AN IMPROVEMENT IN PROPELLERS FOR VESSELS
Year: 1880

page_text: LETTERS PATENT to John Bonaventure Ward, of the City and County of
San Francisco, State of California, United States of America, Gentleman, for
the Invention of "AN IMPROVEMENT IN PROPELLERS FOR VESSELS."
COMPLETE SPECIFICATION filed by the said John Bonaventure Ward in
the Great Seal Patent Office on the 31st March 1880.
JOHN BONAVENTURE WARD, of the City and County of San Francisco, State
of California, United States of America, Gentleman. O AN IMPROVEMENT IN
PROPELLERS FOR VESSELS."
My Invention relates to certain improvements in propellers, and it consists in
the employment of a peculiarly formed elastic blade which is united to the hub,
upon which are formed flanges upon the arc of a circle so as to give the greatest
strength at this point. These blades are formed with a straight line face, and of a
substance of an elastic nature, the outer edge being in the arc of a circle so as to
increase the efficiency of the blade.
It further relates to certain details of construction in the matter of the
point of junction of the blade and hub flange, as is more fully described on the
accompanying Drawings, in which Figure 1 is a perspective view of my improved
propeller; Fig. 2 is an edge view of one of the blades; Fig. 3 is a side view of
the same; Fig. 4 shows the angle of the blades to one another.
The curved line faced propeller in its rotation breaks off the head of the water
column at the instant that it gives it the thrust, thus throwing the water into
inefficient foam up to the line of the edge of resistance.
The reaction of the water column upon the propeller, which is the cause of the
forward movement of the vessel, is not then effective for that purpose until its solid
end or head has passed through the space of foam before mentioned. This, with
the diminution of its effective force owing to the advance of the vessel, causes the
loss known as the "slip." Then this column of water meets at an angle the curved
line of the advancing propeller and gives the unpleasant intermittent jar to the
vessel, engine, and machinery.
These objections I have overcome by constructing my improved propeller in a
peculiar form, in which the blades are elastic. The hub A may be cast or wrought, as

page_text: desired, and is keyed on to the shaft B in the usual manner. Projecting from the hub
are the flanges C, as many separate flanges being formed as there are blades to the
propeller. The edges of these Hanges are formed in the arc of a circle, preferably,
in small propellers, of half the diameter of the blade D. Slots a are made in the
edges of the tanges, into which may be inserted the blades D and secured by bolts
or rivets, as shown. These flanges on the hub are turned to the angle required for
the blade.
When the hub and flanges are cast supplemental flanges C₁ of the same form as
the flanges C may be put on the hub on the opposite side of the blades from the
flange C. These supplemental flanges C' fit firmly against the blades and set on
the flange shoulder as shown, the screw bolts or rivets passing through the main
flange and blade, passing also through supplemental flange. A broad bearing is
thus given on both sides of the blades. Were it not for the supplemental flange,
which acts as a sort of washer, the bolt or rivet heads would strain on the blade
in backing the steamer and the heads might be torn off. Moreover if the
plates do not fit perfectly in setting up the screws the casting forming the
flange might crack. With the supplemental flange mado separate there is no
liability of this, since the face can be made to fit. The supplemental flange
however distributo this strain all over that part of the blade next to the main
flange. To preserve an even strain the flange-shoulder and supplemental flange
may be also slotted and keyed as shown in Fig. 2 when the propeller is of larger size.
Where cast iron is used this construction is much preferable to making the flange
thick and then cutting a deep slot in the center into which the blade could fit, since
by cutting off the rivet heads the supplemental flange is removed, and the blade is
then free to be taken off.
In making the hub and flanges of wrought iron however a slot may be made in
the center into which the blade may be put, the flanges then being double. A
sheet of copper or other soft metal may be inserted alongside of tho blade to equalizo
the pressure.
The blades are formed of elastic steel without any curves or hollows, a perfectly
flat surface being presented to the water. This straight line faced elastic propeller
blade in its rotation makes a clean cut in the resisting water column, thus avoiding
the slip.
The curved line propeller blade in ordinary use breaks the head of the resisting
water column, throwing it into foam and producing the slip. The straight line
faced elastic propeller makes a clean cut on the head of the resisting water column
and produces no foam. The reaction of the water column is instantaneous, continuous,
and effective, the propeller receiving the reactive effect of the resisting water column
on the same surface that gave the original thrust, hence there is no slip, but on
the contrary, since the reactivo effective effect of the elastic blade when its modulus
of elasticity is properly adjusted with regard to the resistance to be overcome will
cause the vessel to overrun the distance usually allowed to the pitch of the propeller.
As a wheel is a continuous lever so is this propeller a continuous even wedge or
inclined plane giving great efficiency.
The end of the blade is formed in the arc of a circle, as shown, for greater
efficiency. Being preferably of steel it may be made thin and light, and will not
be broken by any ordinary blow. Moreover it is much lighter and simpler of con-
struction than those which are cast.
The form and proportions shown give the maximum strength with minimum
weight, and the maximum effective straight line face of blade thrust with the
necessary strength of shank and grip. The edge resistance is very slight in
proportion to the area of blade, and the liability of breakage from strain or
concussion is lessened. In case any one of the blades becomes injured at any time
that single blade may be removed and replaced without disturbing the other blades
or removing the hub from the shaft, as is usually necessary with cast iron propellers.
This form combines all the advantages of straight and curved line propellers, while
the elastic blade avoids the jar on engine and machinery.
1

page_text: It will be seen that other methods may be employed to secure the blade to the
hub, such as casting the blades into the hub, which might be preferable in some
cases where economy is desired.
Having thus described my Invention, what I claim as new and desire to secure
by Letters Patent is,―
1. The plane-faced movable propeller blades D with their outer edges preferably
in the arc of a circle, and made of an elastic metallic substance, said blades being
adapted to be secured to the hub by means of flanges which are cast to the required
angle for the blades, substantially as and for the purposes herein described.
2. The straight line faced propeller blades D with their outer edges preferably
in the arc of a circle, and formed of sheet steel or other elastic metallic substance,
in combination with the flanges C cast with or forming part of the hub A, said
flanges being provided with slots a for holding the blades and cast on the angle
desired for the blade, whereby the blades may be made thin, elastic, and separate
from the cast or wrought hub, but may be easily attached to it or removed from it,
substantially as herein described.
3. The flanges C cast on the hub A and longer on one side than the other, the
longer side being the semi-radius of the blade, in combination with the removable
circular straight line faced blade D, wheroby a broad bearing is given to the
propeller blade at its most effective point, substantially as herein described.
4. In a propoller having blades formed separately from the hub I claim the
flange C provided with the slots a, said flanges being given the angle desired for
the blades, whereby the blades may be formed with straight line faces, and at the
same time be given the necessary angle to propel the vessel, substantially as herein
described.
5. In a propeller having blades formed separately from the hub and provided
with flanges having the angle desired to be given to the blades, and to which the
blades D are secured, I claim the supplemental flanges C¹ through which the
securing bolts pass, whereby the blades have broad bearings on both sides and
the removal of said blades is facilitated, substantially as herein described,
In witness whereof, I, the said John Bonaventure Ward, have hereunto set
my hand and seal, this Fourteenth day of February, A.D. 1880.
Witnesses,
FRANK A. BROOKS,
S. H. NOURSE.
JOHN BONAVENTURE WARD. (LS.)