AN IMPROVED PROPELLER FOR STRAM NAVIGATION
Year: 1870

page_text: LETTERS PATENT to George White, of 68, Queen Street, Cheapside,
in the City of London, Patent Agent, for the Invention of "AN
IMPROVED PROPELLER FOR STRAM NAVIGATION."-A communication from
abroad by Mr. Wilhelm Hacker, Naval Engineer, of Pola, in the
Empire of Austria.
Sealed the 14th March 1871, and dated the 17th September 1870.
PROVISIONAL SPECIFICATION left by the said George White at the
Office of the Commissioners of Patents, with his Petition, on the
17th September 1870.
I, GEORGE WHITE, of 68, Queen Street, Cheapside, in the City of
London, Patent Agent, do hereby declare the nature of the said Inven-
tion for "AN IMPROVED PROPELLER FOR STEAM NAVIGATION,” (a communica-
tion to me from abroad by Mr. Wilhelm Hacker, Naval Engineer, of
Pola, in the Empire of Austria), to be as follows :-
This Invention has for its object an improved propeller for steam
navigation. It relates to screw propellers of that class in which a ring
united by helical arms to a boss carries on its periphery a number of

page_text: propelling blades, and the improvements are designed to render such
propellers more economical, efficient, and reliable in working than
heretofore.
The use of the helical arms as propelling surfaces in propellers of the
kind above referred to has been found to involve the absorption of an
amount of power disproportionate to the propelling effect produced
thereby.
Now according to this Invention instead of using the helical arms
within the ring as propelling surfaces they are constructed and arranged
with a finer pitch than that of the blades which are outside of the ring,
such difference of pitch being equivalent in extent to the amount of
the assumed slip, so that whilst the vessel is being propelled at full
speed through the water by the outer blades the central arms will
simply pass through the water without thereby influencing the progress
of the vessel. The helical arms are equal in number to the number of
propelling blades employed, and are by preference made what is known
as double fish-bellied in cross section, and with sharp edges. In order
to support and strengthen those portions of the blades which lap over or
extend beyond the sides of the ring, the ring is formed or provided with
side pieces or brackets, which are curved more or less so as to practically
extend the width of the ring without materially increasing its weight or
the resistance to the rotation of the propeller in the water. The pro-
pelling blades are formed with their peripheries cut off or curved
gradually, commencing at their leading corners, whose heights are
consequently proportionately lower than those of the following ends of
the blades.

page_text: the year of our Lord One thousand eight hundred and seventy, in
the thirty-fourth year of Her reign, did, for Herself, Her heirs and
successors, give and graut unto me, the said George White, Her special
licence that I, the said George White, my executors, administrators,
and assigns, or such others as I, the said George White, my executors,
administrators, and assigns, should at any time agree with, and no others
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "AN IMPROVED PROPELLER FOR
STEAM NAVIGATION," (a communication to me from abroad by Mr.
Wilhelm Hacker, Naval Engineer, of Pola, in the Empire of Austria),
upon the condition (amongst others) that I, the said George White, my
executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe- and
ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal
Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said George White, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof (that is to say) :-
:-
This Invention has for its object an improved propeller for steam
navigation. It relates to screw propellers of that class in which a ring
united by helical arms to a boss carries on its periphery a number of
propelling blades, and the improvements are designed to render such
propeller more economical, efficient, and reliable in working than
heretofore.
The use of the helical arms as propelling surfaces in propellers of the
kind above referred to has been found to involve the absorption of an
amount of power disproportionate to the propelling effect produced
thereby.
Now according to this Invention instead of using the helical arms
within the ring as propelling surfaces they are constructed and arranged
with a finer pitch than that of the blades which are outside of the ring,
such difference of pitch being equivalent in extent to the amount of the

