The official tests of the Caudron-Renault C.570 were conducted at the French government’s flight test center located in Istres, France. The C.570 was a French racing aircraft developed in the late 1930s, and its testing was crucial for evaluating its performance and capabilities.

If you would like more detailed information about the specifications or historical context of the Caudron-Renault C.570, feel free to ask!