Narrower Terms (9)

• Air as a test gas
• Expansion tubes (Hypersonic wind tunnels)--Test gases
• Helium as a test gas
• Hexafluoroethane as a test gas
• Hypersonic wind tunnels--Test gases
• Nitrogen as a test gas
• Oxygen as a test gas
• Sulfur hexafluoride as a test gas
• Wind tunnels--Test gases