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United States Patent |
5,203,523
|
Ferguson
|
April 20, 1993
|
Dirigible airship
Abstract
An airship in the form of a self-powered, elongated dirigible which
comprises at least three sections connected together by joints. The
sections including a front section with propulsion devices and control
surfaces, at least one intermediate section designed to carry a payload
and a rear section with control surfaces. The joints allow limited
articulation between sections under gust conditions and tend to return the
sections to aligned condition in calm air. A cover may provide a
streamline exterior shape for the airship; alternatively the sections may
have rims which mate together when there is no articulation to provide a
smooth exterior shape.
Inventors:
|
Ferguson; Frederick D. (P.O. Box 599, Station B, Ottawa, Ontario, CA)
|
Appl. No.:
|
757059 |
Filed:
|
September 9, 1991 |
Intern'l Class: |
B64B 001/02 |
Field of Search: |
244/30,24,29,95-99,3,131
|
References Cited
U.S. Patent Documents
43449 | Jul., 1864 | Andrews | 244/30.
|
922549 | May., 1909 | Wheeler | 244/52.
|
1004662 | Oct., 1911 | Kuenzel | 244/30.
|
1144578 | Jun., 1915 | Andersson | 244/30.
|
1372925 | Mar., 1921 | Andersson | 244/30.
|
1594073 | Jul., 1926 | Short | 244/30.
|
1718109 | Jun., 1929 | Brown | 244/30.
|
1818138 | Aug., 1931 | Howland | 244/3.
|
3079106 | Feb., 1963 | Whitnah | 244/30.
|
3180590 | Apr., 1965 | Fitzpatrick | 244/30.
|
3232562 | Feb., 1966 | Cella | 244/30.
|
Foreign Patent Documents |
409164 | Apr., 1910 | FR | 244/30.
|
413494 | Mar., 1911 | FR | 244/30.
|
Primary Examiner: Peters, Jr.; Joseph F.
Assistant Examiner: Ellis; Christopher P.
Attorney, Agent or Firm: Beveridge, DeGrandi, Weilacher & Young
Claims
I claim:
1. An airship in the form of a self-powered, elongated dirigible which
comprises at least three sections connected together by joint means, said
sections including a front section with propulsion means and control
means, at least one intermediate section with load carrying means but
without propulsion means, said load carrying means being independent of
any load carrying means of adjacent sections, and a rear section with
control surfaces; said joint means allowing limited articulation between
adjacent sections in any plane up to at least 10.degree. from the co-axial
state under gust conditions and tending to return the sections to aligned
condition in calm air said joint means including extensible means which
are pretensioned to prevent any articulation of the airship sections until
a predetermined bending force is exceeded; said joint means providing a
streamline exterior shape for the airship at least when the sections are
aligned.
2. An airship according to claim 1, wherein said three sections include
spherical balloons, said joint means including cover means extending
between the sections and providing said streamline exterior shape.
3. An airship according to claim 2, wherein at least a portion of the space
between spherical balloons of adjacent sections and within the cover means
is taken up with bags containing lifting gas at lower pressures than said
spherical balloons.
4. An airship according to claim 1 wherein each section has a rigid force
and aft central structural member, adjacent ends of the structural members
being connected by articulated joints.
5. An airship according to claim 1 wherein the extensible means are elastic
cables connecting outer peripheries of said sections.
6. An airship according to claim 1 wherein said extensible means are cables
connected to powered winches and connecting outer
7. An airship according to claim 1, wherein each of the gas containing
sections has an internal ballonet and means for compressing air into said
ballonet.
8. An airship in the form of a self-powered, elongated dirigible, which
comprises at least four buoyant gas containing sections, each section
having a fore-and-aft central axis, the sections being connected by
articulated joints including extensible means joining the peripheries of
adjacent sections and allowing limited articulation in any plan between
adjacent sections; the sections including front and rear tapered sections
and at least two intermediate cylindrical sections, the ends of adjacent
sections having reinforcing rim elements which mate together to provide a
generally streamline transition between the two sections when the sections
are co-axial; said extensible means being pre-tensioned to prevent any
articulation of the sections until a predetermined bending force is
exceeded.
