GB2098947A

GB2098947A - Reefing a tethered sail for marine or other use

Info

Publication number: GB2098947A
Application number: GB8214703A
Authority: GB
Original assignee: BP PLC
Current assignee: BP PLC
Priority date: 1981-05-21
Filing date: 1982-05-20
Publication date: 1982-12-01

Abstract

A spar-less elevated sail is controlled by drawing together or allowing the shroud lines to separate and thereby to draw in or open the canopy. In one embodiment a reefing ring 7 surrounds the shroud lines of the sail and is positioned by control lines 6. In a modification (not shown) the reefing ring is formed by the mouth of a flexible fabric or concertina like tube (8) which can be used to stow the shroud lines or the sail when not in use. Another reefing arrangement includes a draw string around the periphery of the sail. Alternatively the sail may be reefed by using two sets of shroud lines of differing lengths. <IMAGE>

Description

SPECIFICATION Elevated sails and their control The present invention relates to kites and more particularly to the deployment of kites for the propulsion of water going vessels.

The ever increasing cost of energy particularly in the form of increasing oil prices have led to renewed interest in the total or partial propulsion of water going vessels such as cargo ships, tankers and yachts by use of wind energy. In particular, elevated sails or kites which have been proposed and used for the propulsion of ships have certain advantages over, say, vessel mounted sails. These advantages include the ability to fly at an altitude where the winds are generally strong and stable.

The present invention relates to improved means for the control of kites suitable for use in the total or partial propulsion of water going vessels. By the term kite, it is intended to include elevated sails and any tethered flying surface.

Thus, according to the present invention, there is provided a method of control of kites from a water going vessel comprising (a) connecting the kite to the flying lines by means of a pulley and block or the like and (b) attaching one or more control lines to the flying lines at one end and the kite sail at the other end whereby movement of the flying line around the pulley causes the control line to alter the flying characteristics'of the kite.

When ram air wing and parachute elevated sails are rigged symmetrically about their centre lines (mid point of leading edge to mid point of trailing edge), the sail will fly in an undiverted arc upwards from its point of launch. It is possible to deflect these drawing the shroud lines together, the drawing means being remotely operable and a flying line for the sail.

Ram air wings or lifting parachutes can be reefed in flight to reduce the tether line tension when required, for example, during wind squalls or during launching and recovery. The reefing operation may be performed under practical conditions with a minimum number of control lines, control force and without the use of electrical components on the sail according to the following techniques.

A smooth ring 1 is fitted over the shrouds 2 and its position controlled by one or more lines 3 operating through turning rings 4 on the shrouds or incorporated in the sail so that the ring is pulled towards the canopy 5 of the sail when the control line is pulled to reef the sail (figures 1 (a) and 1 (b)).

When the degree of reefing is required to be reduced, it is usually sufficient to slacken the line controlling the ring through the canopy or shroud turning rings when the tendency of the shrouds to resume their unrestrained configuration will cause the ring to move down and give less reefing.

However, the position may also be controlled directly with a pair of lines 6 to pull the reefing ring 7 up or down. This process is compatible with a two line flying system (figure 2).

The internal diameter of the reefing ring suitably varies from a minimum diameter of the order of magnitude of the minimum diameter of the tapering shroud lines, e.g. 40 mm, up to a maximum size usually of the order of one tenth of the flying diameter of the kite, e.g. of the parachute type.

The reefing ring may be the mouth of a flexible fabric or concertina-like tube 8 which can be used to stow the shroud lines or the whole parachute system when the kite is not in use (figure 3).

The reefing ring may be a simple smooth edged ring or may be divided internally to give many apertures 9 (figure 4). Each aperture, in use, has one or more shroud lines passing through it. This form of ring makes repacking the kite easier after use and avoids the ring twisting on the shrouds and causing the control lines to bind and become ineffective.

