IMPROVEMENTS IN SCREW PROPELLERS
Year: 1878

page_text: LETTERS PATENT to Herbert John Haddan, of the Firm of Herbert and
Company, Patent Agents, of 67, Strand, in the City of Westminster, Civil
Engineer, for the Invention of "IMPROVEMENTS IN SCREW PROPELLERS." A
communication from abroad by Henry Daniel Deane, of Brooklyn, King's
County, State of New York, United States of America.
COMPLETE SPECIFICATION filed by the said Herbert John Haddan at the
Office of the Commissioners of Patents on the 29th March 1878.
HERBERT JOHN HADDAN, of the Firm of Herbert and Company, Patent Agents,
of 67, Strand, in the City of Westminster, Civil Engineer.
"IMPROVEMENTS IN
SCREW PROPELLERS." A communication from abroad by Henry Daniel Deane, of
Brooklyn, King's County, State of New York, United States of America.
This Invention relates to that class of devices for propelling vessels known as
screw propellers, and in the present instance consists in a novel application to the
several blades of such propellers of a series of perforations, preferably conical in
form, as will herein-after be fully set forth and described.
In the Drawing, which forms an essential part of this Specification,-
Figure 1 is a front elevation of a screw propeller in which the Invention is fully
embodied, and Fig. 2 is a side elevation of the same, one blade being shown in
section.
The saine reference letters in both Figures will locate and point out corresponding
parts.
The Invention consists in forming in the body of the various blades of a screw
propeller a series of perforations, which may be of such size and form, and be so
located in the blades at such points as may be deemed best suited for the purpose.
In the Drawing A, B, C, D. represent the blades of a screw propeller, which are
cast and affixed to the shaft in the usual manner.

page_text: a designates the series of perforations which are formed therein where the blades
are cast, or they may be drilled therein by any of the usual mechanical processes.
The form I prefer for these perforations is conical, in the form of a truncated
cone or that of a tunnel or funnel shape, as illustrated in the Drawings. But the
form of these perforations may be varied without changing the character of the
Invention.
It will be seen that as the propeller revolves the wide inouth of the perforations
in each blade is presented to the water, a portion of which as the impact takes place
is forced into the perforations, and by the action of the inclined surface of the walls
of the perforations ejected from the openings to the rear of each blade, such ejection
of course taking place with considerable force and in such quantities that no
vacuuin is formed in the track of each blade. The formation of these cone-shaped
perforations increases the superficial area of the surface of each blade, giving cach
an additional hold on the water, increasing the propelling power.
:-
The Invention aims to accomplish the following objects :-
The provision of a screw propeller that shall increase the speed of the vessel and
decrease the amount of fuel consumed, and the Invention secures this desideratum
with the following advantages:-An increase of the superficial area of the propelling
surface without enlarging the size of the blades; this will be readily understood
as being due to the amount of surface gained by reason of the walls of the conical per-
forations, the direct action thereon by the water naturally increasing the propelling
power or action of the blade as it impinges on the water. As the blade revolves
the water that is forcibly ejected through the base of the conical perforations in
cach blade forms powerful jets or columns of water which are met by each suc-
ceeding advancing blade; in fine, this action of the perforations on the water is
simply forming what in the use of the ordinary propeller would be back water into
a strong current, which is always moving in a reverse direction towards and
impinging on the various blades of the propeller, thus giving them the increased
resistance sought for.
In the use of the common propeller it is a well settled fact that a vacuum forms
behind each of the blades, remaining as long as the blade moves in the water; this
results in decreasing the propelling power and in the constant jar of the machinery
and vessel, caused by the continual succession of blows as each blade strikes the
solid water that enters between the blades. By the use of the perforated blades
all objections of that nature are obviated.
It will also be found that these perforated blades will act as a regulator or
governor to the engines, which are quickly checked by reason of the resistance
offered to the blades, and this resistance naturally increases with the increase of the
number of revolutions of the propeller, which varies as the propeller is operating in
solid water or in a partial vacuum. The speed of the propeller will in this case be
reduced with an increase of driving power, inasmuch as the friction against the
surface of the walls of the various conical perforations becomes more intense, and
with an increase of speed the currents or columns of water ejected from the rear
of the blades run against the following blades with increased force. The resistance
thus met therefore serves to regulate or control the speed of the engines, they being
by the solid work made to work easily and steadily, preventing unnecessary wear,
strain, or breakage either of blades or engine.
It is a well-known fact that in the present use of screw propellers each blade
thereof is depriving its succeeding blade of its grip on the water, the blades working
as it were in foam instead of solid water, resulting in a great loss of power, therefore
the eradication of this difficulty is a desideratum long sought for, and it is now
fully accomplished by the use of the new perforated blades.
Furthermore, a very considerable saving of fuel will be effected by the use of the
perforated blades, not only by increasing the speed of the vessel and shortening
the voyages, but by economising the daily consumption of fuel while so doing.
In reversing the movement of the propeller an advantage is gained in power, as

page_text: the openings again act to prevent the vacuum, the wheel operating in solid water
instead of foam.
I claim as new, a screw propeller, the several blades of which are provided with
a series of perforations, such perforations being in the form of a cone, a truncated
3 conc, a tunnel, a funnel, or otherwise shaped, such perforated propeller blades
applied and operating as and for the purposes substantially as herein shown and
set forth.
In witness whereof, I, the said Herbert John Haddan, have hereunto set iny
hand and seal, this Twenty-ninth day of March, in the year of our Lord
1878
H. J. HADDAN. (L.S.)