GB2339410A

GB2339410A - Aerial control device

Info

Publication number: GB2339410A
Application number: GB8604536A
Authority: GB
Inventors: John Stephen Lingard
Original assignee: GQ Defence Equipment Ltd
Current assignee: GQ Defence Equipment Ltd
Priority date: 1985-02-25
Filing date: 1986-02-24
Publication date: 2000-01-26
Anticipated expiration: 2006-02-24
Also published as: GB2339410B; GB8604536D0; GB8504769D0

Description

2339410 AERIAL CONTROL DEVICE The present invention relates to aerial

control devices for controlling the aerial path of a load in which a canopy is attached to the load to form an aerial load assembly in which, in use, the canopy inflates and takes up a trailing disposition in relation to the load.

As is well known, general purpose parachutes simply control the rate of descent of a parachutist without - providing any directional control. Where directional control is required a driving parachute is used in which the canopy is so constructed and arranged as to produce in response to aerial movement of the canopy a driving component force on the canopy transverse to-the direction of air flow relative to the canopy. The direction of the driving component force is determined by the direction of orientation of the canopy and the parachute is steered by providing control lines attached to the canopy and manipulated by the parachutist.

Parachutes are of course widely used simply for controlling the descent of stores and equipment discharged from supply aircraft. Use is made of parachutes of particular construction for that purpose but they do not have directional control features. Indeed, the driving parachute used by parachutists would if used for controlling the descent of stores and equipment have no means of steering it and its use would be more of a hazard than an advantage.

2 It is one object of the present invention to provide a driving parachute which can be used to advantage in controlling the aerial descent of loads such as stores and equipment. 5 In the discharge of aerial loads, such as stores and equipment, from aircraft flying at low level and high speed it has been found difficult using conventional parachutes to decelerate the loads to the correct ground impact speed and give the load the correct impact orientation since the flight time of the load is usually found to be too short. A method of overcoming this difficulty is to deploy from the discharged load, as a first stage, a lifting parachute, which has the characteristics of a driving parachute and which after release of the load from the aircraft inflates and lifts the load above the aircraft flight path, thereby providing for a main parachute deployed as a second stage an increase in descent altitude and an increase in the time available to decelerate the load to a desired impact speed and orientate it to a desired angle of impact with the ground. Whilst such lifting parachutes have been constructed and used successfully they have essentially neutral roll characteristics and slight imperfections in the manufacture of the canopy can lead to rolling moments which result in the load being driven sideways or downwards rather than in the required upward direction.

It is a further object of the present invention to provide a lifting parachute which does not suffer from the above-mentioned disadvantage.

i According to the present invention there is provided an aerial control device for controlling the aerial path of a load, comprising a driving canopy for attac - hment to the load to form an aerial load assembly in which the canopy inflates and in an aerial movement of the assembly takes up a trailing disposition in relation to the load, the driving canopy being so constructed and arranged as to produce in such aerial movement a driving component force on the canopy transverse to the direction of air flow relative to the canopy and in a driving direction determined by the direction of orientation of the canopy in roll, thereby to produce a modification of the aerial path of the assembly in which a transverse component of air flow relative to the canopy is produced or maintained, and canopy roll control means responsive to the transverse component of relative air flow to maintain the canopy in a predetermined direction of orientation in roll relative to the transverse component of relative air flow.

In all of the embodiments of the invention hereinafter to be described, the canopy roll control means take the form of one or more control panels arranged symmetrically with respect to a plane of symmetry which contains the roll axis of the canopy and which lies in the driving direction of the canopy. The control panel or panels then present to the transverse component of the relative air flow areas which create a restoring couple about the roll axis of the canopy to restore the canopy to its driving direction following a deviation therefrom.

4 In a first embodiment of the invention hereinafter to be described, two planar canopy roll control panels are provided which are arranged on opposite sides of the plane of symmetry and are so mounted in relation to the canopy as to extend away from the roll axis of the canopy in directions inclined to each other and inclined at equal angles and in opposite directions to the plane of symmetry.

In a second embodiment of the invention hereinafter to be described a single arcuate canopy roll control panel is provided which extends on each side of the plane of symmetry and symmetrically with respect thereto while in a third embodiment of the invention two arcuate control panels are provided which are arranged in spaced relation on opposite sides of the plane of symmetry. In a fourth embodiment hereinafter to be described a single planar canopy roll control panel is provided which lies in the plane of symmetry.

