US3499326A - Air-collecting balloon for sampling air at high altitude - Google Patents

Description

March 10, 1970 P, MADlER ETAL AIR-COLLECTING BALLOON FOR SAMPLING AIR AT HIGH ALTITUDE Filed Jan. 18, 1968 2 Sheets-Sheet 1 INVENTORs TIE/M 5 MA PIER ods/e r Asa/'24- RAY/10,442 9 4 110V: we?

ATTORNEYS March 10, 1970 mA ET AL 3,499,326

AIR-COLLECTING BALLOON FOR SAMPLING AIR AT HIGH ALTITUDE Filed Jan. 18, 1968 2 Sheets-Sheet 2 INVENTORS 'PIERRE MAD/EA Roesgr RzG I 74- BY 4; a

3,499,326 Patented Mar. 10, 1970 rm. (:1. tion 1/22 US. Cl. 73-4215 16 Claims ABSTRACT OF THE DISCLOSURE An air-collecting balloon of suitable volume which is empty and closed at the time of launching is lifted to a high altitude by a carrier balloon of any suitable type by means of a central suspension cable. The air-collecting balloon is so constructed that, when it has attained the desired altitude, it opens, fills with the air to be collected, separates from its carrier balloon and closes automatically so as to trap the collected air as it finally descends.

This invention relates to a method of sampling air at altitudes ranging from 3,000 to 33,000 meters and to a collecting balloon for the practical application of said method.

Among the different methods and devices which have been employed up to the present time for sampling air at high altitudes, the method of traction by aircraft has sometimes been resorted to, but it has naturally proved impossible by this means to take samples at very high altitudes. On the other hand, other systems which entailed the use of balloons did in fact permit sampling at high altitude but required a fairly long time at maximum altitude (3 to 4 hours) in order to collect the necessary quantity of air (approximately 8 kgs.). Consequently, searches for balloons and equipment after landing had to be made over distances of up to hundreds of kilometers from the point at which they had been released and often beyond national borders, thereby creating major problems of recovery.

The aim of the present invention is therefore to describe a method and device for bringing back to the ground approximately 8 kgs. of air which have been collected at varying altitudes between 3,000 and 33,000 meters with a maximum-altitude or ceiling time which is reduced to a minimum.

The invention mainly consists of a method in which an air-collecting balloon of suitable volume which is empty and closed at the time of launching is lifted to a high altitude by a carrier balloon of any suitable type by means of a central suspension cable, said air-collecting balloon being so constructed that, when it has attained the desired altitude, it opens, fills with the-air to be collected, separates from its carrier balloon and closes automatically so as to trap the collected air as it finally descends.

The invention further consists of an air-collecting balloon which is intended to carry said method into effect and essentially comprises inside a flexible envelope having a general shape which is especially tetrahedral a flexible inner-tube element which is inflated but not rigid at the ground, said inner-tube element being intended to become rigid during its ascent as a result of expansion of its inflation gas and then to assume a general shape which is especially an equilateral triangle whose three apices are attached to the three top apices of the envelope; a central cylindrical hose, the upper end of which is joined to the pole of the envelope by a cone frustum fitted at its base in a metallic pole-ring suspended by means of three cords from the central cable and the lower end of which is joined to the bottom apex of the envelope by means of a metallic strainer, said strainer being brought back to the initial position against said pole-ring and suspended from the central cable by means of a thin cord which is cut at high altitude by a pyrotechnic knife ignited by a timer, said central hose being initially turned inside out and coiled down on said strainer; three T-shaped junction tubes which serve to join the arms of said inner-tube element in pairs to three vertical tubes each fitted with a valve for regulating the pressure of said inner-tube element and suspended from the central cable by means of three cords; a suitable weighting of said strainer being additionally provided in order to produce the downward motion thereof in the axis of said central cable after said ignition and the suitable extension of said central hose to the air-collecting position.

A better understanding of the invention will in any case be gained from the complementary description which now follows and from the accompanying drawings, it being understood that said description and drawings are given solely by way of indication and not in any sense by way of limitation.

