GB2141079A

GB2141079A - Canopy loading system for ram air parachutes

Info

Publication number: GB2141079A
Application number: GB08404811A
Authority: GB
Inventors: Elek Puskas
Original assignee: Para Flite Inc
Current assignee: Para Flite Inc
Priority date: 1983-06-10
Filing date: 1984-02-23
Publication date: 1984-12-12
Also published as: AU2515884A; GB2141079B; GB8404811D0; FR2547274A1; FR2547274B1; DE3410871A1; AU547976B2

Abstract

An airfoil-shaped canopy (12) of a ram air inflated parachute (10) has load point attachments (40) spaced chordwise along all of the ribs (26) which internally separate the inflating air cells (28). Each load suspension line (16) extending from a payload riser (18) is connected through a load distributing system (38) to at least four canopy load points consisting of a chordwise spaced pair and a spanwise spaced pair of attachments to the canopy. <IMAGE>

Description

SPECIFICATION Canopy loading system for ram air parachutes This invention relates to forward gliding ramair inflated canopy parachutes of the type disclosed in U.S. Pat. No. 3,724,789 to Snyder, and more particularly to a load distributing system for the canopy of such parachutes.

Ram air inflated parachutes of the foregoing type have an airfoil-shaped canopy, the forward glide and load carrying characteristics of which depend on the maintenance of a relatively high lift/drag ratio which is adversely affected by distortion of the outer canopy surfaces from the ideal airfoil curvatures and by the drag of the load lines through which the payload is suspended from the canopy.

From experience, a canopy of a given size has been provided with an optimum number of load lines attached to the canopy at chordwise spaced load points designed to establish inflated canopy surfaces with acceptable distortion from the ideal airfoil lift curvature. Although less distortion from the ideal airfoil surface occurs with the use of more load lines, the drag is also increased so that some compromise is necessary.

It has also been found advisable to locate the chordwise spaced load point attachments of the load lines to the bottom surface of the canopy along the ribs which internally separate the canopy inflating air cells. Such air cells extend chordwise from the open intake at the leading edge of the canopy to the trailing edge. Thus, distortion from the ideal airfoil surface will occur along those ribs at which the load points are located. To minimize the number of load lines utilized and the drag associated therewith, heretoffore some of the rib locations on the bottom canopy surface are free of load point attachments. In this manner, a predetermined lift/drag ratio is achieved for the desired forward glide characteristic of any given size canopy and associated payload capacity.

It is therefore an important object of the present invention to provide a ram-air inflated, forward glide parachute having an unexpectedly large payload capacity.

Another object in accordance the foregoing object is to provide the ram air inflated parachute with an improved airfoil lift surface so as to maintain forward glide characteristics for larger payloads.

Yet another object of the invention is to provide a ram air inflated parachute with more than what was heretofore believed to be an optimum number of load lines in order to more reliably suspend heavier payloads.

In accordance with the present invention, canopy loading of a ram air inflated parachute of the type disclosed in U.S. Pat. No.

3,724,789, aforementioned, is applied to all of the air cell dividing ribs including the outer ribs or side panels of the canopy. Although the number of load suspension lines is thereby increased, such increase is minimized by use of a load distributing system through which loading is more evenly distributed amongst chordwise spaced load point attachments to the bottom surface of the canopy aligned along each of the ribs. Such distribution of loading is preferably limited to canopies designed with an even number of ribs or an odd number of air cells.

The load distribution system includes a first set of flexible force transmitting suspension branch lines secured at their upper ends directly to the canopy by each of the aforementioned load point attachments. Adjacent pairs of these branch lines, spaced chordwise according to one embodiment, are secured to each other at their lower ends by branch junctions spaced a predetermined distance below the inflated canopy. A second set of forcetransmitting, suspension branch lines are secured at their upper ends to the aforementioned junctions. Adjacent pairs of spanwise spaced branch lines of the second set are interconnected at their lower ends to primary load lines by junctions spaced further below the canopy according to said one embodiment. The primary load lines are connected as usual by a pair of risers to the payload harness.

