STRATEGY FOR SAFEGUARDING AN AIRSHIP IN THE EVENT OF HEATING OF ITS SOLAR GENERATOR

Abstract

A stratospheric airship includes a nonrigid balloon equipped with a solar generator arranged on the upper part of the nonrigid balloon intended to be illuminated in flight by the sun, the airship comprising: at least one device for managing the position of the centre of gravity of the airship; at least one device for stabilizing the attitude of the airship; and a module for the coupled control of the devices, configured to control the airship, when the speed of travel of the airship with respect to the surrounding air is below a first threshold (S1) and/or the temperature of the solar generator is above a second threshold (S2), in such a way that it rotates by substantially half a turn about its longitudinal axis (AL), so as to protect the solar generator from illumination by the sun.

Claims

1. A stratospheric airship comprising a nonrigid balloon equipped with a solar generator arranged on the upper part of the nonrigid balloon intended to be illuminated in flight by the sun, the airship comprising: at least one device for managing the position of the centre of gravity of the airship; at least one device for stabilizing the attitude of the airship; and a module for the coupled control of said devices, configured to control the airship, when the speed of travel of the airship with respect to the surrounding air is below a first threshold (S1) and/or the temperature of the solar generator is above a second threshold (S2), in such a way that it rotates by substantially half a turn about its longitudinal axis (AL), so as to protect the solar generator from illumination by the sun.

2. The stratospheric airship according to claim 1, wherein the first threshold (S1) is below 10 ms.sup.−1.

3. The stratospheric airship according to claim 2, wherein the first threshold (S1) is equal to 5 ms.sup.−1.

4. The stratospheric airship according to claim 1, wherein the second threshold (S2) is below 120° C.

5. The stratospheric airship according to claim 4, wherein the second threshold (S2) is equal to 100° C.

6. The stratospheric airship according to claim 1, wherein the device for managing the position of the centre of gravity of the airship is an active device.

7. The stratospheric airship according to claim 6, wherein the active device for managing the position of the centre of gravity of the airship comprises controlled elements configured to shift weights.

8. The stratospheric airship according to claim 7, wherein the controlled elements comprise actuators and return devices.

9. The stratospheric airship according to claim 7, wherein the weights comprise elements carried on board the airship.

10. The stratospheric airship according to claim 6, wherein the active device for managing the position of the centre of gravity of the airship comprises at least one element able to move around the balloon.

11. The stratospheric airship according to claim 1, wherein the device for managing the position of the centre of gravity of the airship is a passive device.

12. The airship according to claim 11, wherein the passive device for managing the position of the centre of gravity of the airship comprises a predetermined positioning of elements carried on board the airship, so that the centre of gravity of the airship is situated between its longitudinal axis (AL) and the solar generator.

13. The stratospheric airship according to claim 12, wherein the on-board elements comprise at least one electric battery, and/or at least one fuel cell and/or at least one fuel tank.

14. The stratospheric airship according to claim 1, wherein the device for stabilizing the attitude of the airship is an active device.

15. The stratospheric airship according to claim 14, wherein the active device for stabilizing the attitude of the airship comprises aerodynamic control surfaces and/or gimbal-mounted thrusters and/or side thrusters and/or flywheels.

16. The stratospheric airship according to claim 1, wherein the device for stabilizing the attitude of the airship is a passive device.

17. The stratospheric airship according to claim 16, wherein the passive device for stabilizing the attitude of the airship is a pendulum return induced by a predetermined siting of the centre of gravity of the airship, away from the longitudinal axis (AL).

18. A method for controlling a stratospheric airship comprising a nonrigid balloon equipped with a solar generator arranged on the upper part of the nonrigid balloon intended to be illuminated in flight by the sun, wherein the position of the centre of gravity of the airship and the stabilization of the attitude of the airship are controlled in a coupled manner so that, when the speed of travel of the airship with respect to the surrounding air is below a first threshold (S1) and/or the temperature of the solar generator is above a second threshold (S2), the airship rotates by substantially half a turn about its longitudinal axis (AL) so as to protect the solar generator from illumination by the sun.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention will be better understood from studying a number of embodiments described by way of entirely nonlimiting examples illustrated by the attached drawings, in which the figures:

[0033] FIG. 1 schematically illustrates a stratospheric airship, according to one aspect of the invention;

[0034] FIG. 2a schematically illustrates a stratospheric airship, according to one aspect of the invention;

[0035] and FIG. 2b schematically illustrates a stratospheric airship, according to the aspect of the invention of FIG. 2a;

[0036] FIG. 3a schematically illustrates a stratospheric airship, according to one aspect of the invention; and

[0037] FIG. 3b schematically illustrates a stratospheric airship, according to the aspect of the invention of FIG. 3a.

DETAILED DESCRIPTION

[0038] In all of the figures, the elements that have identical references are similar.

[0039] FIG. 1 depicts a stratospheric airship 1 comprising a nonrigid balloon 2, a gondola 3, thrusters 4 and a device 5 for stabilizing the attitude of the airship.

[0040] The nonrigid balloon 2 comprises a solar generator 6 arranged on the upper part of the nonrigid balloon 2 intended to be illuminated in flight by the sun. The solar generator 6 may be internal or external to the balloon 2.

[0041] The gondola 3 carries the power supply and control systems as well as the technical equipment needed for the various missions of the airship, which may involve observation, surveillance or telecommunications.

[0042] The solar generator 6 makes it possible by day to power the on-board equipment, and to recharge the electrical energy storage system which then takes over at night.

