inch        #b1dej                  
#h-;inch          #caf                  
#h-;inch        #a1gfj                  
#aj-;inch        #b1ajj                 
#aj-;inch          #fjd                 
#aj-;inch        #a1gde                 
#ab-;inch        #b1jbj                 
#ab-;inch        #a1jdf                 
#ab-;inch        #a1gcj                 
----------------------------------------
----------------        #c ,weight      
uncapped4  ,for intermediate thickness  
the velocity shall be determined by     
interpolation4  7b7 ,armor-piercing     
shell4 ,two capped shell1 sandloaded to 

standard weight1 shall be fired against 
a hard-faced ,harveyized armor plate    
secure to a timber backing in a manner  
satisfactory to the ,chief of ,ordnance1
 of #c-;inches thickness for #e-;inch   
and #f-;inch shell1 #d-;inches for      
#h-;inch shell1 #e-;inches for #aj-;inch
 shell1 and #f-;inches for #ab-;inch    
shell1 with a velocity#d of about #a1dbj
 f4s4 for the #e-;inch shell1 #a1bbj    
f4s4 for the #f-;inch shell and #ibj    
f4s4 for the #h-;inch1 #aj-;inch and    
#ab-;inch shell at impact1 with the     
requirement that the shell shall go     
through the plate unbroken1 and then be 
in a condition for effective bursting4  
#d ,the weight of powder charge to give 
the prescribed velocity       will be   
determined shortly before the test1 cast
 iron projectiles       of proper weight
 being fired for the purpose2 this      
weight of       charge will be taken as 
giving the prescribed velocity to the   
projectiles undergoing test4            
99       99       99       99       99  

7c7 #ab-;inch deck piercing shell4 ,two 
shell1 sandfilled to standard weight1   
will be fired with a striking velocity  
sufficient to pass completely through a 
#d-a_/b-;inch nickel-steel              
protective-deck plate inclined so as to 
give an angle of impact of #fj degrees1 
and to be supported by a suitable       
backing of wood2 or both shell shall be 
subjected to such alternate ballistic   
test as the ,department may judge to be 
an equivalent to the above in its effect
 upon the projectile4                   
99       99       99       99       99  
,the nickel-steel protective-deck plate 
shall be manufactured by the open-hearth
 process and shall contain about #c-a_/d
 per cent of nickel1 not more than six  
one-hundredths of one per cent of       
phosphorous2 not more than four         
one-hundredths of one per cent of       
sulphur1 shall be the best composition  
in all respects4  ,it shall be oil or   
water tempered and annealed1 and the    
whole plate shall be subjected to the   

same treatment at the same time4        
,tensile test will be made after final  
treatment4 ,one longitudinal specimen   
for tensile test will be taken from each
 plate4 ,each shall show a tensile      
strength of at least #hj1jjj pounds per 
square inch and an elongation in #b     
inches of at least #bg per cent4        
,bending tests will be made as follows3 
,a piece cut from the plate shall be    
doubled cold around a curve of which the
 diameter is not more than the thickness
 of the piece tested without showing any
 cracks4 ,the ends of the piece are to  
be parallel after bending4 ,these       
specimens shall be #ab inches long1     
#a-a_/b inches wide1 and #a inch thick4 
,at the discretion of the inspector1    
bending specimens #a_/b inch square     
taken with a hollow drill1 may be       
substituted4 ,such specimens must bend  
cold to #ahj degrees flat1 without sign 
of fracture on outer surface4  7d7      
#ab-;inch ,torpedo ,shell4 ,two shell1  
sandloaded to standard weight1 will be  

fired from a gun or mortar into a sand  
butt with a pressure in the powder      
chamber of about #cg1jjj pounds per     
square inch to test structural ability4 
,if the shell are found not seriously   
deformed by discharge from the piece and
 in a condition for effective bursting1 
the lot will be accepted4  ,if any of   
the shell fail to pass this test1 the   
lot will be rejected4  ,the following   
extract from the ,circulars and         
,specifications of the ,navy ,department
 concerning ,armor ,plate and           
,appurtenances for ,vessels of the      
,u4,s4 ,navy1 7,april #bb1 #aijg7 while 
pertaining to another subject1 will be  
pardoned if introduced here for the     
purpose of demonstrating the seemingly  
paradoxical requirements a manufacturer 
is called upon to meet3  7,par4 #fj47   
,the ballistic test for acceptance of   
armor shall be made as strictly as      
practicable in accordance with the      
following tables1 the ,department       
reserving the right to use guns of other

