A New or Improved Method of and Apparatus for Propulsion, specially applicable for the Propulsion of Torpedoes, Aerostats, and other Bodies Lacking in Stability.
Year: 1897

page_text: Date of Application, 31st Dec., 1897
Complete Specification Left, 31st Oct., 1898-Accepted, 31st Jan., 1899
A New or Improved Method of and Apparatus for Propulsion, specially
applicable for the Propulsion of Torpedoes, Aerostats, and other
Bodies Lacking in Stability.
I, WILLIAM THOMAS CARTER, of Orchard Villa, The Crescent, Maidenhead, in
the County of Berks, Gentleman, do hereby declare the nature of this invention
to be as follows;
-
My invention relates to a new or improved method of and apparatus for pro-
pulsion specially but not exclusively applicable for the propulsion of torpedoes,
erostats and other bodies lacking in stability, by means of which certain
advantages are obtained.
In order that the nature of my invention may be readily understood I shall
proceed to describe it with reference to the propulsion of torpedoes, that being a
field in which my invention is specially applicable.
It is well known that if it be attempted to propel a torpedo by means of a screw
propeller in the same way as one would propel a ship that the attempt would fail
on account of the want of stability of the torpedo itself. Thus let us assume that
we construct a torpedo with a single screw propeller driven by an ordinary motor,
the movable part of which is attached to the propeller shaft and the fixed part
of which is attached to the body or shell of the torpedo. It would be found, when
we attempted to drive the torpedo, that after a given speed of the motor had been
attained the power exerted by the motor instead of propelling the torpedo would
cause it to spin on its longitudinal or geometric axis and no useful result or only
a very small useful result would be obtained.
To surmount this difficulty two propellers have been employed revolving in
opposite directions. These propellers have been mounted upon concentric shafts
which latter have been connected together by bevel gearing or the like in such
manner that whereas the central shaft is driven with a given speed in one angular
direction, the outer or sleeve shaft is driven at an equal speed in the other direc-
tion, the propeller on the central shaft being necessarily placed behind the
propeller on the sleeve shaft and this for obvious mechanical reasons. ⚫
Such an arrangement would probably act efficiently if the two propellers were
acting under the same conditions; but the conditions vary, for whereas the lead-
ing propeller, namely that mounted on the sleeve shaft, is revolving in solid
water as it is termed, the following propeller, namely that mounted on the central
shaft, is revolving in broken water as it is termed, so that an equal effect is not
produced by the two propellers.
Attempts have been made to rectify this by making the following or rear pro-
peller of larger size so as to make up for the loss of efficiency due to its working
in broken water and it is possible that by this means the difficulty might be
successfully overcome provided the relative sizes of the two propellers could be
varied for all different rates of speed and for all other conditions of working. As

page_text: that cannot be done the device of merely making the two propellers of different
size is insufficient.
By means of my invention I have succeeded in overcoming the difficulty
referred to.
In carrying my invention into effect I also employ two propellers mounted on
concentric shafts but I cause the angular velocity or each shaft and therefore of
each propeller to be independent of that of the other shaft and propeller and
instead of causing the two propeller shafts to rotate with an equal angular velocity
or at angular velocities which have a fixed ratio the one to the other, I cause the
angular velocity of each to vary not in accordance with that of its neighbour but
in accordance with the work which it itself has to do or the resistance which it
itself has to overcome.
I accomplish this by means of what I shall for the purposes of this specification
teim a reaction device."
.
By the term reaction device I mean a device which shall fulfil the functions
of a motor and at the same time tulfil the functions of a coupling which shall
transmit energy from one moving body to another moving body in such manner
that the rate of movement of the one body shall bear no fixed ratio to the rate
of movement of the other body, all as will be hereinafter described.
