REFLECTOR: FW: Wing root fairings

[Richard Riley]

At 10:13 AM 8/14/2007, you wrote:

Once I asked Ilan Kroo how serious aircraft designers settled on 
fairing radius size.  He said take the radius of the designers thumb, 
scale it up by the scale of the wind tunnel model.

>This may have been touched on by others, but a small radius is less
>efficient but a large radius will show compression and tension stress
>cracks since our birds are quite flexible the paint will crack then
>peel.  My radius at the wing and strake to fuselage is the contour of my
>index finger (gloved)and I have stress cracks in the paint where the
>spar comes through the fuselage.

In the Long EZ/Cozy world the biggest occurrence of this is at the 
fuselage/landing gear bow intersection.  The solution is to bond the 
fairing to the fuselage, but let the gear float inside the fairing, 
with a very small - less than 1/16" gap - in between.

>The spar flexes as it leaves the RG
>box and lay ups attaching it to the firewall.  Alan Shaw would be one
>expert on air flow and he loves the Blended wing (see Atlantica).

Atlantica has very serious aero issues.

If anyone wants to do serious, Klaus-like work on reducing drag, the 
first thing to do is tuft and streak test the upper/inside wing to 
winglet junction.  I know it's different than the Rutan's, but all 
the Rutan birds have an enormous amount of separated flow there.  The 
Vari-EZ is the least bad, the E-Racer is the worst bad. 


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