9. An airship according to claim 8, wherein the front section has
propulsion means and wherein the said intermediate sections have load
carrying means but no propulsion means.
10. An airship according to claim 8, wherein each said intermediate section
is generally cylindrical and has a length: diameter ratio of less than
1.5:1.0.
11. An airship according to claim 10 having at least three intermediate
sections.
12. An airship according to claim 8, wherein said sections include a front
section having at least three radially extending mountings each carrying
propulsion means and associated movable flaps for control of direction.
13. An airship according to claim 1, wherein said rear section has at least
three radially extending fins or tail plane surfaces.
14. An airship according to claim 1, wherein each of the sections is
provided with mooring means.
15. An airship according to claim 1, wherein said sections include a front
section provided with an air ballonet for ballasting, with crew quarters,
and with directional control means, and wherein said front section is
connected to the next following section by separable coupling means and is
such that it can be flown in controlled manner when separated from
following sections.
16. An airship according to claim 8, wherein said rear section has at least
three radially extending fins or tail plane surfaces.
17. An airship according to claim 8, wherein said joint means are arranged
so that adjacent ends of the sections can articulate up to at least
10.degree. from the co-axial state.
18. An airship according to claim 8, wherein each of the sections is
provided with mooring means.
19. An airship according to claim 8, wherein said cover means comprises
skirts which bridge any gaps between adjacent sections and which are each
individual to a joint between adjacent sections so as not to interfere
with separation of sections at other joints.
20. An airship according to claim 8 wherein said sections include a front
section provided with an air ballonet for ballasting, with crew quarters,
and with directional control means, and wherein said front section is
connected to the next following section by separable coupling means and is
such that it can be flown in controlled manner when separated from
following sections.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a self-propelled and steerable airship (a
so-called "dirigible").
2. Related Art
Conventionally, large airships have been made with buoyant gas held in gas
bags contained within a rigid elongated enclosure; this requires a fairly
complex structure which is expensive to build. Also, such structures are
subject to high stress when windy or stormy conditions are encountered,
and when landing and taking off, and there have been disastrous failures
of airship structures in these conditions. The stress problems become more
serious as the size increases, partly due to well known effects of scaling
up structures, and partly because the effect of wind shear increases with
the length of the airship. Small airships, the so-called blimps, are made
without any rigid structure but these cannot be made in an ideal
streamlined shape and are structurally unsafe beyond a certain size.
SUMMARY OF THE INVENTION
The present invention avoids the overall rigidity and resultant structural
problems of the conventional large dirigible by using a series of sections
flexibly connected together.
In accordance with the present invention, a self-powered, elongated
dirigible airship comprises at least three gas containing sections, each
section having a gas bag or balloon with a fore-and-aft axis, the three
sections being connected by articulated joints means which provide a
streamline exterior shape for the airship at least when the sections are
aligned. When the airship is subjected to substantial bending moments it
can bend; accordingly the components of the airship are not subjected to
very large bending moments or compressive forces. The sections include a
front section with propulsion means and control means, at least one
intermediate section with load carrying means but without propulsion
means, and a rear section with control surfaces.
The joint means may include outer cover means bridging any gaps between the
sections and providing a streamline exterior shape for the airship.
The joint means preferably includes extensible elements which may be
elastic cables, or may be cables connected to powered winches. Such
elements are preferably arranged at close to the maximum radius of the
airship.
The front section and rear section are tapered and the intermediate section
or sections are of substantially constant diameter. A plurality of
identical intermediate sections may be used to provide modular
construction.
The sections may each include a structural member extending along the axis,
with articulated joints connecting the ends of the structural members.
Each section of the airship contains ballasting means whereby it can be
made neutrally buoyant. The intermediate section or sections, which will
be the only sections carrying substantial pay load, are made capable of
neutral buoyancy both loaded and unloaded. In order to minimize effects of
temperature and atmospheric pressure on the buoyancy, either:
(1) Gas containing sections are used comprising relatively small bags or
balloons which contain the buoyant gas (normally helium) at a pressure
sufficiently above atmospheric pressure that the shape and size of the bag
or balloon is substantially unaffected by normal changes in atmospheric
pressure and temperature including those caused by ascent or descent; or
(2) Gas bags or balloons are used which contain internal ballonets for
receiving compressed air; the air acting as ballast and being supplied at
suitable pressure so that the internal pressure of the gas bag or balloon
always exceeds the atmospheric pressure by a suitable amount, allowing
outer dimensions to be relatively constant.
