Improvements in the Blades or Wings of Propellers, Fans, and similar Apparatus.
Year: 1887

page_text: Date of Application, 26th May, 1887
Complete Left, 24th Feb., 1888
Complete Accepted, 29th Mar., 1888
Improvements in the Blades or Wings of Propellers, Fans, and
similar Apparatus.
I, FRANCIS JAMES CROSSLEY of 32 Meetinghouse Lane, Peckham in the County of
Surrey, Cabinet Maker, do hereby declare the nature of this invention to be as
follows:-
The object of my invention is the formation of a surface which shall replace the
helicoidal or screw surface of which the blades or wings of propellers, fans and similar
apparatus generally form a part. The ordinary helicoidal surface is generated by a
line (generatrix) simultaneously rotating round and progressing along an axis which
in the case of propellers fans &c. is also the axis of the propeller &c.
The improved surface which is the subject of this invention and of which the blades
or wings of a propeller, fan &c., may consist wholly or in part is generated as
follows: In a circle having for its centre the point which represents the vertical
trace or end view of the axis and having a diameter about one quarter (more or less)
of the diameter of the propeller or similar apparatus, I take as many points as I desire
the propeller to have blades. As the centre of the circle represents the end view of
the axis so each of these points will represent the end view (vertical trace) of other
lines running in the same direction as the axis. The generating line of my improved
surface turns or pivots upon each of these points in succession but the end which is in
this point does not advance along the line of which that point is the end view.
Previous to commencing any movement for the formation of the surface, the genera-
ting line occupies the following position:-One end of it is in one of the points in the
circle above mentioned, the line is also in contact with the line of which the adjacent
point is the end view and it is prolonged beyond its point of contact with that line until
its other (and outer) end meets a plane which cuts the axis at a given distance from the
plane of the circle already mentioned and by the intersection of which plane with the
generating line the diameter or periphery of the propeller &c. is determined. It will
therefore be seen that the generating line is not in its first position at right angles to
the axis, but that the end which is in one of the points of the circle is in advance of
the intersecting plane just referred to and which the other (and outer) end of the
generating line touches. The inner end of the generating line is now turned or

page_text: pivoted on the point in the circle, but still remains in that point & does not advance
(as does the inner end of the generatrix of a helicoidal surface). The outer end of the
line does however advance and as the line moves round or pivots on the point-the
outer end of the line advances towards the plane in which is situated that point when
it becomes at right angles to the axis, and, passing thro' this plane it completes the
generation of the surface by finishing at an angle greater or less as regards the plane
from which it commenced its movement but inclined in the opposite direction.
In making the above movement the outer end of the generating line should
follow a curve which becomes more and more parallel to the axis the farther it
advances from the plane which it originally touched. The whole or part of the
surface generated as just described forms one blade or wing of a propeller, fan,
or similar apparatus and the surfaces for the other blades are formed in the same
manner from other points in the circle in accordance with the number of blades
required.
I sometimes turn the inner end of the generating line round a point in the axis
instead of in a circle surrounding that axis.
The generating line may be straight, curved or partly straight & partly curved.