The aerial control device according to the invention may with advantage be used to provide lift for a parachute assembly controlling the aerial descent of a load discharged from an aircraft flying at low level and high speed. For this purpose, the device is used to produce an initial ascent of the assembly following its discharge from the aircraft. Preferably, the device is deployed as a first stage to bring the assembly discharged from the aircraft to an increased altitude at which a main parachute of the assembly is then deployed as a second stage to control aerial descent of the load to ground level. To provide maximum lift, the canopy roll control panel or panels are so disposed in relation to the driving direction of the canopy as to maintain the driving component force on the canopy in opposition to the transverse component of relative air 5 flow.

In order for the canopy-of the device to withstand loads imposed upon it at high discharge speeds, the canopy is preferably formed by a plurality of gores each of which is formed by a plurality of spaced ribbons which extend across the gore in spaced parallel relationship and which are so spaced apart from each other as to provide high porosity gores, and the driving component force on the canopy is created by the provision of one or more gore areas of nil porosity.

Where the device according to the invention is employed in a parachute assembly for controlling simply the aerial descent path of a load and where no undue deceleration forces are placed on the assembly following discharge from an aircraft, the canopy may be formed by a plurality of gores all of which are constructed from a nil porosity fabric apart from one or more gore areas of high porosity, the driving component force being created by the provision of the gore areas of high porosity.

Where the canopy of the aerial control device according to the invention is employed as a driving canopy in a parachute assembly used simply for controlling the aerial descent path of a load the canopy roll control panel or panels may with advantage be used to modify the final descent phase of the assembly. Where the 6 control panels are so disposed in relation to the driving direction of the canopy that the driving component force on the canopy acts into the transverse component of relative air flow, the control panels automatically direct the driving canopy into a prevailing wind for landing to compensate to some extent for wind speed and to minimise the speed of the load over the ground at impact. A parachute assembly having a driving canopy with panels so disposed would be found particularly advantageous in the final descent phase of a parachutist who is unconscious or otherwise incapacitated and unable to steer his driving parachute by manipulating the control lines provided on the parachute.

For other purposes, a driving parachute assembly may be provided in which the driving canopy is provided with control panels so disposed that the driving component force acts out of the relative air flow. in this configuration, the driving canopy produces a driving component force in the same direction as a prevailing wind and gives rise to a high horizontal velocity component of the load relative to the ground. Advantage could be taken of a driving parachute assembly so constructed to achieve maximum distance of travel over the ground during aerial descent of the load.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in.which:- I Fig. 1 is a schematic side view of a lifting parachute according to a first embodiment of the invention, Fig. 2 is a schematic end view of the lifting parachute 5 shown in Fig. 1, Fig. 3 is a diagram showing canopy roll control panels of the lifting parachute shown in Figs. I and 2 in a roll disposition in which they are stabilised into the transverse component of relative air flow, Fig. 4 is a diagram corresponding to that of Fig..3 and showing the canopy roll control panels in a roll disposition inclined to the transverse component of relative air flow, Fig. 5 is a schematic diagram of the trajectory of an aerial load discharged from an aircraft under the control of a lifting parachute, Figs. 6 and 7 are schematic side and end views of a lifting parachute according to a modification of the first embodiment of the invention, Figs. 8 and 9 are schematic side and end views of the lifting parachute according to a second embodiment of the invention, Fig. 10 is a diagram showing the canopy roll control panel of the lifting parachute illustrated in Figs. 8 and 9 in a roll disposition in which it is stabilised into the relative air flow, Fig. 11 is a diagram corresponding to that of Fig. 10 and showing the canopy roll control panel in a roll disposition inclined to the relative air flow, Figs. 12 and 13 are schematic side and end views of a lifting parachute according to a third embodiment of the invention, Figs. 14 and 15 are schematic side and end views of a lifting parachute according to a fourth embodiment of the invention.

Fig. 16 is a schematic perspective view of a driving parachute for controlling the descent of an aerial load in accordance with a fifth embodiment of the invention.

Fig. 17 is a schematic side view of part of the driving para chute shown in Fig. 17, and Fig. 18 is a schematic end view from below of the driving parachute shown in Fig. 17.