Concerning the first option, balloons containing buoyant gas at pressures
substantially higher than atmospheric, so-called "superpressure" balloons,
have previously been used as free flight balloons for atmospheric
monitoring and for small manned balloons. While such balloons were
spherical, more complex forms of superpressure balloons and lifting
devices incorporating such balloons are described in U.S. Pat. Nos.
4,696,444 (issued Sep. 29, 1987) and 4,711,416 (issued Dec. 8, 1987), both
to Regipa. Both of these patents show superpressure balloon structures of
cylindrical shape. Although the latter balloons are described as
superpressure, they also contain air ballonets, thus combining the two
options above.
One form of my airship suitable for small sizes of airship utilizes a
plurality of gas containing sections in the form of spherical, balloons
which are flexibly connected together as described above and enclosed
within a casing having a generally cylindrical central section which
provides a streamlined shape similar to that of known dirigibles. Such
spherical balloons may be superpressure balloons normally designed to
accommodate safely an internal pressure of say 35 millibars above
atmospheric pressure or higher. At least a portion of the space between
the balloons of adjacent sections and within the cover is taken up with
bags containing lifting gas at lower pressures.
In large sizes of airship superpressure bags are uneconomical and probably
unsafe, and accordingly each gas containing section includes a gas bag for
buoyant gas at just above atmospheric pressure combined with a ballonet
for receiving air ballast, compressor means being provided to admit air
for descending. Admission of air in this way reduces the gas storage space
in the section so increasing the gas pressure to balance the increase in
atmospheric pressure as the airship descends, and maintains the outer
dimensions essentially constant without requiring high pressures. The
intermediate gas containing section or sections may be cylindrical,
preferably being fairly short, i.e. about 1:1 and in any event less than
1.5:1 in length to diameter ratio. Use of cylindrical sections minimizes
gaps between sections which need to be bridged by the cover means to give
a streamline shape. Where the ends of adjacent sections fit well together,
no cover means is necessary, since gaps only occur under extreme
conditions.
Preferably, the airship has at least four articulated gas containing
sections, each of which is circular in cross section. Each section may
have a rigid axially extending structural member, the four sections being
connected by universal joints which connect adjacent ends of the
structural members and by cables which connect the outer peripheries of
adjacent sections. The cables may be tensioned so as to prevent any
articulation of the airship sections until a predetermined bending force
is exceeded. However, use of a rigid axle member is not essential, and a
flexible tensile member may alternatively be used to hold the intermediate
sections to a predetermined length.
The airship of this invention will preferably use a balloon or gas
bag/ballonet combination designed so that it can be filled with helium at
ground level and can hold all the helium while operating at up to 12,000
ft. which will be the maximum altitude for unloaded flight. Although
provision is made for dumping helium in the event of excess
internal/external pressure differential, it is not envisaged that dumping
will normally occur. When the airship is not carrying its normal load, it
will carry ballast such as water or loads held by cargo-carrying brackets.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be more particularly described with reference to the
accompanying drawings, in which:
FIG. 1 is a side view of a first airship in accordance with the present
invention;
FIG. 2 is a front end view of the same airship;
FIG. 3 is a partly cut away and partly longitudinal sectional elevation of
the same airship as shown in FIG. 1;
FIG. 4 is a side view in section of the forward end section of the airship;
FIG. 5 is a frontal view of the first section of the airship, also in
section;
FIG. 6 is a top plan view of the forward end section of the airship, also
in section;
FIG. 7 is a sectioned side view of the second section of the airship; the
third section being the same;
FIG. 7a is a detail of FIG. 7, showing the load supporting arrangement;
FIG. 8 is a cross sectional view of the first section of the airship;
FIG. 9 is a side view of the junction parts of the forward end section and
second sections of the airship;
FIG. 10 is a side view of the tail end section of the airship, partially
sectioned;
FIG. 11 is a front end view of the end section of the airship, also
partially sectioned;
