Waste of time for much other than fairly gross testing.

You should read the Soartech 8 book of Michel Selig. In there he went into the requirements of the wind tunnel and the need for low turbulence values. It's quite the eye opener. Believe me, just sticking a honk'in great fan at the end of some heating ducting isn't going to tell you much at all.

You'd be better off with test models that you hand launch.