US 3058694 A
Description (OCR text may contain errors)
Oct. 16, 1962 c. P. FA'ZIO ETAL BALLAST RELEASE DEVICE FOR BALLOONS Filed July 19, 1960 FIG.2
l8 FIG. I
BALLAST RELEASE DEVEQE FGR EALLQQNS Charles P. Fazio, Hull, Robert M. Nelson, Arlington, and
Beverly A. Niclrerson, Concord, Mass., assignors to W. R. Grace & (30., Cambridge, Mass, a corporation of Connecticut Filed July 19, 1960, Ser. No. 43,322 3 Claims. (Cl. 244-31) This invention relates to a device for the control of the altitude of flight of a balloon. More particularly, this invention relates to a device which releases ballast in respsonse to an increase in atmospheric pressure incurred when a balloon descends in flight.
It has become quite common, in recent years, to rely on balloons for use in the investigation of the higher atmosphere. The balloons which are predominantly used are of the so-called constant level variety, i.e. their level of flight is fairly constant. It has been found that during daytime flights the performance of such balloons has been extremely satisfactory. On many occasions, however, when such balloons have been released late in the afternoon, they have not remained at a constant level of altitude for the desired length of time. What happens, in actual practice, is that the balloon, after reaching a maximum level in altitude, slowly descends for the balance of the flight.
This descent in flight, which starts just before sunset, is caused by a decrease in the volumetric size of the gas in the balloon. Just before sunset, the temperature of the gas in the balloon starts to decrease. As a result, the volumetric size of the gas contracts and the balloon begins to descend. In the art, this effect on the balloon has been minimized by the jettisoning of ballast from the balloon, the latter action decreasing the total weight the balloon must carry in its flight.
Several automatic devices have been conceived for the purpose of jettisoning ballast from balloons but each, in its turn, has been found to be very complex in design, expensive and cumbersome in operation.
We have invented a ballast jettison device, which may be used in connection with constant level balloons, which is mechanical in design, automatic in operation, yet simple in nature. This device is so designed that it will not jettison ballast while the balloon is rising or floating at a constant altitude. When the balloon begins to descend, however, the device will come into operation and will jettison its ballast load thus giving the balloon an added degree of free-lift. As a result, the balloon will again rise and will float at a substantially constant altitude level. The device is also designed so that the jettisoning of the ballast may be accomplished in one complete operation, or it may be controlled so that the ballast is discharged in more than one operation.
As stated previously, this device is simple in design. In general, it consists of a reservoir, the mouth of which is open to the atmosphere and the bottom of which is provided with a discharge port, the latter being adapted with an outwardly opening closure. The reservoir is filled with fluid, the buoyant forces of which support a float which in principle is the device known as the cartesion diver. In definition, a cartesion diver is a hollow float the lower end of which is provided with an opening for the ingress of fluid into the hollow interior of the float in response to an increase in fluid pressure. The gaseous volume contained in the interior of the diver being the factor which, at any one time, determines the degree of buoyancy of the diver in the fluid. This float is connected to the closure by means of a flexible attachment such as a string. When the reservoir is filled with fluid, the float rises as a result of the buoyant forces exerted by the fluid. The float in turn exerts a vertical pulling force on the string which is transmitted to the closure, and a fluid-tight seal is created between the discharge port and the closure, the latter seal being maintained as long as the vertical pulling force of the float exceeds the pressure of the fluid on the outwardly opening closure.
A principle, well-known in hydrophysics, however, is that a pressure applied to a given area of fluid, enclosed in a vessel, is transmitted undiminished to every equal area of the vessel. Therefore, when the pressure surrounding the reservoir is increased, the increase is transmitted to every part of the fluid contained in the reservoir. As a result, the pressure in the interior of the hollow float is less than the pressure on its exterior, and fluid enters into the float by way of the opening, provided for this purpose, in the bottom of the float. The increase of fluid in the interior of the float, as a result of this pressure change, correspondingly results in a decrease of the volume of gas in the float. As mentioned previously, the buoyancy of the float depends on the volume of gas contained therein. As a result of increasing pressure, the gaseous volume in the float is decreased, the buoyancy of the float is decreased, the float sinks, and the vertical pulling force on the closure is decreased. At this point, where the vertical pulling force is no longer in equilibrium with the pressure of the fluid on the outwardly opening closure, this latter force exceeding the former, the outwardly opening closure will be forced to open allowing the fluid contained in the reservoir to escape to the atmosphere through the discharge port. This action will result in a decrease in the weight the balloon must carry at this altitude, and the balloon will rise.
