US3625461A

US3625461A - Load-landing device

Info

Publication number: US3625461A
Application number: US868018A
Authority: US
Inventors: Paul Francois Guienne; Paul Aime Lebargy
Original assignee: Bertin et Cie SA
Current assignee: Bertin Technologies SAS
Priority date: 1968-10-23
Filing date: 1969-10-21
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: DE1953413A1; GB1292329A; FR96031E

Abstract

A load-landing device wherein a load-carrying plate dropped from an aircraft carries underneath its lower surface substantially frustoconical inflatable bags which are carried in their turn by an intermediate plate provided with perforations through which the bags communicate with the inside of skirts depending from the intermediate plate. Thus when the device is dropped, the volume confined within the skirts is fed with air out of the bags so that the cushions formed within said confined volumes sustain the device and allow it to move over the ground as long as it has not collapsed completely, after which it can progress over the shoes incorporated with it.

Description

llnite States Patent 2,774,560 12/1956 Johnson Inventors Paul Francois Guienne Paris; Paul Aime Lebargy, Les Clayes-sous-Bois, both of France Appl. No. 868,018 Filed Oct. 21, 1969 Patented Dec. 7, 1971 Assignee BERTIN & Cie

T IFsh France Priority Oct. 23, 1968 France 171003 LOAD-LANDING DEVICE 7 Claims, 11 Drawing Figs.

US. Cl 244/138 R llnt. Cl 864d 1/08 Field of Search 244/ 100, l 3 8; l 8 8/ l 5 References Cited UNITED STATES PATENTS Primary Examiner-Milton Buchler Assistant E.raminer- Paul E. Sauberer Attorney-Stevens, Davis, Miller & Mosher ABSTRACT: A load-landing device wherein a load-carrying plate dropped from an aircraft carries underneath its lower surface substantially frustoconical inflatable bags which are carried in their turn by an intermediate plate provided with perforations through which the bags communicate with the inside of skirts depending from the intermediate plate. Thus when the device is dropped, the volume confined within the skirts is fed with air out of the bags so that the cushions formed within said confined volumes sustain the device and allow it to move over the ground as long as it has not collapsed completely, after which it can progress over the shoes incorporated with it.

'PATENTED nE-c new 3.625451 SHEET 2 UF 3 PATENIEMEE m. 3525461 SHEET 3 BF 3 LOAD-LANDING msvrcr:

In the US. Pat. No. 3,266,757 a device is described which is designed so as to damp the impact on a landing surface, such as the ground, of a load the downward speed of which has a vertical component of a few meters per second, this being in particular the case of a load released with a parachute or else at a low altitude without a parachute, this device cutting out the danger of a frictional contact with the ground leading to a turning round of said load. In said prior arrangement the plate carrying the load was provided with bags formed each by a deformable fluidtight wall connected on the one hand with said carrier plate and on the other hand with an intermediate plate or board the lower surface of which carries skirts defining with the ground chambers or spaces communicating with the corresponding bags through ports provided in said intermediate plate.

According to a particular feature of said device, any horizontal cross section of the bag has an area which is smaller than any horizontal cross section of the associated skirt.

Such a feature allows a preferential crushing of the bags rather than of the skirts to be obtained upon impact with the ground so that the fluid contained in said bags may escape into the sustaining fluid cushions in the skirts through the communication ports in the intermediate plate. The cross sections of the ports affording a passageway are gauged in a manner such that the pressure prevailing in the bag may rise up to a value sufficient for the desired vertical deceleration to be ensured.

Now according to our present invention, the coefficient of loss of head in the communication ports is such that, in an embodiment of the device including frustoconical or the like bags over also frustoconical confining spaces and for each of such a combination of a bag and confining space, the following is true:

s being the total area of the gauged ports S the area of the opening defined by the free lower edge of the skirt D the diameter of last-mentioned area h the height of the leak gap under the skirts S the area of the larger base of the frustocone defined by the bag.

