IMPROVEMENTS IN OR APPLICABLE TO SCREW PROPELLORS
Year: 1884

page_text: I GEORGE FREDERICK ASKEW of 14 Cromwell Terrace, Galbraith Street, Isle
of Dogs, Poplar in the County of Middlesex, Engine Fitter, do hereby declare
the nature of said Invention for IMPROVEMENTS IN OR APPLICABLE TO SCREW
PROPELLORS to be as follows:-
The Invention has for its object improvements in or applicable to scrow pro-
pellors whereby the skin friction of the propellor in its passage through the
water is reduced or counteracted.
For this purpose I form along the leading edge of each blade of the propellor
a passage which communicates with a passage formed longitudinally through the
propellor shaft which longitudinal passage communicates with a radial passage
formed in the faces of the shaft coupling or in an enlargement formed on the
propellor shaft. This radial passage is in communication with a surrounding
chamber into which water, soap and water, or other liquid or air is forced by
any suitable apparatus.
The passage along the leading edge of each propellor blade is provided with a
longitudinal opening on one or both sides thereof of such form as to cause the
liquid or air issuing therefrom to pass across the entire driving face, or if desired
across both faces of the propellor blade in a contrary direction to the motion of the
propollor.
By these means I interpose between the propellor blade and the body of the
surrounding water a thin sheet of liquid or air moving across the face or faces of
the propellor blades whereby the friction of the propellor in passing through the
water is reduced or counteracted.
These longitudinal openings are in the form of narrow slits, the edges of which
are so shaped as to cause the water to issue therefrom in the direction desired.

page_text: GEORGE FREDERICK ASKEW of 14 Cromwell Terrace Galbraith Street Isle of
Dogs in the County of Middlesex, Engine Fittor, do hereby declare the nature
of my invention for IMPROVEMENTS IN OR APPLICABLE TO SCREW PROPELLERS
and in what manu e same is to be performed, to be particularly described
and ascertained in and by the following statement:-
My invention has for its object improvements in or applicable to screw pro-
pellers whereby the skin friction of the propeller in its passage through the
water is reduced or counteracted.
For this purpose I form along the leading edge of each blade of the propeller
a passage which communicates with a passage formed longitudinally through the 1
propeller shaft which longitudinal passage communicates with a radial passage
formed in the faces of the shaft coupling or in an enlargement formed to strengthen
the shaft at the part in which the radial passage is drilled. This radial passage is
in communication with a chamber surrounding that part of the shaft in which
it is formed and into which water soap and water or other fluid or air is forced
by pumps or other suitable apparatus.
The passage along the leading edge of each propeller blade is provided with a
longitudinal opening on one or both sides thereof, of such form as to cause the
liquid or air issuing therefrom to pass across the entire driveing face or if desired
across both faces of the propeller blade, in a contrary direction to the motion of the
propeller.
By these means I interpose between the propeller blade and the body of sur-
rounding water a thin sheet of liquid or air forced across the face or faces of the
propeller blades, whereby the skin friction of the propeller in passing through
the water is reduced or counteracted.
"
Referring to the accompanying drawings Fig. 1. is a longitudinal section through
the stern of a vessel which shows a propeller and shaft to which my invention is
applied, "a" is a chamber surrounding the coupling "b" and provided with two
stuffing boxes "c" "c" through which the propeller shaft passes. Water soap and
water or other fluid or air is forced into the chamber " α by a pump or other
suitable apparatus and passing through the radial passage "d" along the longi-
tudinal passage "e" into the passages "f" "f" formed along the edges of the
propeller blades it is forced across the faces of the said blades in the manner shewn
at Fig. 5.
The methods in which form the passages along the blades of the propeller are
indicated by Fig's. 2. 3. and 4.
In some cases I form the passage by means of a fitting peice "g" of suitable
form rivetted or otherwise attached to the edge of the propeller blade as shewn at
Fig. 2. In other cases I cast the passage in the propeller blade as shewn at Fig. 3.
In cases where I wish to cover both faces of the propeller blade with a sheet of
water or other liquid or air I form a passage along the edge of the blade of the
form shewn ab Fig. 4. In every case I form the said passages with a narrow
opening pointing backwards and of which the front edge overlaps the rear edge

page_text: in order that the streams of water or other liquid or air may be caused to issue
therefrom in the desired direction and may be forced across the blades of the
propeller. In some cases I form two or more passages of the form above described
one in the middle of the blade and one at the leading edge, this is more suitable
for very wide blades.
Haveing 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
.
1st The principle of covering the blades of a propeller with a sheet of water
soap and water or other fluid or air forced across the propeller blades in a contrary
direction to that of its motion, thereby reduceing or counteracting, the friction of
the propeller in passing through the water.
2nd The device of forming in each blade of the propeller one or more passages of
the forms shewn by Figs. 2. 3. and 4. and providing each of such passages with an
opening pointing backwards with the front edge of the opening overlapping tho
rear edge as shewn in section on Figs. 2. 3. and 4.
3rd The device of surrounding the coupling or an enlargement on the propeller
shaft with a chamber containing water soap and water or other liquid or air under
pressure, and of conveying the said water soap and water or other liquid or air
through a radial passage formed in the coupling of the propeller shaft or in an
enlargement thereon and through a longitudinal passage formed along the propeller
shaft communicating with the passages in the blades of the propeller.
Substantially as before mentioned and described.