As a result of the foregoing load distributing arrangement, each load line is connected to at least four canopy load point attachments. The chordwise spacing between such attachments and their locations along all of the ribs accounts for less deviation from the ideal chordwise airfoil curvature because of less load per canopy attachment to effect an aerodynamic improvement. A wider spanwise dimension for the canopy when inflated is achieved because of less spanwise distortion as a result of closer spanwise spacing of the canopy attachment points. The spanwise wider inflated canopy and the increased number of load lines provides a larger payload capacity. Forward glide at the glide lift/drag ratio despite the increased drag of more load lines should be maintained because of the improved aerodynamics of a canopy surface.

Figure 1 is a perspective view of a ram air inflated forward glide parachute embodying the canopy load distribution system of the present invention.

Figure 2 is a front elevation view of the parachute shown in Figure 1 in an inflated airborne condition.

Figure 3 is a partial side sectional view taken substantially through a plane indicated by section line 3--3 in Figure 2.

Figure 4 is a partial rear elevational view of the parachute shown in Figures 1-3.

Referring now to the drawings in detail, a ram air inflated, airfoil gliding type of parachute is shown, generally denoted by reference numeral 10. The parachute includes a flexible canopy 1 2 that is airfoil shaped when inflated. A payload 14 is shown suspended from the canopy in Figure 1 by a plurality of load suspension lines 1 6 connected through a pair of spanwise spaced risers 1 8 to the payload harness 20.

The canopy 1 2 includes a top panel surface portion 22 and a bottom panel surface portion 24 interconnected by a plurality of spanwise spaced ribs 26 which separate a plurality of air cells 28. The air cells extend chordwise of the canopy from an air intake opening at the leading edge portion 30 of the canopy to a trailing edge 32. At opposite spanwise end portions of the trailing edge, an array of connecting lines 34 connect the trailing edge to a pair of aerodynamic steering control lines 36.

The foregoing parachute 10 is generally well known, including its construction and operation. However, in accordance with the present invention, primary load suspension lines 1 6 are operatively connected to the canopy 1 2 by a load distributing system generally referred to by reference numeral 38 through which the canopy in its inflated airborne condition is loaded at a plurality of spaced load points on the bottom surface portion 24 along all of the ribs 26. The load distributing system is preferably limited to a canopy having aneven number of ribs 26 or an odd number air cells in order to more evenly distribute the payload loading along all ribs.

The load distributing system includes canopy load attachment means 40 of conventional or suitable form at each of the load points on the bottom portion of the canopy through which a plurality of flexible suspension branch lines 42 are directly connected to the canopy. Pairs of adjacent, chordwisespaced branch lines 42 are interconnected by branch junctions 44 spaced a predetermined distance below the airborne canopy. A second set of suspension branch lines 46 are provided, and adjacent, spanwise spaced pairs of such branch lines 46 are interconnected directly with the primary load suspension lines 1 6 by junctions 48 at locations spaced below the junctions 44 in the illustrated embodiment. The junctions 44 and 48 are formed by Nylon thread, for example.The branch lines 46 thus transmit loading between the primary load lines 1 6 and the junctions 44 to spanwise spaced locations on the canopy. The branch lines 42 and 46 may be made somewhat lighter than the load lines 1 6 since the load per branch line is reduced.

It will be apparent from the foregoing description that each load line 16 is connected by the load distribution system 38 to at least four load points by attachment means 40 on the canopy, thereby minimizing the increase in number of suspension lines to a value less than the increase in number of load points resulting from the loading of the canopy along all of the ribs. Nevertheless, an even distribution of loading amongst the increased number of load points on the canopy is achieved so as to reduce deviations of the canopy surface from the ideal chordwise airfoil curvature and also widen the spanwise width of the inflated canopy by reduced spanwise deviation. In view of such airfoil surface improvement and increase in spanwise width, the load capacity of a parachute 10 of a given dimension is increased above the heretofore expected amount. It is also believed that despite the increase in the number of load suspension lines associated with parachute 10 and the accompanied increased drag, as compared to parachutes of the same general type and dimension, the same lift/drag ratio is obtained because of the improved airfoil surface condition. Also, with the increased number of load lines, the load per line directly attached to the canopy is reduced so that cross-sectionally smaller lines may be utilized to minimize drag.

