Propulsion apparatus and method using boil-off gas from a cryogenic liquid

A propulsion system and method are disclosed for controlling the attitude and drag of a space vehicle. A helium dewar contains liquid helium which cools an experiment package. The helium is heated or vented to keep the temperature between 1.5 and 1.7 degrees K to maintain adequate helium boil-off gas as a propellant without adversely affecting the experiment package which is contained in the helium dewar for protection from solar heating. The apparatus includes auxiliary heater and temperature sensor for controlling the temperature of the helium. The boil-off gas propellant is delivered to thruster modules to control vehicle attutude and compensate for drag

Space Shuttle Lightning Protection

The technology for lightning protection of even the most advanced spacecraft is available and can be applied through cost-effective hardware designs and design-verification techniques. In this paper, the evolution of the Space Shuttle Lightning Protection Program is discussed, including the general types of protection, testing, and anlayses being performed to assess the lightning-transient-damage susceptibility of solid-state electronics

Perfect bell nozzle parametric and optimization curves

Nozzle contour data for untruncated Bell nozzles with expansion area ratios to 6100 and a specific heat ratio of 1.2 are provided. Curves for optimization of nozzles for maximum thrust coefficient within a given length, surface area, or area ratio are included. The nozzles are two dimensional axisymmetric and calculations were performed using the method of characteristics. Drag due to wall friction was included in the final thrust coefficient

Effects Of Shift Work On Insulin Dependent Diabetics

Over 25% of the work force is comprised of insulin-dependent diabetics. The purpose of this descriptive study was to determine the impact of shift work on blood sugar levels in insulin-dependent diabetics. Rogers\u27 Theory of Homeodynamics was the conceptual framework guiding the study. The research question was does rotating shift work have an impact on blood sugar levels in insulin-dependent diabetics. The total sample (N = 40) was selected from 100 insulin-dependent diabetics who work at an industrial plant in midwestern Alabama. Thirty insulin-dependent diabetics who were working rotating shifts and 10 insulin-dependent diabetics who worked regular day shift were used for comparison. Blood sugar levels were measured daily during shift rotations, and measurements were taken on the insulindependent diabetics who worked regular day shifts. The hypothesis generated was there will be no difference in blood sugar levels in persons who work shift work and those persons who work regular hours. Examination of the data revealed a 2.20% increase in blood sugar level when the insulin-dependent diabetic subjects (n = 30) worked the night shift. There was an 11.9% increase in blood sugar level in the diabetic subjects (n = 30) when they worked the evening shift. Analysis of the data using the student t test revealed a significant difference between the blood sugar levels of those who worked shift work and those who worked regular hours (t = 4.52; p \u3c .004). Implications for nursing and recommendations were presented