FR2631602A1 - Tethered balloon serving as a parasol - Google Patents

Abstract

The invention relates to a lighter-than-air parasol using solar energy and coming back to the ground in the event of being released. The flexible envelope includes, on the drawing 1/1, a round piece 1 with centre 3 and a conical piece 2 having an aperture 8 at the point 4. The shaft 5 linking 3 to 4 supports the centre of upward thrust 13 below the centre of gravity 14. The tube 6 which is toric in cross-section and inflatable by the valve 7 imposes its circular shape. The shadow 11 projected originates from the radiation from the sun 12 which is collected to heat the air in the envelope. The parasol fixed to the ground by the wire 9 comes back in the event of being released by reason of 13 and 14. The hot air escapes through 8 and the tape 10 prevents it operating like a parachute. The return to the ground is quick.

Description

 We know the aerostat rising above the ground surface using gas lighter than the ambient air contained in its envelope. We know the solar balloon rising like an aerostat thanks to the free heating of L 'sir de on enveloped by solar radiation.

 We know the parasol intended to cast its shadow to protect from the sun. It then becomes possible to make a parasol made of a captive solar balloon.

It suffices for this balloon to support its own weight by heating up via solar radiation to project its own shadow onto the ground.

 Such a parasol has qualities of lightness. It is without dancing to gusts of wind unlike other parasols, car-deprived of any hard or heavy material.

 However, such an umbrella could escape into the crowd in the event of awkwardness, as happens to children playing with a balloon. The umbrella would be lost to its owner and would clutter the atmosphere.

 The invention provides a solar parasol having a center of upward pressure situated below the center of gravity. The parasol therefore tends to turn around when it is released. The permanent opening of the envelope situated at the bottom in normal operation then lets out the hot air and the parasol losing its upward force returns itself to the ground.

 The boomerang and solar parasol is made of a light, flexible and waterproof material. Plastic films or silk-type fabrics will add to the qualities mentioned thermal qualities adapted to the rise in the temperature of the air in the envelope. solar radiation.

 In drawing 1/1, a first piece (1) of round shape, of radius R hermetically adheres to a piece (2) of conical shape. The piece (1) is transparent to solar radiation which heats the piece (2) d '' a color absorbing solar radiation to heat the internal air.

 We designate by (3) the center of the round part (1), by (4) the tip of the cane, by xR the height of the cone going from the center (3) to the tip (4) on the axis (5) .

 A stent consists of an O-tube shown in section (6), pressurized via a valve (7) imposes on the flexible envelope its circular shape. The tip of the cone (4) is pierced with a permanent opening (8 ) allowing Air to circulate between inside and outside of the enclosure, if only to fold the parasol.

 A wire (9) fixes the parasol to the Jol. A ribbon (10) stabilizes the parasol in the wind. The shade projected (11) on the ground corresponds to the radiation of the sun (12) intercepted to heat the air of the envelope.

 The center of the upward beam (13) and the center of gravity (14) are located inside the envelope and on the axis (5) for an obvious reason of symmetry. It is shown that the center of thrust (13 ) is below the center of gravity (14) when the materials used for the places (1) and (2) have the same mass per unit area. The mass of the O-tube (6) Cleaves the center of gravity even more (14 ) verg the top.

 If the parasol is released, it rises, tending to turn over. The permanent opening (8) of the flexible envelope evacuates the hot air, causing a disappearance of the upward force and a precipitated return will see the aol.

The ribbon (10) plays in the precipitated return phase an anti-parachute function further accelerating the return.

 Taking into account the known materials, namely approximately ten grams per square meter, of the recoverable solar energy, the practical realizations situate the dimension of the radius R in the order of magnitude of the beam. The value of the parameter. x is optimizable to maximize the upward force.

 We define the ascending force F as equal to the difference between the pouch of Archlmede A and the weight P.

For a given power W of solar radiation per unit area and a given radius R, the temperature rise T of the air in the envelope decreases as x increases.

 In fact, the heat exchange surface with the surrounding air increases with x. The outlet A increases when the volume and T increase, that is to say with x and, for a given ray R. For a weight material given by unit of area, the weight increases with x, for R given.

Those skilled in the art will be able to write the complete quad: F = AP
F = f (R, U, x, K) where K represents parameters such as ambient temperature, heat conduction, weight per unit area of the material, constant of ideal gases, volume weight of air, rise in temperature. .

 The derivative with respect to å x vanishes for a value of x corresponding to a maxImum of F.I1 then R and U are necessary large enough for F to be positive and allow aerostation.

Claims (7)

Claims 1) Device of the aerostat type, the flexible envelope of which presents in the aerostation phase a permanent opening (8) directed downwards, characterized by the precipitation of a phase of return to the terrestrial surface, due to forced evacuation carrier gas via (8) following the disparity in the voltage of the line (9). 2) Device according to claim 1 using the sun's radiation (12) to heat the air in the envelope, characterized by the projection of a shadow (11) serving as a parasol during a captive aerostation phase created by the line ( 9). 3) Device according to soumlcatlon 1 characterized by a location of the center of thrust (13) under the center of gravity (14) during the aerostatIon phase, thus causing a reversal and the entry into the precipitated return phase as soon as the link tension (9). 4) Device according to claim 2 characterized by an optimisatIon of the envelope in terms of volume and surface in order to maxImize the ascending force defined as equal to the difference between the buoyancy and the weight. 5) Device according to claims 3 and 4 characterized by the conical shape of the envelope (1) and (3) having a permanent opening (8) in the tip of the cone (4). 6) Device according to claim 5 characterized by an O-tube (6) under pressIon by valve (7) Imposing On the flexible envelope (1) and (2) its circular shape.  7) Device according to claim 1 characterized by a limitation of the parachute effect of the envelope during the precipitated return phase thanks to the use of a kite tail or flexible ribbon (10).