 calibres than designated for any plate 
if it is deemed advisable4  ,in the test
 of armor of ,class ,a there shall be   
three impacts with striking velocities  
as given in the following table1 capped 
armor-piercing projectiles being used3  
----------------------------------------
--------      ,wt4 of shell ,calibre of 
,thickness of ,striking        capped   
gun       plates     velocity           
,pounds      ,inches      ,inches       
,ft4-seconds                            
----------------------------------------
--------          #aje           #f     
#e         #a1dea          #aje         
#f          #f         #a1fdh           
#aje           #f          #g           
#a1hcf          #afe           #g       
#f         #a1dfd          #afe         
#g          #g         #a1fca           
#afe           #g          #h           
#a1gia          #bfj           #h       
#g         #a1dei          #bfj         
#h          #h         #a1fjc           
#bfj           #h          #i           

#a1gda          #eaj          #aj       
#i         #a1deh          #eaj         
#aj         #aj         #a1efh          
#eaj          #aj         #aa           
#a1fgf          #hgj          #ab       
#aa         #a1dbd          #hgj        
#ab         #ab         #a1ead          
----------------------------------------
--------  ,the first impact shall be    
located near the central portion of the 
plate1 and the other two impacts shall  
be located as directed by the ,bureau2  
no impact1 however1 to be nearer another
 impact or an edge of the plate than    
#c-a_/b calibres of the projectile used4
  ,on these three impacts no projectile 
or fragment thereof shall get entirely  
through the plate and backing1 nor shall
 any through crack develop to an edge of
 the plate or to another impact4        
99       99       99       99       99  
,from the above it is seen that a       
manufacturer supplying both armor-plate 
and shell to the ,government is called  
upon to produce a shell with sufficient 

integrity to completely penetrate1 and  
without breaking up1 his armor-plate of 
sufficient thickness to resist that     
shell4  ,the capping of projectiles     
consists in placing over the point a    
cone or mass of metal of comparative    
softness4 ,in the ,united ,states       
services soft steel is used for the     
purpose4 ,authorities disagree as to the
 exact function which the cap plays1    
some claiming it to act as a lubricating
 metal facilitating the passage of the  
projectile1 others claim that it gives  
an initial shock to the armor-plate     
before the shell proper has struck it1  
which latter then strikes the plate in a
 state of molecular unrest1 and1        
therefore1 of impaired resisting power4 
,firing tests of shell at armor-plate at
 oblique angles have proven the capped  
shell superior1 which would indicate    
that the cap in this instance at any    
rate is capable of securing a hold on   
the plate which the bare point of the   
shell cannot1 in so much as uncapped    

shells glance off4 ,at any rate capped  
projectiles are1 on the whole1 superior 
to the uncapped and the practice of     
capping is recommended as an additional 
advantage when used in conjunction with 
the improvements here-in-after          
described4  ,at a specified distance    
from the base of the shell a groove or  
band-score is turned for the rotation   
band4 ,for projectiles under #g-;inches 
calibre1 pure copper is usually         
employed1 but for larger calibre an     
alloy of #ig-a_/b per cent of pure      
copper and #b-a_/b per cent of nickel is
 used and is annealed before banding4   
,the rough bands are in a form of solid 
rings cut from drawn tubes or           
cylindrical castings1 and must be       
carefully hammered into the score or    
preferably pressed in by hydraulic      
pressure and finally turned to proper   
size1 shape1 and finish4  ,their use has
 been previously described and the      
improvements in armor-piercing shells   
hereinafter described are based upon a  

