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Ok, for those who want to play with it, here is the K&W Streamline Duct
spreadsheet.
I think the instructions on how to use if place on the spreadsheet should to
the job, but if anything is not clear don't hesitate to ask. As is my
practice - the spreadsheet is protected, so you can only enter data and get
the results. If anyone want to suggest changes, I will entertain them and
incorporate them into a revision.
Its probably smart to choose the your inlet/core surface area ratio (A1/A2)
choice in the Data Input Block from the table column A1/A2 index that is
closest to your specified inlet/Core surface areas, however, I do permit you
to choose another column out of the table. It is fun to play with - but, I
am not exactly certain of the consequency of using a coordinate set
generated for one A1/A2 when you are actually using another one.
Also you can only the coordinates for one axis (Height or Width) of you
inlet/core at a time. So you would have to entered the Dimension for your
core for either its Height and get the results and then for its Width and
get the coordinates (unless of course your Height and width were the same).
The Yellow bar that appears on the graph is the point at which 1/2 of the
dynamic pressure is recovered by the duct wall and the other 1/2 by the
sharper diverging remaining section from there to the core surface. The red
bar is simply the end of the curve corresponding to the example from K&W
also inculded for your reference.
I still believe that even if you can only use a portion of the curve that it
is probably better than just pulling something out of the air - but, I can't
prove that.
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
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