REFLECTOR:Vortex Generators on XL

[Jim Sower]

Was said ....

> These are installed on an XL right?

No.  It's a 173 FG retrofitted with gull wing doors.

> How did you establish that you haven't messed up the lift ratio between the
> canard and the main wing?

Not sure what you mean by "messed up".  I did not alter either the main wing or the
canard other than to install VGs.  Jim Price (who is the best authority available to
us on the matter) discussed with me how he did his, and why he did them the way he
did.  I followed his lead.

If one were to install VGs on the wing or canard and not the other, it might "mess up"
the "lift ratio".  I used the same VGs in the same pattern and location on both
surfaces.  No reason to believe that would "mess up" anything.

BTW, do you know how the guys selling them for a buck a pop "establish" that they
aren't "messing up" anything?  I'd bet dollars to doughnuts they don't have *near* as
good science *or* experience in the matter as Mr. Price.

> Have you done stall testing in it since you installed the VG's in an aft limit CG
> loading?

No.  I weigh 250 lbs.  I can't MAKE an aft CG loading.  Traveling with a passenger,
there's over 400# and often closer to 450# in the front seat.  If I had installed VGs
only on the canard , that might be an issue but I did not for that obvious reason.

> If you've added more proportional lift capability to the canard than to the
> main wings you have set your self up for a deep stall scenario.

And, of course if I have NOT added more proportional ..... than .... I have NOT set
myself up for a damned thing.  Price said *nothing* that might indicate that VGs on
both surfaces shift the Aerodynamic Center forward.  I'll have to go with his analysis
unless you have something compelling and credible.

> Though because the increased lift is generated by forward flow over the wings, I
> think it would drop right out of it.

I've no idea what you're talking about here.  Is "forward flow" from trailing edge
toward leading edge?

> The price of your VG's is certainly good,

Agreed.

> they are UV resistant?

I've no idea.  They're made out of door/window molding for your house.  Should that be
UV resistant?  I'm confident that it is.  And in any event, why should I worry about
that or even care?

> How breakable are they?

Hard to cut with household scissors, or razor blade.  Had to use snips/heavy
scissors.  Not brittle at all.

> Most of the VG kits I've seen recommend GE 50 year number II silicone.

Actually, Scott, I don't expect to own this airplane much over 35 or 40 years.  If
some fall off before my thirty years are up, I guess I'll have to just spring another
two freaking cents (adjusted for inflation of course) and replace them.  And of
course, if I want to move them I just do - I don't have to employ destructive
disassembly of my wing ...

I think once again we find ourselves P-V-O-R-T.  Like the proverbial ten-cent tail
wagging the forty-dollar dog.

For all their obvious shortcomings, they seem to be working OK (so far) ... Jim S.