page_text: assumed slip, so that whilst the vessel is being propelled at full speed
through the water by the outer blades the central arms will simply pass
through the water without thereby influencing the progress of the vessel.
The helical arms are equal in number to the number of propelling blades
employed, and are, by preference made what is known as double fish
bellied in cross section and with sharp edges. In order to support and
strengthen those portions of the blades which lap over or extend beyond
the sides of the ring the ring is formed or provided with side pieces or
brackets which are curved more or less so as to practically extend the
width of the ring without materially increasing its weight or the
resistance to the rotation of the propeller in the water. The propelling
blades are formed with their peripheries cut off or curved gradually,
commencing at their leading corners, whose heights are consequently
proportionately lower than those of the following ends of the blades.
Such being the nature of the said Invention, I will proceed to describe,
by reference to the accompanying Drawings, in what manner the same
is to be performed, premising that the same letters of reference are used
to denote corresponding parts in all the views.
Fig. 1 is a front elevation of the improved propeller; Fig. 2, a side
elevation of the same; Fig. 3 an elevation of the face of one of the
propelling blades; Fig. 4 a section of the ring and of one of the helical
arms connecting same to the central boss, and Fig. 5 a view of the
periphery of the ring with one of the propelling blades and its brackets.
The ring A of the propeller is (by preference) made plano-convex in
cross section as shewn in Fig. 4, and is formed with side pieces or
brackets B (Figs. 2 and 5). Upon the exterior of the ring A are four
similarly constructed equidistant helical propelling blades C which
project beyond the ring at both its sides and are there supported by the
side pieces or brackets B. The pieces or brackets B also serve practi-
cally to increase the width of the ring A, and thus more effectually to
separate the central column of water from that situated outside of the
ring, and they are made thinner at their edges so as to pass easily
through the water. The ring A is connected to the central boss D by
means of the helical arms E which are rounded on both faces and have
One of these arms
their edges sharpened as shewn in section at Fig. 4.
is situated immediately beneath each of the propelling blades C as shewn
in Figs 1 and 4, there being as many arms as there are propelling blades,

page_text: and care should be taken that the arms do not project beyond the sides of
the ring at their junction with it. The propeller revolves in the direction
shewn by the arrows. The propelling blades C are inclined slightly out
of the vertical line towards the rudder and their sides are sharpened at
the back. The helical arms E are not employed for propulsion, but are
arranged so as to offer the least possible resistance to the free passage of
the central water through the ring A, for which purpose they have a
finer pitch than the propelling blades C, the difference being equal in
amount to the assumed slip.
The improved propeller will enable a given speed of ship to be main-
tained with a considerable saving of fuel and with an almost total
absence of the vibration at the stern which results from the employ-
ment of propellers of other kinds at present ordinarily used. This
propeller will also cause much less pressure at the rudder, which having
its broadest part behind the interior of the ring where the water remains
comparatively undisturbed will therefore have to bear no other pressure
than that due to the speed of the ship, and will consequently be worked
very easily. When the vessel is under sail alone, and the screw shaft
disconnected, this propeller will cause very little resistance as the current
will act mainly on the propelling blades C, and will thereby easily keep
the propeller in motion, thus rendering the operation of hoisting the screw
unnecessary.
I would remark that the dimensions and number of the propelling
blades may be varied according to the acting surface required and the
dimensions of the openings in the dead wood of the vessel to which the
propeller is to be applied, the central boss may be of the form shewn
in the Drawings or may be made spherical or otherwise to suit circum-
stances, and the propeller may be either made in one piece or in separate
parts properly fitted together, as will be readily understood by engineers,
without departing from the nature of the Invention.
And having now described the nature of the said Invention, and in
what manner the same is to be performed, I desire to mention that I
know it has been previously proposed to construct screw propellers in
which rings carrying propelling blades have been united by helical arms
to a boss, and I lay no claim to such propellers when not constructed
with the improvements herein-before described, and I hereby declare
that what I claim as the Invention to be secured to me by the hercin-

page_text: before in part recited Letters Patent is, the improved propeller for steam
navigation herein-before described and illustrated in the accompanying
Sheet of Drawings or any mere modification thereof.
In witness whereof, I, the said George White, have hereunto set
my hand and seal, this Sixteenth day of March, in the year of {
our Lord One thousand eight hundred and seventy-one.
Witness,
LEWIS OLRICK.
GEO. WHITE. (L.S.)