Improvements in Projectiles for Rifled Fire-arms.
Year: 1894

page_text: Date of Application, 6th Apr., 1894
Complete Specification Left, 5th Jan., 1895-Accepted, 9th Feb., 1895
PROVISIONAL SPECIFICATION.
Improvements in Projectiles for Rifled Fire-arms.
I, WILLIAM SPOTTISWOODE TREVOR, V.C., of Members' Mansions,
36 Victoria Street, in the City of Westminster, Major-General, Retired, late
Royal Engineers, do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in projectiles for rifled fire-arms.
The object of my said invention is the construction of projectiles of such
improved forms and proportions that the retarding effect of atmospheric resistance
in their flight will be very materially less than that experienced with projectiles of
the types hitherto commonly employed. In the use of projectiles thus improved a
greatly increased range is obtained, as a consequence of the reduction of the
retarding effect aforesaid. I effect such reduction of retardation by preventing the
formation of a vacuum, or any sensible approach to one, in the wake of the projectile,
and by so proportioning the lengths of the head and tail thereof and the curvature
of their respective surfaces, that the force expended in cleaving a passage through
the air at the head shall be, in a large measure, if not fully, compensated by the
reaction of the inflowing air at the tail. Thus the only retarding influence on the
flight of a projectile that need remain is the frictional resistance of so much of its
surface as is in actual contact with the air through which it is passing.
According to my invention I construct an improved projectile the essential form
of which is a spindle having taper or conoidal ends with longitudinal flanges or ribs
thereon.
For example in one form of such improved projectile, constructed as a homo-
geneous and single solid, the so-called spindle constitutes the core or body of the
same and, considered geometrically, is composed of two conoidal segments or
frustums, generally of different lengths and curvatures, but with equal circular bases,
which abut on each other, or upon a disc or short cylinder interposed between them
to form the middle part of the spindle.
Flanges, which may be two or more in number, are formed on each of the
segments or frustums comprised in this spindle, and are arranged symmetrically on
its surface; they completely cover the spindle, save the cylindrical part thereof
when such is employed, except at their lines of intersection with one another, where
the outline of the tapered parts of the spindle is visible. The flanges are of such
cross-section that the surface of each end of the projectile is formed thereby into
alternate ridges and furrows, each ridge at one end having a furrow directly
opposite thereto, in the other end of the projectile. The curves of the furrows,
lengthwise of a projectile with conoidal ends, are practically indistinguishable from
parabolas. The crests of the ridges in the head of the projectile are portions of
ellipses. The crests of the ridges in the tail end of the projectile are preferably
parallel to the longitudinal axis and terminate in straight edges equal in length to
the radius of the said projectile.
The axial planes of the said flanges can be arranged to lie along the length of
the projectile in straight lines parallel to its longitudinal axis, or can be inclined
to the said axis, spirally, in correspondence with the twist of the rifling so as to
ninimise the friction of rotation in the flight.
The functions of the flanges are:
First, to make the projectile centre itself in the bore of the gun, and

page_text: The flanges must be sufficient in number and must possess the necessary solidity,
to fulfil these functions effectively.
Two diametrically-opposed flanges on each extremity of the projectile, each pair
arranged in a plane which is at right angles to that of the other pair, would give
four lines of contact with the bore at angular intervals of a quadrant and so would
But three
suffice to make the projectile practically concentric with the bore.
flanges on each extremity radiating from a common axis, that is to say the longi-
tudinal axis of the projectile, at angles of 120°, and alternating or breaking joint
evenly at the middle of the length of the projectile would effect the centring with
greater certainty than the two pairs of opposed flanges arranged as aforesaid, and
would not necessitate sensible reduction in the section and strength of the flanges,
which would consequently retain their efficiency for taking the twist of the rifling.
The length of the head or front part of an improved projectile constructed
according to my invention is directly proportional to the diameter multiplied by
some function of the intended muzzle velocity; the length of the tail or rear part
is directly proportional to the intended muzzle velocity and the diameter.
Dated this 6th day of April 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
Improvements in Projectiles for Rifled Fire-arms.
