WO2007004018A1

WO2007004018A1 - A parachute

Info

Publication number: WO2007004018A1
Application number: PCT/IB2006/001794
Authority: WO
Inventors: Dominic Anthony Hayhurst
Original assignee: Parachute Industries Of Southern Africa (Proprietary) Ltd
Priority date: 2005-06-30
Filing date: 2006-06-29
Publication date: 2007-01-11
Also published as: ZA200800917B; EP1907282A1

Abstract

The invention relates to a parachute of which the canopy is configured in its deployed/inflated configuration to define an inner/upper segment (20) equivalent to that of a round inflated canopy and an outer/lower segment (22) equivalent to that of an annular inflated canopy. The ratio of the outer/lower segment inflated height (24) to the total inflated height (26) of the canopy and the porosity of the material forming the canopy are such that the rate of descent of a parachute having the canopy and the stability of the parachute, in terms of oscillation during descent, are determined to provide for optimum parachute safety.

Description

A PARACHUTE

THIS INVENTION relates to a parachute.

It is known that in relation to parachute design, the rate of descent of a parachute and parachute stability are major considerations. Parachute types in respect of which these considerations particularly apply include parachutes having a canopy referred to as a round inflated canopy and parachutes having a canopy referred to as an annular inflated canopy. A round inflated canopy, when inflated, defines a substantially round open lower end from which the suspension lines of the parachute extend, the effective diameter of the canopy decreasing from the said open lower end to the apex of the canopy. An annular inflated canopy, when inflated, also defines a substantially round open lower end from which the suspension lines of the canopy extend, the effective diameter of the canopy, however, first increasing from the said open lower end to a maximum diameter and then decreasing to the apex of the canopy, thus defining a annular space around the opening that is filled with air upon inflation and that distinguishes it from a round inflated canopy. In relation to the inflated height of the above canopies, which is the height of the canopies as measured from the plane defining the open lower ends of the canopies to the apices of the canopies, the height of a round inflated canopy conventionally is higher than that of an annular inflated canopy. For the remainder, insofar as the general design and construction of parachutes having canopies of the above type are well known, these aspects in relation to these parachutes are not described further herein.

It must be appreciated in the above regard that other design parameters that apply to the design of parachutes of the above types include the material content of the canopy of such parachutes which determines the outer dimensions of the canopy, the mass of the canopy material used and the size of the package into which a folded parachute, i.e. a parachute before deployment, can fit.

In relation to a parachute that has a round inflated canopy, it is known that a desired slow rate of descent can be achieved, but that due to the mode of air escape from the canopy, parachute stability in terms of oscillation is a problem. In relation to a parachute that has an annular inflated canopy, parachute stability in terms of oscillation is satisfactory, but rate of descent tends to be too fast.

Keeping in mind the abovementioned considerations and design parameters, it has been proposed for the design of a parachute canopy to provide a canopy that includes an inner/upper segment equivalent to that of a round inflated canopy and an outer/lower segment equivalent to that of an annular inflated canopy, thereby to provide a canopy for a parachute having a more acceptable relatively slow rate of descent and improved parachute stability i.e. lower oscillation upon descent. The above can be achieved either by forming the canopy of suitably formed material sections that are secured together and that will define the two segments upon deployment/inflation, or by linking a conventional round inflated canopy with the concept known as vent reefing whereby, with the aid of a set of vent reefing lines acting on the canopy at suitable locations, the canopy upon deployment/inflation is "formed" to define the segments. The results achieved in the above way, although resulting in "improved" parachute canopies, have not proven entirely satisfactory and, as such, it is an object of the present invention to provide a parachute having a canopy of the above proposed type and that is associated with further enhanced qualities in terms of rate of descent and parachute stability.

Any reference hereinafter to a parachute having a canopy that defines an inner/upper segment equivalent to that of a round inflated canopy and an outer/lower segment equivalent to that of an annular inflated canopy, must be interpreted as a reference to a canopy of the above described type and where the configuration is achieved in any one of the two described modes.

