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VG affect on stall
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grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Sun Dec 07, 2008 5:11 pm Post subject: VG affect on stall

Someone told me that VGs do lower stall speed and improve low speed handling but there is a trade off.  They told me VGs cause a plane to stall more sharply or more abrupt  than it would without them.



In other words most planes give warning signs prior to the stall such as the shaking and light control forces in the stick however with VGs this tends to not occurs as the plane nears stall. In other words with VGs, the plane seems to be flying rock solid at slow airspeed say "slow flight" and then all of a sudden the plane is in a fully developed stall with little to no warning.



The ones of you using or have tried vgs, Do you agree or disagree with this?



On my plane in a power off stall without Vgs, It does not give really any warning. When the ASI hits 41 the nose drops. Power on it gives plenty of waring as the prop gets really loud prior to the stall.

lcottrell

Joined: 29 May 2006
Posts: 1490
Location: Jordan Valley, Or

Posted: Sun Dec 07, 2008 5:24 pm Post subject: VG affect on stall

[quote] ---

_________________
do not archive

HShack(at)aol.com
Guest

Posted: Sun Dec 07, 2008 6:55 pm Post subject: VG affect on stall

When I designed & installed my VG's some 7 or 8 yrs. ago, I put 7 on  each wing [these were the aluminum flashing kind].  My stall dropped from  41 to 36.  The stall was still very gentle; in fact it didn't really want  to stall.  

  

 I added 13 more per wing.  Stall dropped another 4 mph, but when she  stalled it was rather violent & scary.  I hated the way it felt, so  went back to the original 7 per wing.  Happy again.

  

 By the way, I also have them under my horiz. stab.

  

 Howard  Shackleford

FS II

SC   

  In a message dated 12/7/2008 8:12:12 P.M. Eastern Standard Time,  grant_richardson25(at)yahoo.com writes:

  	  Quote: 	
		  Someone    told me that VGs do lower stall speed and improve low speed handling but there    is a trade off.  They told me VGs cause a plane to stall more sharply or    more abrupt  than it would without  them.

	






Make your life easier with all your friends, email, and favorite sites vanity&ncid=emlcntaolcom00000010">Try it now.

  [quote][b]

grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Sun Dec 07, 2008 6:57 pm Post subject: Re: VG affect on stall

lcottrell,



What does "Quote" mean?? You agree with my statement?

beauford

Joined: 25 Apr 2007
Posts: 127
Location: Brandon, FL

Posted: Sun Dec 07, 2008 7:18 pm Post subject: VG affect on stall

I used Brother Shackleford's flashing design... 10 per wing... dropped  stall 5 mph indicated... stall remains a non-event...

 straight ahead and slow to break at normal acceleration... I also put 3 per  side under the horizontal stab and can tell a big difference in

 elevator authority near stall speed...since these worked out so well, went  nuts and put 3 per side on the vertical

 stab to see if it would give more rudder authority for slips...some small  improvement, but not as much as on the wings

 or the horizontal stab.   Bystanders report that the  airplane now whistles as it passes by...

  

 Thoroughly Generated Beauford

 FF-076

 Brandon, FL

 Do not archive

 [quote]   ---

lcottrell

Joined: 29 May 2006
Posts: 1490
Location: Jordan Valley, Or

Posted: Sun Dec 07, 2008 7:36 pm Post subject: VG affect on stall

[quote] ---

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zeprep251(at)aol.com
Guest

Posted: Mon Dec 08, 2008 4:10 am Post subject: VG affect on stall

Disagree,

        G.Aman MK-3C  400hrs

 

 

 

 

   

 

   

 

 --

grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Mon Dec 08, 2008 5:07 am Post subject: Re: VG affect on stall

Howard,



Do you have a drawing for your Vgs?

smlplanet(at)msn.com
Guest

Posted: Mon Dec 08, 2008 6:04 am Post subject: VG affect on stall

I used the small alum VG's between each rib on the wings and dropped my  stall speeds. 10 mph solo and 8 mph duel and also increased the rate of climb  solo 300-400 fpm. The over all performance was increased plus  shorter ground roll and landing for short strips.

 I have warp drive prop and increased the pitch 3 deg's for better  cruise speeds which increased the speed between 10-15 mph and didn't affect any  thing other than dropped climb rate 100-200 fpm. Mark III C / 912UL

 I have been thinking about putting them on the horizontal stab. but heard  that it drops the tail faster at stall speeds when landing with ground  effect. Did you noticed this to be true or not and if not how do you have  the 3 VG's spacing?

