Landing and anchoring mechanism for an airship

A landing and anchoring mechanism for an airship takes advantage of the ship's supporting frame that has a row of cross-ribs interconnected by lengthwise beams arranged between neighboring ribs. In order to make it possible to land on any landing field even without conventional and costly apparatus, and to anchor the airship against the effects of wind and weather, a bi-pod landing gear is combined with an anchoring device. The landing gear is articulately connected to the supporting frame on the one hand and to the airship gondola by respective landing gear lateral rocker arms on the other hand. The bi-pod landing gear is arranged in a crosswise plane in front of the aerodynamic center of wind pressure of the airship. At least a portion of the anchoring device is provided on the floor of the airship gondola in the area of the attachment of the landing gear lateral rocker arms to the gondola floor. The anchoring device is provided for connecting the airship with a mooring on the ground, whereby another portion of the anchoring device may be located on the ground.

FIELD OF THE INVENTION 
The invention relates to a landing and anchoring mechanism for an airship 
with a supporting frame comprising a row of bulkhead or cross-ribs and 
longitudinal beams arranged therebetween. 
BACKGROUND INFORMATION 
All known types of airships, including rigid airships, keel or semi-rigid 
airships or pressurized non-rigid airships, possess one or more landing 
wheels which are arranged on the gondola and sometimes on the lower tail 
fin. After landing on these wheels, the airship is held through bow lines 
by a ground crew until a mobile or stationary mooring mast or pylon is 
coupled with the airship. 
The coupling location between the airship and the mooring mast is either 
located at the bow of the airship or, for a low mast, under the belly of 
the airship in front of the center of lift. 
Masts for anchoring at the bow of the ship must be able to withstand a high 
tilting moment. Such masts are highly loaded and very heavy in order to 
achieve the required stability for a mobile mast. Stationary masts are 
anchored into the ground and require high anchoring forces. 
Masts for anchoring at the forward body section of the airship, the tilting 
moment is considerably smaller, typically 50%, but instead a rolling 
moment arises in the airship because the ship is restrained below the 
aerodynamic center of wind pressure, that is to say when a wind blows 
laterally against the airship, the airship will roll sideways at a 
considerable roll angle, that can be than 25.degree., until it has again 
turned itself into the wind. 
At least for pressurized non-rigid airships, this type of anchoring is 
critical due to the large forces acting on the envelope skin. Therefore, 
this type of anchoring is hardly ever practice used in. 
Fundamentally, the anchoring of an airship is carried out in such a manner 
that the airship is held or restrained at a location forward of the 
aerodynamic center of wind pressure, so that when the wind blows laterally 
against the airship, the airship turns into the wind like a weather vane. 
In this manner, the airship offers the least aerodynamic resistance. 
It is a disadvantage of such an anchoring that an anchor mast or mooring 
mast is absolutely necessary for anchoring an airship. This sharply limits 
the operation of airships, because it can only take off and land at a 
prepared base. A mooring mast must be available for every off-field 
landing. For this reason, ferrying trips over long distances are not 
possible or only possible with a large expenditure and effort for 
preparations. When unplanned off-field landings are necessary, for 
example, due to a breakdown of the airship, the result is often a total 
loss, as is shown by airship history. Moreover, such mooring masts are 
expensive. 
A further disadvantage of anchoring an airship with the aid of a mast is 
that the mast, or for mobile masts the mast vehicle, represents an 
impediment or obstacle for the landing airship because the airship cannot 
exactly maintain the intended landing point due to shifting winds. The 
airship then drifts into the mast and is usually severely damaged. 
Examples are known for the last five years in which, of sixteen 
pressurized non-rigid airships operating around the world, the envelope of 
two of these ships became "a total loss" in such an accident. 
However, the problem of over-shooting the mast is partially circumvented by 
using movable masts, which are only driven into position once the airship 
is stationary. The disadvantage of such a method is, however, to be seen 
in that the airship must be held by a large holding crew (approximately 15 
persons are necessary for holding a small airship of approximately 6000 
m.sup.3) until the mobile mast is driven into place and anchored. 
