Under a series of contracted analytic and experimental studies, we have been increasing the size of inflated parabolic structures for use in space and determining surface accuracy. The primary user for this technology is the Solar-Powered Rocket, where hydrogen gas is heated to a high temperature by solar energy, rather than chemical or electrical means. To make the solar rocket work, very large (typically 150-ft. diameter), highly-accurate (typically surface accuracy better than 1 mrad slope error), lightweight paraboloids are needed. Based on subscale surface accuracy tests, there is a concern if a full size system can be constructed that meets the accuracy requirements. An analysis was performed that indicates when absolute error is held nearly constant, the slope error will be greatly reduced as size increases. A major source of error is the elastic modulus of the plastic film used for the reflector. Modulus data published by the film manufacturers are average values and cannot be used in determining the gore dimensions required to obtain the desired reflector shape. Modulus data as a function of stress is presented. Tests have been performed on 1 and 3 meter on-axis and 3 meter off-axis parabolas. The results to date indicate that surface shape errors do not increase directly with size. Further work in progress is needed to properly evaluate the scaling of surface error with size.