Stratospheric airships are lighter-than-air (LTA) vehicles that have the potential to fly extremely long-endurance missions at altitudes of 18-22 km. Previous work has shown that optimal ascent trajectories may be planned which utilize anticipated wind conditions in order to achieve minimum-time and minimum-fuel flight. The airship is represented by a three-dimensional point mass model, and the equations of motion include aerodynamic lift and drag, vectored thrust, added mass effects, and accelerations due to mass flow rate, wind rates, and Earth rotation. A representative wind profile is used for planning, which is based on historical meteorological data and measurements. Optimal trajectories are found by first defining an optimal control problem with both terminal and path constraints, then using direct collocation to develop an approximate nonlinear parameter optimization problem of finite dimension, which is solved using SNOPT. In this paper, we analyze the performance of optimal ascent trajectories with respect to solar energy production during ascent, and quantify the sensitivity of the solutions to small changes in drag coefficient and wind model parameters. Sensitivity to the drag and wind model is approximated through numerical simulations. Results indicate that solar energy is sufficient to power ascent flight, but that significant energy loss can occur for certain types of trajectories. The sensitivity analysis shows that optimal solutions change gradually with respect to changing wind and drag parameters, and offers deeper insight into the characteristics of optimal airship flight.