REFLECTOR:Vortex Generators on XL

[KeithHallsten]

Jim,

20% chord is pretty clear on the canard, but since the wing is tapered the
chord is different at every station along the wing.  Did you place the VGs
at an ever-decreasing distance from the leading edge as you move outboard on
the wing to maintain true 20% chord at each VG location, or use 20% of an
average chord for the group of VGs on the wing?

Where are you getting rectangular VG's for $0.02 each?

Keith


----- Original Message ----- 
From: "Jim Sower" <canarder@frontiernet.net>
To: <reflector@tvbf.org>
Sent: Wednesday, December 03, 2003 5:26 PM
Subject: Re: REFLECTOR:Vortex Generators on XL


> The short answer is no.  There will be a decrease in cruise speed (they do
after all
> undeniably have drag) but my best information is that it's not detectable
with the
> naked eye.  I observed none on my plane.  All of my VG info comes from Jim
Price who
> in addition to impressive academic credentials in Aero Engineering holds a
world
> altitude record (35000'+ in a NA O-320 Long-EZ).  He encouraged me to
change mine from
> wedge shaped to rectangular, and to move them from the 25% chord line to
20%.  I did
> so just for the hell of it - it seemed a couple of truly trivial changes,
but the
> little buggers only cost two cents each - and was surprised at the amount
of
> improvement that seemed way out of proportion to what I actually changed.
> That's how it works for me ... Jim S.
>
> John Dibble wrote:
>
> > Do vg's affect cruise speed?
> >
> > John
> >
> > Chuck Jensen wrote:
> >
> > >Jack,
> > >
> > >Everything I do is trial and error.....though I did use the patterns
> > >provided by Velocity.  They are installed on both the canard and wing
(and
> > >both sides, naturally).  I don't remember the exact count but buy a 100
> > >(they're cheap) and use the extra for replacements.  To paint them,
after
> > >scuffing the bottom on sandpaper, I just stuck them on packing tape and
gave
> > >a few light coats of enamel for UV protection.
> > >
> > >Do us a favor.  Before you install, do a few altitude stalls and see if
you
> > >can nail a number.  After installation, repeat and see what difference,
if
> > >any, you note.  Maybe you already have a hard number for touchdown IAS
that
> > >you can reference---that would make a before/after comparison even
simpler.
> > >Most seem to think it reduces touchdown by 5 to 7 kts.
> > >
> > >Chuck Jensen
> > >
> > >
> > >
> >
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> --
> Jim Sower
> Crossville, TN; Chapter 5
> Long-EZ N83RT, Velocity N4095T
>
>
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