REFLECTOR: Vortex generators

Rene Dugas dugasd at bellsouth.net
Mon Mar 30 22:39:11 CDT 2009


How do fences inboard to the aileron work to decrease spanwise flow  
outboard? I'm trying to picture the effect. I don't doubt it.   
Inquiring minds just want to know how folks think it works.  Tuft  
testing would be sweet.

Rene' Dugas
Sent from my iPhone 3G

On Mar 30, 2009, at 10:48 AM, "RBrim" <rbrim at PerformanceSolutionsTech.com 
 > wrote:

> 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 6 
> 3) and approximately a 1.5 - 2 kt drop in cruising air speed.  The c 
> ruise speed drop measurement was imprecise, - used flying in triangl 
> es 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 s 
> olve the problem.  Previously (I’ve done this twice) I removed half  
> of the vgs on the carnard, both seemed to have neglible effect on th 
> e lift during slow speed produced by the carnard and benficial effec 
> t 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 engin 
> e 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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>
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>
>
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>
>
> -- 
> Mike W.
> 1997 Velocity Elite RG
> Franklin /IVO Electric CS
> Dual GRT EFIS Synthetic Vision
>
> <trailing edge stall fence.gif>
> <TEFence2.jpg>
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