' In the accompanying drawings:

FIG. 1 is a general diagrammatic view of an air-col lecting balloon in accordance with the invention;

FIG. 2 is a detail view showing the mode of connection to one of the top apices of the envelope.

It is apparent from FIG. 1 that the air-collecting balloon is provided with two special devices in addition to the conventional bag, or envelope 1. One of these devices consists of an inner-tube element 3 which contains at the outset a measured quantity of gas, the expansion of which at high altitude has the effect of endowing said inner-tube element with rigidity and said envelope 1 with its normal shape. The inner-tube element referred-to can be a cylinder which is folded, for example, in the shape of an equilateral triangle whose apices are attached to the three points such as the point 5 of the envelope 1. The other device aforesaid consists of a central hose 7 v which is joined to the pole of the balloon by a cone frusturn 9 fitted at its base in a pole-ring 11 of metallic tubing and which is attached to the hook 13 by means of the strainer 15 which is also formed of metallic tubing.

Any untimely filling is prevented by ensuring imperviousness of the empty balloon during its ascent. To this end, the strainer 15 is brought back against the pole-ring 11 (which is lined for this purpose with-polyurethane foam) and covered by the coupling cone 9 of the central hose 7, said hose being turned inside out like a glove finger and coiled down above the strainer 15. The entire envelope 1 surrounds this central unit as a skirt.

Filling at high altitude is carried out by releasing the strainer 15 by means of a pyrotechnic knife (not shown) which is ignited by a timer 17. The strainer 15, which is suitably weighted for the purpose, moves down in the axis of the central cable 19, is accompanied in its motion by the central hose 7 and permits the surrounding air to penetrate into said hose, then into the collecting balloon through the base of the strainer 15.

Emptying during descent of the balloon is prevented by reason of the fact that the complete assembly is released and subjected to dynamic pressure and that the internal overpressure consequently flattens the central hose 7 whilst the collected air is recompressed and reaches the top portions of the envelope 1 in which it remains trapped.

Tests have justified the use of polyethylene for the fabrication of the inner-tube element 3, this being the only material at the present time which can be produced directly in extruded sheaths having a maximum Width of 3 1.65 m. when laid flat, thus resulting in an inner-tube element having a maximum diameter of 1.05 in. However, a method of assembly by bonding offers the possibility of utilizing other plastic materials of much greater strength. The two diameters employed are 0.53 m. (sheath having a width of 0.83 m. in the flat state) and 1.05 111. (sheath having a width of 1.65 m. in the flat state) in accordance with the table given hereunder.

Ground tests have shown that, in order to prevent lateral flexion or buckling, it is advisable not to exceed 12 to 14 diameters for the length of one side of the element.

This condition is satisfied in the case of all the balloons of the table, except for the collecting balloon of 550 m. which should receive an inner-tube element 1.20 m. to 1.30 m. in diameter.

The air-collecting balloons at present employed are equipped with inner-tube elements having a thickness of 150,41. Ground tests have demonstrated that the inner-tube element which has a diameter of 1.05 m. bursts at an over-pressure of 25 mb. along a generator-line which is parallel to the direction of rolling. However, holes appear above 22 mb. in the two folds which are formed in the hot state during winding and in various fault locations. The yield strength of the polyethylene employed at ambient temperature and at a pressurization rate which is comparable to ascensional conditions is consequently of the order of 8 g./cm.=;t. The small tolerance allowed by these figures at the time of inflation of the inner-tube element on the launching site has motivated the adoption of a thickness of 200 in the case of future inner-tube elements and the installation of a safety valve at each of the three points, particularly in view of the fact that, even without the occurrence of a burst, any leakage of the inner-tube element into the collecting balloon is liable to impair the analysis of the collected air.

The consideration last mentioned could well point to the advisability of inflating the inner-tube element with a gas which is not present in the composition of the collected air.