According to a further feature of our invention, the arrangement of the bags and their shape allow the lateral relative movements of the plate carrying the load with reference to the intermediate plate to be limited. The axes of said bags which are for instance substantially cylindrical are parallel with the carrier plate or with the intermediate plate or again the bags may assume the shape of volumes the bases of which are defined by sections of a straight line extending in substantial parallelism and connected with each other by arcs of a circle the vertical transverse cross sections of said volumes assuming substantially the shape of isosceles trapeziums.

According to further features of our invention, the arrangement includes means for improving the expansion of the bags and possibly of the fluid-containing spaces within the skirts during the dropping of the load. Said means may be constituted by elastic members which are compressed as long as the intermediate plate is near the carrier plate or else by weights or fairings connected with the intermediate plate or with the confining shirts by gauged connecting members in a manner such that said different members break when the device is released after the bags have expanded.

In the accompanying drawings given by way of example:

F IG. 1 is a diagrammatic elevational view of a device incorporating the improvements according to the invention;

FIG. 2 is a cross section through line II-II of FIG. 1, on which the load has not been illustrated and which shows the condition of the bags before the impact with the landing surface;

FIG. 3 is a view similar to FIG. 2 illustrating the beginning of the stage during which the speed of descent of the load is braked and the device can move over cushions of a compressed fluid;

FIG. 4 is a view similar to FIG. 2, illustrating the end of the speed-damping stage;

FIGS. 5 and 6 are respectively a partial view similar to FIG. 2 and a partial view similar to FIG. 1, illustrating the engage ment of the device over the landing area through the agency of shoes;

FIG. 7 is a diagrammatic view from above of an embodiment of the device the carrier plate of which is not illustrated;

FIG. 8 is a partial sectional view through line VIII-VIII of FIG. 7;

FIG. 9 is a partial view similar to FIG. 8 showing modifications in the bags;

FIGS. 10 and 11 are views similar to FIG. 7 showing other arrangements for the bags.

Turning to FIGS. 1 to 6, the latter show a device including a load-carrying plate 1 underneath which there extends an intermediate plate or board 31 while bags 32 are fitted between the two

plates

1 and 31 and skirts 33 secured to the lower surface of the intermediate plate are directed towards the landing surface 34 on the ground. The bags and skirts may be executed for instance by means of a fabric covered by a fluidtight coat which is impervious for the fluid used and which may be constituted by a mixture having a base rubber or an elastomer. The shape of said bags and skirts may vary, but it is advantageously of revolution. The bags are advantageously of a substantially frustoconical shape, their larger base being rigid with the intermediate plate 31. Obviously however our invention is applicable as well with bags the shape of which is different and is for instance that of a section of a prism or a frustopyramid. The skirts 33 are advantageously frustoconical and stand in substantial coaxial relationship with the bags. Their larger upper base is also secured to said intermediate plate.

As more particularly apparent from inspection of FIG. 2, any cross section of a bag 32 is smaller than any cross section of the confining volume enclosed by the associated skirt 33. In other words, if S is the cross section of the smaller base of the frustocone defined by the skirt 33 and S, the cross section of the larger base of the frustocone defined by the corresponding bag it is possible to write down The spaces in the bags 32 and the volume enclosed by the skirts 33 communicate through openings 35 formed in the intermediate plate 31 is provided by a plate 36 showing ports 37 having a gauged cross section s2, the sum s of said cross sections being defined as a function of the weight of the load, of its speed of impact on the ground and of its desired vertical deceleration. However the coefficient defining the loss of head in the gauged ports 37 should be such that in each system including a frustoconical bag 32 and a frustoconical skirt 33 the following formula is satisfied where s is the total area of the gauged ports 37 (S=Zs2) S, the area of the circular bearing surface of the cushion defined by the free edge of the skirt 33 resting on the landing surface 34 D the diameter of said surface (s=(11'D )/(4) h the height of the leak gap left free by the skirt 33 over the landing surface 34 S the area of the larger base of the frustocone defined by by the bags 32.

The plate 36 may be removable whereby it is possible to select one of several such plates in which the sum s of the cross sections of the gauged ports 37 satisfies various conditions of operation as concerns the load, the speed of approach of the load towards the landing surface and the like, This makes it easier to adjust the coefficient of loss of pressure.

