IMPROVEMENTS IN PROJECTILES AND IN APPLIANCES OR SABOTS CONNECTED THEREWITH OR THERETO
Year: 1877

page_text: LETTERS PATENT to John Barnard Pearse, of 166, Fleet Street, in the City of
London, for the Invention of "IMPROVEMENTS IN PROJECTILES AND IN APPLIANCES
OR SABOTS CONNECTED THEREWITH OR THERETO." A communication from
abroad by John Gazzam Butler, Captain of Ordnance, Watervliet Arsenal,
West Troy, United States of America
Sealed the 15th March 1878, and dated the 17th September 1877.
COMPLETE SPECIFICATION filed by the said John Barnard Pearse at the
Office of the Commissioners of Patents on the 17th September 1877.
JOHN BARNARD PEARSE, of 166, Fleet Street, in the City of London. " IMPROVE-
MENTS IN PROJECTILES AND IN APPLIANCES OR SABOTS CONNECTED THEREWITH OR
THERETO." A communication from abroad by John Gazzam Butler, Captain of
Ordnance, Watervliet Arsenal, West Troy, United States of America.
The object of this Invention is improvements in projectiles and in appliances or
sabots connected therewith or thereto, by which the many obstacles presented by
the present modes of fitting sabots to projectiles are obviated, especially that of
the dislodging of sabots therefrom by the excessive force of the concussion due to
the explosion.
With a view to a clear comprehension of the full object and scope of this Inven-
tion, preliminary reference is had to the Drawings, Figures 1 and 2, which represent
certain forms of sabots or gas checks which have been applied to the bases of rifle
projectiles for the purpose of securing rotation, and which it is the object of this
invention to so improve as to render them more efficient and reliable.
In the service of rifled cannon it has been found that an impression of the rifling
may be satisfactorily secured by the action of the discharge upon a concave or a
convex disc, which is thereby flattened against the base of the projectile, at the
same time forcing a circular wedge or key upon a conical surface provided for that
purpose upon the rear end of the projectile.

page_text: Sabots of this nature, however, are extremely liable to strip from the projectile,
either in the gun or during flight, mainly owing to the distortion of the sabot by
the force of discharge which acts to enlarge and therefore to loosen it upon the
projectile, so that the moment the projectile leaves the gun and the powder gases
cease to act upon it, it detaches from the iron body of the projectile partly from the
compressed confined air behind it, and partly from entrance of gas under it. To
correct this evil recourse has been had to riveting, and also to a central bolt with a
large head, but these devices are often ineffectual.
Projectiles fitted with sabots of the known form are illustrated on the annexed
Drawings, Figures 1 and 2, in which two forms of sabots D and D¹ are illustrated,
and which are intended to be forced upon the base of the projectiles A, and thus
wedged outward into the grooves of the rifling. This, however, loosens the sabot
at the points a and a³, thus allowing the gas to enter under and behind the sabot,
and force it off as soon as the projectile passes the restraint of the bore.
In the case of large projectiles of this character the sabots must cover a very
considerable portion of the base of the projectile, and thus receive an aggregate of
one to several million lbs. pressure upon it, so that besides the tendency to strip by
the leakage of gas under the sabot a very powerful and injurious wedging strain is
brought upon the gun. This wedging must needs be powerful, in order to properly
and sufficiently impress the rifling upon the wedging sabot, which has the hard
and unyielding body of the projectile under it; this wedging, indeed, must actually
cause a flow of the brass sabot from under each land, which is flat and broad, and
not wedge-shaped, into the adjacent grooves.
It is the object of the present Invention to avoid this tendency of the sabot to
strip from the projectile by a more secure attachment to secured increased strength
by a change of form to limit and control the injurious wedging and upsetting
strain referred to, and at the same time to depend less upon this wedge for rotation
than upon an expansible feature of the projectile of much easier action upon the
walls of the gun, and upon the lands of the rifling.
The present Invention is based on detail improvements upon Letters Patent
granted to John Gazzam Butler on the 17th May 1872, No. 1510.
In the accompanying Drawings Figure I. represents a side elevation of an
improved projectile with sabot attached, shown in section; Figure II. is an end
view of the same, and Figure III. shows a modified form of sabot.
In these three Figures similar letters indicate corresponding parts.
A represents the iron body of the projectile, the base of which consists of the
frustrum of a cone B, and a central portion or extension C of somewhat smaller
diameter; D is an improved sabot, which consists of a double-flanged ring, the
outer flange K fitting over the conical or tapered part B of the projectile, and having
an outer diameter equal to that of the body of the projectile, and the inner flange P
threaded and secured upon the threaded extension Ĉ.
The part B of the projectile is notched, as shown in Drawing, to secure additional
grip of the sabot in conveying rotation to the projectile in a manner to be explained.
The inner flange P fits closely over the part C of the projectile, and forms with
the surrounding concave or saucer-shaped portion of the sabot an annular groove
or gas chamber E, into which the powder gases enter, so as to produce the
simultaneous spreading of the circumferential lip O, and of the lower lip or
flange P.
The action of this projectile is as follows:-The gun being discharged the sabot D
is driven forward upon the projectile, the forward part K wedging outward upon
the conical surface B until windage is filled, or a slight impression of the rifling is
received upon it, while the other and expansible portion O is expanded freely into
the rifling by the direct action of the gases. The threaded part C and flange P
prevent the sabot from springing or being thrust backward, while at the same time
the downward pressure of the gases in the direction of the arrow upon the flange
or lower lip makes it a practical and efficient gas check, and efficiently prevents