According to the invention there is provided a parachute that includes a canopy having an inner/upper segment equivalent to that of a round inflated canopy and an outer/lower segment equivalent to that of an annular inflated canopy, the ratio of the outer/lower segment inflated height to the total inflated height of the canopy being between 0,1 and 0,4 and the porosity of the material forming the canopy being between 20 and 60 cubic feet per minute (cfm).

The material porosity figure referred to particularly constitutes a figure as determined by the test standard commonly known as TEXTEST FX 3300.

According to a preferred embodiment of the invention, the ratio of the outer/lower segment inflated height to the total inflated height of the canopy is in the order of 0,268, whereas the porosity of the material forming the canopy is in the order of 40 cfm. It will be understood that both the above parameters can be greatly variable within the limits defined and the specific parameters will be determined by other design features to be associated with the parachute canopy, as well as application requirements of the parachute.

For a parachute, in accordance with the invention, in respect of which the outer/lower segment configuration is achieved by employing vent reefing lines, the parachute includes vent reefing lines that are secured to the canopy at a location defined by a circular line that defines the top level of the outer/lower segment of the canopy and at the lower end of the canopy, the vent reefing lines determining the configuration of the canopy and the circular line dividing the inner/upper segment of the canopy and the outer/lower segment of the canopy. The vent reefing lines particularly may extend from the lower end of the canopy to the point of confluence of suspension lines of the parachute, the suspension lines extending from the lower end of the canopy to a harness arrangement whereby the parachute is securable to the body of a person with the canopy folded in a package form that can be carried on the back of the person. Alternatively, the vent reefing lines may comprise extensions of suspension lines of the canopy that extend from the lower end of the canopy, the vent reefing lines extending from the lower end of the canopy to the circular line that defines the top level of the outer/lower segment of the canopy.

The final design of the parachute of the invention and, particularly, the parachute canopy, will take into account also other design parameters relevant to canopy design in terms of material content, mass, foldability into a package form, and the like.

Still further, the canopy of the parachute of the invention may define a vent opening at its apex and may define drive slots therein and have steering lines extending therefrom that, in use of the canopy, permit opening and closing of the drive slots for steering the canopy. The drive slots particularly permit "forward" displacement of the parachute during descent in order to enhance still further parachute stability. It will be appreciated that the configuration and design of the drive slots are greatly variable.

Further features of a parachute, in accordance with the invention, including an explanation of the features and clarification of the features, as well as benefits associated with these features, are described hereafter with reference two examples of parachutes, in accordance with the invention, that are illustrated in the accompanying diagrammatic drawings. In the drawings: Figure 1 shows a schematic perspective view of a first embodiment of a parachute, in accordance with the invention;

Figure 2 shows a detail of a segment of the parachute of Figurei ;

Figure 3 shows a schematic perspective view of a second embodiment of a parachute, in accordance with the invention;

Figure 4 shows a detail of a segment of the parachute of Figure 3;

Figure 5 shows in perspective view the configuration of an actual parachute of the type shown in Figure 3; and

Figure 6 shows a plan view of the canopy of the parachute as shown in Figure 5.

Referring initially to Figures 1 and 2 of the drawings, a first embodiment of a parachute, in accordance with the invention, is schematically shown and is designated generally by the reference numeral 10. The parachute 10 includes a canopy 12 of which the material configuration is essentially equivalent to that of a conventional conical canopy, i.e. a round inflated canopy. The canopy 12 has a set of suspension lines 14 (only two lines shown) extending from the operative open lower end 16 thereof, i.e. the end that defines the opening through which air enters the canopy upon deployment thereof. The suspension lines 14 all meet at a point of confluence which coincides with the location of a harness arrangement, or the like, whereby the parachute is harnessed to the body of a person and which is associated with a package within which the folded parachute can be located before deployment. In this regard the configuration of the canopy and the suspension lines of the parachute are essentially conventional.

