Our first phase of activity, at the Guidonia supersonic wind tunnel, was devoted to studying and designing the necessary apparatus for carrying out systematic research. (See Captain Gasperi's paper, read before the Lilienthal Congress in 1937-) This apparatus consisted principally of:—

1. (1) A series of transformer jets, to create the requisite speeds in the test chamber;

2. (2) A balance, to determine the forces exercised by aerodynamic phenomena upon the objects under test;

3. (3) The striometric and interferometric apparatus.

The initial study was long and laborious; since we lacked the great help furnished by previous research, which is nearly always forthcoming in similar studies, we had to proceed by means of successive experiments until the apparatus took its final shape. Eventually we evolved a series of jets, a balance and an optical installation which we hope are permanent. These, however, being still under construction, have not yet been tested.