SOLAR RADIATION ON A CATENARY COLLECTOR by M. Crutchik and J. Appelbaum ERRATA Replace by or add to: p. 215 Mission to Martian surface will require electric power. A power supply that requires little installation time, being light weight and stowed in a small volume can be accomplished by a photovoltaic (PV) array. A tent-shaped structure with a flexible PV blanket for solar power generation is proposed in [1], Fig. 1. The array is designed with a self-deploying mechanism using a pressurized gas expansion. The structural design for the array uses a combination of cables, beams and columns to support and deploy the PV blanket. The array is stowed with the blanket either folded or rolled. The main contribution to the stress in the structure is due to the tension in the cable which supports the PV blanket. The shape of the PV blanket is determined by a optimization between reduction in the cable tension and increase in blanket area. Under the force of gravity a cable carrying a uniformly distributed load will take the shape of a catenary curve, fc(y), with respect to the Y-Z plane, Fig. 2. p. 217 Because of the shape of a catenary-tent-collector, a self-shading effect occurs on one of its sides (side B in Fig. 2). in this article we anaiyze the shadow shape ami area. Based on these results, the beam insolation on the collector is calculated. We also determine the diffuse and the albedo insolation on the collector. An example for the planet Mars is given for the location of Viking Lander 1. Results for the parabolic approximation is given in Appendix B. With the results developed in the previous section, the beam irradiance in W or W/m2 and the beam insolation in Whr/day or Whr/m2-day on the catenary-tent- collector can be determined. The diffuse and albedo components will be added to the beam to get the global irradiance and insolation. A north-south facing catenary-tentcollector will be considered. A generalization to any arbitrary oriented tent may be obtained using eq. (4).
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