The Transonic Wind Tunnel is an induced-type closed-circuit tunnel with a 0.6 m × 0.8 m test section. The tunnel is operated by high-pressure air injected downstream of the test section through a circular injector. The operating range is M = 0.2 ÷ 1.1. The typical duration of a test depends on the Mach Number, it varies between about 100 seconds at the lower Mach Numbers and 25 seconds at the maximum Mach Number. For speeds up to M = 0.35 a secondary ejector, consisting of a rake of tubes mounted near the test section exit, is used. The test section is 1.5 m long, the Reynolds Number range is 5 ÷ 17 × 106/meter, the dynamic pressure range is 2,000 ÷ 42,000 Pa. The stagnation pressure is slightly higher than the atmospheric pressure and the stagnation temperature is in the range 00 ÷ 300 C depending on the atmospheric temperature and on the rate of pressure drop in the compressed air vessels.