REFLECTOR: Best Configuration for Trailing Edge Fences

[Dennis Martin]

Al,

Thanks for the photo of the trailing edge on your wing and details on use of
rudders, etc. Good to know EZ fliers have done the tuft testing, etc. I
think you're right about the radiator turbulence on the wing roots creating
a bit of extra turbulence. I'm going ahead with the same configuration that
you and Jim Agnew are using (VGs combined with inboard fences). Jim sent me
some templates for the fences - they look very similar to what you're using.
BTW, what is your weight and your landing speed?

I'm doing final rigging on the rudders tomorrow, then on to fences and VGs.
I still have a few interior details with lighting, etc. Upholstery is done
on seats, and a great artisan will help me with finishing interior.  I'm
probably a 1-2 months away from takeoff.

All the best,

Dennis

On Sat, Apr 4, 2009 at 10:34 AM, Al Gietzen <ALVentures at cox.net> wrote:

>  Dennis;
>
>
>
> I also have aileron fences – inboard of the aileron.  I don’t have the
> dimension handy, but you can see them on the attached photo.  I don’t have
> before/after experience with them as I put them on at the get-go – prompted
> primarily by tuft-testing done by local EZ flyers showing a layer of
> span-wise flow at high AOA.  At high AOA the normal flow begins separation
> toward the trailing edge, and flow comes down off the sides of the fuselage,
> and flows outward under the separation. The slower the speed, the thicker
> and more forward the layer.  I chose to assume the same would be true for
> Velocity – and possibly further aggravated by the air exiting my wing-root
> oil cooler and radiator.  That’s a factor for you as well.
>
>
>
> Of course the span-wise flow would negate the effectiveness of the ‘up’
> aileron, and add to the adverse yaw.
>
>
>
> Those same tests showed nothing but straight flow under the wing, so my
> guess is that extending them below the wing would have little effect, except
> possible inhibiting some spill off the end of the aileron in the down
> position.  I extended mine an inch or so below following the example of
> Claus Savier.
>
>
>
> I also have VGs on the wing, only in the area of forward of the aileron.
>  That did seem to make some improvement is low speed handling.  Still, lazy
> use of rudders as you get slow on landing will result in considerable
> adverse yaw when making corrections with the ailerons.
>
>
>
> I may at some point experiment with some VGs on the canard.
>
>
>
> On a related issue, some have noted improved aileron response by sealing
> the gap at the aileron hinge line.  I taped the gap and could not tell any
> difference in handling. Perhaps it has to do with the size of the gap, which
> is very small on my plane.
>
>
>
> About time for your first flight?
>
>
>
> Al
>
>
>
> -----Original Message-----
> *From:* reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] *On
> Behalf Of *Dennis Martin
> *Sent:* Friday, April 03, 2009 10:57 AM
> *To:* reflector at tvbf.org
> *Subject:* REFLECTOR: Best Configuration for Trailing Edge Fences
>
>
>
> Rodney, thanks for the photos & dimensions on your trailing  edge fences .
> I'm ready to install fences - just a few questions for those flying with
> fences:
>
> 1) If you have trailing edge fences, how many are recommended on each wing?
>
> 2) I have a photo of a FG 173 with 3 fences on the leading edge. What's the
> difference in performance vs trailing edge?
>
> 3) Science requires replication of the experiment. Besides Rodney, is
> anyone else flying with trailing edge fences?
>
> 4) My primary objective is to reduce landing speed, and  increase control.
> Besides VGs, which fence formula is best to achieve this goal?
>
> Thanks in advance,
>
> Dennis
>
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-- 
All the best,
Dennis
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