Aeronautics and astronautics – Aircraft structure – Load accommodation
Reexamination Certificate
2002-04-22
2003-03-18
Carone, Michael J. (Department: 3641)
Aeronautics and astronautics
Aircraft structure
Load accommodation
C244S137400
Reexamination Certificate
active
06533220
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for hanging a load on a helicopter, having at least one load-bearing cable which has a first cable section, which is off-center in relation to a longitudinal axis of the helicopter, and a second off-center cable section located opposite, the load-bearing cable being connected to the helicopter, on the one hand, and to the load, on the other hand.
Such a device is known from DE 196 23 562 A1. A further device of this type is known from DE 195 22 564 C2.
A device of the type mentioned at the outset generally serves for transporting a load hanging on a helicopter.
Within the context of the present invention, loads may be, for example, goods or baskets in which people are carried.
A specific application of such a device is that of transporting workers in a basket to overhead power transmission lines on which installation work or repairs have to be carried out or on which aviation signal balls are to be fitted. In the case of such overhead transmission-line work, the helicopter brings the basket with the workers to beneath the overhead transmission line and then raises the basket, a laterally projecting fork being arranged on the basket, with the result that the basket grips beneath the overhead transmission line by way of the fork. The helicopter then raises the basket until the basket is secured on the overhead transmission line with a certain amount of tensile stressing.
Examples of other possible uses of such a device are for transporting people to cooling towers, television towers, etc, in order to carry out work thereon, or using the arrangement for rescue purposes, for example in the event of fires in high-rise buildings, in the case of which a basket for carrying people has to be positioned in front of windows or balconies or on the building roof.
While the following description describes the invention in an application for overhead transmission-line work, it goes without saying that the present invention is nevertheless not restricted to this application. Such an arrangement may be used, in principle, for transporting loads, by means of a helicopter, to locations which can only be reached from the air or can be reached from the air more easily than from the ground.
A general problem with transporting hanging loads by helicopter is that the load tends to swing and rotate. In particular swinging of the load beneath the helicopter in the direction transverse to the longitudinal axis of the latter constantly changes the position of the center of gravity of the overall helicopter/load arrangement, which may result in critical flying situations. The helicopter pilot then has to compensate for such changes in the center of gravity.
In order to avoid swinging in the direction transverse to the longitudinal axis of the helicopter, DE 691 01 704 T2 describes a device which is intended for hanging a load on a helicopter and has two off-center load-bearing cables, the two load-bearing cables being fixedly attached to the helicopter by one end and to the load by the other end. Rotation of the load about the vertical axis is thus largely avoided. The tendency of the load to swing in the direction transverse to the longitudinal axis is also reduced in this way.
Since it is nevertheless the case that swinging of the load suspended on load-bearing cables cannot be prevented completely, this known device, having two separate lateral load-bearing cables, results, in the case of the load swinging in the direction transverse to the longitudinal axis, in load-changing forces acting abruptly on the helicopter because, as the load swings, one of the lateral load-bearing cables is essentially relieved of stressing, while the other load-bearing cable is abruptly subjected to stressing. Such abrupt changes in tensile force, however, may result in dangerous flying situations for the helicopter.
In order to avoid this, DE 196 23 562 A1 and DE 195 22 564 C2 have proposed a device of the type mentioned at the outset which has a crossmember which is fastened on the helicopter and extends transversely to the longitudinal axis of the helicopter. The crossmember has outer deflecting rollers, the load-bearing cable being guided over the deflecting rollers. The load-bearing cable has its free ends fixedly attached directly or indirectly to the load. Starting from the end attached to the load, the load-bearing cable thus runs by way of a first cable section, off-centrally in relation to the longitudinal axis of the helicopter, to the first deflecting roller on the crossmember, horizontally from there to the opposite, second deflecting roller of the crossmember and, from there, the second cable section then leads, once again off-centrally in relation to the longitudinal axis, back to the load, where the other end of the load-bearing cable is fixedly attached to the load.
The load-bearing cable can thus be moved relative to the crossmember and, accordingly, can be displaced along the crossmember relative to the helicopter.
Since, instead of two separate lateral load-bearing cables, one continuous load-bearing cable is used, abrupt changes in load force are avoided in the case of the load swinging.
However, this known arrangement is disadvantageous because the load-bearing cable can be displaced relative to the helicopter at the helicopter end. This is because it is not possible, by straightforward design means, for the load force acting on the load-bearing cable to be picked up from the load-bearing cable itself since, on account of the mobility of the load-bearing cable in the region of the helicopter, a corresponding load-measuring device cannot be integrated there. If a strain gauge were integrated in the load-bearing cable in the region of the crossmember, it would be constantly moving as well, as would the electric cabling by means of which such a force-measuring device is connected to display devices in the cockpit. Since, furthermore, for safety reasons, such a load-bearing cable has to be capable of being cut, for which purpose, in the case of the known device, at least one cutting device is provided on the load-bearing cable in the region of the crossmember, this would further mean, in the case of the load-bearing cable being cut, that the force-measuring device would be lost or damaged. In order to allow load-force measurement, it is thus provided, in the case of the known device, to suspend the crossmember itself on the helicopter by means of cables and to pick up the load force from these cables, although this is associated with increased outlay.
A further disadvantage of the known device is the crossmember itself, which, on account of its projecting dimensions, makes the installation of the device more difficult and, moreover, has a high dead weight, which results in the load which can be raised by the helicopter being reduced.
The object of the invention is thus to improve further a device of the type mentioned at the outset.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved, in respect of the device mentioned at the outset, in that ends of the load-bearing cable are fixedly attached to the helicopter, and in that the load-bearing cable is connected to the load in a manner in which it can be moved relative to the latter, such that the load can be displaced along the load-bearing cable.
In contrast to the known device, the load-bearing cable in the case of the device according to the invention is not itself of continuous design; rather, its ends, at the helicopter end, are fixedly attached to said helicopter. In contrast, the load-bearing cable is connected to the load such that the load can be displaced freely along the load-bearing cable, with the result that, in the case of the load swinging, abrupt changes in load force, which may adversely affect the flying stability of the helicopter, are avoided because both cable sections of the load-bearing cable are always kept under stressing. Since the load-bearing cable, however, is not itself of continuous configuration, this advantageously makes it possible for a
Carone Michael J.
ecms Aviation Systems GmbH
Semunegus Lulit
St. Onge Steward Johnston & Reens LLC
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