page_text: the entrance of gas under the sabot, and between it and the iron body of the
projectile.
Although experience has proved that this form of sabot will grip the projectile by
friction alone with sufficient force to rotate the projectile without material lost
motion, yet, as an additional precaution to this end, the base of the projectile may
be notched, as shown at N in the Drawings, so that when the sabot is crowded upon
the base B it will be nipped at different points, and held against the rotative effect
of the rifling. These notches will also serve as channels for the
of the
suddenly compressed air behind the sabot.
The description of Figure II. corresponds in all respects with that of Figure I.,
except that the lower flange or lip P is not threaded, and is intended to slide for-
ward with the rest of the sabot; and when driven forward, as far as the shoulder of
B will admit, is then crimped into the circumferential notch N, thus securing the
sabot more firmly to the projectile.
Where the screw thread is used it is probable that the friction of the sabot, aided
by the fact that it is screwed "home" in the direction of the rifling, will effectually
prevent its independent rotation on the projectile, otherwise the notches N of the
base B or conical surface are deemed advisable.
Although it is preferred to use the screw thread, particularly in projectiles
of large calibre, yet it is probable that the downward pressure of gases upon the
lower or inner flange will be sufficient to sink it into any irregularities of
surface i provided for the purpose upon the base of the projectile in place of the
screw. In such cases as in Figures IV. and V. the sabot would be slightly forced
upon the projectile in its manufacture, the "bite" being secured by means of gas
pressure upon the flange P to retain the sabot in position upon the projectile during
its passage through the gun, and during flight. The side slip of the projectile is
prevented by the notched base or cone already described.
With a view to easing somewhat the action of the wedging portion K of these
sabots upon the rifling, they may be notched upon their exterior surface, as shown
at x in the various Drawings.
Whether or not the screw thread be used the tapered or conical part B of the
projectile may be notched circumferentially, as shown at i in Figures IV., V., VI.,
and XIV., and thus the sabot may be additionally secured to the projectile after
firing.
In Figure VI. the sabot will be seen to be slipped over an octagonal-shaped base,
which provides against its lateral motion on the shot.
Various other forms of sabots are shown, all of which, however, embrace the
fundamental principle of combining with the wedging portion of the sabot a lower
flange or lip (and most generally also an upper or outer lip), which shall operate as
a gas check in excluding the gas from its interior, and which also by its extent of
surface is capable of a more secure attachment to the projectile, which attachment
is likely by gas pressure to be more firın after the discharge than before it.
Figure VII. shows the lower flange P to be separate from the rest of the
sabot, which it holds in place against the base of the projectile, while the
octagonal extension V prevents lateral displacement. The inner lip is represented
by b.
In Figure VIII. the sabot is shown locked upon the projectile by means of the
slots L, and the inner projecting lugs or studs G.
In Figure IX. there is no upper flange to the sabot, and the extension C, instead
of being cylindrical, is tapered to the same angle as the part B. The object of
this will be apparent; as the sabot is driven forward by the discharge the part K is
expanded, and this compels the partial expansion of the disc D. When the part C
of the projectile is cylindrical this causes a separation of the lower or inner part
of the sabot from the projectile, thus allowing entrance to the gases of discharge.
It is the object of the lower lip or flange P to prevent this, as has been already
explained; but the same effect can be obtained by tapering the part C of the
projectile, so that the inner edge of the sabot shall always be as tight as the outer

