Q1_Aircraft: Re: [Q1_Aircraft] Digest Number 97

The chord-wise placement of VG's on the GU airfoil is
extremely important!

Anything forward of this reduces the stall differential that
exists between the front and rear wing. That can prove to be
dangerous. You must not tamper with a the plane's need to
stall the canard first.

Placing the VG fenceline closer to the leading edge can
empower the canard to the point where it might get the
canard to the critical angle of attack and thus stall the rear
wing.

YOU DO NOT WANT THAT UNDER ANY CIRCUMSTANCES!

The tested and proven position for VG's on a GU profiled
canard is 50% of chord. The leading edge of the sail should
be 50% from the leading edge or trailing edge of the elevator.
It doesn't matter, take your pick.

I prefer measuring to the back of the elevator as it's easier to
be more precise If the wing has any taper but the airfoil shape
is still a GU, then simply measure 50% at the root, 50% at
the wing tip and snap a chalk line between the two. Then
place the nose of the sails along that datum.

As for density, The wind tunnel tests suggest that the wing is
fully optimized when the VG density is one per inch for the
entire span. Remember please that this statement is being
made only in the context of fixing the trim loss that occurs
in wet conditions, nothing else. On more conventional
planforms, VG placement for stall reduction follows a different
density and placement schedule. Please do not confuse the
two.

I do not approve of using these devices on the rear wing of a
canard aircraft. That can produce unpredictable and
dangerous consequences.

The safe and proven pattern for placement on the canard is
alternating back and forth (left and right), 15 degrees to the
streamline. Each pair of VG's thus produces an 'arrowhead'
pattern into the streamline.

On another related subject

Last April the owner of a RANS S-7 in Idaho purchased a kit of
VG's from me. He tried them on his plane and, like other S-7
owners succeeded in safely reducing the stall speed
dramatically. (45 mph down to 25)

He then copied the VG delta design and altered it's shape with
no apparent knowledge of the how it works or the wind
tunnel data that produced it. He then plagiarized the
documentation that has evolved over 18 years and has since
been making all sorts of wild assertions about what VG's will
do.

I've 18 years of experience treating all sorts of aircraft and
have the database of owners and the endorsements to show
the extent of my experience with these devices. I would
never make some of the claims that he does!

This guy has put up a web site: www.landshorter.com

I invite you go look at it. I know that it may sounds nuts to
invite people to look at a competing web site. I am not
concerned.

One thing you will notice is that he provides the web sites of
every VG promoter that is more expensive than his, like he is
doing you a favor. However he deliberately avoids providing
the web site where he bought HIS!

The reason is funny but apparent. He is charging 20% MORE
and can ill afford you finding that out.

Aside from his obvious plagiarism, hypocritical posturing and
price gauging, he is ignorant of the fact that he has violated a
United States patent!

He does advertise an unconditional money back guarantee.
Those who fell for his racket and are considering exercising
that option, may wish to do so quickly.

I suspect he won't last 18 months, much less 18 years.

When I started this business, everyone said I was nuts to
charge so little. My position then and now is that VG's are
safety devices and need to be affordable.

I've kept them in the same price range for almost 20 years
and intend to continue to do so. Any increases will reflect the
costs of doing business: increases in material prices, shipping,
etc.

I hope this helps


For more information, please visit our web site:

www.vortexgenerator.net

The contents of this message and any attachments were checked by Norton AV
before being sent, using an AV list not more than 24 hours old.



[Non-text portions of this message have been removed]

Dear CCI,

You'll definitely get my order. Go with the strength, I say.

All power to you for this innovation, it has probably saved countless
lives.

Rob

--- In This email address is being protected from spambots. You need JavaScript enabled to view it. , ccivortex@b... wrote:
> The chord-wise placement of VG's on the GU airfoil is
> extremely important!
>
> Anything forward of this reduces the stall differential that
> exists between the front and rear wing. That can prove to be
> dangerous. You must not tamper with a the plane's need to
> stall the canard first.
>
> Placing the VG fenceline closer to the leading edge can
> empower the canard to the point where it might get the
> canard to the critical angle of attack and thus stall the rear
> wing.
>
> YOU DO NOT WANT THAT UNDER ANY CIRCUMSTANCES!
>
> The tested and proven position for VG's on a GU profiled
> canard is 50% of chord. The leading edge of the sail should
> be 50% from the leading edge or trailing edge of the elevator.
> It doesn't matter, take your pick.
>
> I prefer measuring to the back of the elevator as it's easier to
> be more precise If the wing has any taper but the airfoil shape
> is still a GU, then simply measure 50% at the root, 50% at
> the wing tip and snap a chalk line between the two. Then
> place the nose of the sails along that datum.
>
> As for density, The wind tunnel tests suggest that the wing is
> fully optimized when the VG density is one per inch for the
> entire span. Remember please that this statement is being
> made only in the context of fixing the trim loss that occurs
> in wet conditions, nothing else. On more conventional
> planforms, VG placement for stall reduction follows a different
> density and placement schedule. Please do not confuse the
> two.
>
> I do not approve of using these devices on the rear wing of a
> canard aircraft. That can produce unpredictable and
> dangerous consequences.
>
> The safe and proven pattern for placement on the canard is
> alternating back and forth (left and right), 15 degrees to the
> streamline. Each pair of VG's thus produces an 'arrowhead'
> pattern into the streamline.
>
> On another related subject
>
> Last April the owner of a RANS S-7 in Idaho purchased a kit of
> VG's from me. He tried them on his plane and, like other S-7
> owners succeeded in safely reducing the stall speed
> dramatically. (45 mph down to 25)
>
> He then copied the VG delta design and altered it's shape with
> no apparent knowledge of the how it works or the wind
> tunnel data that produced it. He then plagiarized the
> documentation that has evolved over 18 years and has since
> been making all sorts of wild assertions about what VG's will
> do.
>
> I've 18 years of experience treating all sorts of aircraft and
> have the database of owners and the endorsements to show
> the extent of my experience with these devices. I would
> never make some of the claims that he does!
>
> This guy has put up a web site: www.landshorter.com
>
> I invite you go look at it. I know that it may sounds nuts to
> invite people to look at a competing web site. I am not
> concerned.
>
> One thing you will notice is that he provides the web sites of
> every VG promoter that is more expensive than his, like he is
> doing you a favor. However he deliberately avoids providing
> the web site where he bought HIS!
>
> The reason is funny but apparent. He is charging 20% MORE
> and can ill afford you finding that out.
>
> Aside from his obvious plagiarism, hypocritical posturing and
> price gauging, he is ignorant of the fact that he has violated a
> United States patent!
>
> He does advertise an unconditional money back guarantee.
> Those who fell for his racket and are considering exercising
> that option, may wish to do so quickly.
>
> I suspect he won't last 18 months, much less 18 years.
>
> When I started this business, everyone said I was nuts to
> charge so little. My position then and now is that VG's are
> safety devices and need to be affordable.
>
> I've kept them in the same price range for almost 20 years
> and intend to continue to do so. Any increases will reflect the
> costs of doing business: increases in material prices, shipping,
> etc.
>
> I hope this helps
>
>
> For more information, please visit our web site:
>
> www.vortexgenerator.net
>
> The contents of this message and any attachments were checked by
Norton AV
> before being sent, using an AV list not more than 24 hours old.
>
>
>
> [Non-text portions of this message have been removed]