C. DE ZAFRA.PROJECTILE.APPLICATION FILED DEC. 10, 1906.
Figures 1, 2 and 3. Different views of a projectile
United States Patent Office
Carlos De Zafra, Of New York, N.Y.
Projectile
No. 863,248
Specification of Letters Patent.Patented Aug. 13, 1907.
Application filed December 10, 1906, Serial No. 347,055
To all whom it may concern:
Be it known that I,Carlos de Zafra, a citizen of the United States, residing at New York city, county of New York, and State of New York, have invented certain new and useful Improvements in Projectiles, of which the following is a specification.
My invention, relates to an improved form of explosive shell or other projectile, and more particularly to those projectiles which are reinforced by longitudinal ribs.
It further relates to a method whereby such a projectile may be made.
The object of my invention is to provide a shell having a maximum strength or perforating power, together with a maximum capacity for an explosive charge, 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 thereof, and in reinforcing the interior of the shell with ribs which shall run in the same direction, starting at the base of the projectile and ending at the top end of the inner chamber.
In the drawings, Figure 1 is a side view of a projectile, the grain or fiber of which is indicated by dotted lines. Fig. 2 is a longitudinal section showing the interior ribs. Fig. 3 is a transverse section on the line 3—3, Fig. 2.
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 kinds, yet such a straight longitudinal rib is itself liable to a sheering and disruptive stress along transverse lines when the projectile strikes, due to the rotative inertia of the projectile in its flight.
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 plate, 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 therein. 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 off, due to the rotatory course when the head of the shell is embedded in an armor plate.
Like letters in the figures designate like parts.
A represents the shell, and B the fuse, B´ being the rotating band which is secured on the shell near the base in the usual way. The hollow portion of the shell consists of a chamber C extending from the base to the forward end of the shell. The walls of this chamber are provided with the ribs D extending from the base to the point of the chamber in a spiral direction. In the drawings, I have shown the pitch of this spiral as one quarter turn in the length of the chamber, but it is to be understood that I may use a greater or less pitch without departing in any way from my invention.
I have shown a pitch of one quarter turn particularly for purposes of illustration, as if a greater pitch had been used the section Fig. 2 would not have shown any one rib entirely.
As will be seen by Fig. 1, the grain or fiber of the metal is also twisted spirally in accordance with the pitch of the ribs D, in this case a quarter turn from the rear end of the projectile to its point.
In order to manufacture a projectile of this character I have devised the following method which I deem preferable, though I do not wish to limit myself thereto. This consists first in casting an ingot from which the solid forging is to be produced. Previous to, during or after the process of forging, the ingot is twisted in a torsion apparatus, 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 desired. 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 pitch. 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 artillery.
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 ribs. 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 rotated, as before explained. Thus the fiber of the shell and the interior ribs will both be given the spiral twist desired.
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 impact, the reaction of which will be along the line coincident with the resultant of the angular or rotative and the trajectoral velocities, which line will lie parallel with the spiral ribs, the pitch of such fiber and ribs having been predetermined by suitable calculation.
The above described methods while not claimed herein are to form the subject-matter of a separate application.
Having described my invention what I claim is:
1. A projectile provided with a chamber extending along its length, 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 thereof.
2. A projectile provided with a chamber extending along its length, the forward end of said chamber being pointed, the walls of said chamber being provided with longitudinal ribs extending in a spiral direction from the base of the chamber to the point thereof.
3. A projectile having the fibers of its material twisted in a spiral direction from the base of said projectile to the end thereof.
4. A projectile having the fibers of its material twisted in a spiral direction from the base of said projectile to the end thereof, said projectile having a central chamber, the walls of which are provided with longitudinal ribs extending in a spiral direction from the base of the chamber to the point thereof.
In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses, this sixth day of December, 1906.
Carlos de Zafra.
Witnesses:Emilo Belari,Emma Roderick.
Bibliography
Ordnance and GunneryBruff
Test Book of Ordnance and GunneryIngersoll
Report on the Art of War in Europe—1854-1855-1856Col. R. Delafield, U.S.A.
Journal of the U.S. Artillery
The Scientific American
Specifications of the Bureau of Ordnance, U.S. Navy Department
Specifications of the Ordnance Department, U.S. Army
The de Zafra Improved Armor-Piercing Shell
The de Zafra Improved Armor-Piercing Shell