study of the stresses sustained by a    
projectile upon impact while rotating   
about its major axis at the high        
rotative velocity which the engaging of 
these bands with the rifling of the gun 
has imparted to the shell4  ,the        
following table compiled by the author  
gives the rotative velocities of various
 projectiles3                           
----------------------------------------
-------------------                     
,muz4                                   
,engy4     ,calibre,wt41 lbs4  ,muz4    
,vel4                ,ft4  ,type of     
,inches ,projectile ,ft4 ,secs4         
,r4,p4,s4 ,r4,p4,m4 ,tons    ,gun       
----------------------------------------
-------------------       #c       #ab  
#hgj    #aci    #h1cdj   #fc ,hotchkiss 
#c4b     #ac4e      #a1fhe    #bec      
#ae1ahj  #bff ,field '#ij       #c4f    
#bj        #a1eej    #bjf   #ab1cfj     
#ccc      #ahia       #c4f     #bj      
#fej     #hf    #e1afj   #ei ,mortar    
#ahij       #e       #de        #a1hcj  

#agf    #i1efja1jde ,siege #ahij        
#g       #aje       #a1jhe     #gf      
#d1efj  #hec ,howitzer '#ij       #g    
#abe         #fij     #di    #b1idj     
#dab ,mortar '#ib                       
----------------------------------------
-------------------      ,u4,s4         
,,sea-,,coast ,,land ,,service ,,guns   
----------------------------------------
-------------------                     
,muz4                                   
,engy4      ,calibre,wt41 lbs4  ,muz4   
,vel4                 ,ft4   ,type of   
,inches ,projectile ,ft4 ,secs4         
,r4,p4,s4 ,r4,p4,m4  ,tons     ,gun     
----------------------------------------
-------------------       #h        #cjj
     #a1iej     #aaa   #f1ffj   #g1ijg  
#ahhh,m      #aj        #ege     #a1ige 
#ie   #e1gjj  #ae1edh  #ahhh,m      #ab 
#a1jjj     #b1ajj      #hd   #e1jdj     
#cj1gej  #aijb      #af      #b1cgj     
#a1ige      #ei   #c1edj  #fd1jhd       
----------------------------------------
-------------------      ,,krupp ,,guns 

----------------------------------------
-------------------                     
,muz4                                   
,engy4      ,calibre,wt41 lbs4  ,muz4   
,vel4                 ,ft4   ,type of   
,inches ,projectile ,ft4 ,secs4         
,r4,p4,s4 ,r4,p4,m4  ,tons     ,gun     
----------------------------------------
-------------------       #f            
#b1fjj    #aib   #ae1ebj                
#c1jjj    #bbb   #ac1cbj                
#h                 #b1bjj    #acc       
#g1ihj              #aj                 
#b1bej    #ajh    #f1dhj                
#ab                 #b1bej     #ij      
#f1djj                                  
----------------------------------------
-------------------  ,from the above    
table it will be noted that the         
,r4,p4,m4 are exceedingly high in some  
cases4 ,upon the impact of a shell with 
armor-plate the physical phenomena occur
 instantaneously and the resultant      
forces are so great that it is          
impossible to mechanically record their 

action4 ,a study of the stresses in the 
shell can1 however1 be made on a        
theoretical basis4  ,in the first place1
 if the projectile were twenty calibres 
in length and of a material offering    
less resistance to torsional stress than
 steel and rotated at the high          
velocities indicated we would find that 
upon impact the torsion would be plainly
 evident as per the following3  ,assume 
a projectile ,a of length twenty        
calibres1 about to penetrate an         
armor-plate ,b of thickness sufficient  
to prevent complete penetration by the  
shell in question4  ,illustration3 ,fig4
 #bg  ,the tendency of the impact is to 
stop the rotation of the projectile1    
owing to the friction between the       
surfaces in contact1 but owing to the   
length of the projectile the point      
receives this retarding influence before
 it can be transmitted throughout the   
body of the shell to its base4 ,the     
consequent result is that the head will 
finally come to a stop while the base is

 still rotating1 however slightly that  
may be4  ,theoretically considering the 
projectile to be composed of a series of
 discs a line drawn parallel to the     
major axis1 while at rest1 would be     
represented by the line cd4 ,upon       
impact1 however1 the rotative force     
tends to create a twisting couple with  
the result that each disc will tend to  
slide on its preceding disc1 so that by 
the time these twisting couples have    
been transmitted to the base of the     
shell the original line cd will have    
taken some such position as de4  ,the   
objection to the present method of      
forging shells is as a result1 the grain
 or fibre of the metal lies parallel    
with the major axis of the forging1 the 
forging process causing an elongation of
 the ingot and the metal grain following
 the direction of elongation4           
,consequently any flaws occurring in the
 material will extend parallel to the   
grain or major axis4 ,if a flaw remains 
undiscovered in a finished              

