REFLECTOR: Vortex generators

Mon Mar 30 10:48:50 CDT 2009

This question seems to come up every couple of years, which suggests there's
a need to have a database somewhere of what works and what doesn't.

On my xlrg, 

1.       vg's provided a 3kt lower stall speed (dropped from 66 to 63) and
approximately a 1.5 - 2 kt drop in cruising air speed.  The cruise speed
drop measurement was imprecise, - used flying in triangles to measure.,

2.       vg's on the carnard add lift and drag during cruise, with a
noticeable increase in down stick pressure needing to be applied.  I clipped
the length of the carnard vgs in half and that seemed to solve the problem.
Previously (I've done this twice) I removed half of the vgs on the carnard,
both seemed to have neglible effect on the lift during slow speed produced
by the carnard and benficial effect at cruise speed.  My anticipation is
that the pattern needs to be re-engineered for the carnard.

3.       vg's on top in front of the naca scoops helped reduce engine temps.
Although in a steep climb, I did not see the improvement, anticipated that
the air is detaching further ahead in a steep climb.  I tried attaching vg's
at the door line on top as well.  Haven't noticed that it helps
significantly.

Trailing edge stall fence on the inside of the ailrons reduced take off
distance by 15% - and gave significant increase in control at low speeds.
No reduction in cruise speed.  This should be a standard on the wing.  

Trailing edge fence on the inside and outside of the aileron produced
significant climb improvement.  I went from a sustained 1,200 to 2,000 with
two large adults in the front seat.  But I removed them because of the
adverse effect on turning.  Basically it wants to fly straight ahead with
four fences on the wing - sure goes up quick though.  

Have attached a couple of pics.  Hope that helps.

Rodney Brim, 

Performance Solutions Technology, LLC

Ph. (707) 487-3000 | Skype. rbatpst
Blog -  www.ManagePro.com/Blog

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Michael Watson
Sent: Friday, March 27, 2009 4:14 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Vortex generators

I've had VGs on wings and canard for nine years now, I would
feel very uneasy landing a Velocity without them.

During my first year flying without them, I came over the numbers
between 80~85 KIAS. That speed gave the feeling of positive control
of rudder and ailerons. I felt that for safety. that seed was just too high.

After installing the VGs, I would have that same feeling between 
67~72 KIAS. Due to the slower landing speed, the plane stops in
a shorter distance saving ware and tare on tires and brake pads.

I have had the airspeed down to 63 KIAS at altitude and it did not
pitch buck. After ten years, I still do not know at what speed it will
start to pitch buck.

On Fri, Mar 27, 2009 at 1:27 PM, <SlvEgl99 at aol.com> wrote:

Can anyone report on performance changes?

Bob Wood

In a message dated 3/27/2009 12:11:23 P.M. Eastern Daylight Time,
scott at tnstaafl.net writes:

I think you missed inserting the link.  Though I think your refering to
these?

http://stolspeed.com/

I saw them in the EAA rag.  They look like the nicest I've seen and are
right in the range of all the other options, not including TC  VG's
which are spectacularly outrageous!

I think I'm going to order a set of these as I pulled off my CCI VG's to
repaint the wings. I was going to glue the old ones back on but these
are so much more user friendly. My main complaint about CCI's are, they
are sharp! And can cut your hand, especially when washing the plane.

I need to  recount how many  are needed for a Std wing &  canard,
though  I still have the CCI's attached to the canard. I could just  put
new ones on the wing..

I love um, VG's that is. Shorter  take off  roll,  slower stall speed ,
faster climb rate,  better aileron response at slow speeds, and
negligible reduction of top end speed.

Scott

Tom wrote:
> Below is a link to some pretty nice VGs--they are fairly inexpensive
> ($97 for 120).
> Questions:
> Are they worth doing?? Do you get enough slower speed benefit to
> offset the ugly factor?
> Is there a template available for install?
> thx Tom
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-- 
Mike W.
1997 Velocity Elite RG
Franklin /IVO Electric CS
Dual GRT EFIS Synthetic Vision

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