A refined and less conservative day-of-launch atmospheric flight loads analysis approach

Abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources gathering and mahtainino the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for redudng this burden, 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-oflaunch winds the rapidly varying features, and only using the more slowly changing components in day-of-launch, placard calculations. The proposed approach takes advantage of a recently-developed methodology that 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. SUBJECT TERMSAtmospheric flight loads, launch vehicles, turbulence, day-of-launch placards AbstractA 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 due only to the turbulent component of the winds, and thus, eliminates the need to include these wind components in the load calculations performed just prior to launch.

Atmospheric Flight Gust Loads Analysis

“…The Monte Carlo turbulence/gust loads analysis approach introduced in this paper has significant potential for more properly defining atmospheric turbulence/gust loads, and reducing unnecessary conservatism in day-of-launch placard calculations. 24 However, the results presented in this paper should only be extrapolated with caution. As discussed in Ref.…”