REFLECTOR: Low Speed Handling

[Pat Shea]

My XLRG has no lower winglets, although I did increase
the overall height of the winglets on my Dynamic Wings
to match the dimensions of the factory's XL prototype.
I knew Brendan and others liked the handling of that
plane which doesn't have lower winglets either. I
worked hard to get symmetrical aileron throw. No vg's.
At altitude it stalls in the 60 to 65 KIAS range
depending on loading. Initially my low speed handling
(under 100KIAS) seemed a little poor but similar to
what other XL drivers have reported. I added trailing
edge fences, put tape across the top of my aileron
hinge line gap, and increased my rudder throw.
Collectively it's working, as low speed handling is
now  fine and I've landed in some pretty gusty
crosswinds. Not sure how my dutch roll tendency
compares to planes with lower winglets, but like
Richard said, if you lead with the rudders below
100KIAS it's non issue. On the other side of the speed
envelope, it cruises over 200KTAS at 7,000' and 75%
power.  

Pat (XLRG, IO-540, 340HP, MT)
   
--- Richard Riley <richard at riley.net> wrote:

>  From my alternate reality -
> 
> Vari Eze's, Long EZ's, Cozy's and Berkuts don't have
> the geometry 
> oddity.  They use pushrods all the way back to the
> ailerons, and the final 
> pushrod hits the aileron bellcrank at 90 degrees
> with everything 
> neutral.  Nonetheless, at low speeds all have
> significant adverse yaw and 
> dutch roll.  Below about 100 knots you lead with
> rudder.  It's an artifact 
> of the highly swept wing.
> 
> 
> >2.  VG's on the wings can help improve aileron
> effectiveness at lower 
> >speeds and hence improve handling on short final. 
> And as I mentioned in 
> >an earlier note, VG's on the canard can also
> improve low speed elevator 
> >effectiveness. I do not have the elevator cuffs
> installed - this also 
> >improves low speed elevator effectiveness.
> 
> On the above aircraft VG's help adverse yaw some. 
> So do trailing edge 
> fences.  See 
>
http://web.archive.org/web/20040208220441/lsecorp.com/KlausInfo/Flowfence.htm
> 
> (It's not on Klaus' site anymore)
> 
> On most Berkuts we have a little, vestigial lower
> winglet that diverts TE 
> spanwise flow at the tip.  One plane, N600SE, didn't
> have them, and ended 
> up with a LOT of dutch roll on final.  TE fences
> helped, but clearly the 
> lower winglet did a lot in that area.  It wasn't
> much - it went from 
> nothing at the thickest point of the wing, straight
> aft, so at the wing TE 
> it hung about 1.5" below the TE.
> 
> I DON'T know if any of this would work on the
> Velocity, it is a different 
> wing and winglet.  But they're possibilities.

> 




		
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