Year: 1887

page_text: Date of Application, 4th Nov., 1887
Complete Left, 18th Feb, 1888
Complete Accepted, 23rd Mar., 1888
DECEDve
I, ALEXANDER VOGELSANG, of Brooklyn, State of New York, in the United States
of America, Engineer and Manufacturer, do hereby declare the nature of this invention
to be as follows:-
:―
This invention relates to four-bladed screw propellers.
Four-bladed screw propellers as hitherto used have generally been made with all
their blades of an uniform shape so that they entirely or almost coincide in side eleva-
tion and those parts thereof which in the sense of rotation are the leading points of
the blade are in the same plane and at the same distance from the axis. All the blades
of such propellers by reason of their form act on the water in a liko manner and this
tends to produce large waves. Each blade of a propeller stirs up the water to a con-
siderable extent and this together with the water rushing after it tends to form whirls,
the leading points of all the blades being in the same plane they will owing to the
rapid rotation of their ends cut into this agitated or churned water, no chance being
given the disturbed water to flow off. The consequence is that with such propellers
the resistance which the vessel in the water opposes to the movement becomes very
considerable. By the experiments of Froude Tiedemann and Isherwood it has been
found that this resistance of the whirls and waves produced by the propeller is from
about 20 to 45 per cent. above that which would be required if the vessel was towed
while the propeller remained motionless.
The object of my invention is to considerably reduce these whirls and waves and
consequently also the inconvenience and loss of movement attending them.
For this purpose the form of the blades of my improved propeller differs from that
of the blades of propellers as hitherto made in that the centre lines of two following
blades form spirals running in opposite directions from the centre of the propeller.
The edges of the blades do not coincide in a plane but cross in such a manner that
supposing the corresponding working faces of two successive blades to be placed one
upon the other, one side-edge of one blade starting from the boss at first comes out-
side the working face of the other blade and then comes within the same at a point

page_text: near its tip; on the other hand the other side-edge of the blade starting from the boss
comes at once within the working face of the other blade only leaving it at a point
near its tip and vice versa.
The parts of two successive blades which first act on the water, that is to say, those
parts of the blades which move in advance of the other parts in the direction of
rotation are situated at different distances from the boss in a plane which is normal to
the axis of the propeller shaft so that when the propeller rotates the foremost part of
one blade is near the tip thereof whilst the foremost part of the next blade is near the
middle portion of its entering edge; the tip of the latter blade is situated (with
regard to the tip of the first blade) on the opposite side of a plane normal to the axis
of the propeller shaft and passing through the middle of the blade at the point where
it joins the boss and vice versû. The blades diametrically opposite each other are
alike.
By my arrangement no blade can enter and work in the water stirred up and
flowing after a preceding blade and the whirling water is consequently allowed to flow
back.
One pair of the blades acts upon the water flowing into the screw from the
circumference whilst the other pair acts on the water flowing directly through
the propeller.
In consequence of the difference in the manner in which the blades work their
reciprocal action is ensured. The whirl movement is considerably reduced, a saving
in motive power is effected and the travelling of the ship is rendered much smoother
there being less shocks and consequently less vibration.
In reversing the direction of movement of the propeller the working order of
the two pairs of blades is reversed so that when moving the ship astern the same
advantages are obtained and the useful effect of the propeller will be therefore con-
siderably greater than that of propellers as hitherto used.
Dated the 4th day of November 1907
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Screw Propellers.
1, ALEXANDER VOGELSANG, of Brooklyn, State of New York, in the United States
of America, Engineer and Manufacturer, 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:
This invention relates to four-bladed screw propellers.
All the
Four-bladed screw propellers as hitherto used have generally been made with all
their blades of an uniform shape so that they entirely or almost coincide in side
clevation and those parts thereof which in the sense of rotation are the leading points
of the blade are in the same plane and at the same distance from the axis.
blades of such propellers by reason of their form act on the water in a like manner
and this tends to produce large waves. Each blade of a propeller stirs up the water
to a considerable extent and this, together with the water rushing after it, tends to
form whirls, the leading points of all the blades being in the same plane they will,
owing to the rapid rotation of the propeller, cut into this agitated or churned water,
the fluid on account of its adhesion showing a reluctance to leave the blades, a great
amount of dead water will always be between them, which must be carried round. The
consequence is that with such propellers the resistance which the vessel in the water
opposes to the movement becomes very considerable. By the experiments of Froude,
Tiedemann, Isherwood, and others it has been found that the resistance produced by
the aforementioned detrimental actions of the propeller amounts to about from 20 to
45 per cent. of the vessel's entire resistance.
The object of my invention is to considerably reduce these detrimental actions and
consequently also the inconvenience and loss of power attending them.
For this purpose the form of the blades of my improved propeller differs from that
of the blades of propellers as hitherto made in that the centre lines of two following
blades form portions of spirals running in opposite directions.
The edges of the blades do not coincide in a plane but cross in such a manner that,
supposing the corresponding working faces of two successive blades to be placed one
upon the other, one side-edge of one blade, starting from the boss, at first comes out-
side the working face of the other blade and then comes within the same at a point
near its tip; the other side-edge of the blade starting from the boss comes at once
within the working face of the other blade, only leaving it at a point near its tip and
cice versa.
The parts of two successive blades which first act on the water, that is to say, those
parts of the blades which move in advance of the other parts in the direction of
rotation are situated at different distances from the boss in a plane which is normal to
the axis of the propeller shaft, so that when the propeller rotates, the foremost part of
one blade is near the tip thereof whilst the foremost part of the next blade is
near the middle portion of its entering edge; the tip of the latter blade is situated
(with regard to the tip of the first blade) on the opposite side of a plane normal to the
axis of the propeller shaft and passing through the middle of the blade at the point