FIG. 12 is a top view of the airship showing how it can bend in severe wind
conditions;
FIG. 13 shows a side elevation of a second, larger airship;
FIG. 14 shows a front elevation of the second airship;
FIG. 15 shows a sectional elevation through the second airship;
FIG. 16 is a view of the front of the second airship with cover parts
removed;
FIG. 17 shows a detail of a connection between two sections of the second
airship;
FIG. 18 shows a longitudinal section through the first two sections of a
third airship;
FIG. 19 shows a cross sectional view on line 19-19 of FIG. 18; and
FIGS. 20a and 20b shows details of the connecting means between adjacent
sections of the third airship.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The airship as shown in FIGS. 1-3 comprises five sections, namely a front
end section 10, three intermediate sections 12a, 12b and 12c, and a rear
end section or tail section 14. These five sections are all linked
together by articulated joint means, and are also connected by cables at
their outer peripheries, which cables control the flexing of the airship,
as will be described. An outer cover 16 connects the sections and provides
a generally streamlined exterior shape for the airship; the cover
nevertheless having bellows-like corrugated sections 16a forming part of
the joint means and allowing bending of the airship without substantial
crumpling of the cover. Each section is circular in cross section and each
forms a surface of revolution about a rigid, hollow axially extending
structural member 18a, 18b, 18c, 18d and 18e extending along its axis,
adjacent ends of the structural members being connected by universal
joints. Each of the sections 12a, 12b, and 12c has mooring means indicated
at M whereby it can be 15 moored to ground fixtures as indicated.
FIGS. 4-6 show the front end section 10, or so called "control" section,
which carries the engines, crew quarters and controls for the airship; it
carries no pay load as such, although some fuel will be carried in this
section (see below). The section includes a gas containing bag 19 having a
hemispherical front end and a hemispherical rear end, and having a
frusto-conical intermediate part which diverges from front to back. Bag
contains two balanced ballonets 20 connected to a compressor means for air
ballasting as explained above. Sufficient air pressure is maintained
within the ballonets (and therefore within the buoyant gas which is at the
same pressure) that the bag maintains essentially fixed dimensions and
shape. A tube connects the two ballonets. The structural member 18a passes
a short distance out of the front and rear ends of the gas bag, and is
anchored to the bag material by means of flanges 19a surrounding the
member 18a. The rear end of member 18a is connected to the front end of
the next structural member 18b by a universal joint, as will be described
more fully below. Member 18a forms part of a framework of tubular members,
which framework includes:
(1) Three radial members 21a, 21b, 21c which are connected to member 18a at
the centre of curvature of the rear most part of the bag, and which
project out intervals, the upper member 21a being vertical. Each of these
structural members has a flange 19a attached to the bag material. The
outer end of each member carries an aircraft type engine 22 at its outer
end, so that its propeller can rotate just clear of the gas bag. Behind
each engine is a cross-vane aileron 23 and rudder 23a, providing yaw,
pitch and roll control. At extreme low speeds in still air individual
thrust trim to each engine is capable of turning the airship.
(2) A member 24 extending from a central point 25 on member 18a to a point
near to the outer end of radial member 21a, being within the confines of
the bag, engine 22.
(3) A member 26 extending down vertically from point 25 and having a lower
end forming a mounting for a crew cockpit or gondola 28.
(4) Two members 30 extending downwardly and inwardly from adjacent the
outer ends of members 21b, 21c to meet the member 26 just above the
gondola, and within the bag. The framework also includes the following
flexible cables used to brace the structural members described, i.e.
(1) three cables 32 extending between the end portions of the members 21a,
21b, 21c, just within the confines of the bag to hold these members at the
correct angular position;
(2) two cables 34, shown in FIG. 4, extending between point 25 and portions
of the members 21b, 21c, just inside the bag material;
(3) cable 36 extending from the front end of member 18a down to the
junction between the members 26 and 30; and
(4) three cables 38 extending from the end portions of members 21a, 21b,
21c, just within the bag material, to the rear end of the member 18a just
inside the bag material.
This arrangement provides rigid support for the engines 22 and the gondola
28. This control section includes, in the gondola, control means for
rudders and or ailerons such as 23, 23a and others carried by the tail
section to be described. The engines 22 have fixed mounts but are
independently controlled for speed and propeller pitch so that they can be
used to alter or to assist in altering the orientation of the airship.
Fuel for the engines will be carried in this control section and also in
section 12a following.
The control section 10 is essentially an independent unit having all
necessary power means, control (by rudders 23a and ailerons 23), fuel, and
ballast means (by ballonets 20), to allow independent, controlled flight.
The section is connected to the next following section 12a by separable
coupling means, and is sufficiently self contained that, in an extreme
emergency, this section may be separated from the remainder of the airship
and land safely.
FIGS. 7 and 8 show the leading intermediate section 12a, or second section,
which is essentially a passive load supporting part. The next intermediate
section or third section 12b is identical, and the third intermediate
section 12c (fourth section of the airship) is structurally the same but
smaller in diameter. These sections have no propulsion means nor any
control surfaces.
As shown, the section 12a has a spherical balloon 50 traversed by the axial
fore and aft member 18b which is connected to adjacent members 18a and 18c
by joints as described below with reference to FIG. 9. FIG. 9 also shows
the flanges 50a by which the ends of member 18b are connected to the
balloon fabric. The member 18b is connected by vertical strut 52 to a load
carrying bracket 54, shown in detail in FIG. 7a, which bracket has a pair
of downwardly projecting lugs 55 suitable for attachment to a payload. The
load carrying part, which can also support a fuel tank, will be seen to be
independent of any load carrying means of adjacent sections so as not to
interfere with flexing of the airship. The bracket 54 is also connected to
the member 18b by cables 57, 58 extending respectively to the front and
rear end of the member 18b, as shown in FIG. 7a. Additional cables, for
example as shown at 59, connect upper parts of the sphere to the member
18b, thus transmitting the lifting forces to the load via this member. The
balloon 50 has two internal air ballonets which allow air to be used as
ballast; the outlines of these ballonets are indicated at 60 in FIGS. 7
and 8. The ballonets are symmetrically arranged relative to the
longitudinal centre of the balloon, and the perimeter of each ballonet is
connected to the interior of the balloon along a generally elliptical path
which extends up to just below the centre line of the balloon. The two
ballonets are connected by a tube 62, and are also connected to an air
compressor, allowing air to be compressed into the ballonet to provide
ballast. Sufficient air pressure is maintained that the spherical balloon
maintains essentially fixed dimension and shape when ascending or
descending; the ballonets can also compensate for changes in atmospheric
pressure and temperature.
FIG. 9 shows diagrammatically the structure connecting the balloon 50 and
the first gas containing section; similar junctions are used between all
of the sections. As shown, the axial structural members 18a, 18b, are
connected together by a universal joint 64 of the cardan type.
As shown in the cut away portion of FIG. 3, the outer peripheries of the
airship sections are connected by extensible cables 70 in the form of
elastic ropes which are anchored to the peripheries of the sections as
seen in the fore and aft view, i.e. at the largest diameters. These cables
also seen in FIGS. 7 and 8 are pre-tensioned so that the two sections only
pivot relative to each other when a predetermined minimum bending moment
is exceeded; this prevents unwanted oscillation of the parts which would
otherwise occur in light winds. These cables, which are preferably at
least 20 in number between each pair of adjacent sections, form a
cylindrical support for the fabric cover 16 which is attached to the
cables to maintain its cylindrical shape. As will be evident from FIGS. 3
and 8, the cables 70 are generally equally spaced around the periphery of
the joint between adjacent sections, and this arrangement, combined with
the use of the cardan joint, allows bending between the sections to occur
in any plane.
As shown in FIGS. 3 and 7, the spaces between the first section 10 and the
second section 12a, within the cables, and between sections 12a and 12b,
are largely occupied by annular helium containing balloons 72, which
contain the helium at a pressure close to atmospheric, i.e. at least
slightly below that of the balloon 50. Each of these balloons 72 has an
external cylindrical surface, an internal surface conforming to the
adjacent spherical balloon, and flat faces contacting each other. These
balloons allow movement of the helium from one side of the airship to the
other, so collapsing and expanding as the sections move relative to each
other. The small spaces near the ends of the member 18b, which are
surrounded by these annular balloons, and also small spaces between the
balloons and the cover 16, contain air and are open to air at the front
end of the airship via the hollow structural members 18a and 18b.
The joints between the other sections are similarly formed. The axial
members 18a 18b, etc. provide a duct communicating the air outside the
balloon to the small spaces between each adjacent section not occupied by
the annular helium balloons.
The tail section 14 is shown in FIGS. 10 and 11. This is similar to the
front end section in comprising an elongated balloon 78 having a forward
hemispherical end, a tapering frusto-conical surface merging with the
forward end and leading to a smaller hemispherical surface at the rear
end. Internal air ballonets 79 are provided, along with an air compressor,
as for the other sections. The tail section includes three tail planes 80
set at 120.degree. relative to each other, and which include an upper
vertical tail plane. These tail planes (or fins) are swept forward so that
the centre of gravity of the tail section is near to the centre of
buoyancy. Each tail plane has a fixed part 80a and a rudder or aileron
section 80b. The fixed part in each case is carried by a structural member
18e at a point adjacent the centre of the front hemispherical surface, and
projecting out through the balloon surface to a support point adjacent the
centre of the tail plane part 80a. The members 82a, 82b and 82c are braced
by cables 84 shown in FIG. 11 which connect end portions just inside the
balloon fabric, and are also braced by forward and rearward cables 86 and
88 shown in FIG. 10 which connect the same end portions to the front end
of the member 18e, and a rear end connection point 90 which is adjacent
the centre of the rear hemispherical surface of the balloon. This
connection point 90 also serves as a mounting for three support members 92
which project both radially and forwardly and support the rear ends of the
fixed rudder portions. These support members 92 also provide hinge means
for the rudder parts 80b. The rudders are controlled from the control
section by electro-mechanical linkages.
FIG. 12 illustrates the ability of the airship to bend in windy conditions;
local wind gusts are indicated by arrows W. Bending is accommodated by the
corrugated sections 16a of the cover, by the universal joints which
connect the structural members 18a, 18b, etc.; and by the movement of gas
within the low pressure helium balloons 72 from one side of the balloon to
the other. Bending is resiliently resisted by the elastic cables 70. Each
section of the airship can bend relative to the next adjacent section by
at least 20.degree.; preferably up to about 30.degree., this bending being
limited by the main balloons pressing against each other in the extreme
position shown.
It will be apparent from considering FIG. 12 that in this condition of high
wind shear no structural element is subjected to large bending forces and
the only parts subjected to substantial compressive forces are the
balloons, in which forces are well distributed. The wind force on the
centre of the airship is largely resisted by the tension in structural
members 18a, 18b, etc., which can easily be made strong enough to resist
the tensile forces. Thus, the airship has the same kind of strength to
weight advantage over a conventional rigid airship as a suspension bridge
has over a standard girder bridge.
In the embodiment described, the gas containing sections are maintained at
substantially constant dimension and shape by using the ballonets to
maintain a suitable differential between internal and external pressure;
about 10 millibars (0.157 psi) overpressure is suitable. However,
superpressure balloons may be used for all of the gas containing sections,
and especially for the spherical balloons, at least for small sizes of
airship. This may avoid the need for ballonets.
Cables 70 have been described as elastic. However, substantially inelastic
cables may be used in association with powered winches, to allow complete
control of the flexing. The winches will preferably include damping means
to minimize oscillatory motion. In either case, some prestressing or like
means would be provided so that the craft can resist small forces without
any bending.
Since mooring means M is provided for each load carrying section of the
airship, this can be secured in place firmly on the ground, unlike with
conventional airships which are moored by a mast at the nose. In order to
allow for different orientation of the ground mooring points, to
accommodate varying wind directions, these may be mounted on circular rail
tracks. Mooring at several sections allows the airship to take off
gradually, front sections being released and rising first, so that the
whole airship has assumed a climbing attitude before the tail is released.
As the forward sections are released, the engine and their rudders are
operated so as to bring the craft into the wind.