The number of lines used to control the reefing ring is influenced by the following conditions. If instability of the sail is to be avoided during reefing, a single line can only be looped through a turning ring at or near the centre of the kite canopy. Single line operation may result in the tension of the control line causing the canopy to be drawn towards the ring rather than the ring to reef the sail. To alleviate this problem, multiple lines for reefing should be arranged symmetrically around the sail. Further, the multiple control lines may be arranged to assist the reefing ring movement initially by applying an inward force at the edges of the canopy (figure 5).

Figure 6(a) and (b) illustrates a technique of reefing the canopies of spar-less kites by using two shroud systems. Thus in figure 6(a) the sail is being flown on first long shroud lines 10 and controlled through its bridle. A second shroud system using shorter shroud lines 11 is left unused. By taking up the second shroud system and releasing the first shroud system, the sail is effectively reefed and the tension in the flying line becomes less. The sail may be unreefed by taking up the first shroud system again and releasing the second shroud system.

Figure 7 illustrates a further technique of reefing a sail. Thus single or dual drawstrings 12 operable from a watergoing vessel are connected to a series of rings 13 spread around the periphery of the inside of the sail canopy. By varying the pull on the drawstrings, the shape of the canopy can be changed to thereby allow control of the kite by effectively reefing and unreefing the sail.

Elevated sails may also be used to provide aerial platforms to lift equipment for photography, surveying, air pollution monitoring, gas sampling, crop spraying, radar operation or communications. Where the loads to be supported exceed a weight of several kilograms the sizes of the sails then required can result in line forces in excess of those readily manhandled.

Claims

1. An elevated sail assembly comprising a sail having a plurality of shroud lines attached

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Elevated sails and their control The present invention relates to kites and more particularly to the deployment of kites for the propulsion of water going vessels. The ever increasing cost of energy particularly in the form of increasing oil prices have led to renewed interest in the total or partial propulsion of water going vessels such as cargo ships, tankers and yachts by use of wind energy. In particular, elevated sails or kites which have been proposed and used for the propulsion of ships have certain advantages over, say, vessel mounted sails. These advantages include the ability to fly at an altitude where the winds are generally strong and stable. The present invention relates to improved means for the control of kites suitable for use in the total or partial propulsion of water going vessels. By the term kite, it is intended to include elevated sails and any tethered flying surface. Thus, according to the present invention, there is provided a method of control of kites from a water going vessel comprising (a) connecting the kite to the flying lines by means of a pulley and block or the like and (b) attaching one or more control lines to the flying lines at one end and the kite sail at the other end whereby movement of the flying line around the pulley causes the control line to alter the flying characteristics'of the kite. When ram air wing and parachute elevated sails are rigged symmetrically about their centre lines (mid point of leading edge to mid point of trailing edge), the sail will fly in an undiverted arc upwards from its point of launch. It is possible to deflect these drawing the shroud lines together, the drawing means being remotely operable and a flying line for the sail. Ram air wings or lifting parachutes can be reefed in flight to reduce the tether line tension when required, for example, during wind squalls or during launching and recovery. The reefing operation may be performed under practical conditions with a minimum number of control lines, control force and without the use of electrical components on the sail according to the following techniques. A smooth ring 1 is fitted over the shrouds 2 and its position controlled by one or more lines 3 operating through turning rings 4 on the shrouds or incorporated in the sail so that the ring is pulled towards the canopy 5 of the sail when the control line is pulled to reef the sail (figures 1 (a) and 1 (b)). When the degree of reefing is required to be reduced, it is usually sufficient to slacken the line controlling the ring through the canopy or shroud turning rings when the tendency of the shrouds to resume their unrestrained configuration will cause the ring to move down and give less reefing. However, the position may also be controlled directly with a pair of lines 6 to pull the reefing ring 7 up or down. This process is compatible with a two line flying system (figure 2). The internal diameter of the reefing ring suitably varies from a minimum diameter of the order of magnitude of the minimum diameter of the tapering shroud lines, e.g. 40 mm, up to a maximum size usually of the order of one tenth of the flying diameter of the kite, e.g. of the parachute type. The reefing ring may be the mouth of a flexible fabric or concertina-like tube 8 which can be used to stow the shroud lines or the whole parachute system when the kite is not in use (figure 3). The reefing ring may be a simple smooth edged ring or may be divided internally to give many apertures 9 (figure 4). Each aperture, in use, has one or more shroud lines passing through it. This form of ring makes repacking the kite easier after use and avoids the ring twisting on the shrouds and causing the control lines to bind and become ineffective. The number of lines used to control the reefing ring is influenced by the following conditions. If instability of the sail is to be avoided during reefing, a single line can only be looped through a turning ring at or near the centre of the kite canopy. Single line operation may result in the tension of the control line causing the canopy to be drawn towards the ring rather than the ring to reef the sail. To alleviate this problem, multiple lines for reefing should be arranged symmetrically around the sail. Further, the multiple control lines may be arranged to assist the reefing ring movement initially by applying an inward force at the edges of the canopy (figure 5). Figure 6(a) and (b) illustrates a technique of reefing the canopies of spar-less kites by using two shroud systems. Thus in figure 6(a) the sail is being flown on first long shroud lines 10 and controlled through its bridle. A second shroud system using shorter shroud lines 11 is left unused. By taking up the second shroud system and releasing the first shroud system, the sail is effectively reefed and the tension in the flying line becomes less. The sail may be unreefed by taking up the first shroud system again and releasing the second shroud system. Figure 7 illustrates a further technique of reefing a sail. Thus single or dual drawstrings 12 operable from a watergoing vessel are connected to a series of rings 13 spread around the periphery of the inside of the sail canopy. By varying the pull on the drawstrings, the shape of the canopy can be changed to thereby allow control of the kite by effectively reefing and unreefing the sail. Elevated sails may also be used to provide aerial platforms to lift equipment for photography, surveying, air pollution monitoring, gas sampling, crop spraying, radar operation or communications. Where the loads to be supported exceed a weight of several kilograms the sizes of the sails then required can result in line forces in excess of those readily manhandled. Claims