page_text: COMPLETE SPECIFICATION.
Improvements in the Blades or Wings of Propellers, Fans, and
similar Apparatus.
I, FRANCIS JAMES CROSSLEY of 32 Meetinghouse Lane, Peckham in the County
of Surrey, Cabinet Maker, do hereby declare the nature of this invention and in
what manner the same is to he performed, to be particularly described and ascertained
in and by the following statement :-
The object of my invention is the formation of a surface which shall replace the
helicoidal or screw-surface of which the blades or wings of propellers, fans & similar
apparatus generally form a part. The helicoidal or screw-surface is generated by a
line (generatrix) simultaneously rotating round & progressing along an axis which is
also the axis of rotation of the propeller or other apparatus. The improved surface
which is the subject of this invention & of which the blades or wings of propellers,
fans &c. may consist wholly or in part may be generated as follows:-In a circle having a
diameter about one quarter (inore or less) that of the propeller or similar apparatus to be
constructed & having for its centre the point which represents the end view or vertical
trace of the axis of the apparatus, I take as many points (more or less equidistant from one
another) as I desire the apparatus to have blades or wings. As the centre of the circle
represents the end view of the axis so also will these points represent the end views
(vertical traces) of other lines running in the same direction as, but not necessarily
parallel to, the axis. The generating-line (generatrix) of my improved surface turns or
pivots upon each of these points in succession but the end which is in this point does
not advance along the line of which that point is the end view. When I say that the
generating-line turns on each point in succession, I mean, that having completed
the generating of so much of the surface as is required for one blade, it passes to an
adjacent point and repeats the operation & so on according to the number of blades
required. Previous to commencing any movement for the formation of the surface, the
generating-line occupies the following position, namely;-One end of it is in one of the
points in the circle above mentioned, the line is also in contact with the line of which the
adjacent point is the end view and it is prolonged beyond its point of contact with that
line until its other (and outer) end meets a plane which cuts the axis at any desired dis-
tance from the plane of the circle in a point in which is the inner end of the generating-
line. The point of contact of outer end of the generating-line with the plane which is at
the desired distance from the plane of the circle determines the diameter of the propeller
or other apparatus. It will therefore be seen that the generating-line is not in its
first position at right angles to the axis, but that the end which is in one of the points
of the circle is in advance of the intersecting plane above referred to and which the
other (and outer) end of the generating-line touches.
The inner end of the generating-line is now turned or pivoted on the point in the
circle, but still remains in that point and does not advance as does the inner end of the
generatrix of a helicoidal surface. The outer end of the generating-line does
however advance and as the line moves round or pivots on the point-the outer end

page_text: of the line advances towards the plane in which is situated that point, where it
becomes at right angles to the axis, and passing thro' this plane it completes the
generation of the surface by finishing at an angle greater or less (as regards the axis)
than that at which it commenced its movement, but inclined more or less in the
opposite direction; it may however complete its movement at or before arriving at
right angles to the axis.
In making the above movement I prefer that the outer end of the generating-line
should follow a curve which leaves the plane which the generating-line at first
touched, somewhat abruptly (that is, not tangentially thereto) and becomes more and
more parallel to the axis the further it advances from the plane, as I find by experi-
ment that a curve of this kind gives the most effective propelling surface. It may
however follow any curve whether it be of the-kind just described or one which is
tangential to the plane or one which changes its curvature at a constant or varying
ratio. The outer end may even (especially with some kinds of generating-lines) follow
a straight line at an angle to the plane, instead of a curve. Of course if the
generating-line remained straight the surface would in such a case be quite flat.
:
The generating-line itself may be any shape, for instance, it may be straight, curved
or partly straight or partly curved when curved or partly so, the amount or ratio of
curvature may be varied between the commencement & termination of the movement
of the generating-line, that is to say, it may commence straight or nearly so & finish
curved, or begin curved more or less & end straight or nearly so.
The whole or any part of a surface generated substantially as just described forms
one blade or wing of a propeller, fan or similar apparatus, & the surfaces for the other
blades are formed in a similar manner from other points in the circle, in accordance
with the number of blades required: the generating-line in each case being placed
for the commencement of its movement, in the position above described.
The blades or wings can be made of any suitable material: they may be of
cast, malleable or sheet metal & when of the latter material they could be hammered
or pressed into shape. The blades might be made altogether in one piece or each
blade separately or in pieces. They would be suitably joined to a boss or centre keyed
or otherwise attached to a shaft or spindle for revolving by pully or any other
suitable means the motive power being steam, gas, water, wind, electricity, manual
or anything that can conveniently be used. A ring or the like may be slipped over the
shaft, and rods, bars, or the like attached or screwed to it, the other ends of the rods or the
like being fastened to the blades so as to prevent their opening, springing or flattening
out & losing shape during revolution. The shaft would be supported in suitable
bearings and in any way found most convenient for the purpose for which the apparatus
is required. The bearings might, for instance, be attached to or form part of arms
fastened to a ring for fixing the apparatus in position for working or those arms might
be fastened to a surrounding cylinder or the like or the spindle might simply run in
properly supported bearings and be turned by a handle with or without multiplying
gear.
The accompanying drawing only shews one mode of generating a surface in accord-
ance with this invention. In this the generating-line is straight & pivots on a point
outside the axis & the outer end follows a curve not tangential to the plane from
which it commenced its movement & the surface is completed with the generating-line
at an angle in the opposite direction to that at which it commenced its movement.
Any of these particulars can of course be varied, for instance, the generating-line may
be other than straight, it may pivot on a point in the axis or more or less outside it,
than is shewn, or the outer end may follow a different course to that shewn or the surface
may be completed at or before it reaches the plane in which is the point of pivoting.
The generating of three blades is shewn but the same explanation will suffice for a
greater or less number of blades and I wish it to be distinctly understood that I
do not confine myself to the particular curves, inclinations, relative proportions or
positions or other details shewn, as they may be varied in many ways (some of which
I have already mentioned) without departing from the invention.
Fig. 1 is a plan. Fig. 2 a front view. & Fig. 3 a side view of a three-bladed

