IMPROVEMENTS IN APPA- RATUS FOR PROPELLING SHIPS OR VESSELS
Year: 1877

page_text: LETTERS PATENT to The Honorable Richard Clere Parsons, of Connaught Place,
in the County of Middlesex, for the Invention of "IMPROVEMENTS IN APPA-
RATUS FOR PROPELLING SHIPS OR VESSELS."
Sealed the 11th December 1877, and dated the 14th June 1877.
PROVISIONAL SPECIFICATION left by the said The Honorable Richard
Clere Parsons at the Office of the Commissioners of Patents on the 14th June
1877.
The Honorable RICHARD CLERE PARSONS, of Connaught Place, in the County
of Middlesex.. "IMPROVEMENTS IN APPARATUS FOR PROPELLING SHIPS OR VESSELS."
This Invention relates to the employment of a fan-shaped propeller in lieu of the
ordinary screw propeller, the object being to economise the power of the propelling
engines and increase the speed of the vessel through the water.
The propellor, which is a stern propellor, is mounted on the ordinary screw
propeller shaft in advance of the stern post, and it consists mainly of two concentric
cylinders, between which helical blades are fitted. In rear of this propeller is a
fixed case, corresponding in construction and in proportion with the propeller, but
with its blades reversed in position. The annular space in the propeller is open at
front to the water, and at rear it communicates with the annular space in the fixed
case.
In order to guide the water to the propeller the hull of the vessel is fitted at its
opposite sides with a pair of plates, segment shaped, in cross section. The rear ends
of these plates coincide with the inner cylinder of the propeller, and their forward
extremities diminish off to nothing on the sides of the ship. When rotary motion
is given to the propeller, it will draw in a large volume of water and discharge it in
the fixed case, the blades of which, acting as fixed guides, will destroy the rotary
motion imparted to the water, and cause it to flow out in a comparatively quiet
stream.
In order still further to reduce the agitation of the water discharged from the
propeller the fixed case is fitted with a conical extension rearwards, which cone may
be either fixed to the stern post or oscillate with the rudder.

page_text: In some cases it may be desirable to mount on the same shaft two propellers
similar to that above described, and to provide for the additional propeller a fixed
case filled with guide blades for arresting the rotary motion given to the water.
I would remark that, if desired, the fan may be enclosed in a casing having an
inlet at some point at or near the bottom of the vessel, so that in case the vessel
meets with a heavy sea and the propeller is raised out of the water, this casing may
form a passage to lead the water to the propeller, and thus prevent the occurence
of what is known as racing.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said The Honorable Richard Clere Parsons in the Great Seal Patent
Office on the 14th December 1877.
"
The Honorable RICHARD CLERE PARSONS, of Connaught Place, in the County
of Middlesex. "IMPROVEMENTS IN APPARATUS FOR PROPELLING SHIPS OR VESSELS."
The chief feature of novelty of this Invention consists in the use. of fixed, guide
blades, set astern of the propeller, and in a reverse position to the propeller blades,
which guide blades are for the purpose of converting the rotatory notion imparted
to the water by the propeller into a-linear motion in the opposite direction to which
the ship is moving, and thereby ensure a rapid delivery of the water from the
propeller. These fixed blades and also the propeller I fit, by preference, in a cylin-
drical or semi-cylindrical casing attached to the ship.
The curves of the propeller blades are hélices, which increase rapidly in pitch
from the leading edge to the following edge. The pitch of the leading edge is
designed so as to cut the water tangentially to its surface, and thereby to prevent-
the blades from beating the water as they enter it. The after part of the blades
receiving this water gradually produces a rotatory motion in it, and in this condition
delivers it to the guide blades.
The guide blades are also helices which increase rapidly in pitch from their leading
to their following edges. The pitch of the leading edge is also designed so as to
receive the water issuing from the propeller blades with a rotatory motion in a
direction tangential to the surface of the blade, and to gradually convert this
rotatory motion into a linear motion in the opposite direction to which the ship is
moving.
The angles and increase of pitch of the propeller and guide blades should, it will
be understood, vary to suit the special requirements of individual ships agreeably to
the rules which at present guide the engineer in designing propellers for ships of
different tonnage and mean speeds.
In the accompanying Drawing,
Fig. 1 shews in sectional elevation my improved propelling apparatus fitted to
the stern of a ship, the section being taken in the line of the axis of the propeller
shaft. Fig. 2 is a plan view of the same, the cylinder which contains the propeller
and fixed guide curves being in section.
Fig. 3 is an end elevation of the propelling apparatus looking at it from the
stern, and Fig. 4 is a transverse section looking at the propeller in the same
direction.
Fig. 5 is a side elevation of the stern end of a ship fitted with propelling apparatus

page_text: according to my Invention, and shewing a casing for guiding the water to the
propeller.
A is the propeller shaft to which is keyed the propellor B, formed with three
blades. The developement of these blades is shewn by the Diagram, Fig. 6, which
illustrates, by transverse sections taken respectively in the lines 1-1 and 2-2 of
Fig. 1, the gradual variation in the pitch of the propeller blades. C is a cylindrical
casing surrounding the propeller, and serving also to support the fixed guide blades
D, which extend from a conical fixed boss D¹ (forming virtually a continuation of
the boss of the propeller) to the casing. Of these guide blades I use by preference
four, two of which will stand in line with the rudder post E, as illustrated at
Figures 2 and 3. The developement of these blades at their circumference is
illustrated at diagram, Fig. 7, which shews a section of one of the blades taken in
the line 3, 3 of Fig. 3.
To prevent what is known as racing I fit the stern of the vessel, at either side
thereof, with a casing F which forms a virtual continuation forward of the upper
portion of the cylindrical casing C, the casing terininating at the lateral swell of the
hull. This casing F, which I prefer to extend down to about the line of the
propeller shaft, forms a kind of hood on either side of the vessel, its object being
to guide the water up to the propeller, prevent the indraft of air, and thus ensure
the propeller acting efficiently even though it should be lifted out of the water when
the ship is encountering a heavy sea.
I would here remark that the increased pitch which I am enabled to give to the.
propeller blades, owing to the utlizing of the rotatory motion of the water by the
fixed guide blades, enables me to reduce the speed of the engines without reducing
the speed of the ship. The pressure on the thrust block is also to a considerable
extent taken up or neutralized by the action of the blades.
Having now set forth the nature of my Invention of "Improvements in Apparatus
for Propelling Ships or Vessels," and explained the manner of carrying the saine
into effect, I wish it to be understood that under the above in part recited Letters
Patent, I claim the means above described for converting the rotary motion
imparted to the water by the propeller into a linear motion in the opposite direction
to which the ship is moving.
In witness whereof, I, Richard Clere Parsons, have hereunto set my hand
and seal, the Fourteenth day of December, in the year of our Lord One
thousand eight hundred and seventy-seven.