 I am getting ready to put a set on my Challenger CWS II to see if it will  help also along with the drooped wing tips, 24' wing  span.  

  



  From: beauford T (beauford173(at)verizon.net) 

 Sent: 2008-12-07 22:18

 To: kolb-list(at)matronics.com (kolb-list(at)matronics.com) 

 Subject: Re: VG affect on stall

 



 I used Brother Shackleford's flashing design... 10 per wing... dropped  stall 5 mph indicated... stall remains a non-event...

 straight ahead and slow to break at normal acceleration... I also put 3 per  side under the horizontal stab and can tell a big difference in

 elevator authority near stall speed...since these worked out so well, went  nuts and put 3 per side on the vertical

 stab to see if it would give more rudder authority for slips...some small  improvement, but not as much as on the wings

 or the horizontal stab.   Bystanders report that the  airplane now whistles as it passes by...

  

 Thoroughly Generated Beauford

 FF-076

 Brandon, FL

 Do not archive

 [quote]   ---

beauford

Joined: 25 Apr 2007
Posts: 127
Location: Brandon, FL

Posted: Mon Dec 08, 2008 6:36 am Post subject: VG affect on stall

Unidentified writer:

 I spaced the ones on the bottom of the stab 6 inches apart and 3 inches  forward of the elevator hinge... as far as the

 tail "dropping" at the stall in ground effect -- yes, with the VG's, it is  now possible to land the FF tailwheel first at full stall if one wishes to... I  weigh about 220 and before the VG's, I ran out of elevator before I could get  the tail quite to 3-point attitude in a full stall...  faced with the  prospect of giving up Gin and/or Cheesecake (note caps) in order to land my  airplane properly, I elected the patented Howard Shackleford VG option and can  now 3 point in a full stall arrival with a slight bit of up elevator left  over...it's an improvement I plan to keep..

  

 bloated beauford

 FF-076, N173BW

 Brandon, FL

 [quote]   ---

apilot(at)surewest.net
Guest

Posted: Mon Dec 08, 2008 11:26 am Post subject: VG affect on stall

To insure that the tips keep flying while the root stalls is why I only used VG's from the wing tips to the inboard end of the flaps.  That leaves a good bit of mid wing to stall first.

HShack(at)aol.com
Guest

Posted: Mon Dec 08, 2008 11:39 am Post subject: VG affect on stall

I no longer have the drawing, but perhaps brother Cottrell or Beauford has  a copy to send you.

  

 Before I learned a little about my computer, I snail-mailed about 50  drawings.  Later, emailed about 200.  It got to be too much.

  

 Now, an outfit called  www.landshorter.com has a nice setup for  about $100 [so I'm told].

  

 VG's give you the most bang for the buck I can imagine.  Worth a C  note & a couple hours.

  

 Howard  Shackleford

FS II

SC   

  In a message dated 12/8/2008 8:08:15 A.M. Eastern Standard Time,  grant_richardson25(at)yahoo.com writes:

  	  Quote: 	
		  Howard,



Do you have a drawing for your  Vgs?



	






Make your life easier with all your friends, email, and favorite scom40vanity&ncid=emlcntaolcom00000010">Try it now.

  [quote][b]

capedavis(at)yahoo.com
Guest

Posted: Mon Dec 08, 2008 3:34 pm Post subject: VG affect on stall

Beauford, Did you say you weigh 220 and from your signature FF it appears that  you fly a FireFly is that correct? I weigh about 215 and am building a FireFly and I was a bit concerned about that short wing ! Before my accident I only weighed 190 and was flying a Firestar with a 503  and that bird had a lot of wing .  If what I determined about your signature is correct , how does it do? do you have a 447? how many feet per min does it climb at ? Sorry about all these questions but there are not many people that fly FireFlys on the list especially not " Bloated" ones . Thank you in advance for any info you could give me . Chris

   From: beauford T <beauford173(at)verizon.net>

To: kolb-list(at)matronics.com

Sent: Monday, December 8, 2008 9:36:02 AM

Subject: Re: VG affect on stall

   Unidentified writer:

 I spaced the ones on the bottom of the stab 6 inches apart and 3 inches forward of the elevator hinge... as far as the

 tail "dropping" at the stall in ground effect -- yes, with the VG's, it is now possible to land the FF tailwheel first at full stall if one wishes to... I weigh about 220 and before the VG's, I ran out of elevator before I could get the tail quite to 3-point attitude in a full stall...  faced with the prospect of giving up Gin and/or Cheesecake (note caps) in order to land my airplane properly, I elected the patented Howard Shackleford VG option and can now 3 point in a full stall arrival with a slight bit of up elevator left over...it's an improvement I plan to keep..

 bloated beauford

 FF-076, N173BW

 Brandon, FL

 [quote] ---

beauford

Joined: 25 Apr 2007
Posts: 127
Location: Brandon, FL

Posted: Mon Dec 08, 2008 5:11 pm Post subject: VG affect on stall

...Brother Davis...   