Although tail plane or fin formations are shown only on the tail section,
in large sizes of airship it is contemplated that other sections of the
airship may have these.
FIGS. 13 to 17 show a second, larger version of the airship. This has many
parts which correspond to those of the first airship and which are
labelled with similar reference numerals increased by 100.
The airship has a front section 110, four intermediate sections 112a, 112b,
112c and 112d, and a rear or tail section 114, each being circular in
cross section and having a rigid, axially extending member 118a, 118b,
118c, 118d, 118e and 118f in the form of a hollow girder. The intermediate
sections are each of generally cylindrical form and mating end surfaces of
all sections are substantially flat. Joints between the sections, which
are described in more detail below with reference to FIG. 17, are enclosed
by outer cover portions or skirts 116, to maintain a streamline shape.
Each section 110, and 112a, 112b, 112c, and 112d has mooring means M.
Front section 110 carries the engines 122 and gondola 128. Engines 122 are
all located below the centre line of the airship and include a forward
upper pair and a rearward lower pair; each pair of engines being carried
by lower radial members 121 which pass out of the bag material and which
terminate in a short wing sections 122', having flaps 122" which are
movable to control the thrust direction. The radial members are stayed by
fore and aft cables 134 and by lateral cables 124 including upper cables
held by king posts 121a extending upwardly from member 118a, themselves
stayed by stayed by cables 136. The front section has ballonets for air
which are not shown but are similar to those shown at 20 in FIGS. 4-6.
Turning now to the intermediate sections 112a, etc., each is in the form of
a cylindrical balloon the exterior casing 115 of which has both
circumferential, hoop like reinforcements and longitudinal reinforcements.
The sections have a length to diameter ratio close to unity and in any
event less than 1.5:1.
The sections each have two discrete ballonets; these are not shown but will
be situated below the centre line of the airship, generally as previously
described with reference to FIGS. 7 and 8. The gas bag is designed for a
pressure of about 10 millibars or about 0.157 psi.
The internal structure of the intermediate sections is similar to that in
the first airship, namely a vertical strut 152 extending down to the load
carrying bracket 154, braced by fore-and-aft cables 157 and 158. Further
cables 159 connect the centre of member 18b to the upper parts of the gas
bag to transmit lifting forces to the strut 152 via member 118b.
FIG. 17 shows a joint between two intermediate sections, which is also
similar to joints between the intermediate sections and the end sections.
At the adjacent ends of two members 118b, 118c are plates 150a which
anchor the longitudinal centres of the gas bag fabric, and these carry
tubes 165 extending internally of the ends of members 18b and 18c. Tubes
165 slidably receive shafts 166; the two shafts 166 are connected by a
universal cardan type joint 164 as illustrated in FIG. 9. The gas sections
are also connected by reinforcing rim elements in the form of resilient
hoops 169 which surround the outer end surfaces of the sections, within
the peripheries of the sections, and which have high friction surfaces in
contact with each other. These hoops are normally held in contact with
each other by elastic cords 170 anchored to rings 171 which extend
circumferentially around the gas bags adjacent their ends. These cords 170
are surrounded by a skirt or cover portion 116 providing a smooth
transition for the joint and maintaining the generally streamline form of
the airship. The arrangement is such that two adjacent sections of the
airship can bend relative to each other, the fulcrum for bending being
near the outer periphery of hoops 169; this bending is restrained by the
elastic cords 171 and is accommodated by sliding of shafts 166 in tubes
165. Bending of up to about 15.degree. between adjacent sections is
permitted, and the length of skirt 116 is of course sufficient to
accommodate this. The minimum amount of bending considered desirable with
this airship would be about 10.degree. .
Unlike in the first embodiment, there is no overall cover for the airship;
its outer surface is comprised of the outer surfaces of the separate
sections and the skirts 116. This makes it relatively easy to remove or
add a section when this is necessary for servicing or to lengthen or
shorten the airship.
The tail section 114 is generally similar to that of the first embodiment
having an axial structural member 118f, and air ballonets (not shown);
again similar reference numerals, increased by 100, are used for
corresponding parts. One addition is a pointed streamlined tail fairing
195.