I may construct my "reaction device " as follows. I take a motor of any con-
venient form, such for example as a rotary fluid pressure motor or an electro-
motor but instead of having one element of the said motor fixed and the other
element of the said motor movable, as in ordinary practice, I mount both elements
in such manner that each will move by mutual action and reaction in an opposite
direction and thus I cause the said motor to fulfil the functions of a variable ratio
coupling as I shall now proceed to describe more in detail.
T
For the purpose of such description I shall assume my motor to be an electro-
motor. In this case I mount both the armature and the field in such a manner
that they are both capable of rotary movement when it will be seen that the
mutual action and reaction between the said field and the armature respectively
will cause the armature to move in one angular direction and the field in the
opposite angular direction. To one of these elements, let us say to the armature,
I attach one of two concentric shafts for example the central shaft and to the
other element, let us say the field, I attach the other shaft, say the sleeve shaft.
By this means the two shafts rotate in opposite angular directions. Upon each
of these shafts I mount a propeller, the leading propeller upon the sleeve shaft
and the following propeller upon the central shaft.
It will now be understood that, the friction of each shaft in its bearings and of
each element of the motor being equal or approximately equal (as can be easily
obtained in practice), the speed of rotation of these two shafts will no longer bear
a fixed ratio to one another but that each will revolve at a speed directly pro-
portional to the resistance which it has to overcome. Thus the following
propeller will rotate at a higher speed on account of the broken water surrounding
it and the energy absorbed by each propeller will be the same, the rates of rotation
of the two propellers varying in ratio with variation of the working conditions.
It will be seen that my
reaction device" in addition to fulfilling its
ordinary functions as a motor fulfils the function of a variable speed ratio
coupling.
<<
The effect of my invention when employed in the case of a torpedo is that the
torpedo is driven in a straight line, in so far as the action of the propellers is con-
cerned, that spinning on its geometric axis is avoided and that the efficiency of
propulsion is increased.
I have hereinbefore described the nature of my invention in connection with
an electro motor but it is obvious that I may similarly employ a fluid pressure
motor by mounting its two elements in such a manner as to cause the said elements.
to move in opposite directions.
I desire it to be understood that I employ the term propulsion in its wide sense.

page_text: Thus, for example, I find my invention applicable not only for propelling vessels
through a fluid but for propelling fluids themselves as in the case of fans and
pumps.
Dated this 31st day of December 1897.
A New or Improved Method of and Apparatus for Propulsion, specially
applicable for the Propulsion of Torpedoes, Aerostats, and other
Bodies Lacking in Stability.
I, WILLIAM THOMAS CARTER, of Sherborne Villa, Norfolk Road, lately of
Orchard Villa, The Crescent, Maidenhead, in the County of Berks, Gentleman, 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 a new or improved method of and apparatus for pro-
pulsion specially but not exclusively applicable for the propulsion of torpedoes,
erostats and other bodies lacking in stability.
In order that the nature of my invention may be readily understood I shall
proceed to describe it with reference to the propulsion of torpedoes, that being a
field in which my invention is specially applicable.
It is well known, that if it be attempted to propel a torpedo by means of a
screw propeller in the same way as one would propel a ship, the attempt would
fail on account of the want of stability of the torpedo itself. Thus let us assume
that we have a torpedo with a single screw propeller driven by an ordinary motor,
the movable part of which is attached to the propeller shaft, and the fixed part
of which is attached to the body or shell of the torpedo. It would be found, when
we attempted to drive the torpedo, that after a given speed of the motor had been
attained the further power exerted by the motor, instead of propelling the
torpedo, would cause it to spin on its geometric axis, and no useful result, or only
a very small useful result, would be obtained from such further power.
To surmount this difficulty two propellers have been employed revolving in
opposite directions. These propellers have been mounted upon concentric shafts
which latter have been connected together by bevel gearing, or the like, in such
manner that, whereas the central shaft is driven with a given speed in one
angular direction, the outer or sleeve shaft is driven at an equal speed in the
other direction, the propeller on the central shaft being necessarily placed behind
the propeller on the sleeve shaft, and this for obvious mechanical reasons.