As mentioned previously, this jettisoning may be accomplished in one complete operation, or it may be controlled so that the ballast is discharged over a period of time, the choice depending on the height of the fluid in the reservoir. If the height of the fluid is suflicient, the float will again rise when the balloon ascends to a higher atmosphere. This is because there is :a decrease in pressure surrounding the reservoir resulting in a decrease in the pressure being transmitted through the fluid housed in the reservoir. As a result, the pressure of the gaseous volume contained in the float exceeds the pressure of the fluid ballast, and the gas expands forcing the fluid out of the interior of the float. When the captive volume of gas in the float expands, it increases the buoyancy of the float and the float rises. in rising, the float again exerts a vertical pulling force on the string. When this pulling force exceeds the pressure of the fluid on the closure, the closure will again form a fluid-tight seal against the port. If the balloon again descends in flight, the operation as heretofore described, will again 'be repeated, and ballast will be released from the reservoir.
*FIGURE 1 is an elevational view of the ballast jettison device, with cross-section cut away, showing the device in ascending flight.
FIGURE 2 is an elevational view of the ballast jettison device, with cross-section cut away, showing the device in descending flight.
Specifically, this device, as illustrated in FIGURE 1, comprises a hollow cylinder 11 which serves as a reservoir for the fluid ballast 12. The upper extremital end 13 of the cylinderis provided with one or more openings 14. These latter openings serve both as inlets, through which the fluid ballast is supplied to the cont ainer, and also as outlets, for the venting of air from the cylinder. The lower extremital end of the cylinder 11 is provided with an end closure 15 (as shown), which may be made from a rubber diaphragm such as the rubbery material from which balloons themselves are made. This end closure has a central opening, formed by an inverted neck 16, and this opening serves as a discharge port through which the fluid ballast is discharged to the atmosphere from the cylinder 11. The base 17 of the inverted neck 16 serves as a valve seal against which a spherical stopper 18 is fitted, the sphere being of a larger diameter than that of the opening formed by the invented neck 16. The sphere 18 is held in position by a string 19, the sphere normally forming a fluid-tight seal with the base 17 of the inverted neck 16 thereby closing the port. One end of the string 19 which passes through the opening formed by the inverted neck 16, is attached to clamp 21 secured to stopper 18, while the other end of the same string is attached to the lower end of the hollow float 22. This float, which is made from impervious, rigid, and non-expansible material, is a cylinder of closed end construction, the lower end of which is perforated. The cylinder 11 contains fluid ballast 12 which provides buoyancy to the float 22, the float being submersibly suspended in the fluid. As a result, the float exerts a vertical pulling force on the string 19 which holds stopper 18 in position against the base 17 of the inverted neck 16. This buoyant float in response to changes in atmospheric pressure, as heretofore described, opens and closes the discharge port and thereby controls the jettisoning of the fluid ballast from the container.
Pre-operatin.-The stopper 18 is fitted and securely held in position against the base 17 of the inverted neck 16. This is usually done manually, and a fluid-tight seal is formed between the stopper 18 and the base 17 of the inverted neck 16. A predetermined amount of fluid 12 is then introduced into the container through the opening 14 in the upper extremital end 13 of the cylinder. As the level of the fluid in the cylinder 11 rises, it provides buoyancy to the hollow float 22 and the float also rises. In rising, the float 22 exerts a. vertical pulling force upon the string 19, which holds the spherical stopper 18 securely against the base 17 of the inverted neck 16, resulting in a fluid-tight seal between the base 17 and the stopper 18.
The device is then secured to the balloon in the conventional manner known in the art. Most usually conventional load loops are attached to the outside of the container providing means for attaching this device to the balloon train line. This device is also mounted below any other instruments which the balloon may be carrying so that it is the last to be released when the balloon starts its ascent.
OperaIi0n.--As the balloon ascends, as illustrated in FIGURE 1, the atmospheric pressure decrease-s causing the air within the float 22 to expand. The float 22 which is made from rigid material, contains perforations 23 in its lower end which provide an outlet for the expanding air 25. The air 25, as a result of the increase in its volume, is forced through these perforations 23 and into the fluid 12 surrounding the bottom of the float 22. The air 25 then rises and is vented out the holes 14 in the upper extremital end 13 of the cylinder 11. This process continues as the balloon ascends and the pressure decreases. In this way, the air pressure Within the float 22 is maintained nearly equal to that of the atmosphere. Once the balloon has reached a constant level of flight, however, the process is discontinued.
