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Vortex Generators
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lgdavid(at)roadrunner.com
Guest

Posted: Thu Dec 31, 2009 8:48 pm Post subject: Vortex Generators

Galin,  What is the URL for your web page?  I am  trying to understand the VGs.   Larry

 [quote]   ---

galinhdz(at)gmail.com
Guest

Posted: Fri Jan 01, 2010 8:54 am Post subject: Vortex Generators

Scott;



My web page is: www.puertoricoflyer.com



But to get a good understanding of the VG's go to: www.stolspeed.com



  They know more about VG's than I ever will.



Galin

N819PR



On Thu, Dec 31, 2009 at 10:33 PM, Larry David <lgdavid(at)roadrunner.com (lgdavid(at)roadrunner.com)> wrote:

  [quote]       Galin,  What is the URL for your web page?  I am  trying to understand the VGs.   Larry

 [quote]   ---

galinhdz(at)gmail.com
Guest

Posted: Fri Jan 01, 2010 12:05 pm Post subject: Vortex Generators

Larry;



Since a picture is worth 1000 words, here is a link to photo's of the VG installation on my web page. I hope this helps.



http://puertoricoflyer.com/cgi-bin/photoalbum/view_photo/2529251

  

Galin

N819PR



On Thu, Dec 31, 2009 at 10:33 PM, Larry David <lgdavid(at)roadrunner.com (lgdavid(at)roadrunner.com)> wrote:

[quote]         Galin,  What is the URL for your web page?  I am  trying to understand the VGs.   Larry

 [quote]   ---

bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Fri Jan 01, 2010 12:55 pm Post subject: Vortex Generators

1/1/2010



Hello Larry, Also see:



http://www.avweb.com/news/reviews/182564-1.html



for an explanation of how VG's work aerodynamically.



'OC' Says: "The best investment we can make is the effort to gather and 

understand knowledge."



=========================================



---

lgdavid(at)roadrunner.com
Guest

Posted: Fri Jan 01, 2010 8:32 pm Post subject: Vortex Generators

Thanks OC,  I understand the principle but was not comprehending the use on 

the bottom of the tail.  Galen's pictures explained the placement.  It looks 

like the VGs are about 2/3s of the way back just a bit  in front of the 

elevator hinge line.  I am still puzzled about how disrupting the boundary 

layer flow across the bottom of the horizontal stab solves the problem. 

Apparently, the VGs are stabilizing the unstable air that is reaching the 

tail.  Do you have a better explanation?  I guess whatever works is fine.

Larry

---

galinhdz(at)gmail.com
Guest

Posted: Sat Jan 02, 2010 7:34 am Post subject: Vortex Generators

Larry;



Think of the elevator as an "upside down" wing. It is pulls the tail down keeping the nose up. That way if you loose "upside down" lift on the elevator, the nose drops, proper airflow is re-established and the airplane flys again.

  

That's why the VG's are placed on the bottom of the elevator, which is the "top" of the airfoil.



Galin

N819PR



On Fri, Jan 1, 2010 at 10:31 PM, Larry David <lgdavid(at)roadrunner.com (lgdavid(at)roadrunner.com)> wrote:

  [quote]--> KIS-List message posted by: "Larry David" <lgdavid(at)roadrunner.com (lgdavid(at)roadrunner.com)>

   

 Thanks OC,  I understand the principle but was not comprehending the use on the bottom of the tail.  Galen's pictures explained the placement.  It looks like the VGs are about 2/3s of the way back just a bit  in front of the elevator hinge line.  I am still puzzled about how disrupting the boundary layer flow across the bottom of the horizontal stab solves the problem. Apparently, the VGs are stabilizing the unstable air that is reaching the tail.  Do you have a better explanation?  I guess whatever works is fine.

   Larry

 ---

sstearns2(at)yahoo.com
Guest

Posted: Sat Jan 02, 2010 10:24 am Post subject: Vortex Generators

Hi Larry,

  

 I think I understand your question...

  

 The goal is to get the airflow to follow the contour of the surface, to stay 'attached'.  When the boundry layer 'separates' it causes a lot of turbluence and a huge amount of drag.

  

 The large scale vortex caused by the VGs causes some drag, but the vortex is very good at keeping the airflow following a highly curved surface or a surface with a sudden break as in an elevator at large deflection.

