Cheers:
I always wondered where the info on the NASA (was NACA) inlet duct
design was to be found and was ready to assail the local library when I
stumbled across details in Tiny Bingelis' "The Sportplane Builder".
Anything to do with aeronautics is bound to be written backwards, so I
set to and have devined a design for an inlet duct to feed a 2in. (51mm)
internal Diameter airduct. At present it is just the shape of the inlet,
so must be revised to suit the ductwork subsequent. Also, I haven't
divined the surrounding structure to compensate for loss of integrity
due to the incursion.
The basis refers to selection of aspect ratio (length/width) of the
surface inlet as 3 to 5. I set out at 4, but it seems too long and thin,
so have opted for 3:1. Thjis produces a shape length of 8.144 inches and
max. depth of 1 inch and appears more in keeping with photos I've seen.
(Ratio of 4:1 is 10.25in by 1.57in deep).
Unless someone has better dimensions/choices, I will fax (I can't scan
yet) a copy of fullsize design for kneeheight inlets for cockpit cool
air each side, on request. Failing acceptance of my size/shape, will
happily send formulae for your own design and the steps involved - which
if you are as old and bent as I, mught save a few minutes puzzling......
Better stuff? Anyone?
Happy landings
Ferg #A064
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