 Yessir, the Kleenex Kolb is a FireFly... True,  the wing is a tad abbreviated, but  there is an upside -- it rides  well in the chop while the

 long-wing sissies are getting the living hell  pounded out of them in the same stuff.  

  

 The little Nazi engine is indeed a 447... when it  deigns to function, it climbs the Fly in a sprightly manner, despite my  gradually accumulated bulk.  With the IVO pitched for climb and the carb needle jacked up a notch to keep up with  the brutal 65 degree temps we have been experiencing here in west Fla this past week, I reckon it did at least 800 fpm or  so, turning 6350 rpm in the climb...Back in the summer in the heat, I  experimented with setting the prop at a more leisurely 6100 to see if fuel  endurance would improve, but it climbed like a Chevy Suburban with low tires, so  I reverted to the climb pitch setting... We are both happier  there...

  

 The single most noteworthy improvement I see from  the VGs on the Fly wing is the ability to execute a power-off flare in ground  effect from a 50 IAS glide without blowing out  the bottom like a bowling ball through a wet newspaper... the VG's add just  enough extra lift at that critical point to make  it safe and fun... otherwise, needed 55 in the glide and mebbe a touch of power  at the flare...  I predict that you will learn to really like the drooping  ailerons.... I think they make a big difference in the ground effect operations  of this short-winged little airplane.

  

 One thing: You did not mention your height...   Am considering hiring a private contractor with appropriate equipment to  sling-load me in and out of the Fly, despite the fact that I skip breakfast and  scrupulously empty my pockets of car-keys, gas station receipts, excess change,  ball-point pens, the spare Arturo Fuente and the little remove-before-flight tag  from the BRS prior to attempting the dreaded FireFly mount or dismount.   Negotiating one's feet safely around the windshield,  whilst simultaneously suspending one's flabby butt in midair over the  seat with both hands on the siderails and a deeply veined purple face, is a real  crowd-pleaser.... Upon landing,  I have been known to feign illness,  or a drunken stupor, and sit quietly in place in the airplane until the  onlookers lost interest and melted away before attempting it.  I don't know  how long your legs are, but I recommend you consider an enlarged windshield  cut-out on the right side.  Saves public humiliation.... until one returns  home, anyway...

  

 Good luck with your Fly, sir...

  

 bucolic beauford

 FF-076

 Brandon, FL

  

  

 ---

Possums

Joined: 03 Nov 2007
Posts: 247

Posted: Mon Dec 08, 2008 6:54 pm Post subject: VG affect on stall

At 08:11 PM 12/8/2008, you wrote:

  	  Quote: 	
		  ...Brother Davis...   

 One thing: You did not mention your height...  Am considering hiring a private contractor with appropriate equipment to sling-load me in and out of the Fly, despite the fact that I skip breakfast and scrupulously empty my pockets of car-keys, gas station receipts, excess change, ball-point pens, the spare Arturo Fuente and the little remove-before-flight tag from the BRS prior to attempting the dreaded FireFly mount or dismount.  Negotiating one's feet safely around the windshield, whilst simultaneously suspending one's flabby butt in midair over the seat with both hands on the siderails and a deeply veined purple face, is a real crowd-pleaser.... Upon landing,  I have been known to feign illness, or a drunken stupor, and sit quietly in place in the airplane until the onlookers lost interest and melted away before attempting it.  I don't know how long your legs are, but I recommend you consider an enlarged windshield cut-out on the right side.  Saves public humiliation.... until one returns home, anyway...

  

  

 bucolic beauford

 	


 I'm thinking you need the "Geezer Lift Chair" option for you Firefly.



  http://www.spinlife.com/Uplift-Technologies-UPEASY-Power-Uplift-Seat-Assists/spec.cfm?productID=73225     [quote][b]

_________________
Possum

Dave Bigelow

Joined: 29 Jan 2006
Posts: 103
Location: Kamuela, