IMPROVEMENTS IN "PNEUMATIC CANNON
Year: 1884

page_text: I WALLACE ALEXANDER BARTLETT of Washington in the District of Columbia
and United States of America, Patent Solicitor, do hereby declare the nature of
my Invention for IMPROVEMENTS IN "PNEUMATIC CANNON" 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 cannon from which the projectile is to be driven by
the force of an elastic gas generated or contained in some source of supply outside
the chamber of the gun.
As the gas I prefer to use is atmospheric air I have called the arm a pneumatic
cannon but it must be understood that steam, carbonic acid gas, or any other gas
which can be stored in a reservoir or flask may be used.
The cannon is specially intended to throw projectiles charged with dynamite,
nitro gelatine or similar high explosive, which cannot be safely fired from a
cannon by the force of gunpowder, owing to the liability of explosion in the gun
from the shock of the firing charge.
So far as I have experimented I find that with care in the arrangement and
manipulation of the yalves, pressure as great as 300 pounds or more per square
inch of sectional area of the bore may be used, and that with such pressure a
range of a mile or more can be attained.
The guns so far used are smooth bore, but I anticipate the use of rifled guns
and much greater pressure and ranges.
The essential features of this system of cannon are a gun tube preferably of
considerable length and breech loading, a flask or reservoir in which compressed
gas is stored and a supply pipe leading from the flask to the gun tube at or near
the breech.
Also an arrangement of valves by which the passage of gas to the gun can
be regulated and to save waste of the gas, it is desirable that the valve be closed
at the instant the projectile leaves the muzzle.
It is desirable that the full pressure of the gas in the flask be brought to bear
on the projectile. Therefore the supply pipe and its valves should be at least as
large as the bore of the gun, or where more than one supply pipe is used their
united area should equal or exceed that of the bore of the cannon.
•
To insure accuracy of fire the gas pressure in the flask should be kept at a fixed
maximum which can be regulated by a safety valve or blow off and after each

page_text: discharge gas should be pumped into or developed in the flask until it reaches
that maximum before the piece is again discharged. This can be done while a
projectile is being placed in the gun.
As the cannon is specially intended for use in fortifications and on ship board,
it will not be difficult with a suitable air compressor and pipe connection; to
maintain a quantity of stored up air in the flask. The larger the flask in
proportion to the capacity of the gun tube the greater will be the pressure brought
to bear on the projectile at the muzzle. A flask from ten to twenty times the
capacity of the gun tube will do well.
In the guns and modifications I have devised it must be understood that I
propose to avail myself of any mechanism for closing the breech and any
mechanism for training the gun now known to artillerists, and that except as
hereinafter claimed I have not devised special mechanism for such purposes I have
however devised means by which facility of training the gun is had, and perfect
communication between the reservoir or flask and the gun at the same time
maintained.
Also mechanism by which a light gun tube may be strengthened and supported;
also mechanism by which the valves may be regulated, controlled and operated,
also special constructions of valves intended for use with this cannon and for no
other purpose and finally some minor details of construction as hereinafter stated.
Reference is now made to the Drawing in which
> Figure 1 is a longitudinal section of a gun tube enclosed in the flask.
Figure 2 is a detail of same with adjusting device. Figure 3 is an enlarged
detail of tube adjusting device. Figure 4 is a rear view of similar detail.
Figure 5 is a cross section. Figure 6 is a sectional plan of one form of cut off
valve. Figure 7 is a sectional elevation of the same. Figure 8 is a side elevation
of cannon with pueumatic cut off. Figure 9 is a rear elevation partly in section.
The gun tube 1 is made to close at the breech by a common breech closing
device 9.
As this tube is long and not required to be of great strength compared
to guns which use powder it is necessary that it should be supported against
bending.
As shown in Figure 1 the tube 1 passes through the flask from end to end and
where it projects at the muzzle it may be supported by a brace or strut 2.
The flask 3 is shown to be in sections which are bolted together but the flask
may be made like a cylindrical steam boiler. When made of considerable length
the flask may be supported by a girder 4* to which a pivot 5 or trunnions 6 may
be applied. Either the flask or the tube may be lengthened by adding sections.
To straighten the gun tube inside the flask. I pass rods 11 through the shell of
the flask or through rings 12 which are interposed at the joints between the
sections. The rods 11 may bear on the gun tube or may be attached to a
collar 10 surrounding said tube.
Where the flask is made up of sections with the end flanges turned in, as at a
or turned out as at a¹, suitable packing as of rubber is interposed at the joints so
that the parts may be bolted together gas tight. When the rings 12 are
interposed the packing will be placed on each side of the rings.
Compressed air or gas is forced into the flask at any convenient point as by a
pipe connecting with the flask at the trunnion. This gas is permitted to enter
the gun tube near the breech at the proper time by a valve either inside the flask
as shown in Figure 1 or outside, and in a passage communicating both with the
flask and tube as shown in Figs. 8 and 9.
I have illustrated a slide valve but it is evident that any other form of valve
may be used. This valve 17 is in casing. 16 which is placed in pipe c c which
leads from the flask to the gun tube.
The valve 17 may be operated so as to open passage through pipe c by a pull
on hook 18 but is normally closed by spring b. Hook 19 may be engaged with
hook 18 by the proper movement of lever e towards the left and then a pull of
said lever to the right will open the valve.

page_text: When the valve is open the compressed air or gas will rush into the gun tube
from the flask and if a projectile is in the proper position in the tube and the
breech closed the projectile will be driven out at the muzzle.
In order to insure the closing of the valve at the proper instant I provide
an automatic mechanism by which the passage of the projectile will operate to
close the valve. To this end I connect a small pipe 13 with the gun tube near
the muzzle. This pipe leads back to the breech of the gun where there is a small
cylinder 14 having a piston and rod 15 which rod bears on the spring hook 19.
When the projectile passes the point where 'pipe 13 leads into the gun tube there
will be a puff of compressed air into the pipe 13. This will move the piston 15
in cylinder 14 and disengage hook 19 from hook 18 so that the spring b will close
the valve.
I do not limit myself to this particular mechanism for operating or closing the
valve, as it is evident that the pneumatic pressure may be made to trip the valve
in various ways, as will be readily understood.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is
1. A pneumatic or similar cannon in which the gas flask is made to surround
and support the gun tube and mechanism by which the same may be trained.
2. A pneumatic or similar cannon and its flask made in sections so that the
length and dimensions of each may be changed substantially as explained.
3. A pneumatic or similar cannon having an operating valve, and mechanism.
by which the passage of the projectile is caused to close the valve.
4. The method herein before described of controlling or regulating the movement
of the operating valve of a pneumatic cannon by the flight of the projectile.
Dated this 4th day of March 1884.