I, WILLIAM SPOTTISWOODE TREVOR, V.C. of Members' Mansions,
36 Victoria Street, in the City of Westminster, Major-General, Retired, late
Royal Engineers, do hereby declare the nature of this invention, and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
My invention relates to improvements in projectiles for rifled fire-arms.
The object of my said invention is the construction of projectiles of such improved
forms and proportions that the retarding effect of atmospheric resistance in their
flight will be very materially less than that experience with projectiles of the
types hitherto commonly employed. In the use of projectiles thus improved a
greatly increased range is obtained as a consequence of the reduction of the
retarding effect aforesaid. I obtain such reduction of retardation by preventing the
formation of a vacuum, or any sensible approach to one, in the wake of the projectile,
and by so proportioning the lengths of the head and tail portions thereof and the
curvature of their respective surfaces, that the force expended by the projectile in
cleaving passage through the air at the head shall to a certain extent be compen-
sated by the reaction of the inflowing air at the tail.
According to my invention the essential form of the improved projectile is that
of a spindle having taper or conoidal ends with longitudinal flanges or ribs thereon.
This so called spindle constitutes the core or body of the projectile and considered
geometrically is composed of two conoidal segments or frustums which may be of
different lengths and curvatures, but which have equal circular bases. These
circular bases may abut on each other, or upon a disc or short cylinder interposed
between them to form the middle part of the spindle, or may overlap each other.
The before-mentioned flanges or ribs, which may be two or more in number, are
arranged symmetrically on the surface of the spindle. These flanges are of such
cross-section that the surface of each end of the projectile is formed thereby into
alternate ridges and furrows.
The curves of these furrows considered lengthwise of the projectile are practically
indistinguishable from parabolas and conform to the curvature of the conoidal

page_text: ends of the spindle. I may form the extremities or sharp edges of the flanges at
the head of the projectile as portions of ellipses while the extremities or sharp edges
of the flanges at the tail of the projectile may be left angular that is to say as
straight edges equal in length to the radius of the projectile or both may be curved.
The axial planes of the said flanges can be arranged to lie along the length of the
projectile in straight lines parallel to its longitudinal axis but are preferably inclined
to the said axis spirally in correspondence with the twist of the rifling so as to
minimize the friction of rotation due to the flight of the projectile through the air.
The functions of the flanges are to make the projectile centre itself truly in the
bore of the gun, and to take the "bite" of the rifling. These flanges must there-
fore be sufficient in number and must also possess the necessary solidity to fulfil
these functions effectively.
In order that my said invention may be clearly understood and readily carried
into effect I will describe the same more fully with reference to the accompanying
drawings which shew various forms of any improved projectile.
All of the forms shewn are developments of the fundamental principle already set
forth riz. a spindle having sharp pointed extremities with flanges radiating
symmetrically from its surface, said flanges extending from end to end thereof with
a spiral twist corresponding with that of the rifling of the gun-barrel, and being
limited in the extent of their radial projection by an imaginary circumscribing and
concentric cylinder whose diameter is equal to that of the gun-barrel at the bottom
of the grooves. Both the head and the tail portion of the projectile can thus be
given the highest degree of sharpness compatible with the relation existing between
the weight of the projectile and its diameter and in this way the resistance of the
air to cleavage in front of the projectile as well as the retarding effects of the
air due to diminished pressure at the rear of the projectile, are considerably
reduced.
Diagrams A, B, and C are theoretical views illustrating the fundamental principle
of construction above mentioned. v, v designate the conoidal segments comprising
the ends of the spindle. The dotted lines w¹, w², w³, w represent the imaginary
concentric cylinder circumscribing the spindle and limiting the extent of the radial
projection of the flanges. Assuming there to be two ridges at each extremity of
the spindle these flanges would respectively extend spirally and approximately from
the points w¹ to and from 200 to w on one side of the projectile, and from
points w¹ to wo and from w° to wo on the other side thereof.
In Diagram A the bases x, a of the conoidal segments abut upon each other on a
central vertical line.
In Diagram B the bases a, a of the conoidal segments do not abut upon each
other but upon a short cylinder interposed between them.
It is
In Diagram C the bases a, a of the conoidal segments overlap each other.
on this last principle in particular that the various form of projectiles, indicated by
the subsequent figures, are founded.