The expansion of the bags 32 and skirts 33 is obtained by reason of the actual weight of the device during the dropping of the latter. The intermediate plate 31 may also be connected through gauged connecting members 38 with a fairing such as 39 (FIG. 1). Said fairing encloses all the parts located underneath the plate 1 when the device is positioned on board an aircraft. When the device is released, the fairing 31 carries along with it towards the landing surface the intermediate plate 31, the carrier plate 1 being braked by the parachute. After expansion of the bags 32 the tensioning of the connecting members 38 rises beyond their breaking limit, which separates the fairing 39 from the remainder of the device.

If the time interval elapsing between the release of the device and the impact of the latter on the landing surface is small, more particularly in the case of a release of the load without any parachute off an aircraft flying at a low altitude auxiliary means may be resorted to. By way of example and as illustrated in FIG. 9, elastic members 50 may be inserted between the cooperating surfaces of the carrier plate 1 and of the intermediate plate 31 within the bags for instance. The device illustrated includes shoes 41 extending advantageously throughout the length of the underside of the carrier plate I. Said shoes 41 are secured to either side of the longitudinal axis of the device through the agency of the arms 42 which are rigid in their turn with the periphery of the carrier plate 1. The length of said arms 42 is such that the shoes engage the landing surface 34 only when the bags 32 and possibly the skirts 33 when no longer fed with fluid under pressure, have been sufficiently crushed as illustrated in FIGS. and 6 as a consequence of the exhaust of the fluid contained in the bags 32 and skirts 33, that is when no progression of the device can any longer be provided over cushions of compressed fluid. Said shoes further then the desired sliding movement of the device over the landing surface. Said shoes as apparent from inspection of the drawings are spaced with reference to the carrier plate 1 whereby the basis of the support is increased and the risks of turning over are reduced.

As apparent from FIGS. 7 to 11, the arrangement of the bags 32 and also their shape provides a limitation of the relative lateral movements of the carrier plate 1 with reference to the intermediate plate 31.

The bags 32 may be constituted by envelopes 43 closed at their ends and the shape of which is substantially cylindrical with an axis parallel with the carrier plate 1 and/or the intermediate plate 31 as illustrated in FIG. 8. The bags may also be given the shape of the volume 44 illustrated in FIG. 9, the bases of which are defined by sections of a straight line which are substantially parallel and interconnected by arcs of a circle, the vertical cross sections of said volume being substantially in the shape of an isosceles trapezium.

A number of the bags may be arranged in a manner such that their longitudinal planes cut one another. Thus the bags may be arranged in substantial parallelism with all sides of the carrier plate 1 and/or of the intermediate plate 31.

Said bags may be distributed in a substantially symmetrical relationship with reference to the medial planes of the

plates

1 and 31 as clearly shown in FIG. 7.

The bags may be advantageously distributed symmetrically with reference to an axis which is substantially perpendicular to the carrier plate 1 and/or to the intermediate plate 31. As also illustrated in FIGS. and 11, the longitudinal plane perpendicular to the carrier plate 1 and/or to the intermediate plate 31 of each of the bags may also extend through the volume defined by the adjacent bag.

It is possible to arrange bags of a substantially equal length in association with plates of a substantially square shape (FIG. 10) or else bags of unequal lengths in association with plates of any desired shape whatever as illustrated in FIG. 11.

The operation of the device is as follows:

Assuming it is dropped by an aircraft with or without a parachute (FIG. 1), the expansion of the bags and skirts is ensured by the parts described hereinabove. At the moment of the impact on the landing surface 34 (FIG. 3) and in accordance with the features of our invention the bags 32 are deformed before the skirts 33 in a manner such that the fluid carried in said bags escapes into the supporting cushions within the confining skirts. Said deformation has for its result a reduction in the inner volume of the bags and an increase in the pressure of the fluid carried in the bags, this depending quantitatively on the cross section of the gauged ports 37 forming passageways and leading to the obtention of the desired vertical deceleration. Throughout duration of the crushing of the bags, the device is adapted to move over the cushions of compressed fluid, which latter are formed in the skirts 33 and are fed by the fluid under pressure passing out of the gauged ports 37. As soon as the bags have been completely crushed and the skirts 33 are partly crushed because they are no longer fed with fluid under sufficient pressure, at such a moment the shoes 41 carry the device over the landing surface 34 which allows the device to continue if required its movement over said landing surface (FIGS. 5 and 6).