page_text: flange K upon the projectile; and in Figure IX. this device is auxiliary to the
lower flange P. Lateral movement may be prevented by the points N on the base
of projectile.
In Figure X. the flange K wedges over a rounding surface B instead of a conical
one.
In Figure XI. the periphery of the sabot is provided with projections J intended.
to fit into the grooves of the gun in loading, while studs K may prevent independent
rotation.
In Figure XII. the part R consists of a ring of lead with projections J to fit
into the grooves in loading, and the expansion of the sabot D squeezes the lead
tightly out against the walls of the gun, thereby closing windage as securely as
desired. This form of sabot, as also Figure XI., would be suitable for English
rifled guns, which have but few rounded grooves into which the projections J could
fit, while other and finer auxiliary grooves could be cut in the guns, and be utilized
by the other parts of the sabot.
In Figure XIII. the sabot is divided into two parts, each with a different
function. The part D is a disc attached by a lower flange P and screw thread to
the base of the projectile. This disc may be of wrought iron.
The part K is a tapered ring of brass, which is let into the periphery of the
disc D, and fits over the base B of the projectile.
The gases of discharge are intended to flatten the disc D against the base B of
the projectile, driving before it the softer ring K, which thus wedged outward
into the rifling. The disc D being of wrought iron may cheapen the production.
Figure XIV. is a modification of the preceding Figure, and Figure XV. is a
modification of Figure XII.
Having now described the nature of the said Invention, and in what manner
the same is to be performed, I declare that I claim as the Invention communicated
to me by John Gazzam Butler as aforesaid,-
Firstly. The several improved sabots and the method of attachment to projectiles
for rifled ordnance, herein-before described and represented in Figures I. to XV. of
the annexed Drawings, as details of Invention based upon the original Patent for
projectiles and sabots, No. 1510, 1872, as herein set forth.
Secondly. I claim a wedging sabot having an internal lip P arranged upon a
threaded base of a projectile, as and for the purposes described and shown in
Figure 1 of the annexed Drawings.
Thirdly and especially. I claim in combination with an expansible ring or cir-
cumferential lip an inner expansible ring-shaped lip to sabots for projectiles, the
two rings acting in conjunction, yet independently of each other, as and for the
purposes set forth.
Fourthly. I claim in combination with single or double ring-lipped sabots, the
inner cone-faced wedge ring to ride upon a conical base edge of the projectile, and
thereby form a gas-tight attachment, as set forth.
Fifthly. I claim in combination with double-lipped expansible rings, the ring
wedge as part of same or detachable therefrom as described, and as shown in the
annexed Drawings.
Sixthly. I claim the employment of double-lipped rings and ring wedges as
sabots in combination with notched or serrated bases of projectiles, as herein set
forth for the purposes described.
Seventhly. I claim the application or employment of soft metal or other material
as a filling between the lipped sabot and the body of the projectile, said filling
being in ring or stud form, as in Figures XII. and XV., for the purposes set forth.
Eighthly. I claim the employment of double-lipped ring sabots having circum-
ferential notches or recesses in their outer surface of the outer lip or of the wedge,
or of both the outer lip and the wedge, whether the cone edge of the projectile base be
circumferentially notched or plain conical form, straight or rounded, as described.
Ninthly. I claim making the bases of projectiles of octagonal or equivalent,

page_text: shape, and the attachment of exteriorly notched wedge and lipped sabots thereto,
whereby the sabot causes the projectile to rotate, as herein set forth.
Tenthly. I claim the special inethod of fastening or locking a sabot to a projectile,
as described with reference to Figure VIII. of the annexed Drawings.
Eleventhly. I claim the employment of a separate expansible lip forming part
of the tightening nut P, Figure VII., or it may be a bolt head in combination
with a plain or a notched outer lip and a plain or notched wedge for preventing
passage of gas of explosion between ring centre b and the base of the projectile.
In witness whereof, I, the said John Barnard Pearse, have hereunto set my
hand and seal, this Thirteenth day of September, One thousand eight hundred
and seventy-seven.
JOHN BARNARD PEARSE. (LS)