OBJECTS OF THE INVENTION 
Therefore, it is the object of the invention to provide a landing and 
anchoring mechanism for an airship of the above mentioned type, which 
makes it possible to land on every landing field even without the 
conventionally typical costly apparatus, and to securely anchor the 
airship against the effects of wind and weather. 
On such landing fields, the apparatus already present for general aviation 
purposes, such as secured parking spaces and storm tie-downs to which 
normally aircraft are tethered should also be useable, with a minimal 
effort and expanse, for anchoring an airship, or to be equipped for 
adaptation to an airship. 
The use of the normally typical, very costly bow masts should remain 
limited to use on special airship landing fields and for anchoring the 
airship against heavy weather effects with wind velocities greater than 6 
to 7 Beaufort. 
SUMMARY OF THE INVENTION 
A landing and anchoring mechanism according to the invention is used for an 
airship having a supporting frame comprising a row of cross-ribs and 
longitudinal beams arranged therebetween as is described for example in 
the German Patent Publication DE-PS 4,018,749 and the German Laying-Open 
Patent Publication DE-OS 4,112,621.1. In the landing and anchoring 
mechanism according to the invention a bi-pod landing gear is mounted in a 
crosswise plane forward of the aerodynamic center of wind pressure in such 
a manner that it is articulately connected respectively to the supporting 
frame on the one hand and to the gondola of the airship by a respective 
landing gear lateral rocker arm on the other hand. In the area where the 
landing gear lateral rocker arms are secured to the gondola floor, an 
additional anchoring arrangement is provided in the gondola center line, 
through which the airship is connected to the anchoring or mooring station 
and to apparatus provided at these stations. 
In this context, the wheel base track of the bi-pod landing gear preferably 
is approximately 0.7 to 1.2 times the maximum airship diameter. 
The landing gear of the invention is articulately connected to the junction 
node points of the cross-ribs and the longitudinal beams either by a 
respective shock absorber strut or by a respective tension cable taking up 
the load from a truss frame of the landing gear. The landing gear can be 
embodied in such a manner that when necessary it can be folded sideways up 
against the airship about its attachment points. For bracing purposes, 
each landing gear lateral link can further be releasably connected to the 
airship gondola by a bracing link. Furthermore, the shock absorber struts 
and the landing gear lateral rocker arms can be provided with an 
aerodynamically advantageous profile in the form of a faring in order to 
reduce the air resistance. At the outer end of each landing gear lateral 
rocker arm, it is rigidly connected to a bearing body, which carries a 
wheel fork for holding a landing gear wheel, whereby the wheel fork with 
the wheel is rotatably arranged in the bearing body. Moreover, the lower 
end of the respective shock absorber strut is articulately connected to 
said bearing body. 
The above mentioned additional anchoring arrangement comprises a ground 
based mooring mechanism and an airship based mooring cable which can be 
let out from and then again retracted into the airship, and of which the 
lower end can be connected to the ground based holding or mooring 
mechanism by a suitable device. 
A winch is provided for reeling the mooring cable out and in, whereby the 
winch can be arranged either in the airship itself or on the ground based 
mooring mechanism, depending on the particular circumstances. 
An anchoring head can be set onto the ground based holding mechanism in a 
freely rotatable manner and is releasably connected to the holding 
mechanism, for example by a clamping device. 
Furthermore, an additional rigid connection for anchoring the airship can 
be provided between the gondola floor of the airship and the ground based 
holding mechanism. Such an additional rigid connection may be in the form 
of a connecting rod respectively articulately connected with the airship 
and with the anchoring head. This connecting rod is adjustable in its 
length and can be lowered from the floor of the airship downward to the 
ground based holding mechanism. The connecting rod is secured to the 
gondola floor in such a manner that the connecting rod deviates from the 
vertical by at least 15.degree. when the airship is anchored in order to 
take up the longitudinal force. 
Finally, it is also conceivable to keep the landing gear on the ground in a 
preassembled state and only connect it to the airship when it is needed 
for anchoring. 
Moreover, a tail wheel is arranged on the airship in the area behind the 
aerodynamic center of wind pressure on the floor of the airship or, for 
example, on the lower stabilizer fin. 
Therefore, it is an advantage of the invention that the airship can be 
safely and securely landed and anchored or moored at an anchoring or 
mooring station with a minimal cost and effort due to ground based 
apparatus and ground personnel by means of a simple and lightweight 
landing and anchoring mechanism.

DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF THE BEST MODE 
OF THE INVENTION 
FIG. 1 shows, in a side view, a partially sectioned airship 1 with a 
supporting frame formed of a row of cross-ribs 3 and longitudinal beams 4 
set therebetween. An airship gondola 2 is suspended from the floor of the 
airship 1 for receiving, for example passengers and as a cockpit. A 
landing gear 5 is arranged in the area of the gondola 2 in front of the 
aerodynamic center of wind pressure S.sub.A of the airship 1. The landing 
gear 5 is connected to the supporting frame on the one hand and to the 
airship gondola 2 on the other hand. An additional landing gear 6 is 
embodied as a single wheel and is arranged on the floor of the airship in 
the area behind the aerodynamic center of wind pressure S.sub.A. Depending 
on the type of the tall unit 9 or stabilizer fin assembly of the airship, 
it is possible to arrange this landing gear 6, for example on a downwardly 
extending vertical stabilizer fin. The tail unit 9 includes rudders 9A and 
elevators 9B as shown in FIG. 1. In addition to the steering achieved by 
the aerodynamically effective stabilizer assembly fins 9 with their 
rudders, the propulsion plants 7, 8 can be utilized not only for providing 
forward drive, but also for steering. For this purpose, the lateral 
engines 7 and the tail engine 8 are embodied as swivelable or tiltable 
engines or are equipped with swivelable or tiltable propellers. 
In FIG. 2 the airship 1 is shown in cross-section in the plane of the 
landing gear. The cross-ribs 3 are once again shown, as well as the outer 
skin or envelope 10 of the airship 1 which is connected to the supporting 
frame at the junction node points between the cross-ribs 3 and the 
longitudinal beams which are not shown. The tiltable engines 7, 8 are 
secured to the supporting frame in a generally known and therefore not 
described manner. The engines 7, 8 serve for providing forward thrust as 
well as for steering. At the illustrated cross-sectional plane in which 
the landing gear lies, the gondola 2 is provided with a transverse 
bulkhead for taking up the arising loads. The loads are transmitted by the 
transverse bulkhead to the gondola suspension points 17, which lie in the 
same cross-sectional plane. In this plane, the gondola 2 is connected by 
guy wires 18 to the lower junction node points of the cross-ribs 3 with 
the not visible longitudinal beams 4 and to the junction node points of 
the next cross-rib or bulkhead plane. In order to stabilize the gondola 2, 
additional pretensioned gas pressure springs 16 or rigid carrying members 
with an overload safety mechanism are installed and connected to the 
cross-rib 3. Moreover, pivot points 19 are secured to the above mentioned 
node points outside of the airship envelope 10, whereby in turn shock 
absorber members 14 guided in shock absorber struts 13 are connected to 
the pivot points 19. The shock absorber member 14 comprises a prestressed 
gas pressure spring and an oil hydraulic shock absorber. The direction of 
force application of the shock absorber strut 13 thereby intersects the 
center of the junction node point of the horizontal and the diagonal 
cross-rib. Respective landing gear lateral rocker arms 15 are articulately 
connected to the gondola floor and meet the shock absorber member 14 at 
the landing gear 5. 
This landing gear arrangement is also shown in FIG. 3 in an enlarged side 
view with a landing gear wheel 21. Additionally, the respective articulate 
connection of a bracing strut 20 with the airship gondola 2 on the one 
hand and the landing gear lateral rocker arm 15 on the other hand is also 
visible in FIG. 3. 
FIG. 4 shows this arrangement in a top view in which the pivot attachment 
points 22 or 23 of the landing gear lateral rocker arm 15 or the bracing 
strut 20 to the gondola 2 are more clearly visible. In order to reduce the 
aerodynamic resistance, the landing gear lateral rocker arm 15, the 
bracing strut 20, and the shock absorber strut 13 can be profiled in an 
aerodynamically advantageous manner, for example, in the form of a lifting 
wing with a wide wing end with two hinge points 22 and a narrow wing end 
for connecting to a wheel bearing body 24. In order to reduce the weight, 
these profiles can be constructed of carbon fiber reinforced composite 
material, aluminum, or the like. 
