Tunnel C Tunnel C in the von Kármán Gas Dynamics Facility at Arnold Air Force Base, Tenn. is used for aerodynamic testing at speeds of Mach 4 and Mach 10, speeds that hypersonic weapons would travel, March 12, 2020. SHARE: Download: Full Size (1.46 MB) Credit: Jill Pickett, Air Force VIRIN: 200312-F-KN521-2004M.JPG Photo Gallery