The material forming the intermediate plate 31 may show a sufficient yieldingness so as to absorb readily the stresses produced at the moment of the impact of the device on the landing surface 34 if the device is then not perfectly parallel with said surface. This is particularly the case when the load is released off an aircraft flying at a low altitude.

The intermediate plate 31 may be made for instance of veneer or of a thermoplastic material such as polyethylene.

We claim:

1. A load-landing device adapted to be released off an aircraft, comprising a load-carrying plate, at least one yielding substantially frustoconical fluid-containing bag fitted underneath the plate, a yielding substantially frustoconical fluidconfining skirt carried underneath and in vertical registry with each bag and terminating at its lower end with a free circular edge, throttled passageways connecting the inside of the skirt with the corresponding bag, the following unequalities being satisfied:

s being the total cross-sectional area of the gauged ports connecting the bag and corresponding skirt S the cross-sectional area defined by the said free circular edge of the skirt D the diameter of said circular edge h the height of the leak gap between the circular edge and the surface on which the device is dropped upon landing, which height is predetermined for a given load S the area of the larger base of the frustoconical bag.

2. A device as claimed in claim 1 comprising an intermediate plate extending underneath the bags and over the skirts and provided with a large opening between each bag and the corresponding skirt and an auxiliary removable plate covering each opening and incorporating the passageways connecting said bag with the inside of the corresponding skirt.

3. A device as claimed in claim 1 comprising an intermediate plate extending underneath the bags and over the skirts and incorporating passageways connecting said bags with the inside of the corresponding skirts and elastic members inserted between the load-supporting plate and the intermediate plate and urging said plates apart to further the expansion of the bags during the dropping of the device.

4. A device as claimed in claim 1 comprising an intermediate plate extending underneath the bags and over the skirts and incorporating the passageways connecting said bags with the inside of the corresponding skirts and elastic members inserted between the load-supporting plate and the intermediate plate and through each bag and urging said plates apart to further the expansion of the bags during the dropping of the device.

5. A device as claimed in claim 1, provided with a parachute, comprising a weight, gauged members securing said weight underneath the other parts of the device and adapted to break under a predetermined tensional stress while the device is being dropped and decelerated by its parachute.

6. A device as claimed in claim 1 provided with a parachute comprising a heavy fairing carrying and enclosing when at rest the other parts of the device, gauged members holding said fairing in position underneath said other parts during the dropping of the device and adapted to break under a predetermined tensional stress while the device is being dropped and decelerated by its parachute.

7. A device as claimed in claim 1, provided with a

Claims

1. A load-landing device adapted to be released off an aircraft, comprising a load-carrying plate, at least one yielding substantially frustoconical fluid-containing bag fitted underneath the plate, a yielding substantially frustoconical fluid-confining skirt carried underneath and in vertical registry with each bag and terminating at its lower end with a free circular edge, throttled passageways connecting the inside of the skirt with the corresponding bag, the following unequalities being satisfied: and S>S1 s being the total cross-sectional area of the gauged ports connecting the bag and corresponding skirt S the cross-sectional area defined by the said free circular edge of the skirt D the diameter of said circular edge h the height of the leak gap between the circular edge and the surface on which the device is dropped upon landing, which height is predetermined for a given load S1 the area of the larger base of the frustoconical bag.

7. A device as claimed in claim 1, provided with a parachute, comprising an intermediate plate extending underneath the bags and over the skirts and incorporating the passageways connecting said bags with the inside of the corresponding skirts, a fairing carrying and enclosing when at rest the other parts of the device, and gauged members securing the fairing to the intermediate plate to hold it in position underneath said other parts during the dropping of the device and adapted to break under a predetermined tensional stress while the device is being dropped and decelerated by its parachute.