projectile--as is sometimes the         
case--the projectile is not only        
weakened thereby1 but the element of    
weakness lies in such a direction that  
the compression forces and counterforces
 produce very much the same results as  
would a wedge driven into a niche1 i4e4 
the separation of adjacent material4    
,the author is in possession of a shell 
in which a longitudinal flaw was        
revealed in the ogive by the cutting    
away of a longitudinal quarter section1 
,fig4 #bh4  ,illustration3 ,fig4 #bh4   
,armor-,piercing ,shell4 ,showing       
position of flaw4  ,there are1          
therefore1 two great forces with which  
to contend in the design of projectiles1
 to one of which1 compression1 has been 
given the greatest attention because of 
its recognized tendency to cause the    
base of the shell to crowd upon the head
 and cause the shell to break up about  
the ogive4 ,the other force1 torsion1   
seems not to have been considered prior 
to the present instance1 at any rate so 

far as the author has been able to      
ascertain1 not because thought to be    
unimportant1 but because of oversight or
 failure on the part of investigators to
 take into consideration in this        
instance1 an element of reaction        
commonly considered in mechanical       
engineering practice1 as in shafting for
 vessels and for power transmission in  
shops1 etc4  ,the writer maintains that 
immediately upon impact the metal in a  
shell assumes a state of physical       
unrest1 due to stresses similar to those
 in a propeller shaft when in motion1   
except that in the former case the      
intensity of the compression stresses   
greatly exceed those in the latter4     
,because a shell is only #c-a_/b        
calibres in length is no criterion that 
the same stresses do not exist there as 
would exist in the theoretical          
projectile considered of twenty         
calibres1 or one of even more           
exaggerated proportions--there would be 
merely a difference in the intensity of 

these stresses4  ,in a projectile making
 one complete revolution about its major
 axis in every twenty-five calibres     
flight1 any one elementary unit area or 
mass in that shell likewise makes one   
complete revolution in the same distance
 of travel1 and the path traversed by   
that unit area or mass is that of a     
spiral of radius equal to the distance  
of that unit area or mass from the major
 axis of the shell1 the diameter of     
which spiral would be the diameter of   
the shell in question--and the pitch    
twenty-five calibres--if said unit area 
were on the surface of the body of the  
shell4  ,upon impact the tendency of    
this unit area would be to continue its 
flight along the continuation of that   
spiral or along the line ed of our      
theoretical shell of twenty calibres4   
,the result would be for each disc      
element theoretically considered to     
crowd upon the next corresponding disc  
element and these two upon the third    
corresponding disc element etc41 such   

crowding taking place along the line ed4
 ,therefore the projectile must be      
designed not only to penetrate1 as well 
as to withstand the great compressional 
stresses upon the advancing head of the 
shell but the body of the shell must be 
so designed as to give a maximum of     
integrity4 ,the torsional stresses act  
along ed1 and in order to resist these  
stresses the shell must be so designed  
that the resisting ability will be      
increased along that line1 re-acting    
along de4  ,this the author advocates by
 means of a twist forging1 in which the 
grain of the metal will lie co-incident 
with the lines of the torsional         
stresses1 and by the introduction of    
spiral ribs lying co-incident also with 
the lines of the torsional stresses and 
the grain of the twist forging          
manufactured by a process indicated in  
the patent herewith appended4 ,by the   
introduction of the spiral ribs it will 
be seen that each disc is reinforced to 
withstand the tendency of the disc      

behind to crowd upon it and that by     
means of a properly designed shell of   
this type the whole energy of the shell 
can be better transmitted to the point  
of impact by means of the spiral ribs   
and twisted grain4  ,furthermore1 should
 any flaws be present in the ingot1     
their size would be reduced by the      
twisting1 as are the spaces between the 
strands of a rope when twisted in the   
proper direction for so doing4 ,also1   
with a flaw in a finished projectile1   
and lying in a spiral direction the     
result of the compression stresses would
 be to jump across the flaw or to       
decrease the gap instead of acting      
wedgelike along the flaw causing it to  
open as before mentioned4 ,finally1 an  
increase in integrity means an increase 
in penetrability1 or in the percentage  
of complete penetration1 with the       
ultimate necessity of increasing the    
thickness of armor-plate to successfully
 exclude the improved armor-piercing    
shell4       ,no4 #hfc1bdh4             

