An airship is o operate at 20 m/s in air at staanclard conditions. a model is constructed to2scale and tested in a wind tunnel at the same air temperature to determine drag. what criterion should be considered to obtain dynamic similarity? lf the moel is sicd at ts n/s, what pres should be used in the wind tunnel? if the model drag force is 250 n, what will be the drag of the prototype?

Afan that can provide air speeds up to 60 m/s is to be used in a low-speed wind tunnel with atmospheric air at 35 c. if one wishes to use the wind tunnel to study flat-plate boundary layer behavior up to reynolds numbes of re 10, what is the minimum plate length that should be used? at what distance from the leading edge would transition occur if the critical reynolds nurnber were rer,e = 5 × 105?