FIGS. 18 to 20 show parts of a third embodiment of airship, generally
similar to the second embodiment although somewhat larger. There are
however two important differences between the third airship and the
second; i.e.
1) The third airship has no rigid axial member in its intermediate
sections, i.e. all those sections between the front section and the rear
section; and
2) The third airship has no cover means extending between its sections.
Referring to FIG. 18, it will be seen that the front section 210 is similar
to that of the second embodiment in having a central, axial, structural
member 218a which supports radial members 221 which pass out through the
sides of the section where they carry engines 222; in this embodiment 6
engines are provided below the centre-line of the airship and an
additional engine 222a is mounted at the top, for directional control.
Each engine is associated with a short wing section having a flap at the
rear of the engine for directional control. The radial members 221 are
stayed by cables held by king posts 221a. The axial member 218a is
connected to the gas bag material by cables 227. The front section carries
gondola 228, and also has air ballonets which are not shown but are
similar to those shown at 20 in FIGS. 4-6.
The airship has four identical intermediate sections 212a, 212b etc., of
which the first two are shown in FIGS. 18-20. These sections are somewhat
similar to those of the second embodiment, although the length to diameter
ratio is slightly less, namely about unity or slightly less. The main
difference is that these sections do not have any rigid axial member;
instead cables 218 are used to connect circular hub members 250 at the
ends of the sections to maintain the sections at fixed length. Compared to
sections having a rigid member, sections 212a etc. are easier to construct
and to inflate; they can be delivered to site in an axially collapsed
condition, and then inflated, initially, with their ends surfaces in a
horizontal plane before being rotated through 90.degree. to the
orientation shown. The external dimensions to the sections are determined
by cables, some of which are shown at 259. Each section are a ballonet, as
indicated in outlines at 260 in FIG. 19.
FIGS. 20a and 20b shows the means whereby adjacent sections are joined
together.
Surrounding the end of each section is a hoop-like member 261 having an
inner surface which is concave in cross-section to conform to the curved
corner shape of the balloon fabric 215, and which has an outer cylindrical
surface forming a continuation of the main cylindrical outer surface of
the section. The members 261 also have flat or interfitting abutting
surfaces so that they can fit together as shown in FIG. 20a when the
airship is in its normal flying attitude; accordingly these provide a
generally streamline transition between the sections. The alignment of
adjacent sections is maintained by cables 270 held by winches 271. These
winches are such as to provide a tension on the cables but allow these to
be pulled out from the winches (at about a constant tension) when an
excessive bending force is applied to the airship; this condition being
illustrated in FIG. 20b. Under such forces, sections will pivot about
contact points at the peripheries of adjacent members 261.
Each hoop-like member 261 is connected by radial, spoke-like cables 262 to
the circular hub member 250. These cables define the end shape of the
balloon sections which bulge slightly between the cables. In addition to
forming a hub for cables 262, members 250 provide a connecting means
between adjacent sections, in manner comparable to the plates 150a and
associated means of the second embodiment. Here, each plate member 250 has
slidable therein a tubular member 266, 267, which are connected together
by universal joint 268. This arrangement maintains the axes of the balloon
sections in the correct relationship during bending. Tension in cables
270, along with friction between parts 261a, prevents relative rotation
between sections. The surfaces 261 may be roughened or toothed to more
positively prevent such relative rotation.
These connecting means allow a deflection of at least 10.degree., and
preferably about 15.degree., between each section of the airship.
As indicated, in this embodiment no cover means are provided to bridge the
gap between adjacent sections. This naturally will result in
non-streamline flow whenever the airship sections becomes deflected
relative to each other by excess sideways forces. However, the tension in
cables 270 is maintained such that deflection only occurs in rather
extreme conditions during which maintaining good speed is not of great
importance.
The tail section (not shown) will be similar to that of the second
embodiment, being provided with an axial structural member and with air
ballonets.
A large airship as described, having say four intermediate sections, is not
only structurally safer than a conventional large airship, due to its
ability to bend, but is also expected to be economical in construction.
This arises because the intermediate sections are all identical, and are
structurally simple, being unencumbered with any propulsion means or
control surfaces.
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