US39942A

US39942A - Improvement in rifled projectiles

Info

Publication number: US39942A
Authority: US
Publication date: 1863-09-15
Anticipated expiration: 1880-09-15

Description

J. MGMURTRY.

I Projectile. No 39,942. Patented Sept. 15, 1863.

Witnesses:

N.FETERS PHOTO LITHOGRAPHER, WASHINGTON, D c.

Jonx ndnunrnr, or LEXIN IMPRQVEMENT 1N RIFLED PROJ PATENT Orricn.

GTON, KENTUCKY.

ECTILES.

Specification forming part of Letters Patent l\ *o. 39,942, dated September 15, 1863; autedated October 16, 1862.

To aZZ whom it may concern: I

Be it known that I, J OHN MeMUR'ray, of Lexington, in the county of Fayette and State of Kentucky, have invented a new and use ful Improvement in Projectiles for Smooth- Bore Guns, Cannon, 850.; and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the annexed drawings, making a part of this specification, in which- Figure 1 represents a side elevation of my improved projectile. Fig. 2 represents a sectional elevation of the same, showing its mini feature, marked 0. Fig. 3 represents a top or front view of same. Fig. at represents a top View of the same projectile as would be seen in a transverse section near the rear end, as indicated by dotted line on Fig. 5, with the channels B B made of equal depth from the circumference of the projectile between the rifles A A, commencing at the point where the twist begins, next the forward end, as shown, and gradually assume a uniform depth from the external circumference of the projectile, for the purposes hereinafter explained.

My improvement is intended to give, when shot from smooth-bore guns, cannon, &c., the same spinning or rotary motion as from those of rifled bore, and thereby secure the same accuracy as from the rifled gun, with greatlyincreased force "and range, to those f om the rifled gun, &c. Recent experiments, both in the United States of America and England, demonstrated that there was nearly double the crushing force in the ball shot from the old sixty-eight-pound smooth-bore cannon as from the ball shot from the best one-hnndred-pound rifled cannon; also, that the speed of the ball from the smooth-bore was over two thousand feet per second, whereas the speed of the ball from the rifled cannon w 'as very little over one thousand feet per second. The scientific men give us the above facts, but not the reason therefor. The reason for this great disparity of speed and force is believed to be caused by the great resistance of the ball against the rifles of the rifled cannon, which also prevents the ball from receiving the full force of the powder until in the act of leaving the nozzle of the cannon. Consequently the expanded and weakened force of the powder in the rifled cannon must necessarily be greatly inferior to that of the smooth-bore cannon, whose ball receives the full force of the powder from the breech instead of at the muzzle, as in the case of the rifled gun.

In my improved projectile, elongated sub stantially as shown in annexed drawings of same, I make two or more channels or rifles in same at equal distances from each other, commencing near the point of the projectile and running toward the rear end-say about one-third of the distancestraight, and then gradually assuming an increasing spiral curve toward the rear end, as will be readily understood by reference to annexed drawings of same at Fig. 1. By this arrangement of the rifles A A and channels B B. the point of the projectile is left free from the action of the wind, which is received at the rear end of the ball in full force by the increasing spiral form of the rifles A A, thereby serving to give the spinning motion to the projectile so essential for accuracy, and also serving the same purpose as the feathers do on the Indian arrowviz., giving accuracy to the point. I make the channels B B in two ways, as will be seen by reference to Figs. 3 and at of the annexed drawings, for the following reasons: I make the bottom of the channels B B in the form of a circle, terminating one side of same in coincidence with the exterior circumference of the projectile, fort-he purpose of avoiding the reac tion of the riflesAA, &c., on the air consequent on the spinning motion of the projectile, as shown in Fig. 8. I also make the channels B B of equal depth from the exterior circumfer ence of the projectile, as shown in the transverse section of same at Fig. 4 and the side elevation of same at Fig. 5, for the purpose of obtaining any benefit that may be gained from the reaction of the rifles A A on the air when made as shown in Figs. at and 5. This is done with reference to the received axiom that action and reaction are equal, less the friction, which, iftrue, would cause the projectile made as Fig. 4 to pass through the air with very little resistance, which future experience alone can determine.

I do not claim the making of spiral grooves or channels on projectiles, for this may have been done in certain ways by others; but

projectiles, in combination with the omission of that portion of the channels B B from the front of the projectile to that part of same when thetwist of the channels commences, substantially as described, and for the purposes set forth.

January 8, 1862.

JOHN MOMURTRY.

Attest:

Z. GIBBONS, J. A. BosTwIcK.