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11. SPACE SCIENCES

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"A Method of Obtaining a Complete Balance of Life within a Closed System" was the ingenious project of Richard P. Bentley of Tupper Lake, New York. It was exhibited at the Tenth National Science Fair.

"The following is a report on the method by which I propose to maintain a complete balance of life ecology within a closed system. This experiment is important because the method could be put to practical application on long-term space flights and in submarines to eliminate the large area of space required to store food and oxygen. It would be of great value in any situation where food supply, oxygen supply and waste removal had to be self-contained and where there was a limited amount of space for storage.

The major parts of the apparatus consist of a living chamber, a septic tank and an algae tank.

I am now using only the algae Chlorella in the apparatus, because to date I have been unable to obtain living cultures of Scenedesmus and Anacystis nidulans. These types of algae are needed to supplement the necessary amino acids con­taining sulfur and certain other nutrients in which Chlorella is deficient. The algae serve as nourishment for the mice, which I am using as my test animals.

In the septic tank I am using a type of anaerobic bacteria to break down the carbon compounds into methane and then into carbon dioxide and water, and a type to break the urea down to ammonia or some other nitrogen compound that the algae can use.

Operation

Important: Follow the operation through on the Schematic Diagram of the system.

The foul air leaves the living chamber through tube (A) and is pumped by the air pump up through the algae tank, where the carbon dioxide given off by the mice and a few trace gases from the septic tank dissolve into the nutrient solution. Dissolved in the nutrient solution, the CO2 is used by the algae. Free of CO2, the air, along with O2 given off by the algae, rises to the top of the algae tank. The purified air, along with water vapor evaporated from the warm water, passes up through tube (B) and into the water-cooled con­denser, where most of the water vapor condenses and runs out of the condenser into the water reservoir through open­ing (C). The somewhat drier air also passes out of the con­denser into the top of the water reservoir through opening (C), and then out of the water reservoir through tube (D), by which it is returned to the living chamber.

Air Rump

The mice will be fed unprocessed algae according to the following scheme.

When Valve I is in the open position the algae flow from the algae tank through tube (E) and through Valve I up into compartment (F) until the surface of the liquid reaches the end of tube (I), where it will stop rising because of the air pressure in the top of compartment (F). When Valve I returns to the closed position and Valve II goes to the open position, the algae flow out of compartment (F) and into the centrifuge, which is spun at a high speed until the algae separate from the nutrient solution and collect around the outer rim of the centrifuge because they are heavier than the nutrient solution. Valve III is then opened and the nutrient solution is drawn off through tube (G), leaving the algae which, when Valve IV is opened, are drained from the cen­trifuge and flow through tube (H) into the food dish within the living chamber. The nutrient solution which was drawn off in the centrifuge passes down into the septic tank and then back up into the algae tank.

To supply the mice with a constant drinking water supply, I have designed the following apparatus. When the water in the water reservoir reaches a certain level, the water over­flows into tube (J), which fills water container (K), which, after being filled, overflows into tube (L) and runs down through the living chamber into the septic tank. The water in container (K) also flows through tube (M), which goes straight up inside vertical container (N) where it will over­flow from tube (M) upon demand and run down tube (O), at the bottom of which it will hang in a drip from which the mice drink. While not in use the water neither runs freely out of the tube nor back up the tube.

The excreta of the mice pass through the wire mesh which acts as the floor of the living chamber into the water beneath it, and when the food dish is tipped and Valve V is opened, the water in the water reservoir runs down, washes out the food dish and continues on down and flushes the pool of water in the bottom of the living chamber down into the septic tank. When this occurs, the water at the other end of the septic tank overflows into compartment (P). When the ris­ing level of the water in compartment (P) reaches a certain point, the float makes an electrical contact which starts the water pump and turns on the ultraviolet lamps. The water pump pumps the water containing dissolved minerals and organic compounds out of compartment (P), through tube (Q), between the ultraviolet lamps, which kill most of the bacteria in the water, and on up through tube (Q) into the algae tank.