page_text: where it joins the boss and vice versa. The blades diametrically opposite each other
are alike.
In order to enable my invention to be fully understood I will describe how it can be
carried into practice by reference to the accompanying drawing in which
Figure 1 is a side elevation of a four-bladed screw-propeller constructed according
to my invention.
Figure 2 is a rear elevation drawn to an enlarged scale, illustrating the form and
arrangement of the blades.
Figure 3 is a plan, and
Figure 4 is a side clevation of the same.
Similar letters in all the figures indicate similar parts.
Referring to figure 1 it will be seen that the two blades A A placed diametrically
opposite each other are alike as are also the other two blades B. B.
In figures 2, 3 and 4 one of the blades B, in order to facilitate description is shown
in dotted lines placed over one of the blades A, as by this means it will be seen what
portion of the plane of one blade works within the plane of the other blade.
In figure 3 the working surface of the blade A is indicated by vertical parallel lines
whilst that of the blade B is indicated by horizontal parallel lines; the arrows without
feathers indicate the direction of motion of the propeller and the feathered arrows
that of the vessel.
As shown in figures 2 and 4 the centre lines, and y, y of the working
surfaces of the propeller blades form portions of spirals which, starting from the
same peripheral line of the boss, run in different directions. The edges of the blade A
are indicated by the letters a, b, c, d, e, f, g and the edges of the blade B by the
letters a, b, c¹, d¹, e', j", y¹. The line a, b, c, d represents that portion
of the edge of the blade A which in rotation moves in advance whilst the
line gerepresents the portion of the edge of the blade B which moves in
advance.
As shown in figures 2 and 4 the leading points d and f" of the two blades A and B
are situated at different distances from the boss and the part a, b, c of the edge of the
blade A is situated within and the part c, d, e outside the working face of the blade B.
The part of the blade A is situated outside, and the part f, e, within the working
face of the blade B. The result of this form and arrangement of the blades A and B
is that the two blades A A, figure 1, advance with their tips d whilst the other
blades B B advance with their middle parts situated between the boss and the tips of
the blades.
The point of the blade B is placed at the same distance from the boss as the
-point of the blade A; and the said points d' and d are, as shown in figures 3 and 4,
situated on opposite sides of a plane z, z which is normal to the axis of the propeller
and traverses the point a on the boss so that the tip d of the blade B does not act on
the water which is acted upon by the tip of the blade A. The same remark applies
to the intermediate parts and respectively.
The tip of the blade A having regard to the direction of forward movement of
the vessel is in advance of a point of the blade B situated between e¹ and at the
same distance from the boss and, on the other hand, the point of the blade B is in
advance of a point similarly situated between and con the blade A.
By my arrangement no blade can enter and work in the water stirred up and
rushing in after a preceding blade and the whirling water is consequently allowed to
flow back.
One pair A. A of the blades acts upon
eircumference whilst the other pair B, B
the propeller.
•
the water flowing into the screw from the
acts on the water flowing directly through
In consequence of the difference in the manner in which the blades work, their
reciprocal action is ensured. The whirl movement is considerably reduced, the blades
not carrying dead water round with them, a saving in motive power is offected and the
travelling of the ship is rendered much smoother, there being less shocks and conse-
quently less vibration..

page_text: In reversing the direction of movement of the propeller the working order of
the two pairs of blades is reversed so that when moving the ship astern the same
advantages are obtained and the useful effect of the propeller will be therefore con-
siderably greater than that of propellers as hitherto used.
The blades may be formed integral with the boss, or they may be made separate
therefrom and attached to the boss in any approved manner.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. A screw propeller having its blades formed and arranged in such a manner that
the parts thereof which, in working, move in advance are the tips of one pair
of blades and the middle portions of the other pair of blades the said parts being
situated at different distances from the boss, the edges of the blades crossing in such
a manner that, supposing the corresponding working faces of two successive blades to
be placed one upon the other, one side edge of one blade, starting from the boss,
at first comes outside the working face of the other blade, and then within the same
at a point near its tip; the other side edge of the blade, starting from the boss,
coming at once within the working face of the other blade and only leaving it at a
point near its tip, substantially as herein before described.
2. The improved propeller constructed and arranged to operate substantially as
herein before described and illustrated in the accompanying drawing.
G. F. REDFERN & Co.,
4, Sonth Street, Finsbury, London,
Agents for the Applicant,