Improvements in Apparatus for Aerial Navigation.
Year: 1894

page_text: Date of Application, 4th Dec., 1894-Accepted, 5th Jan., 1895
COMPLETE SPECIFICATION.
Improvements in Apparatus for Aerial Navigation.
1, NICHOLAS HERMANN BORGFELDT, Manufacturer, of 221, Rodney Street, in
the City of Brooklyn, Kings County, State of New York, United States of
America, 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 :-
My invention relates to apparatus for aerial navigation, and has for its object to
provide an apparatus which will navigate the air without the employment of
balloons or other equivalent means for securing buoyancy. That is to say, an
apparatus which is capable of being sustained and propelled in the air by the effort
of the operator, advantage being taken of the dynamic force of the winds to assist
such operation, as will more fully hereinafter appear. To this end my invention
consists in the construction hereinafter set forth, shewn in the accompanying
drawings, and more particularly pointed out in the claims, together with such
structures as may be justly considered equivalent structures in view of the state of
the prior art. In principle, my invention is based upon the principles governing
the flight of birds as at present understood, and presents for its chief advantage the
fact that the wings or sails hereinafter described are effective to co-operate with
any wind which may be blowing to move the apparatus both on the upward and on
the downward stroke of the driving mechanism, having therefore a duplex or
double action instead of being effective only during half the time, as at present
practised.
In the drawings, forming part hereof-
Figure 1 is a perspective view, partly broken away, showing one form of my
invention;
Figures 2 and 3 are end views showing the wings in different positions;
Figure 4 is a plan view of the frame or skeleton of the wings;
Figures 5 and 6 are fragmentary views of parts of the wings, showing details
thereof, as will be fully explained hereinafter;
Figure 7 is a sectional view on line 7-7 of Figure 4 showing the method of
pivoting the wing-rods to the centre shaft;
Figure 8 is a detail plan view of a section of the end of a wing showing a method
of attaching the fabric of the wing covering to the skeleton ;
Figure 9 is a side view of the apparatus resting on the ground;
Figure 10 is a detail perspective view of the underside of the centre of the
wings; and
Figure 11 shows a modified form of wing-rod;
Figure 12 is a modification of the supporting-framing.
In the drawings, A is a platform to which may be pivoted, or otherwise suitably
secured, suspending rods a a, the pivots being indicated at bb. These rods may
be cross braced in any suitable manner, as by braces c c. This platform and
its system of suspending rods may be variously constructed; for instance, the
platform A may be a narrow board to which a single pair of suspending rods is
connected, the whole being suspended by two or more rods connected to each one
of the pair of suspending rods, as shown in Fig. 12. The platform A forms a
support for the operator of the machine, and has mounted thereon guide-rods dd
on which work the tubes forming the connection for operating the wings.
These wings are secured to rock shafts D D and consist of outer sections B B and

page_text: .
inner sections C C lying on either side of the rock shaft D, and to these rock
shafts D the rods a a are pivoted so that the platform and its suspending rods are
supported from the rock shafts D D.
Referring particularly to Figure 4, I have shown in plan the skeleton for the
wings as made up, wing-rods e e extending from a centre shaft E fastened securely
to the rock shafts D D (as shown more clearly in Figure 8), and having their ends
bent backwards at e¹. Connecting rods e pivotally secured to the centre shaft E
serve to connect the centre shaft and the rock shafts D D.
I desire it particularly to be understood that both the wing-rods and the con-
necting rods may be secured to the centre shaft by pivoting or otherwise in any
manner that will allow the wings to have free motion on said centre shaft, but I
prefer to pivot them by hinge-loops, as shown in Figure 7. To form an additional
brace for the inner structure I attach longitudinally extending stiffening rods F
on the inner section C of the wings, and to these stiffening rods I connect the
tubes which form the connection for operating the wings from the platform.
The entire structure is trussed or braced by suitable guys d' d' d' d' d³ dª d² d³ d³ d¹º.
Cords extend from the extremities e¹ of the wing-rod e to the rock shaft D.
Similar cords g extend from the centre shaft E to the rock shaft D D and preferably
extend parallel to the wing-rods and the connecting rods, as shown. To the
skeleton thus formed is secured suitable fabric, such as a textile fabric, so as to
cover the same. The method of covering the wing is specifically illustrated in
Figure 8, wherein it will be seen that a separate covering is applied to the frame
formed by the outer end of the wing-rod e and the cord f, and the frame formed by
the inner end of the wing-rod e and the cord 9. These separate coverings overlap
each other slightly, as shown, in Figure 5, the rods of one section or frame over-
lapping the cord of the other section or frame, so that when the wing is moving in
one direction it will serve to retain the air on account of the flexible cord of one
section bearing against the overlapping rod of an adjacent section (Fig. 5), that is
to say, when the wing is swung, it will retain the air upon the downward movement
of the wing section, and upon the upward movement will allow the air to pass
freely through on account of the flexibility of the cords fand g, there being no stiff
overlapping rod for the cord to bear against when the wing section is receiving an
apward movement (see Fig. 6).
The detailed operation of my apparatus is as follows: I will suppose the
apparatus to be resting on its base on the ground or other support facing in the
direction from which the wind is blowing, and the wings to lie in the position
shown in Figure 1. The operator stands upon the base, and grasping the tubes !!
gives them a reciprocating up and down motion between the limits substantially
as shown in the two extreme positions in Figures 1 and 3. This will have the
effect of rocking the wings upon the shafts D D as axes. The sections B and C
of each wing are so proportioned as to produce about an equal effect, and it will
be observed that upon the down stroke of the tubes the inner sections C will be
brought down and the outer sections B will be raised. Thus, upon the down stroke
the sections C will serve to confine the air in the manner of a wing, while the air
is allowed to pass freely through the ascending outer sections B. Upon the up
stroke of the tubes the inner sections C will be raised, allowing the air to pass
freely therethrough, and the outer sections B will be brought down contining the
air. If this reciprocating mction of the tubes be rapid enough, the rapid beating
of the air being in all respects analogous to the flapping of a bird's wings, the
apparatus will rise in the air with more cr less rapidity, the dynamic force of the
wind and the force produced by flapping the wings, forming a couple, the resultant
of which will be the line of direction of the ascent of the apparatus.
When the apparatus has attained the desired elevation, the wings need not be
flapped so vigorously as was necessary when setting the apparatus in motion, but a
quick motion of the tubes of short amplitude assisted by the force of the wind
blowing, will be sufficient to produce motion through the air, the flexible bent ends
of the sections B serving to propel the apparatus forward.