This wheel bearing body 24 is shown in an enlarged view of the landing gear 
in a front view in FIG. 5 and in a top view in FIG. 6. As is clearly 
visible, an upper part 24A of the wheel bearing body 24 is rigidly 
connected to the landing gear lateral rocker arm 15 by bolts 24B while the 
shock absorber member 14 is articulately connected with the upper part 24A 
of the wheel bearing body 24, for example, by a bolt connection 24C 
inserted in an eye of the piston rod of the shock absorber member 14. A 
lower part 24D of the wheel bearing body 24 is connected to a top portion 
43A of a fork 43 whereby the wheel bearing body 24 is rigidly connected 
with the landing gear lateral rocker arm 15 and pivotally connected with 
the shock absorber member 14. However, the upper part 24A and the wheel 
fork 43 holds the landing gear wheel 21. The upper and lower part 24D of 
the wheel bearing body 24 are preferably so embodied that the wheel fork 
43 with the wheel 21 is rotatable about a vertical axis 43B through the 
bearing body 24. This can, for example, be achieved by removing and 
repositioning a bolt 25, whereby the wheel 21 is again locked in a 
position rotated by 90.degree.. However, this rotation could be carried 
out from the cockpit by means of suitable mechanisms that are not 
described in detail, whereby it would become possible to steer the airship 
on the ground. This is especially practical if a vertical landing of the 
airship 1 is no longer possible, for example, due to a high operating load 
or due to the loss of lifting gas, so that the airship 1 must carry out an 
aerodynamic landing on its landing gear such as is carried out by other 
aircraft. 
An alternative to this landing gear arrangement is shown in FIG. 14. In 
this case, the shock absorber members 14 with the shock absorber struts 13 
and the landing gear lateral rocker arms 15 are omitted. Instead, the 
landing gear is connected to the gondola 2 as a truss frame 48 made of 
individual beams or as an interconnected truss assembly. The force 
transmission to the cross-rib 3 is carried out by tension cables 49 
instead of the shock absorber member 14 and the shock absorber strut 13. 
In the embodiment of FIG. 14 it is particularly easily possible, when 
necessary, to arrange the landing gear in such a manner that it may be 
folded sideways to lie up against the side of the airship or the gondola 
body after the attachment points and the bracing strut have appropriately 
been disengaged. 
Independently of the above described two different embodiments of the 
bi-pod landing gear, the wheel base or track width of the landing gear is 
preferably within the range of 0.7 to 1.2 times the maximum airship 
diameter in order to achieve a sufficient lateral bracing or support of 
the airship. 
Furthermore, it is possible to keep the entire preassembled landing gear in 
a constant state of readiness on the ground and only attach it to the 
airship by means of the above described attachment points for the purpose 
of anchoring the airship. In this manner the weight of the landing gear 
can be saved and a correspondingly larger usable load can be transported. 
The additional mooring or anchoring arrangement that is provided to 
supplement the bi-pod landing gear according to the invention for 
connecting the airship to an anchoring or mooring station will now be 
described in further detail with reference to FIG. 7. Equivalent reference 
numbers in this figure and in the following figures indicate the same 
components so that repetition of items can be avoided that have already 
been described above. According to FIG. 7 the additional mooring 
arrangement comprises three components, namely a holding or mooring 
mechanism 50 provided on the ground, a retractable holding or mooring 
cable 26 1, and a clamping device 28 carried by the airship 1. The 
provided on the airship and the clamping device 28 are airship based 
holding cable 26 connectable with the ground based holding mechanism 50 as 
will now be described. 
The ground based holding mechanism 50 is constructed, for example, of 
aluminum or steel, as a mooring or anchor plate 38A which is secured by 
heavy load dowels and screws 38 to a concrete slab 39 or directly to the 
landing field. An anchor or mooring 37 is welded onto the anchor plate. 
The clamping device 28 can be set onto and connected with the anchor or 
mooring 37 when the airship 2 has landed. 