The algae tank is illuminated internally with four white fluorescent lamps. The fluorescent lamps are inserted into plastic tubes placed horizontally through the tank. The edges of the open ends of the tubes are sealed to the edges of holes in the sides of the tank, thereby permitting easy access to the fluorescent lamps.

It is my hope that the design of the system presented herein, with the exception of the design of the algae tank, is an original contribution to the development of a closed system adequate to sustain life.

References

1. Gaume, James G., M.D.—"Plants as a Means of Balanc­ ing a Closed Ecological System"
   
2. Gaume, James G., M.D.—"Design of an Algal Culture Chamber Adaptable to a Space Ship Cabin"
   
3. Gaume, James G., M.D.—"Sealed Cabins and Artificial Atmospheres"
   
4. Gaume, James G., M.D.-"Nutrition in Space Operations"
   
5. RIAS,   Inc.,   Report   #   29—"Photosynthetic   Gas   Exchangers," principal investigator:   Dr. A.  R.  Rrall  and authorized contact negotiator: Guy Ullman"

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6. Experimentation in Aerodynamics," the project of Leland B. Jackson, Atlanta, Georgia, was presented at the Ninth National Science Fair.

"Introduction

My project is the culmination of four years of experimenta­tion in aerodynamics. In the ninth grade I constructed the wind tunnel as my general science project and used it to determine the lift-drag ratio of several scale model airplanes. In the tenth grade I still worked with lift-drag ratios; but only airfoils, or wings, were experimented with. Various air­foils were classified according to their capabilities and proper­ties and were related to the type aircraft for which they were best suited. (A detailed description of these experiments, along with the graphs and calculations made, may be found in the last section of this log.)

I entered my lift-drag experiments in the 1956 Atlanta Science Congress. In this congress were two projects dealing with photoelastic stress analysis—one in solids and one in liquids. These projects employed polarized light to produce visible patterns of stress in these substances. Since this could be done in solids and in liquids, I wondered if this process might also be employed to show stress in gases, especially around an airfoil. I asked several sources at both Georgia Tech and Lockheed, but could find no evidence that this had ever been tried before. Detailed descriptions of my work with polarized light are included in this log, and although results have so far been negative, many conclusions and projections could be formed.

Still interested in stress analysis, I learned of experiments using a water table which would produce patterns similar to those the polarized light experiments were designed to produce. I therefore designed and constructed a water table and used it to obtain patterns of shock-wave formations and density distributions around an airfoil.

Wind Tunnel Experiments

Having become interested in producing stress patterns in gases through the use of methods employed for photoelastic stress analysis, I mounted polarized glass in both sides of the test section of my tunnel. Photoelastic stress analysis works briefly as follows. A beam of polarized light, or light limited by a piece of polaroid to a vibration in only one direction, is directed through a transparent medium. This medium if un­stressed allows the beam to pass unaltered. However, if a stress in the medium has altered the index of refraction in a certain direction, a rotation of the polarized ray will be set up, producing elliptically polarized light. This resulting light, when passed through a second piece of polaroid, produces a pattern of the stress within that medium. These patterns are somewhat circular, alternately colored lines; and the closer these lines are together, the higher the stress is at that point. This rotation from plane to elliptically polarized light is called birefringence.

In liquids, if a solution of elongated molecules is at rest, the molecules' random positions will not alter the plane polar­ized light. However, if the liquid is set in motion, these molecules tend to align themselves with the direction of the flow, and the higher the stress on the liquid, the more they align themselves. This corresponds to the altering of the solid's index of refraction and also produces elliptically polarized light; it is known as streaming birefringence.

I was hoping that in gases the difference in the densities surrounding an airfoil in flight would bend the polarized rays so as to produce patterns of the variations around the air­foil (shock waves, density variations, etc.).

Through a new motor, propeller and gear arrangement, I increased the pressure in the tunnel; however, no patterns were produced. I introduced various gases and smokes into the tunnel, including smoke from pine straw, smoldering rags, etc., and carbon dioxide from dry ice in water, but I still was not able to obtain the desired results. I did not con­tinue with experiments along this line, for it was apparent that too great a volume of air passed through my tunnel for an introduced gas or smoke to be anywhere near pure and have any effect. Also, since any introduced gas was not recirculated, it was lost forever once it had passed through the tunnel.