page_text: apparatus. A. A. is the axis. B. C. D. three points outside that axis. B'B', C'C',
and D D are side views and B2 B2, C3 C, & D2 D2 are plans of lines
running in the direction of the axis and of which the points B. C. & D. are
the end views. F. G is a side view & F¹ G¹ a plan of the plane cutting the axis
at the desired distance from B C & D & from which plane the movement of the
generating-line begins. F'G' & F³ G³ are respectively a side view & plan of the
plane of B. C. & D. The generating-line of blade Z is B. C. I. of blade Y it is CDI
& of blade X it is DBI. and the numbers 12. 3. 4. 5 &c. shew the successive posi-
tions of the outer end of the generating-lines from the commencement of their move-
ment at 1 to their termination at 13. The inner end of the respective generating-line
pivots or turns on the points B C&D, as the case may be. The blades may contain
more or less of the surface than is shewn ; in practice, I prefer to cut away a portion
of each blade about equal to B. 9. 13-C. 9. 13. and D 9 13.
For propelling or moving the medium in which the apparatus works, in the direction
of arrows W W&W' W', the blades should be revolved in the direction V V. For certain
purposes the curve followed by the outer end of the generating-line may be the
reverse of that shewn, that is to say, the surface may be such that it will present a
convex or quasi-convex face to the medium, somewhat as shown by the dotted
curve N. N. N. of Fig. 1, instead of a concave or quasi-concave one as shewn from 1
to 13 in blade X. Fig. 1.
Two or more apparatus may be put behind one another and revolved in the same or
different directions.
Any apparatus constructed in accordance with my invention may be wholly or partly
surrounded by or encased in, a cylinder, tube, ring, cone or the like, revolving with
the apparatus or remaining stationary or the tops of the blades may be turned over
or have pieces fastened to them to form parts of a surrounding cylinder or the like &
so prevent the radial discharge of the medium.
Having now particularly described & ascertained the nature of my said inven-
tion & in what manner the same may be performed, 1 declare that what I claim is :-
1. An improved surface for the blades or wings of propellers, fans, & similar
apparatus, generated substantially in the manner and manners hereinbefore described
& partly shewn in the accompanying drawings and any mere modification or imitation
of any or all of them.
2. Any surface which can be generated in the manner & manners substantially as
hereinbefore described whether actually so generated or not.
3. The manufacture & use of propellers, fans & similar apparatus having wings or
blades which are wholly or in part surfaces the same as or similar to those generated
substantially as hereinbefore described & partly shewn in the drawing & any mere
modification or imitation of any or all of them.
4. The combination & use of two or more apparatus constructed in accordance with
this invention & placed behind one another & revolved in the same or different direc-
tions, substantially as hereinbefore described, or any mere modification thereof.
5. In apparatus constructed in accordance with this invention the use and application
of tubes, cylinders, cones, rings or the like wholly or partly surrounding or encasing
the apparatus & revolving with them or not.
6. In apparatus constructed in accordance with this invention the turning over of
the tops of the blades to prevent the radial discharge of the medium in which the
apparatus works or the affixing thereto of pieces of metal or the like for the same
purpose.
Dated this 92nd dose of Wab 1000