Effect of Reynolds Number and Aeroelastic Scaling Upon Launch-Vehicle Ground-Wind Loads

What is it about?

A wind tunnel effort was conducted to evaluate the importance of key scaling parameters in characterizing launch vehicle response to ground wind loads at the pad prior to launch. Vortices can shed in the wake of the vehicle and produce nearly sinusoidal lift and drag loads. When these oscillatory loads have a frequency close to the natural structural modes of the vehicle, large structural oscillations and loads can result. The behavior of this interaction is governed by scaling parameters. Matching these scaling parameters in a wind tunnel test is difficult and requires unique test facilities. Therefore, many vehicle developers have opted to test in smaller and less expensive facilities that do not match these scaling parameters properly. This research effort has demonstrated that not matching these scaling parameters can result in unconservative estimates for dynamic vehicle loads and could also produce incorrect design guidance. Examples are presented with experimental data. As a result, launch vehicle designers and operators should test at adequate facilities or risk reaching improper conclusions.

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