Improvements in Propellers for Ships.
Year: 1889

page_text: Date of Application, 8th May, 1889
Complete Specification Left, 7th Feb, 1890-Accepted, 8th Mar., 1890
PROVISIONAL SPECIFICATION.
Improvements in Propellers for Ships.
I, HENRIC CHRISTIAN VOGT of No. 4 Aagade Copenhagen Denmark, Civil Engineer
and Naval Architect do hereby declare the nature of this invention to be as
follows
-
According to my invention the two diametrically opposite blades of the propeller
are rigidly connected to or formed in one with a central cylindrical part or axle which
can turn freely in a boss fixed on the propeller shaft. This propeller when rotated
will thus only be in continual equilibrium when the greater part of its acting area is
aft of the produced axis of symmetry through the aforesaid central axle If the two
blades are cast in one with the central axle, the boss must be made in halves or parts
to insert the propeller whereupon the parts are again united When such a propeller
is rotated in the following currents of the ship the pitch angles of the blades will con-
tinually change equally but in the opposite sense whereby the forces acting on the
blades will continually balance each other so as to permit the blades to be broadest
'near the circumference without causing injurious vibrations. Heavy strains will also
be avoided such as are usually caused by the pitching of the ship and the consequent
varying depth of immersion of the propeller. The vessel will also turn with greater
facility. When the engine is reversed the propeller will of itselt turn 180° to be in
equilibrium whereby it is as effective in driving astern as ahead. But if there be not
space enough for the propeller to turn 180 degrees in such manner, stops are
provided to limit the angle of turning when the engine is reversed. The boss wherein
the central axle of the propeller blades turns may be lined with lignum vitæ or the
like.
On account of the continual and very small opposite changes in the angles of the
pitch of the blades the propeller may be called a revolving fish-tail propeller.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Propellers for Ships.
I, HENRIC CHRISTIAN VOGT, .of No. 4, Angade, Copenhagen, Denmark, Civil
Engineer and Naval Architect, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and ascer
tained in and by the following statement.
毋
'
The two bladed propeller although the most efficient is not in general use owing to
the vibrations it produces, and in order to mitigate this defect the blades have to be
considerably tapered towards the tips, that is, to say reduced in area where they are
most effective.
Now according to my invention I produce a two bladed propeller which with the
acting area broadest near the circumference and having the most efficient shape,
produces no vibrations, while its diameter can be materially reduced because the most
effective area is near the circumference
The two diametrically opposite blades of my propeller are rigidly connected to or
formed in one with a central cylindrical part or blade axle which can turn freely in a
boss fixed on the propeller shaft The turning may be limited or not by a rigid or
yielding stop
These blades have their acting area aft of the axis of their axle to keep the propeller
in equilibrium when rotated.

page_text: t
The propeller shown in Figure 1ª from belund, and in Figure 1b from above and in
the enlarged vertical and horizontal sections through the boss Figure 2 and Figure 2b
has two opposite blades B ri_idly connected to or formed in one with a central
cylindrical part or blade axle A, which can turn freely in a boss N, or be limited in
turning by a yielding stop or laminated spring I, which is fixed in the boss N
having its flexible end inserted in the base of one of the blades B. The boss N
is secured to the propeller shatt S. To be in steady equilibrium when rotated,
this propeller must have its acting area aft of the produced aforesaid axle A If
the two blades are cast in one with the central axle, the boss will be made in
halves or parts, to insert the propeller.
When such a propeller is rotated in the currents of different velocities, following
or dragged by the ship, the pitch angles of the blades will constantly vary equally
in opposite sense indicated by the arrows, and as much as the springs I permit;
the forces acting on the blades will thus balance each other, wherefore the blade
area can be made broadest near the circumference, and thus the most economical
use is made of the diameter available without causing vibrations.
To increase the turning and manoeuvring power of warships, the spring I can
by means of the screw E, be disconnected from the propeller, the flexible end of
the spring only fitting into a recess in a knob on the base of the blade. Instead
of having the screw E at the end of the spring I it might be in a recess by the
side of the spring I; but the different modes of moving the said springs are too
numerous to be mentioned.
When the propeller is set free, it works quite as well as before, (unless the
pitching of the vessel should bring it out of the water), the wear and tear in the
boss is of course greater when the propeller is set free, but the co-t of new
linings in the boss, and on the central axle, 18 of small moment in comparison
with the enormous increase in manoeuvring power gained, for the blade which, at
the moment, goes against the direction of turning of the stern will yie'd, decreasing
its pitch and resistance to the turning the increase in pitch of the opposite blade
being just, as much, thus facilitating the turning When the engine is reversed,
the blade axle with the blades turns 180° immediately, to be in a new state of
equilibrium when revolving, and is thus as effective in driving astern as ahead.
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
other
1. A two bladed propeller in which the blades are rigidly connected with
by a b'ade axle which is able to move in; and enclosed by the boss like a shaft in a
bearing, thus enabling the thrusts on the blades to balance each other in the following
currents of a ship. whereby vibrations are avoided without tapering the blades sub-
stantially as set forth.
2. In a two bladed propeller of the character described the employment of a yielding
stop or spring for the purpose of making the oscillations of the propeller in the
following currents of a ship as élastic as possible with minimum of oscillations to
annihilate vibrations substantially as set forth.
3 The construction of two bladed propeller shown on the drawings.
Dated this Seventh day of February 1090.
or rebruary toyu.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.