IMPROVEMENTS IN SCREW PROPELLERS
Year: 1885

page_text: I, JULES ALBERT BERLY, Civil Engineer and Electrician of N° 3 Deronda Road
Herne Hill London S.E. do hereby declare the nature of my invention for
IMPROVEMENTS IN SCREW PROPELLERS to be as follows:-
The object of my invention is the construction of a compound screw propeller of
any given number of blades and the essential feature of which consists in having
one blade, or two diametrically opposed blades, or more than two blades of a
certain pitch whereas the other blades are of a different pitch. The pitch of the
blades themselves may be a varying instead of a given one. The screw thus
constructed, although applicable to rotary pumps or ventilating fans is most
particularly adapted to the propulsion of ships.
If, for example, I consider a screw propeller with four equidistant blades 1. 2. 3. 4.
the two diametrically opposed blades 1 and 3 will have a pitcli p and the two other
blades 2 and 4 also diametrically opposed will have a different pitch p¹ greater
or smaller than p according to the direction of the rotation and to the side from
which the propeller is looked at.
For instance if the blade 4 is on the starboard side and the propeller is reviewed
from the stern, its downward motion taking place from right to left the pitch p
of both this blade 4 and its opposite blade 2 is smaller than the pitch of blades
1 and 3.

page_text: The accompanying drawing represents three views or projections of a screw-
propeller with four blades and of the type which I call the "Monnier Compound
screw propeller."
Fig. 1 is an elevation showing the propeller as it is seen when viewed from
behind the rudder; the blade D is on the starboard side.
Fig. 2 is an horizontal projection of the propeller.
Fig. 3 is a profile of the propeller, seen from the starboard side.
The arrows indicate the direction of the rotation of the propeller when the ship
is going ahead.
The thread is right-handed.
The pitch of the blade B is equivalent to that of the blade A the measure of
the latter being shown in Fig. 2.
The pitch of the blade C is equivalent to that of the blade D the measure of the
latter being given in Fig. 3.
The pitch common to blades A and B is greater than the pitch common to
blades C and D.
The two blades of the same pitch are diametrically opposed but their respective
positions may be altered as well as the number of blades of the greater or of the
smaller pitch.. For instance a "Monnier Compound Propeller" of three blades
could be constructed with either one blade of the greater and one of the lesser
pitch or two blades of the greater and one of the lesser pitch. The same applies to
any propeller, whatever the number of blades with which they are provided.
Each blade of a "Monnier Compound Propeller," instead of being constructed
with a regular pitch, may be constructed with a varying or gradually increasing
one; and the blades may be inclined and also be made in various forms or shapes.
The slant faces of the blades, and particularly of the smaller pitch ones may be
on one side or on the other of the propeller.
'
'
The principle of the "Monnier Compound Propeller or Fan is based on the
two different effects which are simultaneously produced upon the liquid or gaseous

page_text: bodies surrounding the propeller or the fan by the combination of the two unequal
pitches with which the blades are separately provided.
FANS.
This system of propeller may also be used for the propulsion and the direction of
aerostats, or as a fan for ventilating, blowing, pumping or other purposes.
The number of blades, their pitch or shape, the respective number and position of
the blades of greater pitch and those of smaller pitch, the mode of fixing the
propeller or fan on its shaft or of securing the blades to the body may be altered
and varied according to requirements.
- 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:
The construction of propellers or fans in which one portion of the number of
blades are of a certain pitch and the remaining blades are of a different pitch, as
bereinbefore described and illustrated.