Referring first to Fig. 1, the lifting parachute shown comprises a canopy 11 having a plurality of gores 12 joined together along main seam lines 13. Each of the gores 12 is formed by a plurality of ribbons 14 which extend across the gore in spaced parallel relationship and are so spaced apart from each other as to provide a high porosity gore. The ribbons 14 may be made from a nil-porosity nylon fabric or from a material sold under the trade name "Kevlar". In the region of the periphery of the canopy, an area of nil porosity is I 9 - formed bya lining panel 16 of a nil porosity nylon fabric which is mounted as a lining to the ribbons 14 in this region,with the area lined by the pan-el 16 extending round the canopy so as to include several 5 adjacent gores.

In the canopy 11, twelve gores only are shown for illustration purposes, with gores Nos. 1,2,11 and 12 containing the area lined by the panel 16. For some 'applications a canopy of larger dimensions may be required. The number of gores may then correspondingly be increased and the lined area also increased as required.

Rigging lines 170 to 181 are secured at the periphery of the canopy 11 to the main seams 13 and are brought together at their other ends for connection to a riser assembly point 18 of a support harness (not shown) used for securing the canopy to the load. In addition, there is further provided a central rigging line 19 which extends from the apex of the canopy to the riser assembly point 18 along the central roll axis of the canopy.

As best seen in Fig. 2, two canopy roll control panels 20 and 21 are connected at their outer ends to rigging lines 174 and 178 and at their inner ends to the central rigging line 19 which is held on the central axis of the canopy by the panels 20 and 21 and by tie cords 23 and 24 connected between the central rigging line 19 and the rigging line 170. The roll control panels 20 and 21 which are of identical shape and size are made from a nil porosity nylon fabric and are held under tension between-the outer rigging lines 174 and 178 and the central rigging line 19 by the tie cords 23 and 24.

The lifting parachute illustrated in Figs. 1 and 2 can advantageously be used to impart lift to an aerial load discharged from an aircraft flying at low level and high speed and for this purpose is deployed as a first stage to bring the discharged load to an increased altitude at which a main parachute is deployed, as a second stage, to control descent of the lo ad to the ground. A typical trajectory for a load discharged in this way and controlled by a lifting parachute and a main parachute is illustrated in Fig. 5, which shows an is initial falling trajectory A following discharge of a load 27 from an aircraft 28 and during deployment of a lifting parachute 29, followed by a rising,trajectory B produced by the lift from the lifting parachute 29 and followed in turn by a descent trajectory C where descent of the load 27 is controlled by a main parachute 10.

it is well known that provision of panels of different porosities in a driving parachute gives rise to a driving component force transverse to the direction of air flow relative to the canopy. Where the lifting parachute of Figs. 1 and 2 is used as the lifting parachute 29 of Fig. 5 and is deployed behind the load 27 discharged from the aircraft 28, the canopy 11 inflates behind the load 27 with the relative air flow substantially parallel to the roll axis of the canopy 11. Provided the load 27 with its parachute assembly is so discharged from the aircraft 28 that the canopy 11 is deployed with the area lined by the panel 16 uppermost, the driving canopy 11 becomes subjected to a driving component force upwards and causes the load 27 to follow the rising trajectory B shown in Fig. 5. The driving canopy 11 in addition to providing lift decelerates the load 27 and a point in the trajectory is reached where the load 27 has reached its maximum altitude and has been decelerated to a speed at which the main parachute 10 can safely be deployed, the characteristics of the main parachute 10 being so chosen that the load is decelerated to a desired impact speed and impacts with the ground at a desired angle of impact.

It will however be appreciated that the driving canopy 11 provides lift only if it is deployed in the correct roll attitude following discharge of the load 27 from the aircraft 28. Furthermore, to provide maximum lift the roll attitude at deployment must be maintained to achieve maximum altitude for the deployment of the main parachute 10.

Control panels 20 and 21 are provided, as shown in Figs. 1 and 2, to roll stabilise the canopy 11 into the air flow relative to the canopy so that once lift is produced the direction of lift is maintained by the stabilising effect of the panels 20 and 21 on the canopy 11.

