A 2-dimensional, small high speed cryogenic wind tunnel was constructed at National Defense Academy (N. D. A.) in 1985, using the stainless steels of SUS 304 and SCS 13 as materials of the pressure shell. The features of the cryogenic tunnel and its operation procedures are described. The initial operational tests were intensively performed to refine the general operation method to the optimum for the present tunnel with the original manual control systems. Those tests showed that the original

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... ontrol systems were fairly acceptable, but had to be modified to automatic controls for more precise control of the tunnel flow conditions at cryogenic temperature range and expanding its actual operational envelope.