Figures 1 to 10 illustrate a construction of the projectile in which there are two
sharp edges at each of its extremities; Figure 1 being a longitudinal elevation
with the sharp edges at the tail vertical; Figure 2 another longitudinal elevation
with the sharp edges at the head vertical; Figure 3 a front elevation; Figures 4,
5, 6, 7 transverse vertical sections taken respectively on the lines 1, 1 ; 2, 2; 3, 3;
4, 4 of Figure 1; Figures 8 and 9 longitudinal vertical sections taken respectively
on the lines 5, 5 and 6, 6 of Figure 2; and Figure 10 shews a development of the
surface of this projectile.
Figures 11 to 20 illustrate a modified construction of the projectile in which
there are three sharp edges at each of its extremities, Figure 11 being a
longitudinal elevation; Figure 12 a plan; Figure 13 a front elevation; Figures 14,
15, 16, 17 transverse vertical sections taken respectively on the lines 1, 1; 2, 2;
3, 3; 4, 4; of Figure 11; Figures 18 and 19 longitudinal vertical sections taken
respectively on the lines 5, 5 and 6, 6, of Figure 12 and Figure 20 shews a
development of the surface of this projectile.

page_text: Figures 21 to 30 illustrate a further modified construction of the projectile in
which there are four sharp edges at each of its extremities; Figure 21 being a
longitudinal elevation; Figure 22 another longitudinal elevation of the projectile
when turned an eighth of a revolution axially; Figure 23 a front elevation ;
Figures 24, 25, 26, 27 transverse vertical sections taken respectively on the
lines 2, 2; 3, 3: 4, 4; 5, 5; of Figure 21; Figures 28 and 29 longitudinal
vertical sections taken respectively on the lines 6, 6; and 7, 7, of Figure 22 and
Figure 30 shews a development of the surface of this projectile.
It should be stated that the longitudinal sections shewn at Figures 8, 18 and 28
are for the sake of clearness taken only through the head portion of the projectile
that is to say they terminate at the grip-band; it being understood that any
longitudinal section through the tail portion would be identical therewith if taken
in the same relative position and if said head and tail portions were of symmetrical
form.
Like letters of reference indicate similar parts in all the figures.
A is the core body or spindle which in every case is composed of two conoidal
segments arranged as indicated in Diagram C which I find to be the best arrange-
ment, a considerable increase in the effective length of both the head and tail
portions being thereby obtained without adding to the total length of the projectile
or in anywise impairing its efficiency. A is the head of the projectile and A² is
the tail. B are the flanges extending spirally around the core body or spindle A
and terminating at the head and tail thereof in sharp wedge-like extremities b.
The peripheral faces &¹ of these flauges constitute an endless zigzag grip-band and
gas check extending continuously around the projectile.
Referring first to Figures 1 to 10 where the projectile is shewn with two edges
at the head and two at the tail it will be seen that the outline of the hereinbefore
mentioned furrows at the ends of the projectile are not visible owing to the sides
of the flanges B blending insensibly where they meet the surface of the core A
and thus leaving no line to indicate their junction. These flanges are of a cuniform
character (see Figure 10) and their faces b' and sides 62 when seen in cross section
(Figures 4 to 7) are approximately circular arcs. The curvature of the circular
ares composing the faces are, from end to end of the projectile, of the same
radius as that of the bore of the gun-barrel, whilst the curvature of the circular
arcs composing the sides of the flanges decreases as said flanges advance from
the extremity of either conoidal segment and approach that place in the core
where the base of the said conoidal segment ends.
It will be seen that in this form of the projectile the two terminal edges b, b
lie diametrically in line with one another and thus present a sharp cutting edge at
each extremity of the projectile. As will be observed on reference to Figures 3
to 7 the cutting edge at one extremity of the projectile is not at right angles to the
cutting edge at the opposite extremity a slight angular deviation existing between
them owing to the helical arrangement of the flanges.
The extremities of the flanges at the head of the projectile are curved (Figure 2)
so as to avoid sharp angular projecting points which would be inconvenient when
handling the projectile and likely to interfere with the ready insertion thereof into
the breech of the gun. The extremities of the flanges at the tail of the projectile,
being enclosed in a cartridge case do not offer the above disadvantages and may
therefore be left straight as shewn. There is an obvious advantage in keeping the
tail of the projectile straight and as strong as possible to prevent distortion thereof
by the shock due to the discharge.
