Improvements in Screw. Propellers.
Year: 1891

page_text: Date of Application, 13th Jan., 1891
Complete Specification Left, 11th Mar., 1891-Accepted, 18th Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in Screw. Propellers.
We, CHARLES MYERS, of Phillips Park Road, Beswick, Manchester, in the
County Lancaster, Designer, and MATTHEW WELLS, of Hardman Street,
Deansgate, Manchester, aforesaid, Oil Merchant, do hereby declare the nature of
this invention to be as follows :-
:-
This invention relates to improvements in the screw propeller for steam ships
described in the Specification of Letters Patent No. 12730 of 1888 and is designed
with the object of obtaining greater speed or driving the vessel faster.
It consists essentially in constructing the front arm of the looped blade with the
striking edge tangential to or approximately tangential to the boss at the point of
contact with it and parallel or approximately parallel to the face of the boss and
with the rear edge of the back arm of the looped blade radial or approximately
radial to the centre of the shaft and extending to a considerable degree beyond
the face of the boss the pitch of the blade being increased at the back so as to be
greater than at the front or forward edge.
In carrying out the invention instead of making each blade of the propeller
symetrical as shown in the Specification of our former Patent we prefer to make
each blade with the striking edge of the front arm of the loop approximately
straight and tangential to the hub or boss and nearly parallel to the vertical face of
the boss and so as not to overhang the face of the boss while the back arm we
make with the edge approximately radial to the centre of the shaft and over-
hanging the vertical face of the boss to a considerable extent. To give the required
curve to the blade the front arm of the loop will be made shorter than the back
arm, and the pitch of the screw will be gradually increased to the back of the
blade.
By thus making the front arm of the looped blade more erect a better grip of the
water is obtained at the point of contact and we consider that a gain in speed will
be the result.
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Screw Propellers.
We, CHARLES MYERS, of Phillips Park Road, Beswick, Manchester, in the
County of Lancaster, Designer, and MATTHEW WELLS, of Hardman Street,
Deansgate, Manchester, aforesaid, Oil Merchant, 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 the screw propeller formed with looped
blades helically disposed, described in the Specification of Letters Patent
No. 12,730, of 1888, and is designed with the object of obtaining greater speed
therefrom, or power of driving the vessel faster.
It consists essentially in constructing the front or forward arm of each looped
blade with the striking edge approximately straight and tangential to the boss at
the point of contact with it, and in a plane parallel or approximately parallel with
the face of the boss; and the back arm of each looped blade with the rear edge
radial or approximately radial to the centre of the boss, and inclined to the face of
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page_text: the boss, so as to overhang or extend to a considerable degree beyond it, the pitch
of the screw being increased towards the back so as to be greater than that nearer
to the front or forward edge.
It will be fully described with reference to the accompanying drawings.
Fig. 1, elevation.
Fig. 2, plan.
Fig. 3, sectional elevations.
Fig. 4, expanded view of one blade.
Fig. 5, elevation of a single blade with base for connecting it to the boss.
Instead of making each blade symmetrical, with the two arms thereof in the same
relative position to the boss, as shown in the Specification of the former Patent,
we make the front arm A, of the loop, with the striking edge a approximately
straight, and in a plane approximately tangential to the boss or hub C, at the point
where it touches it; and in side elevation this striking edge a is practically parallel
to the face of the hub C, so as not to overhang it at all. And we make the back
arm B of the looped blade with the rear edge b approximately radial to the centre
of the boss or hub C, and, as seen in side elevation, overhanging or extending
beyond the vertical face of the boss to a considerable degree.
h
The front arm A of the looped blade is thus made more erect than the back or
following arm B, and a better grip of the water is obtained at the point of
contact with the blade, and we consider that a considerable gain in speed will
result.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
1. A screw propeller blade, of the form of a severed loop, constructed with the
striking edge of the front or forward arm of the loop approximately tangential to
the hub or boss at its point of contact therewith, and parallel to the face of the
boss, and with the rear edge of the other arm of the loop approximately radial to
the centre of the boss, and inclined at a considerable degree to, and overhanging
its vertical face, substantially as described and shewn.
2. A screw propeller having the blades constructed and arranged substantially as
described and shewn.
Dated this 26th day of February 1891.
WM. P. THOMPSON & Co.,
Manchester, Liverpool, and London, Patent Agents.