Year: 1886

page_text: Date of Application, 29th Nov., 1886
Complete Left, 23rd Aug., 1887.
Complete Accepted, 21st Oct., 1887
I ALFRED THEODOR ZEISE of Ottensen, German Empire, Engineer do hereby
declare the nature of this invention to be as follows :-
This invention relates to improvements in screw propellers and the object of the
same is to equalize the pressure over the whole surface of the propeller wings.
Heretofore when calculating the effect of propelling screws only the outer parts of
the surface of the wings being most effective ones, could be taken into consideration
as in consequence of the diminishing circumferential velocity the effective pressure
is decreasing towards the axis during the rotation of the screw. Hence the main
effect of the screw has been calculable as dependent on those parts of the wing
surface outside of half the radius. The form or the size of the wing or the pitch are
co-ordinated to obtain the effect. In the first place the common mathematical screw
with rounded corners, in which the breadth of the wings at the outer circumference
is, in comparison with their breadth at the axis, of the same proportions as the way;
made during the rotation of the periphery of the screw, to the pitch, may be regarded
as representing that class of screw propellers, which obtain the effect required by the
area of the outside halves of the wings. The loss of work caused by this construction
is prevented in the other case-with regard to the pitch-in such a manner that the
wings are made equally broad everywhere, or they are shaped like a leaf towards the
outside. In such cases a pitch radially decreasing towards the nave has been applied
besides the variable peripherical pitch as by Griffith and afterwards by Hirsch;
thereby the effect falls to the outside halves of the wings, and moreover a quick
discharge of the whirling currents, caused by the decreased pressure, is obtained.
Besides these and other propeller screws as employed heretofore the new French
one, the Mangin propeller and the Thornycroft propeller-exist a large number of
different constructions; but they all show, that the useful effect depends on the
correct form and pitch of the outside halves of the wings.
Screw propellers constructed according to my invention possess in comparison with
the above mentioned constructions, important advantages in use attributable to the
effect of the inside halves of the wing surfaces arising from the peculiar construction
of the pitches. This effect is obtained in such a manner, that the pitch increases from

page_text: the periphery towards the nave, as to augment the pitch and consequently the
pressure, proportionally to the decreasing distance from the nave, in as much as the
circumferential velocity of the rotating screw is reduced towards the nave.
I preferably construct such propeller screws with increasing pitch towards the nave
in such a manner that supposing a special pivot-line for each wing; this pivot line is
placed between the outside end of the wing and the axis of the propeller parallel to
the latter. On such lines the wings are constructed as usually. The distance between
the axis of the propeller and the auxiliary construction line is variable and depends
on the desired degree of increased pitch. The nearer that the auxiliary line is placed
towards the screw axis, so much the less increases the augmentation of the pitch, for
each wing when joined to the nave shows, with regard to the screw axis, a pitch,
which increases gradually towards the axis and will be greatest at the auxiliary line.
This effect arises from the difference in length between the radius of the completed
screw and the radius at which each separate wing has been originally formed. The
pitch of such screw, as calculated from the screw axis, is shown in the following
formula x = DX in which is the pitch of the screw, D the diameter of such
d,
screw, y the pitch of each separate wing, d the diameter, at which the separate wings
have been formed.
By moulding such screw propeller a spindle, to which the modelling board or sleeker
is pivoted is placed exactly in the auxiliary line for moulding each wing separately.
Thereby a very exact transition from one pitch to another is secured and the desired
augmentation of pressure is obtained by correctly placing the auxiliary line.
The most important element with regard to the velocity of these screw propellers is
the pitch at the outside periphery; all other pitches down to the nave serve only to
compensate the loss of pressure caused by the decreasing circumferential velocity of
the wings towards, the nave. As in this construction the surface of the wings at the
outside periphery can be reduced considerably, the advantage resulting therefrom is
caused by the reduction of the resistance produced by friction and the water to be
removed. The formation of whirls at the nave as in the ordinary screws and the
downwards suction at the stern resulting therefrom in most ships is entirely prevented,
thus the useful effect of the propellers is augmented by the gain of force.
Dated the 29th day of November 1886.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London,
Agents for the Applicant.

