<<Following is an article that I wrote last year. I have also included an
Excel spreadsheet where you can plug in your own engine size and scoop
diameter.  Lorn H. Olsen>>

Lorn,
The calculations you presented appear to recommend the inlet to be sized for
a 1:1 velocity ratio - in other words the velocity in the inlet is equal to
the free airstream velocity.  I see other recommendations that are for
velocity ratios between 0.4 and 0.7, producing much of the pressure recovery
ahead of the inlet.  The advantage of that, as I see it, is that pressure
recovery ahead of the inlet is quite efficient and requires less recovery
inside the duct, reducing the required length.  Also, at lower airspeeds the
inlet is more efficient as there is less chance for flow separation inside
the duct.  What do you think?

Gary Casey