1. An elevated sail assembly comprising a sail having a plurality of shroud lines attached around the periphery of the canopy, means for drawing the shroud lines together, the drawing means being remotely operable and a flying line for the sail.

2. An elevated sail assembly according to claim 1 in which the drawing means comprises a ring encircling the shroud lines.

3. An elevated sail assembly according to claim 1 or claim 2 in which the ring is operable by a line or lines, the line or lines passing from the ring to the operator via the canopy of the sail.

4. An elevated sail assembly according to any of the preceding claims in which the drawing means comprises the mouth of a concertina or bellows like tube capable of accommodating the shroud lines or sail.

5. An elevated sail assembly according to any of the preceding claims in which the drawing means comprises a disc divided internally into a plurality of rings, each ring being capable of accommodating one or more shroud lines.

6. An elevated sail assembly according to any of the preceding claims in which the shroud lines are attached symmetrically around the periphery of the canopy.

7. An elevated sail assembly according to claim 1 in which the drawing means comprises a plurality of attachment points around the periphery of the canopy and a line, remotely operable, which passes through each of the attachment points whereby pulling or release of the line causes furling or unfurling of the canopy.

8. An elevated sail assembly according to any of claims 1 to 7 in which the flying lines are connected to the shroud lines through a pulley and block or the like, the drawing means being connected to an operable by the flying lines.

9. Elevated sail assemblies as hereinbefore described and with reference to Figures 1 to 7 of the accompanying drawings.

10. Vessels whenever fitted with elevated sail assemblies according to claims 1 to 9.

11. A method of controlling a spar-less elevated sail comprising the steps of (a) encircling the shroud lines of the sail with means for drawing the shrouds together (b) passing a control line from the drawing means to the canopy of the sail and thence to a controller whereby releasing or withdrawing the control line causes the means for drawing to allow the shroud lines to separate or be drawn together and thus opening or drawing in the canopy.

12. A method according to claim 11 in which the means for drawing comprises a ring encircling and slidable over the shroud lines of the sail.

1 3. Methods of controlling elevated sails according to any of claim 1 to 9.

14. Methods of controlling elevated sails as hereinbefore described and with reference to Figures 1 to 7 of the accompanying drawings.