Such an arrangement would probably act efficiently if the two propellers were
working under the same conditions; but the conditions vary, for whereas the
leading propeller, namely that mounted on the sleeve shaft, is revolving in solid
water as it is termed, the following propeller, namely that mounted on the central
shaft, is revolving in broken water as it is termed, so that an equal effect is not
produced by the two propellers.
Attempts have been made to rectify this by making the following or rear
propeller of larger size, or of coarser pitch, so as to make up for the loss of
efficiency due to its working in broken water; and it is possible that by this means
the difficulty might be successfully overcome provided the relative sizes or pitches

page_text: of the two propellers could be varied for all different rates of speed, and for all
other variations of the conditions of working. As that cannot be done, the device
of merely making the two propellers of different size or pitch is insufficient.
By means of my invention however I have succeeded in overcoming the difficulty
referred to.
In carrying my invention into effect, I, also, employ two propellers mounted
on concentric shafts; but I cause the angular velocity of each shaft, and there-
fore of each propeller, to be not in any fixed ratio with that of the other shaft
and propeller; and instead of causing the two propeller shafts to rotate with an
equal angular velocity, or at angular velocities which have a fixed ratio the one to
the other, I cause the angular velocity of each to vary in accordance with the
work which it itself has to do, or the resistance which it itself has to overcome.
I accomplish this by means of what I shall for the purposes of this specification
term a
reaction device."
"
By the term reaction device" I mean a device which shall fulfil the functions
of a motor and at the same time fulfil in a sense the functions of a variable ratio
coupling which shall transmit energy between two moving bodies in such manner
that the rate of movement of the one body shall bear no fixed ratio to the rate
of movement of the other body, all as will be hereinafter described.
I construct my "reaction device" as follows I take a motor of any
convenient form, such for example as a rotary fluid pressure motor, or an electro-
motor, but instead of having one element of the said motor fixed and the other
element of the said motor movable, as in ordinary practice, I mount both elements
in such manner that cach will move by mutual reaction in an opposite direction
to the other; and thus I cause the said motor to fulfil the functions of a variable
ratio coupling as I shall now proceed to describe more in detail.
In order that my invention may be more readily understood I have appended
hereto a sheet of diagrams to illustrate the following description.
Of these drawings,
Figure I is a diagrammatic side elevation illustrating a propeller mounted on
a sleeve shaft and connected with one element of a motor.
Figure II is a diagrammatic side elevation of a propeller mounted on a central
shaft connected to the other element of a motor.
Figure III diagrammatically shows in part side elevation and part section the
parts represented respectively in Figures I and II arranged in operative
combination.
Figure IV diagrammatically illustrates an electro-motor driving propellers
which are employed, not for the propulsion of a body through a fluid, but for the
propulsion of a fluid itself. The diagram thus represents the application of my
invention for the purposes of a pump, ventilating fan or the like.
For the purposes of describing the principle of my invention as diagrammati-
cally illustrated in Figures I, II and III, I shall assume that the motor I am
using is an electro-motor: and I symbolically represent it in the said figures by
two discs 1 and 2, one of said discs, it matters not which, representing the
armature and the other the field. I mount both the armature and the field in
such manner that they are each capable of rotary movement: and it will be
readily understood that the mutual reaction between the said field and the arma-
ture will cause the field to move in one angular direction whilst the armature
is caused to move in the opposite angular direction. Let us assume for the
purposes of description that disc 1 represents the field and that disc 2 represents
the armature. To one of the elements of the motor, let us say to the field 1, I
attach one of two concentric shafts, for example the central shaft 3, and to the
other element, let us say the armature 2, I attach the other shaft, say the sleeve
shaft 4. By this means the two shafts 3 and 4 are caused to move in opposite
angular directions. Upon each of these shafts I mount a propeller, the leading
propeller 5 upon the sleeve shaft, and the rear or following propeller 6 upon the
central shaft.