  

 Scott



--- On Fri, 1/1/10, Larry David <lgdavid(at)roadrunner.com> wrote:



 [quote]

From: Larry David <lgdavid(at)roadrunner.com>

Subject: Re: Vortex Generators

To: kis-list(at)matronics.com

Date: Friday, January 1, 2010, 8:31 PM



 --> KIS-List message posted by: "Larry David" <lgdavid(at)roadrunner.com (lgdavid(at)roadrunner.com)>



Thanks OC,  I understand the principle but was not comprehending the use on 

the bottom of the tail.  Galen's pictures explained the placement.  It looks 

like the VGs are about 2/3s of the way back just a bit  in front of the 

elevator hinge line.  I am still puzzled about how disrupting the boundary 

layer flow across the bottom of the horizontal stab solves the problem. 

Apparently, the VGs are stabilizing the unstable air that is reaching the 

tail.  Do you have a better explanation?  I guess whatever works is fine.

Larry

---

helixaviation(at)btintern
Guest

Posted: Sat Jan 02, 2010 10:42 am Post subject: Vortex Generators

Gents,

  

 With the VGs fitted has anyone recorded any reduction in cruising speed or control flutter close to VNE?

  

 John

 [quote][b]

kentpyle(at)iland.net
Guest

Posted: Sat Jan 02, 2010 12:13 pm Post subject: Vortex Generators

kentpyle(at)iland.net
Guest

Posted: Sat Jan 02, 2010 12:13 pm Post subject: Vortex Generators

No, Kent

 [quote]   ---

lgdavid(at)roadrunner.com
Guest

Posted: Sat Jan 02, 2010 1:25 pm Post subject: Vortex Generators

galinhdz(at)gmail.com
Guest

Posted: Sat Jan 02, 2010 1:25 pm Post subject: Vortex Generators

Kent;



I have not experienced any of those, but have not flown near Vne yet.



Galin

N819PR



On Sat, Jan 2, 2010 at 2:13 PM, Kent Pyle <kentpyle(at)iland.net (kentpyle(at)iland.net)> wrote:

  [quote]

 

 [b]

bakerocb

Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA

Posted: Sat Jan 02, 2010 2:18 pm Post subject: Vortex Generators

1/2/2010



Hello Larry, You wrote:



1) "I understand the principle but was not comprehending the use on the 

bottom of the tail."



You have gotten excellent responses to this question from both Galin and 

Scott -- I don't think that I could add much in that arena.



2) "Apparently, the VGs are stabilizing the unstable air that is reaching 

the tail.  Do you have a better explanation?"



Unstable air (commonly called a burble in the aerodynamics lexicon) is 

indeed a problem for pitch control at high angles of attack for the KIS 

TR-1. But the burble that is creating this problem is being caused by the 

pinched in area in the wing to fuselage juncture. When a major air 

detachment (burble) is created by this pinched in area and the burble then 

flows aft to the horizontal tail surfaces while the pilot is attempting to 

hold a very precise nose attitude during the landing flare the resulting 

disturbance can be a sudden change in pitch attitude, usually nose down.



Three ways that can be used to help alleviate this particular burble problem 

are:



A) Carry or add a little engine power above idle so that a more positive and 

continuous airflow is generated in that wing to fuselage junction.



B) Make a larger fillet / fairing in that wing to fuselage junction as 

Julian Bone did to help the air flow stay detached better.



C) Put a small strake or vortex generator on the fuselage just forward of 

the upper surface of the wing to put some higher energy air into that wing 

to fuselage juncture. You can see examples of this technique on the later 

models of the Cirrus SR-22 airplane, on some of the RV-8 home built 

airplanes, and in a picture on this website labelled "Nacelle strakes bolt 

on".



http://www.avweb.com/news/reviews/182564-1.html



3) "I guess whatever works is fine."



I think that everything works a little bit better with understanding.



'OC' Says: "The best investment we can make is the effort to gather and 

understand knowledge."



===================================================



---

kentpyle(at)iland.net
Guest

Posted: Sun Jan 03, 2010 4:39 pm Post subject: Vortex Generators

It sez on page three of the sales booklet, you  should expect no changes in high speed performance. grin  Kent

 [quote]   ---

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