Aeronautics and astronautics – Landing gear
Patent
1997-09-15
1999-08-31
Jordan, Charles T.
Aeronautics and astronautics
Landing gear
244101, 244107, B64C 2556
Patent
active
059442824
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a landing shock absorber for air loads or pilotless aircraft hereinafter both referred to as "aircraft", equipped with brake parachutes.
BACKGROUND OF THE INVENTION
In a known landing shock absorber of this type (DE 33 23 348 C2), the outer bag and inner bag are both formed from an airtight, plastically-deformable tubular sheet, with the two tubular sheets being inserted into one another, and the end of each sheet being reverse-drawn through the other end. Openings for the introduction of compressed gas into the inner and outer bag remain between the resulting four walls of the ends, which are reverse-drawn into one another; the degree of filling of the inner and outer bags can be set variably using valve elements. The ratio of gas inflations in the inner and outer bags is set as a function of parameters such as falling speed and weight of the air load or aircraft. The inner and outer bags can have different volumes.
In a landing shock absorber of this type, the landing shock damping is effected by the expansion of the cushion skins and the valves. This damping is relatively passive, so bouncing and toppling of the air load or aircraft during landing cannot be reliably precluded. Furthermore, lateral stability is relatively low upon impact.
SUMMARY OF THE INVENTION
It is the object of the invention to increase the lateral stability of a landing shock absorber of the type mentioned at the outset, and, at the same time, to reliably preclude toppling of the air load or aircraft. Moreover, the landing shock absorber is intended to be individually adaptable to its respective intended use, because its damping characteristic can be influenced simply, allowing it to achieve optimum function.
In accordance with the invention, the object is accomplished in a landing shock absorber for aircraft including brake parachutes and comprising a landing cushion for creating damping upon impact of the aircraft, the landing cushion having an inflatable inner bag including a pressure-tight, plastically deformable sheet. The inner bag defines a plurality of inflatable air chambers, and at least one opening between the chambers for establishing communication between the chambers. The landing cushion further includes an outer bag enclosing the inner bag and having a greater internal volume that an internal volume of the inflatable air chambers of the inner bag when the chambers are inflated, the outer bag including a tear-resistant fabric defining a plurality of throttle openings therein.
In the landing shock absorber of the invention, impact energy is essentially absorbed by the inner bag, which has multiple air chambers; the damping path can be determined by the extensibility of the inner bag sheet and the number of air chambers. Upon impact on the ground, the air chambers in the inner bag are tightly compressed, causing a specific overpressure to build up, which destroys the inner bag. The air exiting the air chambers is released in a defined manner via throttle openings in the outer bag, whereupon the overpressure is reduced in a controlled manner and with a time delay. This effects very good damping with a controllable damping path. The tightly-inflated air chambers of the inner bag offer high lateral stability during impact. The outer bag, which is slightly more expensive to produce, is made of a tear-resistant, tightly-knit fabric having throttle openings, and is up to 90% reusable, which helps to reduce operating costs.
The landing cushion (inner bag and outer bag) is simple to produce; only a (disk-shaped) cut of a fabric run is required, which is welded or stitched to form a balloon-like structure. The sheet or fabric is available commercially; the throttle openings are cut into the periphery, above the seam. The outer bag, whose volume is greater than the sum of all of the inflated air chambers of the inner bag, forms a sort of cylinder upon impact. The packing volume of the landing shock absorber is small, so complicated valves are not necessary.
Advantageous embod
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Clausnitzer Hans-Juergen
Schweren Johann
Dinh Tien
Jordan Charles T.
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