page_text: It will be found that in order to get the most efficient results, advantage must
be taken of any wind which may be blowing, but the apparatus may be used for
slowly descending when there is no wind blowing.
When it is desired to descend, the wings may be held still, for instance, in the
position shown in Figure 2, and the dynamic force of the wind together with the
weight of the operator and apparatus will form a couple, the resultant of which
will be the line of direction of the descent. When the apparatus is in motion
through the air, slight changes of direction may be imparted to it by the operator
by swinging the rods a upon their pivots b, the guide-rods d being sufficiently
flexible to allow of such movement, when the wings will act with greater force on
one side of the centre of gravity than on the other, and the apparatus will be given
a tendency to turn.
The operator may also cause the apparatus to descend, by shifting the centre of
gravity forward; for instance, by stepping forward on the base or platform, thereby
inclining the front of the platform and wings downward, and descending on an
inclined plane.
When the apparatus is in rapid motion and it is desired to ascend, the operator
may facilitate the action by shifting the centre of gravity to incline the platform
and wings backward, and tilt the front upward.
When the changes of direction have been accomplished, the operator restores
the parts to their normal position and continues his course in a straight line.
It may sometimes be found desirable, if a strong wind is blowing, to provide a
base or bearing of large area for the apparatus in order that the apparatus may
stand firmly on the ground, and an effective start be made. For this purpose I
may provide extensions 61 61, as shown in Figures 1 and 9. I may also find it
desirable to cover the gap between the centre shaft and the ends of the wing
secti ons C C with a strip of fabric i, as shown in Figure 10. This strip may have
its edges free, in order that the air may be free to circulate during the upward
stroke of the centre shaft and be confined during the downward stroke.
In Figure 12 I have shown the wing-rods as curved or bent, in order to more
effectively confine the air, and in Figure 3 I have shown steps or handles ll near
the base for moving the tubes. These tubes may also be operated by using one or
both feet and throwing the weight of the body upon the tubes. These steps may
be made adjustable so that they may be turned out of the way when not required
for use.
I desire it to be expressly understood that I in no wise limit myself to the
construction and arrangement herein shown, as the device may be greatly varied
without departing from the spirit of my invention, the main feature of which is to
provide an apparatus to utilize the double acting wing principle above set forth,
together with such details of construction as may be necessary to the efficient
operation of the apparatus.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. In an aerial apparatus, the combination of wings, each having an outer and
an inner section, the inner sections of the wings being pivotally connected to each
other and each wing being pivoted intermediate of its sections, together with
mechanism for swinging the wings on their pivots, all arranged so that a movement
of the operating mechanism will swing the sections of each wing in opposite
directions, as set forth.
2. In an aerial apparatus, the combination with a centre shaft, of wing-rods
pivoted thereto by one end and connected to rock shafts intermediate of the ends
of the rods, each of said wing-rods having combined therewith a section of fabric,
all arranged in such a manner that each wing-rod overlaps the section of fabric
attached to the next adjacent wing-rod, as set forth.
3. In an aerial apparatus, the combination of wings, each having an outer and

page_text: inner section, each wing being pivoted intermediate of its sections, together with
a centre shaft to which the inner section of each wing is pivoted, as set forth.
4. The combination with a base A of wings provided with stiffening rods F F,
of sliding tubes 11 fastened to the stiffening rods F F together with guide-rods d d
co-operating with the tubes and mounted on the base, substantially as described.
5. The combination with pivoted wings of a base A, suspending rods a attached
thereto, said rods being also attached to the wing pivots, substantially as
described.
6. The combination with a base A and suspending rods a a pivotally attached
thereto and mechanism for operating wings, of wings carried by said rods and said
wing operating mechanism, substantially as specified.
7. In an aerial apparatus, a pair of double acting wings pivoted intermediate of
their ends and to a centre shaft and arranged to confine the air upon the down
stroke and to allow free circulation upon the up stroke, in combination with
operating mechanism for the wings connected to the wings by pivotal connections,
as set forth.
Dated this 4th day of December 1894.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.