Overview of the High Reynolds Number Ascent Wind Tunnel Test of the Space Launch System at the National Transonic Facility

Abstract

Transonic, high Reynolds number wind tunnel testing for the Space Launch System (SLS) ascent flight environment was conducted in the National Transonic Facility (NTF) at the NASA Langley Research Center from December 2019 to April 2021. The test was sponsored by the SLS Program and the NASA Engineering & Safety Center with the objective of assessing and characterizing Reynolds number effects on the ascent aerodynamics of the SLS launch vehicle. The cryogenic test article was a 1.75%-scale representation of the SLS Block 1 Cargo configuration that was fabricated mostly out of stainless steel, but with several additive-manufactured components including the Solid Rocket Booster (SRB) attach brackets and the SRB nozzles. This was the first use of additive manufacturing on structural components of a cryogenic model in the NTF, therefore, post-fabrication material testing and inspections were performed to satisfy safety requirements. Force & moment and surface pressure data were acquired for Mach numbers between 0.50 and 0.95 over a range of Reynolds numbers based on core stage diameter between 2x10^6 and a maximum of 40x10^6 corresponding to 45% of flight Reynolds number. Additionally, flow visualization data using Pressure Sensitive Paint were acquired with a focus on the SRB forward attach area, which is susceptible to Reynolds number sensitivity at transonic speeds. This paper provides an overview of the test campaign including details on the unique test article and the experimental setup and test execution. General test findings and observations are also presented, but the majority of the test results and data analyses are provided in a companion paper.