A simplified explanation of the action of the roll control panels 20 and 21 on the driving canopy 11 may conveniently be made by reference to Figs. 3 and 4 which are end view diagrams of the canopy 11 trailing the load 27 and following discharge of load 27 from the aircraft 28. As will be seen, the control panels 20 and 21 are arranged at equal angles to the driving direction of the canopy indicated by the arrow D. As lift in the canopy 11 is developed a downward component force E created by relative air flow transverse to the canopy 11 applies equal downwardly directed forces on the two panels 20 and 21 in the initial deployed disposition shown in Fig. 3. If, as a'result of some slight manufacturing imperfection of the canopy 11, the canopy 11 has a tendency to roll clockwise as illustrated diagrammatically in Fig. 4, the force on the panel 20 becomes greater than that on the panel 21 and produces a restoring couple on the canopy 11 about the roll axis R of the canopy 11 to bring the two panels 20 and 21 and the canopy 11 back to the disposition shown in Fig. 3. Conversely, if the canopy 11 has a tendency to roll in a counterclockwise direction a clockwise restoring couple is produced to return it to the disposition shown in Fig. 3.

In a modification of the first embodiment of the invention illustrated in Figs. 6 and 7, the lifting parachute shown is formed by a canopy 11 of the same form as the canopy described with reference to Figs. 1 and 2, with rigging lines 170 to 181 and the central rigging line 19 arranged in the same manner as the rigging lines in Fig. 1. The canopy roll control panels 30 and 31 are however mounted within the canopy 11 where they are connected at their outer ends to the canopy 11 and at their inner ends to the central rigging line 19, which is held in position on the roll axis of the canopy by tie cords 25 and 26 connected between the central rigging line 19 and one of the main seams 13 of the canopy 11.

The control panels 30 and 31 of the lifting parachute shown in Figs. 6 and 7 roll stabilise the canopy 11 in the same manner as the control panels 20 and 21 of the lifting parachute shown in Figs. 1 and 2.

In the second embodiment of the invention illustrated in Figs. 8 and 9 the lifting parachute shown is formed by a canopy 11 of the same form as the canopy described with reference to Figs. I and 2. The canopy roll control panels 20 and 21 of the Fig. 1 arrangement are however replaced by a single arcuate roll control panel 40 located in the region of the skirt of the canopy 11 on the side thereof opposed to the lining panel 16 and extending between rigging lines 175 and 177.

The action of the roll control panel 40 in the lifting parachute shown in Figs. 8 and 9 is illustrated in Figs. 10 and 11. As will be seen from Fig. 10, the control panel 40 extends through equal angles to each side of the driving direction D of the canopy. As lift in the canopy 11 is developed a downward component force E created by relative air flow transverse to the canopy 11 applies equal downwardly directed forces on the two sides of the canopy 40 in the initial deployed disposition shown in Fig. 10. Any tendency for the canopy 11 to roll clockwise as illustrated in Fig. 11 causes the relative air flow E to produce a restoring couple on the canopy 11 about the roll axis R and bring the panel 40 back to the disposition shown in Fig. 10. Conversely if the canopy 11 has a tendency to roll in a counterclockwise direction a clockwise restoring couple is produced to return it again to the disposition shown in Fig. 10.

In the third embodiment of the invention illustrated in Figs. 12 and 13, the lifting parachute shown is again formed by a canopy 11 of the same form as the canopy described with reference to Figs. 1 and 2. The canopy control panels 20 and 21 of the Figs. 1 and 2 arrangement are however replaced by arcuate control panels 50 and 51 located as shown in the region of the skirt of the canopy 11, with the panel 50 being connected to and extending between the rigging lines 171 and 173 and the panel 51 connected to and extending 15. between the rigging lines 179 and 181. Clearly, the control panels 50 and 51 act to roll stabilise the canopy 11 into the relative air flow E so that once lift is produced the direction of lift is maintained.

In the fourth embodiment of the invention illustrated in Figs. 14 and 15 the lifting parachute shown is similarly formed by a canopy 11 of the same form as that described with reference to Figs. 1 and 2. The canopy roll control panels 20 and 21 of the Figs. 1 and 2 arrangement are however replaced by a single roll control panel 60 located within the canopy 11 in the region of the skirt portion and connected to and extending between the central rigging line 19 and the rigging line 176. As with the other embodiments of the invention hereinbefore described, any tendency for the canopy 11 to move out of its initial driving direction D is opposed by the restoring force applied to the panel 60 by the relative air flow E.