The parachute 10 also includes a set of vent reefing lines 18 that extend from a location operatively above the lower end 16 of the canopy 12 and defined by a circle that lies in a plane parallel to the plane of the opening defined by the end 16 of the canopy, the vent reefing lines extending towards the point of confluence of the suspension lines 14 as described above and as illustrated, it being envisaged that the number of vent reefing lines 18 will be equal to the number of suspension lines 14, which in turn will be equal to the number of material segments that peripherally surround the opening of the canopy and hence form the canopy.

The effective length of the vent reefing lines 18 is such that the canopy 12, when inflated, is formed into a configuration in which the inner/upper segment 20, disposed operatively above the defined circle from which the vent reefing lines 18 extend, is equivalent to that of a round inflated canopy, whereas the outer/lower segment 22 disposed operatively beneath the said circle from which the vent reefing lines 18 extend, is equivalent to that of an annular inflated canopy.

As is clearly apparent from the drawings, the vent reefing lines 18 effectively provide for the maximum diameter of the canopy 12, which would ordinarily have been equal to the diameter of the opening defined at the lower end 16 of the canopy 12, to be increased substantially, thus providing the parachute 10 with improved parachute stability (lower oscillation) during its downward descent after its deployment.

In order to optimize parachute stability in this regard, the ratio of the operative vertical height of the annular segment 22, as indicated by the line 24, to the total inflated height of the canopy 12, as indicated by the line 26, must be between 0,1 and 0,4 and, optimally, must be in the order of 0,268.

In order to enhance still further the stability qualities of the parachute 10, the material forming the canopy has a porosity between 20 and 60 cfm and, preferably, a porosity in the order of 40 cfm. It will be understood in this regard that although the passage of air through the canopy material as a result of its porosity will increase the rate of descent of the parachute, a porosity between the figures indicated is considered an optimum porosity in order to optimize the rate of descent of the parachute 10 with its stability during descent.

It will be understood in the above regard also that the design of the parachute 10 and its canopy 12 will be associated with a conventional determination of other design parameters including material content, mass and foldability, it being submitted that the design of the parachute 10 in this regard is optimized, while the division of the canopy effectively into an inner/upper segment 20 and an outer/lower segment 22, provides the canopy with improved qualities in terms of rate of descent and parachute stability. Clearly, all the above parameters are greatly variable and the final design of the canopy of the invention will particularly be determined by operational requirements.

Referring now to Figures 3 and 4 of the drawings, a second embodiment of a parachute, in accordance with the invention, is schematically shown and is designated generally by the reference numeral 30. With like parts being designated by the same reference numerals as before, the parachute 30 again includes a canopy 12 that has suspension lines 14 extending from the operative open lower end 16 thereof, the canopy 12 again being effectively divided by vent reefing into an inner/upper segment 20 and an outer/lower segment 22, as described with reference to the parachute 10 as illustrated in

Figure 1 of the drawings. In this embodiment of the invention, vent reefing is achieved by the effective extension of the suspension lines 14, providing vent reefing lines 32 that extend merely from the lower end 16 of the canopy to the location indicated, the vent reefing lines 32 and the suspension lines 14 thus being effectively integrated with one another, while achieving the same height ratio as determined by the lines 24 and 26, as described above.

It is submitted that the parachute 30 is associated with the same benefits that are associated with the parachute 10 and, therefore, these are not described in further detail herein. In respect of both the parachutes 10 and 30, it is proposed to provide drive slots, e.g. slot formations, on one side of the canopy 12, thus providing for slight "forward" motion of the parachute during its descent which, it is submitted, can still further enhance parachute stability, i.e. provide for lower oscillation. Still further, the parachutes of the invention can be associated with any other features commonly associated with parachutes of the general type and the invention extends also to all such parachutes that incorporate the essential principles of the present invention. The material forming the canopies of the parachutes as described also is conventional, although clearly adapted to provide for the required optimum porosity to be associated with the canopies, as explained above. Alternatively, a specially designed material may be provided for forming the canopies of the parachutes of the invention.