,,patented ,,aug4 #ac1 #aijg4      ,c4  
,,de ,,zafra4      ,,projectile4        
,,application ,,filed ,,dec4 #aj1 #aijf4
      ,illustration3 ,,fig4 #a4         
,illustration3 ,,fig4 #b4               
,illustration3 ,,fig4 #c4               
,illustration3 ,witnesses     ,names are
 illegible      ,carlos de ,zafra       
,inventor      ,by his ,attorney ,hensey
 ,gough     ,united ,states ,patent     
,office  ,,carlos ,,de ,,zafra1 ,,of    
,,new ,,york1 ,n4,y4  ,projectile   ,no4
 #hfc1bdh  ,,specification ,,of         
,,letters ,,patent4 ,patented ,aug4 #ac1
 #aijg4  ,application filed ,december   
#aj1 #aijf1 ,serial ,no4 #cdg1jee   ,to 
all whom it may concern3  ,be it known  
that ,i1 ,,carlos ,,de ,,zafra1 a       
citizen of the ,united ,states1 residing
 at ,new ,york city1 county of ,new     
,york1 and ,state of ,new ,york1 have   
invented certain new and useful         
,improvements in ,projectiles1 of which 
the following is a specification4  ,my  
invention1 relates to an improved form  

of explosive shell or other projectile1 
and more particularly to those          
projectiles which are reinforced by     
longitudinal ribs4  ,it further relates 
to a method whereby such a projectile   
may be made4  ,the object of my         
invention is to provide a shell having a
 maximum strength or perforating power1 
together with a maximum capacity for an 
explosive charge1 and the invention     
consists in forming the projectile with 
the fibers or grain of the metal running
 in a spiral direction from the base of 
the shell to the top thereof1 and in    
reinforcing the interior of the shell   
with ribs which shall run in the same   
direction1 starting at the base of the  
projectile and ending at the top end of 
the inner chamber4  ,in the drawings1   
,figure #a is a side view of a          
projectile1 the grain or fiber of which 
is indicated by dotted lines4 ,fig4 #b  
is a longitudinal section showing the   
interior ribs4 ,fig4 #c is a transverse 
section on the line #c--c1 ,fig4 #b4    

,while the tendency to rupture is very  
much lessened by the use of straight    
longitudinal ribs on the interior of    
shells and projectiles of various kinds1
 yet such a straight longitudinal rib is
 itself liable to a sheering and        
disruptive stress along transverse lines
 when the projectile strikes1 due to the
 rotative inertia of the projectile in  
its flight4  ,the aim of my invention is
 to provide ribs which will be          
coincident with the rotative travel of  
the shell so that when the point of the 
projectile enters an armor plate1 the   
stress of this sudden stoppage of       
rotation will be taken up along the     
fiber or grain of the shell and by the  
spiral ribs therein4 ,thus the sheering 
tendency of the metal in the walls of   
the shell is greatly reduced and greater
 strength is given to resist the        
tendency of the rear end of the shell to
 twist off1 due to the rotatory course  
when the head of the shell is embedded  
in an armor plate4  ,like letters in the

 figures designate like parts4  ,a      
represents the shell1 and ,b the fuse1  
,b' being the rotating band which is    
secured on the shell near the base in   
the usual way4 ,the hollow portion of   
the shell consists of a chamber ,c      
extending from the base to the forward  
end of the shell4 ,the walls of this    
chamber are provided with the ribs ,d   
extending from the base to the point of 
the chamber in a spiral direction4 ,in  
the drawings1 ,i have shown the pitch of
 this spiral as one quarter turn in the 
length of the chamber1 but it is to be  
understood that ,i may use a greater or 
less pitch without departing in any way 
from my invention4  ,i have shown a     
pitch of one quarter turn particularly  
for purposes of illustration1 as if a   
greater pitch had been used the section 
,fig4 #b would not have shown any one   
rib entirely4  ,as will be seen by ,fig4
 #a1 the grain or fiber of the metal is 
also twisted spirally in accordance with
 the pitch of the ribs ,d1 in this case 

