Aerospace & Aviation

Tables of interference factors for use in wind-tunnel and ground-effect calculations for VTOL-STOL aircraft are presented for wind tunnels having a width-height ratio of 2.0. These tables were machine-calculated and are intended for use with the procedures of NASA Technical Report R-124. These tables are presented without comment.

Ammonia and hydrazine were X-irradiated in a preliminary investigation of the effects of ionizing radiations on propellants. A 250-kilovolt, 15-milliampere source was used at room temperature and a distance to provide 90 to 100 roentgens per minute of radiation. Ammonia was irradiated as a vapor at pressures of 100 to 1295 millimeters of mercury with doses of 45 to 104 kiloroentgens of radiation. Less than 1 percent decomposition of ammonia was observed. Liquid ammonia decomposed to the extent of approximately 1 percent with a radiation dose of 115 kiloroentgens. The irradiation of hydrazine vapor at a pressure of 15 millimeters of mercury and a total dose of 590 kiloroentgens resulted in approximately 3 percent decomposition. Both ammonia and hydrazine decompositions involved the formation of nitrogen and possibly hydrogen. In addition to the permanent gases, hydrazine was formed from ammonia and ammonia was formed from hydrazine. All irradiations resulted in the formation of other materials that have not been characterized.

A systemic investigation of screen-accelerator grids was made with an ion rocket having a 10-centimert-diamter electron-bombardment ion source. Mercury ion beams of 0.03 to 0.44 ampere were operated at net accelerating voltages of 900 to 6100 volts. A multihole screen-accelerator grid set passed the greatest percent of an ideal plane diode current with a ration of between-grid spacing to individual hole diameter of approximately 1. Breakdown between the grids occurred at field strengths of 2000 to 3000 volts per millimeter for grid spacings of 1 to 3 millimeters. The accelerator impingement was about 1 percent and caused little erosion of the molybdonum grids, which indicated a grid life of the order of 10000 hours or better. The experimental work was conducted in a bell jar connected to a 5-foot-diameter by 16-foot-long vacuum tank at Lewis Research Center.