Still further, instead of using the vent reefing concept for achieving the configuration of the canopy of a parachute, in accordance with the invention, it is envisaged that the same canopy profile can be achieved by the provision of suitably profiled canopy segments that are suitably secured/stitched together. The invention extends also to parachutes having canopies that are so formed.

Referring now particularly to Figures 5 and 6 of the drawings, an actual parachute of a type equivalent to the parachute as shown in Figures 3 and 4 of the drawings is illustrated and is designated generally by the reference numeral 40. With like parts again being designated by the same reference numerals as before, the parachute 40 includes a canopy 12 that has suspension lines 14 extending from the operative open lower end 16 thereof, the suspension lines 14 being secured to and extending from an anti- inversion net skirt 42 that defines the opening at the lower end 16 of the canopy 12. The net skirt 42 is of a reinforcing material that will avoid inversion of the outer/lower segment 22 of the canopy 12 upon deployment/inflation, while it serves at the same time as a support for the suspension lines 14. As for the parachute 30, vent reefing is achieved by the effective extension of the suspension lines 14, providing for vent reefing lines 32 (not clearly shown) extending from the lower end 16 of the canopy to a reinforcing band 44, the band serving as a reinforcing for the connection points of the vent reefing lines 32 of the canopy and dividing the inner/upper segment 20 and outer/lower segment 22 of the canopy 12. Clearly, the height ratio referred to in association with the parachutes 10 and 30 again applies, as does the material porosity figure.

As shown in Figure 6 of the drawings, the canopy 12 also defines a vent opening 46 at its apex, the vent opening, in addition to the porosity of the material forming the canopy

12, determining the flow rate of air through the canopy and, as such, the rate of descent of the canopy. Drive slots 48, associated with steering lines and as referred to above with reference to the parachute 30, also are provided on one side of the canopy 12, permitting slight "forward motion" of the canopy during descent, in order to enhance still further the stability qualities thereof.

As is clearly illustrated, the canopy 12 is formed of a plurality of material segments that are stitched together in a conventional manner with the aid of reinforcing tape, and the like, the general construction of the canopy 12 and generally of the parachute 14 thus being conventional and not being described further herein.

Claims

1. A parachute that includes a canopy having an inner/upper segment equivalent to that of a round inflated canopy and an outer/lower segment equivalent to that of an annular inflated canopy, the ratio of the outer/lower segment inflated height to the total inflated height of the canopy being between 0,1 and 0,4 and the porosity of the material forming the canopy being between 20 and 60 cubic feet per minute (cf m).

2. A parachute as claimed in Claim 1 , in which the said ratio of the outer/lower segment inflated height to the total inflated height of the canopy is in the order of 0,268.

3. A parachute as claimed in Claim 1 or Claim 2, in which the porosity of the material forming the canopy is in the order of 40 cfm.

4. A parachute as claimed in any one of the preceding claims, which includes vent reefing lines that are secured to the canopy at a location defined by a circular line that defines the top level of the outer/lower segment of the canopy and at the lower end of the canopy, the vent reefing lines determining the configuration of the canopy and the circular line dividing the inner/upper segment of the canopy and the outer/lower segment of a canopy.

5. A parachute as claimed in Claim 4, in which the vent reefing lines extend from the lower end of the canopy to the point of confluence of suspension lines of the parachute, the suspension lines extending from the lower end of the canopy to a harness arrangement whereby the parachute is securable to the body of a person with the canopy folded in a package form that can be carried on the back of the person.

6. A parachute as claimed in Claim 4, in which the vent reefing lines comprise extensions of suspension lines of the canopy that extend from the lower end of the canopy, the vent reefing lines extending from the lower end of the canopy to the circular line that defines the top level of the outer/lower segment of the canopy.

7. A parachute as claimed in any one of the preceding claims, in which the canopy defines a vent opening at its apex.

8. A parachute as claimed in any one of the preceding claims, in which the canopy defines drive slots therein and has steering lines extending therefrom that, in use of the canopy, permit opening and closing of the drive slots for steering the canopy.

9. A parachute as claimed in Claim 1 , substantially as herein described with reference to and as illustrated in the accompanying drawings.