Improvement in Propellers for Steam Vessels.
Year: 1891

page_text: e of Application. 16th Mar., 1891-Accepted, 18th Apr., 1891
COMPLETE SPECIFICATION.
Improvement in Propellers for Steam Vessels.
I, ALFRED COOPER, Manufacturer, of Baltimore City, in the State of Maryland,
United States of America. 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 :-
This invention relates to an improved propeller for steam vessels, and is illustrated
in the accompanying drawings, in which,
Figure 1 represents a side elevation of the hull of a vessel provided with my
improvements;
Figure 2, a cross-section of the same on line 2-2 of Figure 1:
Figure 3, a side view of one of the propellers; and
Figure 4, another view of the propeller taken on line 4-4 of Figure 3.
The letter, A, designates the hull, which has at each side an outside cavity or
chamber,, for the revoluble propeller, C. The shaft, d, projects through the hull
side, and the propeller, C, is mounted thereon, so that the upper part of the
propeller will be housed in the chamber, The two propellers may be on one
shaft, or, as here shown, each may be on a different shaft. The shafts are provided
with cranks, e, or other equivalent means to be driven by engines.
The propellers, C, are an improved construction. They have in the present
instance four radial frames or pairs of arms, /, though obviously a greater or less
number may be used. Each pair of arms carries several blades or buckets, g.
These blades are arranged at an oblique angle to the radial frames, all the blades
The
being inclined in the saine direction, as shown in Figure 3, of the drawings.
arms, are broad on the side, 1, see Figure 3, and narrow or thin on the edges, "",
see Figure 4; by this arrangement the arms in revolving will readily pass through
the water edgewise with least resistance. The blades,, are substantially elliptical
in cross-section, or end elevation, as seen in Figure 3; they are thickest at the
centre and have a gradual taper therefrom toward each edge, g', which is com-
paratively thin and sharp. Thus formed the blades in their revoluble movement,
will readily enter the water, offering the least resistance, but as soon as they pass
below, they act effectively on the water to propel the vessel forward. The blades
are separated; an open space, h, being between one blade and the next one on the
same arm.
The bucket or blade, g, at the extremity of each pair of radial arms, j, serves as
a cross-piece to connect the two arms and at the same time serves as a propeller, as
will be obvious.
Attached to the walls of the hull, A, adjoining the outer side of each chamber, b,
is a downward-extending plate, j, which is partly-circular in shape and is of size to
completely cover the outer side of the propeller. The propeller shaft, d, has its
outer end, d, in a bearing, d, on said downward-extending plate, j.
As will be seen by reference to Figures 1 and 2, the joinder at, k, of the forward
portion of the partly circular plate, j, and hull, A, is flush or even with the side of
the hull, and owing to the convexity of the hull at, l, the lower portion, j', of the
partly-circular plate projects straight down below said point, k, where the parts
join. By this construction the flat side of the partly-circular plate is in parallel
line with the keel, m, of the hull and the said plate does not interfere with the
forward movement of the vessel; at the same time, as the vessel moves forward,
the water at the side of the hull has free access through the passage, n, below the
joinder, k, to the wheel or propeller, C.
This plate, j, it will be observed, serves as a guard or shield to protect the
propeller from injury and also prevents a lateral slippage of the water from the

page_text: propeller blades, g; the whole force of said blades on the water will therefore be
exerted to propel the vessel forward, and the advantage of the full action of the
propeller is in this manner obtained.
The construction, as described, of this propeller is well calculated to operate
effectively without counter-resistance. At the moment the blades on each arm have
done their effective work on the water the arm rises and enters the chamber, 4, and
is carried up over the shaft, and then comes down again with the diagonal blades
in the position to be most effective.
It will be observed that the propeller, constructed to offer the least resistance
and yet give the advantage of a full action of its blades, is thoroughly protected
by the partly-circular plate which also confines the water and prevents its lateral
or outward escape, and ensures that the force of the propeller is concentrated, as
previously explained.
The propellers and guard-plates may be located wherever they will operate most
effectively.
"
It will be evident that the propellers here shown will not (when the sea is rough
and the vessel rolling) get out of water, and therefore the objectionable “racing
of the wheel, under such circumstances, will be avoided.
It is obvious that a vessel may have, in addition to these two side propellers, an
ordinary stern propeller, whereby the propulsive force will be increased.
The propellers may be of wood or metal, and the parts may have any desired
proportion. Slight changes in the construction may be made without departing
from my invention.
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 1
claim is:-
1st. The combination, with the hull of a vessel having at each side a chamber, b:
of a shaft, d, having a crank midway between its ends, and the propeller-wheels
secured to said shaft and having inclined radial frames, 1. carrying rigid blades
arranged all in the same direction and at an oblique angle to the radial frames,
the upper part of each propeller-wheel being housed in one of the chambers,
substantially as specified.
2nd. The combination of the hull of a vessel having at each side a chamber, b,
within the hull; a downward-extending partly-circular plate. j, attached to the
hul on the outer side of each chamber a shaft having its ends in bearings on
said downward-extending plates; and propeller-wheels mounted on said shaft, each
wheel having its upper part housed in one of the chambers, and completely
covered on the outside by the said downward-extending plates, in the manner and
for the purpose set forth.
3rd. The combination of the hull of a vessel having at each side a chamber
within the hull-wall; a partly-circular plate with a flat surface, attached to the
hull and projecting downward from the outer side of each chamber, the lower
portion, of the said plate extending below the point, 4, of its joinder with the
hull and forming a front water passage, n; and propeller-wheels C, mounted so
that their lower portions will be entirely covered on the outer side by said plates,
as set forth.
4th. A propeller-wheel comprising a number of radial frames carrying rigid
blades arranged all in the same direction at an oblique angle to the radial frames,
said blades being substantially liptical in cross-section, that is, thickest at the
centre and tapered on opposite side to thin or sharp edges, as and for the purpose
set forth.
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Dated this Second day of March 1891
ALFRED COOPER.