When the balloon starts to descend, as illustrated in FIGURE 2, due for example to the efiect of sunset, the atmospheric pressure increases. The pressure within the float 22 attempts to follow the atmospheric pressure, and as a result, the volume of the air 24 within the float is forced to contract. In any case, however, the intake of air into the float is prevented because of the fluid seal existing between the atmosphere and the perforations 23 in the bottom of the float. As a result of these conditions, the fluid ballast 12 is forced into the interior of the hollow float 22. This, of course, disrupts the buoyancy of the float 22, and the float sinks, dissipating the vertical pulling force on the string 19 which holds the stopper 18 in position against the base 17 of the inverted neck. The downward force, due to the Weight of the ballast, which is exerted against the stopper 18, at this point, exceeds the vertical pulling force transmitted from the float 22 to the stopper 18 through the string 19 and the stopper is forced out of its position on the base 17 of the inverted neck, as illustrated in FIGURE 2. The fluid ballast 12, at this point, escapes from the cylinder 11 through the opening which serves as a valve port, into the air. This loss of fluid 12 means a loss of weight which the balloon must carry at this specific altitude and the balloon again begins to ascend.
It should be also be noted that the rate of discharge of the fluid ballast 12 from the device, as described above, may be further controlled by providing the lower extremital end of the hollow cylinder 11 with a secondary reservoir 26 as shown. This secondary reservoir, which may be made of plastic or any other strong, light-weight material, is in the shape of a bag having holes, 27 and 28, therein for the discharge of ballast to the atmosphere, the holes being of such a number and such a size as to control the discharge of a specific weight of ballast over a predetermined period of time. In this way, radical changes in the altitude of flight of the balloon are avoided, and the balloon will then slowly ascend to its predetermined level of flight without substantially overshooting such predetermined level.
The foregoing drawings and descriptions illustrate the preferred embodiment of the invention. The invention, however, is not to be construed as limited to the specific form shown. It is well Within the purview of the man skilled in the art to change the size and shape of this device without departing from the spirit of the invention. For example, the overall size of the ballast release device would depend on the size of the balloon to which it is attached. Correspondingly, the size of the hollow float depends on the fluid pressure exerted against the valve closure of sphere, and this pressure in turn, would depend on the size of the reservoir containing the fluid.
As for materials of manufacture, the overall requirement is that the cylinder 11 and the float 22 be made of lightweight material which is strong and rigid in nature. It has been found that a lightweight plastic, which is comparatively strong, is suitable for the construction of the reservoir and the float. However, these parts may be made from a great many materials whose weight and strength will not interfere with the effective operation of the device, as for examplealuminum, pressed paper, foamed plastic, tin plate, and glass. Also the retaining means may be made from many types of flexible materials, even though we have chosen an ordinary string as our specific means. The valve closure should be light in weight and preferably non-porous. And finally, the fluid ballast utilized should be of the type that does not freeze or vary in volumetric size with changes in altitude, specifically it should not freeze at temperatures in the region of about 70 F. These type fluids are wellknown or can be chosen with accuracy by todays average industrial chemist. We have found that alcohol is not only especially adaptable for our purposes, but it has actually proved itself to be useful in experimental flights heretofore performed.
The device is simple in design, cheap, and easily manufactured. It has been found that constant level balloons equipped with the aforedescribed ballast release have had a greater overall performance reliability at high altitudes because of the dependability and effectiveness of this invention.
1. A ballast release device for attachment to a balloon which comprises: a reservoir the upper end of which communicates with the atmosphere; a discharge port provided in the bottom surface of said reservoir, said discharge port being equipped with an outwardly opening closure; a liquid contained in said reservoir; and buoyant means the lower end of which communicates with said liquid, said buoyant means being adapted to operate as a cartesian diver in said liquid and being connected to said closure thereby maintaining said closure in fluid-tight position against said port until there is a substantial increase in atmospheric pressure.
2. A ballast release device for attachment to a balloon which comprises: a reservoir the upper end of which communicates with the atmosphere; a discharge port provided in the bottom surface of said reservoir, said discharge port being equipped with an outwardly opening closure; 2. liquid contained in said reservoir; and a cartesian diver connected to said closure through said port, said diver suspended in said liquid thereby maintaining said 15 closure in fluid-tight position against said port until there is a substantial increase in atmospheric pressure.
3. A ballast release device for attachment to a balloon which comprises: a reservoir the upper end of which communicates with the atmosphere; a discharge pont provided in the bottom surface of said reservoir, said discharge port being equipped with an outwardly opening closure; a liquid contained in said reservoir; and an inverted cup connected to said closure through said port, said inverted cup having an enclosed volume of gas suspending said cup in said liquid thereby maintaining said closure in fluid-tight position against said port until there is a substantial increase in atmospheric pressure.
References Cited in the file of this patent UNITED STATES PATENTS 1,709,930 Bronander Apr. 23, 1929 2,341,351 Barkley Feb. 8, 1944 FOREIGN PATENTS 358,462 Germany Sept. 9, 1922