Very nice picture of the test fixture, Al.  Is there any meaningful way
to test a NACA duct with this setup?

Ernest;

No, the test setup doesn't test the effectiveness of the intake scoop,
it just puts the blower output into the scoop.  It provides data on the
air-side flow characteristics of the radiator - pressure drop and flow
distribution in the core.  For me it confirmed that the pressure drop
across the core was low enough that there should be considerable margin
in the pressure recovery in the duct (scoop); and allowed me to install
baffles in the curved duct to get a relatively uniform flow distribution
over the radiator area.

Al