Here are two pictures of a very fast Tailwind  built by Red   Hamilton
    that I have taken from the Tailwind list.  I am sure they  don't  mind.
      The first photo shows an angled intake which did not work   because it
    was in the boundary layer. There was NO increase in MP.     The  second
    photo shows the improved intake which produced .4"Hg more  MP.   In the
    second example, the prop clears the intake by only  1/2 inch.

      I was surprised that the boundary layer formed so fast in the
    buffeting
    air coming off of the prop.     It is something we need to  keep  in mind
    when building the belly inlet for our rads and oil coolers.

    Jerry

Hi Jerry;
There are a few similar examples of props skimming the intake.  If you
feel lucky, I've heard you can get 0.5"MP with 1/8 clearance!
I am not sure it is all boundary layer effects.  If you add (say 50)
wool tufts to the cowl you will find that probably no-one guessed
the airflow correctly near the intake unless they have seen it on a
similar configuration before.(wool and tape is enlightening)
There is a surprisingly large rotational vector to the airflow, it of
course varies with rpm and forward velocity.

Cheers
Cary


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