Improvements in or connected with Screw Propellers and Ventilating Fans.
Year: 1893

page_text: Date of Application, 11th July, 1893
Complete Specification Left, 29th Jan., 1894-Accepted, 10th Mar., 1894
PROVISIONAL SPECIFICATION.
Improvements in or connected with Screw Propellers and
Ventilating Fans.
I, PATRICK YOUNG ALEXANDER, of The Experimental Works, Bath in the
County of Somerset, Gentleman do hereby declare the nature of this invention to
be as follows:-
-
Screw propellers hitherto constructed have been of considerable weight, thus
rendering them most unsuitable where light machinery is required. By the
employment of screw propellers as hereinafter described, much weight will be
reduced or saved, whilst at the same time the said propellers may be adjusted in
pitch to any required degree. According to my invention I construct the frame-
work of the propeller in a Z like form, the connecting portion of the frame being
slightly twisted. The two extremities of the frame are connected together by a
cord or other suitable means, and the axle of the propeller passes through and is
attached to the centres of the cord and the main frame. The spaces at either end
between the frame and the cord are covered with any suitable flexible material, a
space being preferably left in the centre of the propeller. The length of the
framework or of the connecting cord may be varied by means of screw or other
adjustments, and in varying these lengths, the pitch of the screw may be adjusted
to any degree of fineness.
Screws constructed in the manner herein before described are particularly
applicable for ventilating and for aeronautical apparatus.
Dated this 11th day of July 1893.
BREWER & SON,
London and Leeds, Agents for Applicant.
COMPLETE SPECIFICATION.
Improvements in or connected with Screw Propellers and
Ventilating Fans.
I, PATRICK YOUNG ALEXANDER, of The Experimental Works, Bath, in the
County of Somerset, Gentleman, 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 :-
Screw propellers hitherto constructed have been of considerable weight, thus
rendering them most unsuitable where light machinery is required.
By the employment of screw propellers as hereinafter described, much weight
will be reduced or saved, whilst at the same time the said propellers may be
adjusted in pitch to any required degree.
In order that my invention may be fully understood, I will proceed to describe
same with reference to the accompanying drawings, in which similar letters refer to
like parts in all the figures.
Figs. 1 and 2 are respectively end elevation and side elevation of a screw.
propeller constructed according to my invention.
Figs. 3, 4 and 5 are detail views.
I construct the framework of the propeller of a Z like form, the connecting
portion A of the frame being slightly twisted. The two extremities B of the

page_text: frame are connected together by a stay C, or by other suitable means. The axle D
is connected at G to the centre of the main frame of the propeller, and the stay C
on its way from one extremity B to the other, passes by or through the axle D,
to which it may be attached if desired. The spaces at either end, between
the frame A B and the stay C are covered with any suitable flexible material E;
a space being preferably left near the axle D on each blade of the propeller.
The frame A B and the stay C therefore keep the material Etaut," and according
to the amount of twist given to the connecting portion A of the frame, so the
pitch of the screw is varied, at any distance from the boss.
Referring particularly to Figs. 3 and 4, a joint is shown which may suitably be
employed to allow of the twisting of the propeller to the required pitch. In this
arrangement the connecting portion A of the main frame is composed of two
tubes A and A². The larger tube A¹ is slotted at A. and a clamp H embraces
the tube at the slotted part.
When it is required to twist the ends B of the propeller, the clamp H is
loosened, thereby allowing the portion A2 of the frame to be twisted within the
portion A to any required degree, when the clamp H is fastened, thereby making
a rigid connection. The length of the framework may suitably be adjusted at
the above described joint, and the stay C may be shortened or lengthened at will,
by any suitable adjustment. It will be seen that by varying the length and twist
of the frame A B and of the stay C, the pitch of the screw may be adjusted to
any degree of fineness.
With particular reference to Fig. 5 a screw adjustment is indicated by the
employment of which, the pitch of the propeller may be altered at any point,
without changing the pitch of the tips.
The frames A and A2 are respectively provided with right and left hand
screw threads, and a tube F having right and left. hand screw threads therein,
engages with the screwed extremities of the frames A1 and A2. By turning the
tube F the length of the said frame is readily altered thus tightening or slackening
the stay C and producing the required result.
Propellers constructed in the manner hereinbefore described although capable of
general use, are particularly applicable for ventilating, and for use with aëronautical
apparatus.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. A screw propeller composed of a Z like frame, with the ends connected
by a stay, and having the spaces between the frame and the stay filled in with
flexible material, substantially as and for the purposes set forth.
2. The combination of the frame A B fitted with an adjustable joint, stay C,
flexible material E, and axle D, substantially as and for the purposes set forth.
3. The general arrangement, construction and combination of the various parts
forming the screw propellers substantially as and for the purposes set forth.
Dated this 20th day of January 1904.
BREWER & SON,
London and Leeds, Agents for Applicant.