In this example embodiment the clamping device 28 has a bottom part that 
can be folded open in the manner of a pipe coupling in order to be pushed 
over the conical part of the anchor or mooring 37. Then, the clamping 
device 28 can be folded closed and locked by means of the eye bolt 35 and 
quick clamping levers. The upper part of the clamping device 28 is 
rotatably connected with an axial bearing 34. A length adjustable 
connecting rod 42 is secured to this upper part of the clamping device 28 
by a pivot joint 33. The other end of the connecting rod 42 is 
articulately connected to the floor of the gondola 2 at the bearing point 
30. An end stop of the connecting rod 42 can be provided with a shock 
absorber. This connecting rod 42 with the pivot joint 33 is arranged in 
the center plane of the gondola floor displaced rearwardly relative to the 
landing gear plane, so that the anchoring head 37 with the clamping device 
28 attached to the connecting rod 42 can be moved downwardly away from the 
gondola floor by tilting or folding down the connecting rod 42. This 
movement is controlled from the cockpit or from the ground. 
The holding or mooring cable 26 is stored on a drum of a winch 36 in the 
gondola 2. The winch 36 may, for example, be electrically or hydraulically 
driven. A hook 27 is attached to the end of the holding cable 26. This 
holding cable 26 emerges downwardly out of the gondola floor in the 
landing gear plane, and in fact through a hollow part 28A of the clamping 
device 28. The anchor 37 is also hollow, as seen in FIG. 7, to accommodate 
the hook 27. A cross-pin 40 for holding the hook 27 of the holding cable 
26 is provided in the mooring 37 connected to the ground plate 38A. In 
order to hook the hook 27 into the cross-pin 40 in the mooring 37, the 
mooring 37 comprises the hollow part 28A as a slot or slit through which 
the hook 27 can be guided for engaging the cross-pin 40 as shown in FIG. 
7. 
Another possibility to secure to hook 27 on the ground is to use an eye 44 
according to FIG. 12. In that embodiment the hooking point of the hook 27 
in the eye 44 lies above the anchoring head 46 and is thereby freely 
accessible. In order to make it possible to drive over the ground based 
holding mechanism, for example during maneuvering operations on the 
ground, the embodiment having the cross-pin 40 inside the mooring 37 is 
preferred. Additionally, for this purpose, the mooring 37 can comprise 
angled surfaces such as, for example ramps, on its circumferential sides, 
which allow the wheels 21 to roll over the mooring 37 without damage. 
In connection with FIG. 7 and with reference to the following FIGS. 8 to 
10, the landing and anchoring procedure will now be described. 
The airship 1 is guided toward the ground based holding mechanism in a 
hovering or floating condition, by the aerodynamically effective 
stabilizers 9B and rudder 9A of the tail unit 9 and the pivotable engines 
7 and 8. Then the holding cable 26 and therewith the hook 27 is lowered 
from the gondola floor by means of the winch 36 and then ground personnel 
latch the hook 27 into the cross-pin 40 which can be arranged recessed in 
the ground or in the mooring 37. 
The holding cable 26 is then reeled in by the winch 36 located on board, 
and the airship 1 is securely pulled to the ground against the thrust of 
the propellers until the two wheels 21 of the forward landing gear and the 
wheel of the rear landing gear rest on the ground. The pulling force of 
the winch 36 shall be greater than the maximum lifting or buoyant force of 
the airship 1 minus the weight of the airship or minus half of the upward 
directed thrust force of the pivotable engines 7, 8. The holding strength 
of the winch 36 and the cable 26 must be larger by a factor of 1.5 than 
the greatest arising tension force. 
The securing of the airship 1 on the ground can now be completed by an 
additional rigid connecting rod 42 whereby the airship is anchored against 
higher wind velocities. This is achieved in that the connecting rod 42 is 
tilted or folded down from the gondola floor until the clamping device 28 
can be pushed over the anchor or mooring 37 and be connected and secured 
thereto in the above described manner. The connecting rod 42 takes up the 
longitudinal and crosswise forces arising on the airship 1 and transmits 
them into the ground, while the holding cable 26 prevents a lifting off of 
the airship. Two universal joints 31 in the connecting rod 42 prevent 
undefined force transmissions. 
In this manner, a rigid connection of the airship 1 to the ground is 
accomplished and the two landing gear wheels 21, which provide support or 
bracing at far outward lying points, form a commonly rotating platform or 
turntable with the cross-pin 40 as a fixed center point. 
