Year: 1894

page_text: Date of Application, 6th Oct, 1894
Complete Specification Left, 6th Aug, 1895-Accepted, 21st Sept., 1895
I, The Honourable CHARLES ALGERNON PARSONS, of Heaton Works,
Newcastle-on-Tyne, in tho County of Durham, Engineer, do hereby declare the
nature of this invention to be as follows
-
My invention relates to screw propellers intended to be rotated at high rates of
speed, such as are attained when the steam turbine is utilized for marine
propulsion.
My object is to reduce the weight and thickness of the blades so as to minimise
resistance without reducing the available strength of the propeller.
My invention consists in giving the blades a forward inclination of such extent
as to cause the centrifugal force and the forward propelling thrust to oppose and
wholly or partly neutralize each other.
I have found it necessary in designing propellers of ordinary type to suit the
conditions of propulsion by steam turbine namely high rotative speed and great
water pressure, to thicken up the blades very considerably. This thickening of
the blades materially mereases the loss of power in the propeller, and in order to
obviate the necessity for such thickening give the blades a forward inclination
from the centre outwards
The blades may otherwise be of any ordinary form
When a propeller so formed is duiven at a high speed, the centrifugal force of
the metal of the blade tends to bend it towards a position perpendicular to the axis
of the screw shaft The water pressure on thrust of the propello on the water
tends to bend it ma toward dection, these forces act in opposition and may be
made to wholly or partially neutralize each other, and thus relieve the stress most
calculated to break the blade. The cross section of the metal of the blade may
thus be made much thinner and the efficiency of the propeller increased.
The propeller may have two or any desuable greater number of blades
As an example I may state that in a propeller of three feet diameter
utilizing 2000 horse power at 30 knots speed per hour and revolving at
2000 revolutions per minute, the tips of the blades may usefully be set forward
2 inches from the normal plane of the propeller
Dated this 5th day of October 1894.
MARKS & CLERK,
18 Southampton Buildings, London, W.C, and
13 Temple Street, Birmingham, Agents
5
COMPLETE SPECIFICATION.
Improvements in Screw Propellers
I, The Honotable CHARLES ALGERNON PARSONS, of Heaton Works,
Newcastle-on-Tyne, in the County of Durham, Engineer, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described an ascertained in and by the following statement
-
My invention relates to screw propellers intended to be rotated at high rates of
Improvements in Screw Propellers
I, The Honourable CHARLES ALGERNON PARSONS, of Heaton Works,
Newcastle-on-Tyne, in the County of Durham, Engineer, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described an ascertained in and by the following statement
-
My invention relates to screw propellers intended to be rotated at high rates of

page_text: speed, such
propulsion.
as are attained when the steam turbine is utilized for marine
My object is to reduce the weight and thickness of the blades so as to minimise
resistance without reducing the available strength of the propelleı.
My invention consists in giving the blades a forward inclination of such extent
as to cause the centrifugal force and the formal propelling thrust to oppose or
wholly or partly neutralize each other.
I have found it necessary in designing propellers of ordinary type to suit the
conditions of propulsion by steam turbine namely high rotative speed and great
water pressure, to thicken up the blades very considerably This thickening of
the blades materially increases the loss of power in the propeller, and in order to
obviate the necessity for such thickening I give the blades a forward inclination
from the centie outwards.
The blades may otherwise be of any ordinary form
When a propeller so formed is driven at a high speed, the centrifugal force of
the metal of the blade tends to bend it towards a position perpendicular to the axis
of the screw shaft. The water pressure or thrust of the piopeller on the water
tends to bend it in a forward direction: these forces act in opposition and may be
made to wholly or partially neutralize each other, and thus relieve the stress most
calculated to break the blade The cross section of the metal of the blade may
thus be made much thinner and the efficiency of the propeller increased.
The propeller may have two or any desuable greater number of blades
As an example I may state that in a propeller of three feet diameter
utilizing 2000 horse power at 30 knots speed per hour and revolving at
2000 revolutions per minute, the tips of the blades may usually be set forward
2nches from the normal plane of the propeller.
Refering to the accompanying drawings which illustrate one application of my
invention, A A are the propeller blades inclined forward, B is the propeller shaft
blades and C is the bottom of the vessel. The vessel is propelled forward in the
direction of the arrow.
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. A screw propeller for high speed of rotation in which the blades are given a
forward inclination substantially as herein before described and illustrated.
D
ليم
1
1002
MARKS & CLERK,
18 Southampton Buildings, London, W.C., and
13 Temple Street, Birmingham, Agents for the Applicant