Referring now to Figs. 16 to 18, a driving parachute according to the fifth embodiment of the-invention is shown, which is employed for use in controlling the aerial descent path of a load 110. The canopy 111 is formed by twenty gores 112 joined together along main seam lines 113 and sub-divided by cross seams 114 into panels 115, all of which are made from nil porosity nylon fabric apart from two sets of four driving panels 116 which are made from close mesh nylon fabric net having a high porosity. Rigging lines 210 to 219 are secured to the periphery of the canopy 111 at alternate seam locations and are brought together at their other ends for connection to a-riser assembly 118 of a support harness 128 supporting the load 110. In addition, there is further provided a central rigging line 119 which extends from the apex of the canopy Ill to the riser assembly 118 along the roll axis of the canopy 111. Two control panels 120 and 121 are connected at their outer ends to rigging lines 214 and 216 and at their inner ends to the central rigging line 119 which is held on the central axis of the canopy by tie cords 123 and 124 connected between the central rigging line 119 and a further rigging line 210. The roll control panels 120 and 121, which are of identical shape and size, are made from nil porosity nylon fabric and are held under tension between the outer rigging lines 214 and 216 and the central rigging line 119.

The control panels 120 and 121 control the roll orientation of the canopy Ill in the same manner as the control panels 20 and 21 of the lifting parachute described with reference to Figs. 1 and 2.

In Fig. 16, the driving parachute is shown descending at a predetermined rate and advancing toward the viewer with the canopy oriented with the driving panels 116 in a trailing disposition as shown. With zero wind speed relative to the ground the control panels 120 and 121 are subjected to aerodynamic forces created solely by the relative air flow resulting from the horizontal driving velocity of the canopy 111. In the manner previously described with reference to Figs. 3 and 4, the control panels 120 and 121 will roll stabilise the canopy Ill into a straight line descent path. Where a prevailing wind relative to the ground is experienced, the control panels 120 and 121 will turn the canopy 111 so that the canopy driving component force is in opposition to the horizontal force on the canopy 111 developed by the prevailing wind, thereby minimising the speed of the load 110 over the ground at impact.

With a driving parachute for use by a parachutist, the parachutist is, of course, able to control the driving direction of the canopy by appropriate manipulation of control lines and would with adverse prevailing wind conditions normally direct the parachute into wind to reduce his horizontal speed over the ground at impact.

Where the driving parachute is used for pilots.following ejection from an aircraft in an emergency, the'pilot may be unconscious or otherwise incapacitated and unable to control the driving direction of the parachute prior to impact with the ground and a driving parachute supplied for pilot use could with advantage embody control panels as described with reference to Figs. 16 to 18 so that the parachute of the 17 incapacitated pilot would automatically be brought into wind to produce a minimum horizontal velocity impact.

For some applications, where possibly a maximum horizontal driving range is desirable in the controlled descent of an aerial load or a parachutist, the control panels 120 and 121 of the driving parachute illustrated in Fig. 16 may with advantage be inclined away from the central rigging line in a direction opposite to that shown so that the canopy 111 is roll stabilised out of the relative wind with the driving component force on the canopy 111 acting in the same direction as the prevailing wind.

18

Claims

1. An aerial control device for controlling the aerial path of a load, comprising a driving canopy for attachment to the load to form an aerial load assembly in which the canopy inflates and in an aerial movement of the assembly takes up a trailing disposition in relation to the load, the driving canopy being so constructed and arranged as to produce in such aerial movement a driving component force on the canopy.transverse to the direction of air flow relative to the canopy and in a driving direction determined by the direction of orientation of the canopy in roll, thereby to produce a modification of the aerial path of the assembly in which a transverse component of air flow relative to the canopy is produced or maintained, and canopy roll control means responsive to the transverse component of relative air flow to maintain the canopy in a predetermined direction of orientation in roll relative to the transverse component of relative air flow.

2. A device according to claim 1, wherein the canopy roll control means comprises one or more control panels arranged symmetrically with respect to a plane of symmetry which contains the roll axis of the canopy and which lies in the driving direction of the canopy and wherein the control panel or panels present to the transverse component of the relative air flow areas which create a restoring couple about the roll axis of the canopy to restore the canopy to its driving direction following a deviation therefrom.