a quarter turn from the rear end of the 
projectile to its point4  ,in order to  
manufacture a projectile of this        
character ,i have devised the following 
method which ,i deem preferable1 though 
,i do not wish to limit myself thereto4 
,this consists first in casting an ingot
 from which the solid forging is to be  
produced4 ,previous to1 during or after 
the process of forging1 the ingot is    
twisted in a torsion apparatus1 one end 
of the ingot being held fixed while the 
other end is being rotated by any       
suitable rotative gripping mechanism    
through an arc of the number of degrees 
desired4 ,this will result in what ,i   
term a twist forging in which the grain 
or fiber will lie in any predetermined  
or desired spiral direction or pitch4   
,the spiral ribs which are to lie in the
 direction preferably parallel to the   
grain or fiber of the metal may now be  
formed by the boring process similar to 
that employed in the rifling of modern  
artillery4  ,my projectile might also be

 formed by forming the shell with the   
ribs running longitudinally there along 
in a direct line from front to rear and 
with the fiber of the metal also running
 in a direct line parallel with the     
ribs4 ,the projectile might then be     
reheated for forging and while being    
forged the rear could be held in any    
suitable gripping device and the forward
 end be rotated1 as before explained4   
,thus the fiber of the shell and the    
interior ribs will both be given the    
spiral twist desired4  ,it will be seen 
that with either of these processes the 
fiber of the shell and the spiral ribs  
lie parallel to each other and are most 
perfectly formed to resist the shock of 
impact1 the reaction of which will be   
along the line coincident with the      
resultant of the angular or rotative and
 the trajectoral velocities1 which line 
will lie parallel with the spiral ribs1 
the pitch of such fiber and ribs having 
been predetermined by suitable          
calculation4  ,the above described      

methods while not claimed herein are to 
form the subject-matter of a separate   
application4  ,having described my      
invention what ,i claim is3  #a4 ,a     
projectile provided with a chamber      
extending along its length1 the walls of
 said chamber being provided with       
longitudinal ribs extending in a spiral 
direction from the base of the chamber  
to the forward end thereof4  #b4 ,a     
projectile provided with a chamber      
extending along its length1 the forward 
end of said chamber being pointed1 the  
walls of said chamber being provided    
with longitudinal ribs extending in a   
spiral direction from the base of the   
chamber to the point thereof4  #c4 ,a   
projectile having the fibers of its     
material twisted in a spiral direction  
from the base of said projectile to the 
end thereof4  #d4 ,a projectile having  
the fibers of its material twisted in a 
spiral direction from the base of said  
projectile to the end thereof1 said     
projectile having a central chamber1 the

 walls of which are provided with       
longitudinal ribs extending in a spiral 
direction from the base of the chamber  
to the point thereof4  ,in testimony    
whereof1 ,i have signed my name to this 
specification in the presence of two    
subscribing witnesses1 this sixth day of
 ,december1 #aijf4      ,,carlos ,,de   
,,zafra4      ,witnesses3      ,,emilo  
,,belari1     ,,emma ,,roderick4        
,bibliography   ,,ordnance ,,and        
,,gunnery                               
,,bruff  ,,test ,,book ,,of ,,ordnance  
,,and ,,gunnery                         
,,ingersoll  ,,report ,,on ,,the ,,art  
,,of ,,war ,,in                         
,,europe--#ahed-ahee-ahef               
,,col4 ,r4 ,,delafield1 ,u4,s4,a4       
,,journal ,,of ,,the ,u4,s4 ,,artillery 
,,the ,,scientific ,,american           
,,specifications ,,of ,,the ,,bureau    
,,of ,,ordnance1 ,u4,s4 ,,navy          
,,department  ,,specifications ,,of     
,,the ,,ordnance ,,department1 ,u4,s4   
,,army   ,illustration3 ,the de ,zafra  

,improved ,armor-,piercing ,shell