page_text: It will now be understood that, the friction of each shaft in its bearings and.
of each element of the motor being equal or approximately equal (as can be easily
obtained in practice), the speed of rotation of the two shafts will no longer bear
a
fixed ratio to one another but each will adapt itself to the conditions under
which it is working. Thus the following propelier, on account of its rotating in
broken water, will rotate at a higher speed than the leading propeller which
rotates in solid water: but it will be seen that each propeller absorbs its due
proportion of energy whilst the rate of rotation of the two propellers will vary
with variation of the working conditions.
It will be seen that my "reaction device" in addition to fulfilling its ordinary
functions as a motor fulfils the function of a variable speed ratio coupling.
The effect of my invention when employed in the case of a torpedo is that the
torpedo is in so far as the action of the propellers is concerned, driven in a straight
line, that spinning on its geometric axis is avoided, and that the efficiency of
propulsion is increased.
The advantages of this invention are not however confined to the case of tor-
pedoes. Wherever screw propellers are arranged in tandem, and rotate in a fluid
the invention is applicable owing to the increased efficiency of propulsion obtained.
Thus it may be advantageously employed in the case of ordinary boats or vessels,
which owing to their being sufficiently ballasted have little or no tendency to spin
on their longitudinal axes. This absence of ballasting in the case of torpedoes
renders them particularly suitable as a field for the application of this invention
and it is for that reason that a torpedo has been selected for purposes of special
description in the specification. In the case of erostats there is the same difficulty
of spinning to be overcome and in so far as the present invention is concerned,
the problems to be dealt with are similar to those in torpedoes.
I have hereinbefore described the nature of my invention in connection with
an electro-motor, but it is obvious that I may similarly employ a fluid pressure
motor by mounting its two elements in such manner as to cause the said elements
to move in opposite directions. Fluid pressure motors in which both elements
rotate are sufficiently well known to render superfluous any further description
here. All that is necessary in order to apply them for the purposes of my inven-
tion is to attach each element to one of the concentric shafts either directly or by
suitable gearing or transmitting devices. Such means of attachment are well
known to all engineers.
I desire it to be understood that I employ the term propulsion in a wide sense.
Thus my invention is applicable not only for propelling vessels through a fluid
but for propelling fluids themselves as in the case of fans and pumps.
Such application to the propulsion of fluids is diagrammatically represented in
Figure IV and the devices shown in the said figure may represent those for
pumping or air propelling according to the fluid in which the propellers may be
immersed. In the said figure, 1 represents the field of the electro-motor and 2 the
armature; 3 the central shaft, 4 the sleeve shaft and 5, 6 the propellers mounted
on the sleeve and central shafts respectively. 7 is a bell-mouthed tube within
which the propellers rotate in opposite directions and through which the fluid is
propelled by the action of the said propellers as shown by the arrows.
It will be seen that in the application of my invention the resistance to be
overcome is that of a fluid; and it is only in the case of a fluid resistance that
the elasticity of working, necessary for the fulfilment of the functions of a
"reaction device" as contemplated by my invention, can be obtained.
I am aware that motors have been employed in which both elements have
The main distinction
rotated in opposite directions, and I lay no claim to such.
between such and my invention lies in the fact that in my invention the work
done by the two elements varies in ratio and that each dies its own share of the
work in accordance with the working conditions.
All the elements of mechanism herein before described are well known and there-
fore I do not describe them in detail. In so far as apparatus is concerned my

page_text: invention embraces not new forms of apparatus but a combination of known
mechanical elements producing a new effect.
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. The new or improved method of propulsion of a body through a fluid or of
a fluid itself substantially as set forth.
"
<
2. The reaction device" acting substantially as and for the purpose set forth.
3. The new or improved apparatus for the propulsion of a fluid or of a body
through a fluid which consists in the combination of a reaction device," two
concentric shafts driven in opposite directions by the elements of the said "reaction
device" and two propellers, each propeller being mounted upon one of said shafts
substantially as set forth.