When Mr. Richard T. Whitcomb, head of the supersonic wind tunnel at Langley Air Force Base, Virginia, was in town last year, he observed my project. Although he had never heard of any experiment of this nature, he was of the opinion that my tunnel did not develop enough pressure for an experiment of this type or that air was not dense enough to produce an effect on polarized light.

Although there is the possibility that air molecules are too tenuous and too independent of each other ever to produce an effect upon polarized rays, there are many other approaches using polarized light which still might produce the desired stress patterns. If a smaller, circular, closed wind tunnel system which would recirculate the gas were employed, the gas could obtain a greater velocity through the momentum gathered by recirculation. Also, a gas in an almost pure state could be placed within the system and could be placed under a high pressure even before it was circulated.

If the varying densities around an airfoil do not have an effect on polarized light, it may be that gaseous streaming birefringence can be accomplished if a gas with elongated molecules can be found and employed in the same manner as liquids now are in photoelastic stress analysis.

Water Table Experiments

Still interested in stress analysis, I learned of experiments using a water table which produced patterns similar to those toward which I had been working. My hypothesis on the polarized light experiments had been that if perfected, they would yield a combination of the patterns that could be obtained on a water table. I therefore built a water table in order to produce and study separately the shock-wave and density-distribution patterns.

The water table consists of a tank for the water and a gate at the bottom of this tank which allows a thin, smooth sheet of water to pass over a downwardly sloping piece of glass. A cross section of an airfoil is placed on the glass, and when the flow of water encounters the airfoil, waves are produced in the flow. Under the glass are placed alternately colored lines, and the waves in the flow refract the light rays reflected from these lines, producing patterns of the shock-wave formations. A plain white sheet of paper may be sub­stituted for the lines, in which case the shock waves are shown by the shadows which they cast on this paper.

Patterns of the density distributions around an airfoil also may be produced, for the water displaced by the airfoil on the glass causes the flow to be deeper around the wing. The ratio of this depth to the static or normal depth is equal to the ratio of the densities in the air around a similar airfoil under similar conditions in flight. A chart with points approxi­mately a half inch apart was placed under the glass, and a depth reading was taken at each point. The depth was measured by lowering a pointed object toward the glass until it barely touched the top of the water flow. It was then lowered until it touched the glass, and the number of turns required to do this were carefully counted to the sixteenth of a turn. Since each turn moved the point 1/20 of an inch, the depth could be calculated to 1/320 of an inch. This depth divided by the depth reading taken in the static flow produced the depth ratio, equal to the air density ratio at that point.

A chart showing the pattern of the density distribution around the airfoil was then produced by connecting points of equal ratio to each other by a certain color; the higher the ratio the darker the color used.

The Mach number, or multiple of the speed of sound, which the water table is simulating, is obtained through the following formula: the velocity of the water flow in feet per second divided by the square root of the acceleration of gravity (32.16 ft./sec.2) multiplied by the depth of the water flow in feet. This formula was available for use, but a way to obtain the velocity of the water flow had to be devised.

I knew that pressure is a linear equation with density being constant and depth being the only variable, and therefore the rate of decrease in the pressure of the water in the tank would be even. Therefore, if the time required for the water level to decrease between two depths which were equally above and below the desired depth was clocked, and if the volume of water between these two tank depths was calculated, I would obtain the water velocity at a certain tank depth by dividing this volume by the above described time. The resulting quotient would be a measurement in cubic feet per second. In order for this to be equal to velocity in feet per second, the velocity would have to be multiplied by some measurement in square feet, and this measurement would be the cross-sectional area of the water flow over the table. The velocity of the flow then could be calculated by dividing the volume between the two levels in the water tank by the time required between these two levels multiplied by the cross-sectional area of the flow. This velocity could then be substituted in the Mach num­ber formulas."

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