page_text: ALFRED THEODOR ZEISE of Ottensen, German Empire, Engineer 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 improvements in screw propellers; and the object of the
same is to equalize the pressure over the whole surface of the propeller wings.
Heretofore when calculating the effect of propelling screws only the outer parts of
the surface of the wings being most effective ones, could be taken into consideration
as in consequence of the diminishing circumferential velocity the effective pressure is
decreasing towards the axis during the rotation of the screw. Hence the main effect
of the screw has been calculable as dependent on those parts of the wing surface out-
side of half the radius. The form or the size of the wing or the pitch are co-ordinated
to obtain the effect. In the first case the common mathematical screw with rounded
corners, in which the breadth of the wings at the outer circumference is, in comparison
with their breadth at the axis, of the same proportions as the way, made during the
rotation of the periphery of the screw, to the pitch, may be regarded as representing
that class of screw propellers, which obtain the effect required by the area of the
outside halves of the wings. The loss of work caused by this construction is prevented
in the other case-with regard to the pitch-in such a manner that the wings are
made equally broad everywhere, or they are shaped like a leaf towards the outside. In
such cases a
pitch radially decreasing towards the nave has been applied besides the
variable peripherical pitch as by Griffith and afterwards by Hirsch; thereby the effect
falls to the outside halves of the wings, and moreover a quick discharge of the whirling
currents, caused by the decreased pressure, is obtained.
Besides these and other propeller screws as employed heretofore the new French
one, the Mangin propeller and the Thornycroft propeller-exist a large number of
different constructions; but they all show, that the useful effect depends on the correct
form and pitch of the outside halves of the wings.
Screw propellers constructed according to my invention possess, in comparison with
the above mentioned constructions, important advantages in use attributable to the
effect of the inside halves of the wing surfaces arising from the peculiar construction
of the pitches. This effect is obtained in such a manner that the pitch increases from
the periphery towards the nave, as to augment the pitch and consequently the pressure,
proportionally to the decreasing distance from the nave in as much as the circum-
ferential velocity of the rotating screw is reduced towards the nave.
I preferably construct such propeller screws with increasing pitch towards the nave
in the manner illustrated in the accompanying drawing, in which Figure 1 is a
diagram showing the surface of a wing placed in the plane of the drawing and a
vertical section as well as three horizontal sections at the lines I, II and III of the
wing. Fig. 2 is a side elevation of one wing of the propeller connected with the nave,
and Figure 3 another diagram illustrating the reciprocal position of the three

page_text: sections I, II and III, supposing a special pivot-line m for each wing this pivot
line m is placed between the outside end of the wing and the axis M of the propeller
parallel to the latter. On such lines the wings are constructed as usually. The
distance between the axis of the propeller and the auxiliary construction line is variable
and depends on the desired degree of increased pitch. The nearer that the auxiliary
line is placed towards the screw axis, so much the less increases the augmentation of
the pitch, for each wing when joined to the nave shows, with regard to the screw axis,
a pitch, which increases gradually towards the axis and will be greatest at the auxiliary
line. This effect arises from the difference in length between the radius ac of the
completed screw and the radius b. c at which each separate wing has been originally
formed. The pitch of such screw, as calculated from the screw axis M, is shown in
D × y
the following formula, x =
in which is the pitch of the screw, D the
d
diameter of such screw y the pitch of each separate wing, & the diameter, at which the
separate wings have been formed.
By moulding such screw propeller a spindle, to which the modelling board or sleeker
is pivoted, is placed exactly in the auxiliary line for moulding each wing separately.
Thereby a very exact transition from one pitch to another is secured and the desired
augmentation of pressure is obtained by correctly placing the auxiliary line.
The most important element with regard to the velocity of these screw propellers is
the pitch at the outside periphery; all the other pitches down to the nave serve only
to compensate the loss of pressure caused by the decreasing circumferential velocity of
the wings towards the nave. As in this construction the surface of the wings at the
outside periphery can be reduced considerably, the advantage resulting therefrom
arises from the reduction of the resistance produced by friction and the water to be
removed. The formation of whirls (at the nave as in the ordinary screws and the
downwards suction at the stern) resulting therefrom in most ships is entirely
prevented, thus the useful effect of the propellers is augmented by the gain of
force.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is :—
1. The method of constructing propeller screws by forming each wing separately
by supposing a pivot line for each wing placed between the axis of the screw and the
outside end of the wing, substantially as described.
2. Propeller screws constructed according to the method as described in claim 1.
Dated the 23rd day of August 1887.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London,
Agents for the Applicant.