Refined Day-of-Launch Atmospheric Flight Loads Analysis Approach

A day-of-launch atmospheric flight loads analysis approach that reduces conservatism by better defining the components of flight loads that have to be treated statistically and those that can be established with measured wind profiles just prior to launch is described. The approach introduces the concept of removing from measured day-of-launch winds the rapidly varying features and only using the more slowly changing components in the load calculations performed just prior to launch. The proposed approach takes advantage of two recent developments. The first development defines the spectral boundary, as a function of time, between wind components that can be considered slowly varying and those that change rapidly and, hence, have to be addressed statistically. The second development provides an approach for calculating gust loads caused only by the turbulent components of the winds and thus eliminates the need to include these wind components in the load calculations performed just prior to launch. (Author)