Geographical Variations of Wind Loads on Vertically Rising Vehicles

Abstract

The variation in winds and resulting variations in wind loads on vertically launched vehicles for different worldwide geographical areas are investigated. Methods of determining possible alternate launch sites that offer distinct windwise advantages over presently used sites are discussed; reductions of 50 per cent or more in statistically determined peak winds or in statistical values of wind shears at critical altitudes may be realized. Since peak winds and maximum shears are recognized parameters of wind-induced loading, the variations in peak loads that are expected at different launch sites should reflect significant changes in wind environment with geographical regions. For some particular vehicles, variation of a single parameter, such as maximum wind speed, will produce large differences in computed load histories. An interesting disclosure of subjecting a simulated large liquid-propellant vehicle to various wind inputs is that the peaks of the load histories appear more strongly related to maximum wind shears than to maximum wind speed. For most vertically rising vehicles, the geographical loading variations can be best related to some combination of differences in both peak wind and shears. Several important and practical observations are made as a mean for illustrating the findings of the study. For example, military and defense requirements placed on missiles dictate a specific type of wind environment for evaluation purposes, while optimization of space operations capability requires a very different wind environment for its supporting vehicles.