“…At the expense of test time, total enthalpy and total pressure are added to the flow without the flow dissociation that would occur in a shock tunnel. 18 The X2 expansion tube at the University of Queensland has been used extensively to simulate and measure radiating test flows for several planetary bodies in the solar system, including Earth, Mars, Titan, and Venus, [20][21][22][23][24][25][26] at velocities ranging from 6 -12 km/s. However, when considering simulating entries into the gas giant planets in the outer reaches of the solar system, velocities range from 20 -50 km/s, pushing the performance envelope limits of expansion tubes as they are currently configured, and requiring a firm understanding of the performance trends of the facilities to create useful test conditions.…”