It is apparent from FIG. 2 that, at each apex such as the apex of the envelope 1, the inner-tube element is brought back then gathered together by lashing with cords such as the cord 21 around a T-shaped metallic tube 23 comprising two junction tubes such as the tube 25 which ensure complete communication between the arms of the element 3 and a vertical tube 27 which is fitted with a polyethylene funnel 29 and which traverses the element 3 at the apex 5 of the envelope 1. The tube 27 serves to inflate the element 3 at the ground and is subsequently fitted at its upper end with a safety valve 31 in which a Weighted ping-pong ball 33 is mounted on a conical seat 35 within a lantern-shaped housing 37. Said housing is closed by a cover 39 provided with a ring 41 to which the cord 43 (shown in FIG. 1) is attached in order to attach the collecting balloon to the central cable 19 and therefore to the carrier balloon.

Referring again to FIG. 1, it is apparent that the aircollecting balloon will thus be suspended from the cable 19 by means of three cords such as the cord 43, whilst the pole-ring 11 of said balloon is also suspended independently by means of cords such as the cord 45.

In the workshop, the prior to introduction within the envelope 1, the inner-tube element 3 is inflated to an overpressure Ap (6 mb. in the case of 1.05 m. and 12 mb. in respect of 9.53 m.), using the blower which will later be employed on the launching site, while measuring the inflation time T if necessary. After fabrication, the collecting balloon and the inner-tube element are subsequently delivered empty to the launchin site.

The inflation time t on the launching sit is defined by:

1. Tz & X (1 PA 1 1 wherein:

p =Sp6ClfiC density of the surrounding air at the moment of launching as'established from values of pressure, temperature and relative humidity which are read from a recording device,

=specific density of the air at the ceiling altitude 2 according to the standard atmosphere tables,

A =overpressure permitted Within the inner-tube element,

p =pressure at the ceiling altitude z according to the standard atmosphere tables.

The inflation time as thus determined is divided into three equal periods on each of the three points 5 of the collecting balloon.

The formula given above does not take into account the greenhouse effect heating of the gas within the innertube element 3.

The envelope 1 is at present fabricated from polyethylene 50 in thickness consisting of two layers 25 thick but could very usefully be endowed with increased tearing strength in order to afford better resistance to the stresses exerted during the descent and at the time of landing. Laboratory tests have shown the good adaptation of complex plastic materials having a base of polyethylene, resin, glass fiber or acetate yarn, cotton yarn, etc., terephthalate, rilsan and so forth.

All assemblies are effected by bonding or by glueing to the envelope added parts of polyethylene film or like plastic material having simple shapes such as bands, cones, cylinders, bonding straps and the like. It is essential to ensure that bonding elements are placed in such a manner that they always work under shear stress, thereby preventing tearing.

Detachment of the central hose 7 as well as fixing of the pole-ring 11 and strainer 15 call for careful marking and position-setting, especially in order to prevent twisting. After assembly, the pole-ring 11 is connected to the central cable 19 by means of the three cords such as 45 which are joined to the three cords such as 43 of the three points 5 of the collecting balloon. The strainer 15 is lifted so as to bear against the pole-ring 11 and attached by means of the timer 17 to the same central cable 19 whilst the central hose 7 is coiled down on the strainer 15 outside the envelope 1 by being turned inside out in the same fashion as a glove finger.

The complete assembly is dried out by compression in a compact bundle within a large plastic sheet which contains the complete balloon, which is knotted at the four corners and suspended from a pulley block. The balloon slowly empties under the action of its own weight through the auxiliary hoses which are provided near the pole for pumping the collected air after the descent and which are not shown in the drawings. The collecting balloon is then delivered to the launching area inside its compres sion-drying pack.

What we claim is:

1. A device for collecting air at high altitude which comprises a flexible envelope containing an inner-tube element which is partially inflated but not rigid at ground conditions, said inner-tube element being adapted to become rigid during its ascent due to expansion of the inflated gas, portions of the inner-tube element being attached to portions of the flexible envelope, a hose means disposed in the flexible envelope, the upper end portion of said hose means being joined to a pole-ring of said envelope and the lower end portion being joined to the lower portion of said flexible envelope, said hose means being so connected with the flexible envelope that communication between the interior of the hose and the atmosphere is maintained at its upper end but not between the exterior of the hose and the atmosphere said hose means further being adapted to be coiled up against the pole-ring, a plurality of junction tubes provided in the arms of the inner-tube element, each of said junction tubes communicating with a second tube member at least partially disposed on the outside of said inner-tube element and said flexible envelope and containing a valve means for regulating the pressure of the inner-tube element, each of said second tube members being suspended from a central cable by other cord means, the upper end portion of said hose means also being suspended from said central cable by means of a thin cord which is adapted to be cut at high altitude upon response to a timer means.