3. A device according to claim 2, wherein two canopy roll control panels are provided which are arranged on opposite sides of the plane of symmetry.

4. A device according to claim 3, wherein the control panels are planar panels and are so mounted in relation to the canopy as to extend away from the roll axis of the canopy in directions inclined to each other and inclined at equal angles and in opposite directions to the plane of symmetry.

5. A device according to claim 4, wherein the control panels are arranged to extend between circumferentially spaced rigging lines extending from the periphery of the canopy and a central rigging line extending from the canopy along the roll axis of the canopy.

6. A device according to claim 4, wherein the control panels are located within the canopy and extend between circumferentially spaced points on the inner surface of the canopy in the region of its periphery and a central rigging line on the roll axis of the canopy.

7. A device according to claim 2, wherein two arcuate control panels are provided which are arranged in spaced relation on opposite sides of the plane of symmetry.

8. A device according to claim 7, wherein the arcuate control panels are arranged in the region of - the skirt of the canopy and extend between spaced rigging lines extending from the skirt of the canopy.

9. A device according to claim 7, wherein the control panels are located within the canopy and in the region of the skirt of the canopy.

10. A device according to claim 2, wherein a planar canopy roll control panel is provided which lies in the plane of symmetry.

11. A device according to claim 10, wherein the control panel lies within the canopy in the region of the skirt of the canopy and extends from the canopy to a central rigging line extending along the roll axis of the canopy.

12. A device according to claim 2, wherein an arcuate canopy roll control panel is provided which extends on each side of the plane of symmetry and symmetrically with respect thereto.

13. A device according to claim 12, wherein the arcuate control panel is arranged in the region of the skirt of the canopy and extends between spa6ed rigging lines extending from the skirt of the canopy.

14. A device according to any of claims 1 to 13, wherein the or each canopy roll control panel is of a flexible material.

15. A device according to any of claims I to 14, wherein the'canopy is so constructed and arranged with regions of different porosities as to produce the driving component force.

16. A parachute assembly for controlling the aerial descent of a load including a device according to any of claims I to 15 and load support means connected thereto for support of a load.

17. An assembly according to claim 16, for controlling the aerial descent of a load discharged from an aircraft flying at low level and high speed, and wherein the aerial control device is provided to produce an initial ascent of the assembly following its discharge from the aircraft.

18. An assembly according to claim 17, wherein the canopy is formed by a plurality of gores each of which is formed by a plurality of spaced ribbons which exte nd across the gore in spaced parallel relationship and which are so spaced apart from each other as to provide high porosity gores, and wherein the driving component force on the canopy is created by the provision of one or more gore areas of nil porosity.

19. An assembly according to claim 18, in which the aerial control device is, in use, deployed as a first stage to bring the assembly discharged from the aircraft to an increased altitude at which a main parachute of the assembly is then deployed as a second stage to control aerial descent of the load to ground level.

22 - 20. An assemblyaccording to claim 16, wherein the canopy is formed by a plurality of gores all of which are formed from a fabric of nil porosity apart from one or more gore areas of high porosity, and wherein the driving component force is created by the provision of the gore areas of high porosity.

21. An assembly according to claim 16, wherein the canopy when inflated takes the form of an aerofoil and the driving component force is generated by virtue of the aerodynamic characteristics of the aerofoil canopy.

22. An assembly according to claim 20 or 21, wherein the canopy roll control panel or panels is or are so disposed in relation to the driving direction of the canopy as to maintain the driving component force on the canopy in opposition to the transverse component of relative air flow.

23. An assembly according to claim 20 or 21, wherein the canopy roll control panel or panels is or are so disposed as to maintain the driving component force in the same direction as the transverse component of relative air flow.

