IMPROVEMENTS IN SCREW, PROPELLORS
Year: 1883

page_text: LETTERS PATENT to George Edward Vaughan, of 67 Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
SCREW, PROPELLORS," communicated to him from abroad by Charles + Henry
Mac Donald, of Paris, in the Republic of, France,
PROVISIONAL SPECIFICATION left by the, said, George. Edward Vaughan
at the Office of the Commissioners of Patents on the 19th March 1883...
$
.891 971
GEORGE EDWARD VAUGHAN, of 67, Chancery Lane, in the County ofv Middlesex,
Patent Agent, IMPROVEMENTS IN SCREW PROPELLORS," A cominunication to
me from abroad by Charles Henry Mac Donald, of Paris, in the Republic of
France,
bio t
This Invention relates to improvements in screw propellors of the cycloidal form
biplezairat
in the construction of which the following curves are applied-viz.
The curve of sines
173
Right cycloid
70
Prolate cycloid
Curtate cycloid
Epicycloid
Hypocycloid
Wave lines.
2$
curve
"
The present improvements consist in inclining the blades aft to a cycloid
or any of the above named variations of the same, the inclination being either a
complete curve, or any portion thereof. The effect of this arrangement is to
prevent the water from flying out in a radial direction, and to concentrate the
column of water thrown aft by the screw, thus reducing to a great extent the
"slip" inherent to propellors of this description as hitherto constructed. The fortn
of the improved propellor is represented in figures 1., 2. of the accompanying
drawing.
In order to reduce the friction of the blades, their sections are constructed with
the well known curve of sines as shewn in figure 3. The delineation of the cycloid
curve is shewn in figure 4
U

page_text: To secure the greatest advantage from this method of constructing screw pro-
pellors, they should be cast in gun metal or cast steel as thereby a much sharper
edge, a thinner section of blade, and a smoother surface can be obtained than when
cast iron is employed.
The moulding may be effected in a similar manner to the common propellors,
but instead of being "swept up "with a straight edge lath, the sweeping should be
effected by a lath having its edge shaped to the peculiar curve of the blade.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Edward Vaughan in the Great Seal Patent Office on the
24th August 1883.
GEORGE EDWARD VAUGHAN, of 67, Chancery Lane in the County of Middlesex,
Patent Agent
"IMPROVEMENTS IN SCREW PROPELLERS," a communication to me
from abroad by Charles Henry Mac Donald of Paris in the Republic of France,
This Invention relates to improvements in screw propellers of the cycloidal form
in the construction of which the following curves are applied-viz.:
M1
Hypocycloid
The present improvements consist in inclining the blades aft to a cycloid curve
or any of the above named variations of the same, the inclination being either a
complete curve or any portion thereof. The effect of this arrangement is to
prevent the water from flying out in a radial direction, and to concentrate the 2
column of water thrown aft by the screw, thus reducing to a great extent the
slip" inherent to propellers of this description as hitherto constructed. The form
of the. improved propeller is represented in figures 1., 2. of the accompanying
drawings.
"
In order to reduce the friction of the blades, their sections are constructed with a
the well known curve of sines as shewn in figure 3. The delineation of the cycloid
curve is shewn in figure 4.
To secure the greatest advantage from this method of constructing screw pro-
pellers, they should be cast in gun metal or cast steel as thereby a much sharper
edge, a thinner section of blade, and a smoother surface can be obtained than when
cast iron is employed.
The moulding may be effected in a similar manner to the common propellers,
but instead of being "swept up" with a straight edge lath, the sweeping should
be effected by a lath having its edge shaped to the peculiar curve of the blade.

page_text: Having now described the nature of the said Invention and the manner of
carrying the same into effect, I declare that
What I claim and desire to protect by Letters Patent, is:
The improvements in the construction of the known cycloidal screw propellers,
which consist in inclining the blades aft to a cycloid curve, or any of the above
enumerated variations of the same, the inclination being either a complete curve or
any portion thereof, substantially as, and for the purposes herein set forth and
shewn in the figures of the accompanying drawing.
In witness whereof, I, the said George Edward Vaughan have hereunto set my
band and seal, this twenty fourth day of August in the Year of Our Lord
One thousand Eight hundred and Eighty three.