2. The device of claim 1, wherein the lower end of the hose means is provided with a weighted strainer means.

3. The device of claim 1, wherein the inner-tube element has a cylindrical cross-sectional shape and is folded in the shape of a triangle with the apexes of said triangle being attached to the flexible envelope.

4. The device of claim 1, wherein the pole-ring is associated with a pole means and the hose means is centrally disposed in the flexible envelope and is joined to said pole means at its upper end by a cone frustum Which is fitted at its base in the pole-ring.

5. The device of claim 4, wherein the lower end of the hose means terminates in a strainer means which is provided with a hook means.

6. The device of claim 1, wherein the inner-tube element is made of polyethylene.

7. The device of claim 1, wherein the junction tubes are T-shaped tubes and the second tube member is a vertically extending tube said second tube member communicating at one end with the top portion of the T-shaped tubes.

8. The device of claim 7, wherein the second tube member is fitted at said one end with a funnel means which traverses the inner-tube element.

9. The device of claim 7, wherein the other end of said second tube member is provided with a safety valve means comprising a weighted ping-pong ball mounted on a conical seat and disposed within a housing, said housing being provided with a cover containing a ring element.

10. The device of claim 9, wherein the ring element is attached to the central cable by said other cord means,

said central cable being attached to a balloon means.

11. The device of claim 1, wherein the flexible envelope is made of a synthetic material containing at least one member selected from the group consisting of polyethylene, polyethylene terephthalate, glass fiber, acetate yarn, cotton yarn and rilsan.

12. A device for collecting air at a predetermined altitude which comprises a flexible envelope having a tetrahedral shape containing a flexible inner-tube element which is partially inflated but not rigid at ground conditions, said flexible inner-tube element being adapted to become rigid during its ascent due to expansion of the inflated gas thereby assuming the general shape of an equilateral triangle, the three apexes of said triangle being attached to the three top apexes of the flexible envelope, a cylindrical hose means centrally disposed in the flexible element, the upper end of said hose means being joined to the pole of the flexible envelope by a cone frustum fitted at its base in a pole-ring, the lower end of said hose means being joined to the bottom apex of the flexible envelope by means of a strainer, said hose means being so connected with the flexible envelope that communication between the interior of the hose and the atmosphere is maintained at its upper end but not between the exterior of the hose and the atmosphere said hose means further being adapted to be coiled up such that the strainer means can be positioned against the pole-ring, said strainer means being suspended from a central cable by means of a thin cord which is adapted to be cut at high altitude by a pyrotechnic knife ignited by a timer means, three T-shaped junction tubes provided in the arms of the innertube element in the vicinity of the apexes of said innertube element, each of said junction tubes communicating with a substantially vertical-extending tube which is at least partially disposed on the outside of said inner-tube element and said flexible envelope, said vertical extending tube containing a valve means for regulating the pressure of said inner-tube element and being suspended from a central cable by other cord means.

13. The device of claim 12, wherein the hose means is initially turned inside out and coiled down on the strainer means.

14. The device of claim 13, wherein the pole-ring is connected to the central cable by three cords.

15. The device of claim 14, vwherein, in the deflated state, the strainer means bears against the pole-ring and communicates with the central cable via the timer means.

16. The device of claim 15, wherein the strainer means is provided with additional weight in order to produce a downward motion in the axis of the central cable after said ignition and the extension of said central hose to the air-collecting position.

References Cited UNITED STATES PATENTS 3,063,296 11/1962 Huch et a1. 73-4215 3,085,439 4/1963 Price 73 1215 3,176,327 4/1965 'Oberth 24431 S. CLEMENT SWISHER, Primary Examiner

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