[0043] The airship 1 comprises at least one device 7 for managing the position of the centre of gravity of the airship, at least one device 5 for stabilizing the attitude of the airship, and a module 8 for the coupled control of said devices, so that the airship 1, when the speed of travel of the airship with respect to the surrounding air is below a first threshold S1 and/or the temperature of the solar generator is above a second threshold S2, rotates by substantially half a turn about its longitudinal axis AL so as to protect the solar generator 6 from illumination by the sun.

[0044] Each of the devices (7, 5) for managing the position of the centre of gravity of the airship and for stabilizing the attitude of the airship may be active or passive, even though not all of the cases have been illustrated in detail in the following portion of the description.

[0045] The airship 1 comprises a sensor 9 for measuring the speed of travel of the airship 1 with respect to the surrounding air.

[0046] The first threshold S1 is below 10 ms.sup.−1, and advantageously is equal to 5 ms.sup.−1.

[0047] The second threshold S2 is below 120° C., and advantageously is equal to 100° C.

[0048] When the device 7 for managing the position of the centre of gravity of the airship 1 is an active device, it may comprise controlled elements configured to shift weights 7a. The controlled elements may comprise actuators 7b and return devices 7c, and the weights (7a) may comprise elements carried on board the airship 1 specifically designed to perform this function (such as a ballast) or elements that also perform other functions (such as an energy storage device).

[0049] When the device 7 for managing the position of the centre of gravity of the airship 1 is a passive device, or in other words when the management of the position of the centre of gravity of the airship 1 is entirely passive, it may comprise a predetermined positioning of elements carried on board the airship 1, in such a way that the centre of gravity CdG of the airship 1 is situated between its longitudinal axis AL and the solar generator 6 situated above, facing into the sun, in nominal operation. The on-board elements may comprise at least one electric battery, and/or at least one fuel cell and/or at least one fuel tank or any other equipment the overall mass of which is sufficient to perform this function.

[0050] What is meant by nominal operation is the operation of the airship 1 when its speed with respect to the surrounding air is above or equal to the first threshold S1, and/or when the temperature of the solar generator is below or equal to the second threshold S2.

[0051] When the device 5 for stabilizing the attitude of the airship 1 is an active device, it may comprise aerodynamic control surfaces and/or gimbal-mounted thrusters and/or side thrusters and/or flywheels.

[0052] When the device 5 for stabilizing the attitude of the airship 1 is a passive device, it may consist of a pendulum return induced by siting the centre of gravity CdG of the airship 1 in such a way that it is situated between its longitudinal axis AL and the solar generator 6 situated above, facing into the sun, in nominal operation.

[0053] Two detailed nonlimiting embodiments now follow.

[0054] FIGS. 2a and 2b illustrate a stratospheric airship 1 comprising a passive device 7 for managing the position of the centre of gravity CdG of the airship 1 coupled to an active device 5 for stabilizing the attitude of the airship 1.

[0055] The position of the centre of gravity CdG of the airship 1 is positioned at the desired location, i.e. on the same side as the solar generator 6 with respect to the longitudinal axis AL, or, in other words, between the longitudinal axis AL and the top of the balloon, where the solar generator 6 is situated. In nominal operation of the airship 1, the solar generator 6 faces towards the sun and the attitude is controlled by the active device 5 for stabilizing the attitude, as illustrated in FIG. 2a.

[0056] This operation is performed on the ground before takeoff, by altering the position of various pieces of on-board equipment (avionics equipment, energy storage devices, etc.).

[0057] Once in flight, the attitude of the airship is influenced using the available actuators 5 such as: the aerodynamic control surfaces, and/or gimbal-mounted thrusters and/or side thrusters and/or flywheels, that form an active device for stabilizing the attitude of the airship.

[0058] If the speed of the airship 1 with respect to the surrounding air drops below the first threshold S1 and/or the temperature of the solar generator 6 reaches the second threshold S2, then the airship 1 pivots through approximately 180° about its longitudinal axis AL and the airship finds itself in the position illustrated in FIG. 2b, in which the solar generator 6 is protected from the sun.

[0059] FIGS. 3a and 3b illustrate a stratospheric airship 1 comprising an active device 7 for managing the position of the centre of gravity CdG of the airship 1 coupled with a passive device 5 for stabilizing the attitude of the airship 1.

[0060] The position of the centre of gravity CdG is modified in flight by shifting weights in the required direction. To do that, certain modules 7a installed on the balloon 2 are rendered mobile. The battery modules are particularly favoured for this operation because of their appreciable mass. These modules 7a may be rendered mobile via a very reliable device based on return devices 7c and actuators 7b acting in opposite directions or via a system of actuators on rails or on cables.

[0061] The centre of gravity CdG of the airship 1 is positioned at the desired location in the nominal case, i.e. on the opposite side from the solar generator 6 with respect to the longitudinal axis AL, or, in other words, between the longitudinal axis AL and the payload gondola 3. In nominal operation of the airship 1, the solar generator 6 faces into the sun and the attitude is stabilized passively by the pendulum-return effect induced by the position of the centre of gravity CdG and controlled by the active device 5 for stabilizing the attitude, as illustrated in FIG. 3a.

[0062] If the speed of the airship 1 with respect to the surrounding air drops below the first threshold S1 and/or the temperature of the solar generator 6 reaches the second threshold S2, the active device 7 for managing the position of the centre of gravity CdG brings the centre of gravity CdG back between the longitudinal axis AL and the top of the balloon 2, where the solar generator 6 is situated. This action has the effect of generating a pendulum moment causing rotation by 180° about its longitudinal axis AL and the airship finds itself in the position illustrated in FIG. 3b, in which the solar generator 6 is protected from the sun.