The airship 1 which is exposed to the wind, rotates about this center point 
depending on the wind direction (W1, W2) whereby the two landing gears 5 
support the airship 1 against rolling about its longitudinal axis 
(X-axis). The anchoring between the cross-pin 40 and a fixed point on the 
gondola floor thereby prevents a lifting off of the unloaded landing gear 
leg. 
Thereby, the tail landing gear 6 moves in a circle about this center point, 
as is shown in FIG. 11. In order to secure the tail of the airship against 
lifting off, ballast in the form of sand bags or the like can additionally 
be hanged in place. 
Other possible measures against lifting off of the tail of the airship are 
the active adjustment of the elevator fin 9B by an electronically 
controlled fin control system. Using a so-called mast function of the 
control, the wind direction can be automatically monitored and 
corresponding fin control motions can automatically be triggered which 
push the tail of the airship downward. 
An alternative of the attachment with the connecting rod is seen in FIG. 
12, wherein, a rotatable anchoring head 46 is secured to the anchor plate 
38A by an axial bearing 46A. The hook 27 of the anchoring cable 25 is 
hooked into the eye 44 and the connecting rod 42 is securely attached to a 
bearing point 47 by a journal pin 45 after the landing has been completed. 
An advantage of this embodiment is that the weight of the anchoring head 
46 does not have to be carried along during the flight. 
FIG. 13 shows a further alternative embodiment intended to be used for 
smaller airships having a limited lifting capacity. In this case, a winch 
36A is located in the ground based equipment. According to FIG. 13, 
similarly a rotatable anchoring head 50A is connected to an anchor or 
mooring 50B by an axial bearing 50C. A bearing point 51 for attaching the 
connecting rod 42 is provided on the rotatable anchoring head 50A in a 
manner identical to that described above. 
In FIG. 13 the cross-pin 40 and the eye 44 described above, have been 
replaced by a cable reel 52 and a winch 36A so positioned that the cable 
26 can be guided by the cable reel 52 onto the drum of the winch 36A. In 
this manner the flight weight of the airship 1 is still further reduced 
and the transportable useful load is further increasable. 
For this example embodiment, the landing and anchoring process will now be 
described. 
The holding or mooring cable 26 is thrown down through the gondola floor, 
after opening a floor hatch. A member of the ground crew connects the 
holding cable 26 with a laid out cable of the winch 36A which pulls the 
airship 1 to the ground. Now the connecting rod 42 is tilted down and 
connected to the anchoring head 50A by the bolt 45. If the airship 1 is 
now turned by the wind, then the winch 36A turns along with the airship. 
In all of the described example embodiments, the forces arising in the 
landing gear legs and from the anchor point on the gondola floor are 
directly transmitted into the triangular shaped bulkhead of the supporting 
frame structure lying above the gondola, and from there are transmitted 
further into the entire structure. 
Through aerodynamic calculations it has been verified that the loading due 
to a jolt or shock of landing on the front landing gear legs is of similar 
magnitude as the load arising in mooring or anchoring at a wind velocity 
up to about 7 on the Beaufort scale. 
The anchoring eye or pin on the ground must be properly adapted to the 
arising forces. The presence of such an anchoring eye must be taken into 
account for flight planning. 
In connection with the technical possibilities of an airship according to 
the German Patent Publication No. DE-PS 4,018,749, corresponding to U.S. 
Pat. No. 5,110,070 (Hagenlocher et al.) the described landing and 
anchoring mechanism offers the advantage of great simplicity. The ground 
personnel is reduced to two or three persons. Anchoring masts or mooring 
masts are only necessary at places where a long term mooring is to take 
place. Due to the already provided supporting structure, the additional 
weight necessary for the forward bi-pod landing gear is small. 
When the airship 1 is to be anchored or moored on a mast for long duration 
mooring or when stormy weather is forecast, the front wheels 21 are 
released or disengaged and rotated by 90.degree. about a vertical axis. 
The airship 1 is slightly lifted on the mast, so that only the tail 
landing gear 6 rests on the ground. The wheels 21 of the forward landing 
gear 5 now serve as rolling support or stabilizing brace. 
Although the invention has been described with reference to specific 
example embodiments, it will be appreciated that it is intended to cover 
all modifications and equivalents within the scope of the appended claims.