> > >     Previous posts indicated that parallel sided ducts

 > > are equal to diverging sided ducts up to about .70-.75
 > > mach. Since most of us on this forum will be able to
 > > keep well under those speeds I would like to hear more
 > > opinions on the use of the parallel ducts.(easier to
 > > build)
 > >
 > >     Kell Troyer
 > >
 > > Dyke Delta/13B Rotary Power

 >I have yet to see a NACA paper comparing the two. The extra work
 >is minimal.
 >
 >Paul Lamar

Mike Wills wrote:

   I agree, the extra work is minimal. Using the Excel program that Vlad
 posted  several months ago and again last week. I came up with the
 appropriate data points which I plotted and smoothed in ACAD. Then cut out
 a mold from a chunk of hardwood, covered with packing tape, and vacuum
 bagged in carbon fiber. The whole thing took about 4 hours (not including
 cure time), is strong, and weighs next to nothing.

   Looks pretty trick as well. Could probably sell a boatload to the Honda
 Civic racer crowd. :-)

 Mike Wills

You could sell  two drawings to me right now if you are willing.  One
for 12 inch wide and one for 10 inch.   Jerry

It is as easy to plot it from this data as it is to make a drawing.
x is the percentage distance along the length of the duct and
"Profile" is half the width. The floor is a 7 degree ramp.
You will must plot it on to a large piece of paper 
from a drawing to make a cut out pattern anyway.

Paul Lamar

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