"Neal Fulco" wrote in message
m...
(Paul Lee) wrote in message
. com...
Dang it... I copied the wrong question again... here is the correct
stuff..

back to my original question - to help the situation.

..has anyone investigated placing a few vortex generator tabs near
outer wing part to compensate for the early tip stall tendency?

This could be done with a standard EZ by observing if the bobing stall
frequency increases with addition of a few outboard vortex generators.

Any EZ volunteers out there? Here is the procedu Measure the stall
bobing frequency as a position of CG. Then measure it again after
the few outboard VG's are installed and see if the frequency increases
or decreases with CG position. Would not be very expensive, just time
consuming.

I am building a SQ2000 canard but KLS Composites has designed
the thing so that there is no bobing stall frequency - it simply
descends
at a constant rate. KLS demonstrated that to me in their factory bird.
So I can't do the test - at least in the same way.

----------------------------------------------------
Paul Lee, SQ2000 canard project: www.abri.com/sq2000



Not an answer to your question, but would someone educate me
here....Just how do those "vortilons" on the outer portion of the main
wing inhibit the stall on that portion of the wing? I see them all
the time on the EZ's but I don't know how they work. Thanks

Neal


A vortilon delays detachment of the airflow and therefore increases stalling
AOA and improving airleron effectiveness, by creating vortices along the top
surface that mix free stream air in with the turbulent boundry layer air.
Same as the small vortex generators that are popular on top of leading
edges. However a vortex generator array on top of the leading edge produces
vortices all the time and the vortices are small.

Vortilons poduce much larger and stronger vortices but only at high AOA
because of the low position on the LE (the stagnation point has to move down
to below where the vortilon is). At low AOA the vortilon is mostly just a
fin sticking out in the underwing flow and has a minimal drag penalty. As
AOA increases the vortilon ends up above the stagnation point, and is now in
the upper flow stream, and functions as a big VG. Vortilons work best with
a lot of natrual spanwise flow at high AOA so they can produce vortices
without being angled into the airstream (and resultant drag penalty at low
AOA), which means swept wing a/c.

The Embraer 145 has vortilons that were added during certification, a
classic post-design aerodynamic band-aid to deal with tip stall problems,
same as the EZ.

John