Improvements in Screw Propellers.
Year: 1891

page_text: Date of Application, 3rd Feb., 1891-Accepted, 7th Mar., 1891
COMEDIE FEIATION.
Improvements in Screw Propellers.
We, BENJAMIN FRANKLIN SPARR and MILLARD FILLMORE SPARR, both
Architects and both of No. 77, Sip Avenue, Jersey City, in the County of Hudson
and State of New Jersey, 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 :-
The object of our invention is to provide a screw for the propulsion of vessels
that will increase the speed of the same and that will be applicable without
materially altering the construction of the vessel.
Our invention consists in the novel construction and arrangement of the screw
propeller as hereinafter particularly described and claimed.
Reference is to be had to the accompanying drawings, forming a part of this
Specification, in which similar figures of reference indicate corresponding parts in
all the views.
Figure 1 is a side elevation of part of a vessel, showing our improved screw
applied;
Figure 2 is a rear view of the screw; and
Figure 3 is a front view of the same.
10, is a shaft journaled in the stern of the vessel and receiving rotary motion
from the usual source of power located within the vessel.
A series of perpendicular blades 12, are arranged and secured to the shaft 10, in
convolutions following the curve of a screw, with a gradual taper from end to end
of the shaft. The blades are preferably set on the shaft with a pitch of about
45 degrees relatively to said shaft. By tapering the blades, the screw gradually
engages the water and acts with increasing force from its tapering to its enlarged
end, forcing the water in increasing volume against the backwater, thereby giving
the vessel great speed while reducing the jar or vibration imparted to vessels by the
propellers in common use.
In following the curve of a screw the blades 12 are so arranged and placed on the
shaft that the blades of one convolution intersect the spaces of the next preceding
convolution, as clearly shown in Figures 2 and 3, so that the screw is to a great
extent relieved of the friction and strain of the dead water, which is broken up and
passes directly back from one convolution to another instead of taking its course
through the curve of the screw.
The blade 12, is the last one of the screw, and we have found that when the
body of water leaves the screw it passes off diagonally or at a tangent from the
shaft, exerting its force almost entirely in one direction. The blades 14, engage
the water passing from the screw and distribute its force evenly against the
backwater.
These blades 14, are so placed on the shaft at the end as to revolve in the same
plane with the blade 12ª.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. A screw propeller, consisting of a series of perpendicular blades arranged
spirally on a shaft, substantially as shown and described.
2. A screw propeller, consisting of a series of perpendicular blades arranged
spirally on a shaft and tapering from end to end of said shaft, substantially as shown
and described.

page_text: 3. A screw propeller, consisting of a series of perpendicular blades arranged
spirally on a shaft, with the blades of one convolution set to intersect the spaces of
the next convolution, substantially as shown and described.
4. A screw propeller, consisting of a series of perpendicular blades arranged
spirally on a shaft, with the blades of one convolution set to intersect the spaces of 5
the next convolution, the blades having the same pitch to give a uniform line of
revolution, substantially as shown and described.
5. A screw propeller, consisting of a shaft having a series of spirally-arranged
and tapering blades, and provided with auxiliary blades at its rear end and in the
same plane with the last blade thereof, substantially as described, whereby provision
is made for causing the water passing from the screw to distribute its force evenly
against the back water, as set forth.
Dated Gifs or any of Fortry 1031.
B. F. SPARR.
M. F. SPARR.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.