Electrodialysis in an ion-exchange membrane cell was shown to be technically feasible for the concentration of an azeotropic mixture of HF and water. A flowsheet is presented for recovery of anhydrous HF by distillation and electrodialysis of the azeotropic residue. In the electrodialysis step, 2.6 kwhr of energy per pound of anhydrous product was consumed, with electricity at 1¢ per kilowatt-hour, the total operating cost of the electrodialysis equipment alone, including amortization, would be 6¢ per pound of HF.

Average coefficients of thermal expansion of the temperature range 25 C to approximately 425 C are reported for numerous types of graphite. The dependence of thermal expansion on crystal orientation and crystallite size and the effects of oxidation and cold test hole irradiation are discussed. An empirical relationship between thermal expansion and the initial rate of physical expansion under cold test hole irradiation is formulated.

This letter transmits the data from the 189-D Hydraulics Laboratory flow test on three CG-482 rear pigtails. The tests were run with a standard B, D, Dr and F rear nozzle and rear Parker fitting over the range of flows and temperatures anticipated for early CG-558 operation. The data from the test are given. All three pigtails gave essentially identical results. For comparison the results of previous tests with present rear pigtails are also plotted.

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Report presenting several short two-dimensional subsonic diffusers over a range of throat Mach numbers from 0.3 to 0.9. The designs incorporated an effective diffusion angle of approximately 30 degrees and an area ratio of 3. At a throat Mach number of 0.7, the resulting profile distortion of the unmodified 30 degree diffuser was diminished from about 11 to approximately 4 percent by using any of the configurations.

"The theoretical performance of pentaborane has been recalculated using recent data on the vapor pressure of boric oxide. Previous calculations were based upon vapor-pressure data obtained some years ago by a method not as accurate as that employed in current investigations. The recalculated performance data for pentaborane differ appreciably from previously published data and are considered more accurate for evaluation of the relative potentialities of boron-containing fuels" (p. 1).

Report presenting testing of two airplanes, the F6F-3 and F-86A, fitted with servo equipment for varying in flight the lateral and directional stability and handling characteristics and flown by test pilots to simulate the predicted dynamic behavior of six prototype airplanes. Results regarding the aerodynamic characteristics and pilot opinions for each plane are provided.

Report presenting an exploratory investigation of the effectiveness of outboard horizontal tails in reducing the static longitudinal stability changes with lift coefficient associated with many sweptback wings. The results indicated that outboard horizontal tails can be a very effective means of counteracting the trend toward longitudinal instability characteristics of many sweptback wings. Results regarding the effects of changes in horizontal-tail position, effects of wing fences, average downwash at the tail, effects of changing tail size, lift, drag, and pitching-moment characteristics, and effects of flaps are provided.

Theoretical calculations of specific impulse to determine the separate effects of increasing the combustion-chamber pressure and the nozzle expansion ratio on the performance of the propellants, hydrogen-fluorine, hydrogen-oxygen, ammonia-fluorine and AN-F-58 fuel - white fuming nitric acid (95 percent). The results indicate that an increase in specific impulse obtainable with an increase in combustion-chamber pressure is almost entirely caused by the increased expansion ratio through the nozzle.

Memorandum describing an investigation using two airplanes, an F6F-3 and F-86A, each fitted with servo equipment for varying in flight the lateral and directional stability and handling characteristics, which have been flown by test pilots to simulate the predicted dynamic behavior of six prototype airplanes. The methods of simulation and the types and ranges of variables considered are presented and the results of the individual programs are discussed.