It will be apparent on reference to Figures 8, and 9, that every section of the
head portion or of the tail portion of the projectile taken in a plane parallel to
the axis of the projectile and at right angles to the radial plane connecting said
axis with the edge of the flanges, is lancet-shaped with the longitudinal central line
of the lanect situated in the above mentioned radial plane and the point of the said
lancet situated in the terminal cutting edge of the head (or of the tail) of the
projectile. The sides of the lancet-like sections end where they meet the flanges

page_text: or grip-band. The curvature of the lancet-like sections may for all practical
purposes be considered as circular segmental arcs. If desired these lancet-like
sections may consist of two equal semi-parabolas with their abscissæ in line and
forming the base and with the ordinate common to both and forming the central
longitudinal line. It should however be stated that when the bases of the lancet-
like sections bear a higher proportion to their length than 4:7 the use of circular
segmental curves will be attended with the disadvantage of producing a terminal
edge so blunt as to seriously interfere with the power of the projectile to overcome
atmospheric resistance.
Figures 11 to 20 shew a projectile with three sharp edges bbb at each extremity.
The furrows are clearly visible in this construction at the ends of the projectile
and it will be seen that each sharp edge at one extremity of the projectile has a
furrow directly opposite thereto at the other end. As seen at Figure 12 the sharp
edges radiate from the longitudinal axis of the core at angles of 12°. In other
respects the projectile is similar to that shewn in Figures 1 to 10 and therefore
needs no further description. By this construction the centring of the projectile
within the gun barrel can be effected with greater certainty than with two pairs of
flanges and as no sensible reduction is produced in their section and strength they
consequently retain their efficiency for taking the twist of the rifling.
Figures 21 to 30 shew a projectile with four sharp edges b, b, b, bat each
extremity said sharp edges radiating from the longitudinal axis of the core at
angles of 90° as seen at Figure 23. As in the preceding example each sharp edge
at one extremity of the projectile has a furrow directly opposite to it in the other
extremity.
It will be evident that the number of flanges with which the projectile is
provided may be increased beyond the number hereinbefore indicated but no
advantage will be obtained in employing more than four flanges; and in most
cases three will be found to be the most advantageous number to adopt.
Although I have shewn my improved projectile constructed on the fundamental
form illustrated in Diagram C, I may equally well and in an analogous manner
construct the projectiles on either of the other fundamental forms shewn at
Diagrams A and B.
It is not absolutely necessary to make both the head and the tail portions of
the projectile of the same length. In some cases it may be found advantageous
to make the head portion somewhat longer than the tail portion in order to com-
pensate for the rounding of the head. Otherwise such rounding would have the
effect of throwing the centre of gravity of the projectile behind the centre of its
axis thus giving to said projectile a tendency to turn over during its flight through
the air. In the case of a very long projectile with a low pitch of rifling it might
be found more advantageous to round the tail in correspondence with the head
instead of increasing the length of the head portion, but as already stated care
should be taken to avoid any material reduction in the strength and rigidity of
the flanges at the tail of the projectile.
When the projectile is adapted to be fired from heavy guns and is made of a
very hard metal, which would either be impenetrable by the lands of the rifling,
or, if penetrable, liable to injuriously affect the lands, the surface of the edges of
said flanges may be removed for a distance equal to the height of the lands and be
replaced by a strip or band composed of some comparatively soft metal.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. A projectile the essential form of which is a body core or spindle having
conoidal ends and formed with any suitable number of longitudinally disposed
flanges or ribs radiating symmetrically from the surface of said body core or
spindle and having a spiral twist adapted to the rifling of the gun-barrel
substantially as described and for the purpose specified.

page_text: 2. A projectile formed with a continuous or endless zigzag grip-band and gas
check adapted to engage with the grooving of the rifling in the gun-barrel for the
purpose specified.
3. A projectile having the characteristic features above claimed and constructed
in accordance with one or other of the forms described with reference to
Figures 1 to 10, or Figures 11 to 20, or Figures 21 to 30 of the accompanying
drawings and for the purpose specified.
Dated this 5th day of January 1805
W. S. TREVOR.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.