Claims

1. In a ram air inflated parachute having a flexible airfoil canopy internally formed with chordwise extending air cells separated from each other by spanwise spaced ribs, a plurality of load suspension lines loading the canopy when airborne in an inflated condition, and attachment means for connecting said load lines to the canopy at chordwise spaced locations along less than all of the ribs, the improvement residing in means for increasing the number of the chordwise spaced locations at which the load lines are connected to the canopy to reduce airfoil curvature deviation and maximize spanwise width of the canopy in the airborne inflated condition, including additional attachment means at chordwise spaced locations for connecting the load lines to the canopy along all of the ribs, and load distributing means interconnecting each of the load lines to the first mentioned and additional attachment means for distribution of the loading to all of the ribs.

2. The improvement as defined in claim 1 wherein said load distributing means includes a set of chordwise spaced pairs of branch lines, and a junction interconnecting each of said pairs of the branch lines, one of said sets of the branch lines being directly connected to the canopy by the attachment means, the other of the sets of the branch lines being connected between the load lines and said one of the sets by the junctions.

3. The improvement as defined in claim 1 wherein all of the attachment means are connected to the canopy at a plurality of chordwise spaced load points along each of said ribs for applying said loading on the canopy, and the load distributing means interconnect each of the load suspension lines to the attachment means at two pair of said load points adjacent to each other along two adjacent ones of the ribs of the canopy, whereby the loading is distributed to all of the ribs.

4. The improvement as defined in claim 3 wherein the force transmitting means includes a plurality of pairs of chordwise spaced branch lines, and a branch~ junction interconnecting each of said pairs of the branch lines.

5. The improvement as defined in claim 4 wherein the chordwise spaced pairs of the branch lines are directly secured to the canopy by the attachment means, and the spanwise spaced pairs of the branch lines are connected to those of the junctions interconnecting the chordwise spaced pairs of the branch lines, the other of the junctions being secured to the connectors being secured to the load suspension lines.

6. In the ram air inflated parachute defined in claim 3 having spanwise spaced risers to which a payload is attached and to which the suspension load lines are connected, said canopy including top and bottom surface panel portions extending chordwise between leading and trailing edges and interconnected by the ribs to form the chordwise extending air cells therebetween, the load distributing means of the improvement including first flexible branch lines attached to the canopy at each of said load points, first branch junctions interconnecting said branch lines in pairs at locations spaced from the canopy a first predetermined distance, second flexible branch lines connected to each of said first branch junctions, and second branch junctions interconnecting said second branch lines with the suspension load lines at locations spaced from the inflated canopy a second predetermined distance different from the first predetermined distance.

7. The improvement as defined in claim 6 wherein each of the load lines is connected to at least four of the load attachments on the canopy by the junctions and the flexible branch lines.

8. The improvement as defined in claim 7 wherein each of the pairs of the first branch lines are connected to the canopy at adjacent chordwise spaced load attachments.

9. The improvement as defined in claim 8 wherein the second junctions interconnect the second flexible branch lines in adjacent, spanwise-spaced pairs.

10. The improvement as defined in claim 9 wherein said second predetermined distance is greater than the first predetermined distance.

11. The improvement as defined in claim 6 wherein the second junctions interconnect the second flexible branch lines in adjacent spanwise-spaced pairs.

1 2. The improvement as defined in claim 6 wherein said second pre-determined distance is greater than the first predetermined distance.

1 3. A ram air inflated parachute constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.