24. A lifting parachute substantially as hereinbefore described with reference to Figs. 1 to 4, Figs. 6 and 7, Figs. 8 to 11, Figs. 12 and 13 or Figs. 14 and 15 of the accompanying drawings.

i 25. A driving parachute substantially as - - I hereinbefore described with reference to Figs. 16 to 18 of the accompanying drawings.

e212- Amendments to the claims have been filed as follows 1. An aerial control device for controlling the aerial path of a load, comprising a driving canopy for attachment to the load to form an aerial load assembly in which the canopy inflates and in an aerial movement of the assembly takes up a trailing disposition in relation to the load, the driving canopy being so constructed and arranged as to produce in such aerial movement a driving component force on the canopy transverse to the direction of air flow relative to the canopy and in a driving direction determined by the direction of orientation of the canopy in roll, thereby to produce a modification of the aerial path of the assembly in which a transverse component of air flow relative to the canopy is produced or maintained, and one or more control panels arranged symmetrically with respect to a plane of symmetry which contains the roll axis of the canopy and which lies in the driving direction of the canopy, the control panel or control panels including at least a portion thereof in said plane and presenting to the transverse component of the relative air flow areas which create a restoring couple about the roll axis of the canopy to restore the canopy to its driving direction following a deviation therefrom.

2. A device according to claim 1, wherein the control panels are planar panels and are so mounted in relation to the canopy as to extend away from the roll axis of the canopy in directions inclined to each other and inclined at equal angles and in opposite directions to - 'x 2-S the plane of symmetry.

3. A device according to claim 1 or claim 2 wherein the control panels are arranged to extend between circumferentially spaced rigging lines extending from the periphery of the canopy and a central rigging l.ine extending from the canopy along the roll axis of the canopy.

4. A device according to claim 1 or claim 2 wherein the control panels are located within the canopy and extend between circumferentially spaced points on the inner surface of the canopy in the region of its periphery and a central rigging line on the roll axis of the canopy.

5. A device according to claim 1, wherein a planar canopy roll control panel is provided which lies in the plane of symmetry.

6. A device according to claim 5, wherein the control panel lies within the canopy in the region of the skirt of the canopy and extends from the canopy to a central rigging line extending along the roll axis of the canopy.

7. A device according to claim 1, wherein an arcuate canopy roll control panel is provided which extends n each side of the plane of symmetry and symmetrically with respect thereto.

8. A device according to claim 7, wherein the arcuate control panel is arranged in the region of the skirt of the canopy and extends between spaced rigging lines extending from the skirt of the canopy.

9. A device according to any one of claims 1 to 8, wherien the or each canopy roll control panel is of a flexible material.

10. A device according to any of claims 1 to 9, wherein the canopy is so constructed and arranged with regions of different prosities as to produce the driving component force.

11. A parachute assembly for controlling the aerial descent of a load including a device according to any of claims 1 to 10 and load support means connected thereto for support of a load.

12. An assembly according to claim 11, for controlling the aerial descent of a load discharged from an aircraft flying at low level and high speed, and wherein the aerial control device is provided to produce an initial ascent of the assembly following its discharge from the aircraft.

13. An assembly according to claim 12, wherein the canopy is formed by a plurality of gores each of which is formed by a plurality of spaced ribbons which extend across the gore in spaced parallel relationship and which are so spaced apart from each other as to provide high porosity gores, and wherein the driving component force on the canopy is created by the provision of one or more gore areas of nil porosity.

I 14. An assembly according to claim 13, in which the aerial control device is, in use, deployed - as a f irst stage to bring the assembly discharged from the aircraft to an increased altitude at which a main parachute of the assembly is then deployed. as a sec.ond stage to control aerial descent of the load to ground level.

15. An assembly according to claim 11, wherein the canopy is formed by a plurality of gores all of which are formed from a fabric of nil porosity apart from one or more gore areas of high porosity, and wherei,n the driving component force is created by the provision of the gore areas of high porosity.

16. An assembly according to claim 11, wherein the canopy when inflated takes the form of an aerofoil and the driving component force is generated by virtue of the aerodynamic characteristics of the aerofoil canopy.

17. An assembly according to claim 15 or 16, wherien the canopy roll control panel or panels is or are so disposed in relation to the driving direction of the canopy as to maintain the driving component force on the canopy in opposition to the transverse component of relative air flow.

18. An assembly according to claim 11 or 12, wherein the canopy roll control panel or panels is or are so disposed as to maintain the driving component force in the same direction as the transverse component of relative air flow.

- YzOOO--,z- 9 19. A lifting parachute substantially as hereinbefore described with reference to Figs. 1 to 4, Tigs. 6 and 7, Figs. 8 to. 11, Figs. 12 and 13 of the accompanying drawings.

20. A driving parachute substantially as hereinbefore described with reference to Figs. 14 to 16 of the accompanying drawings.

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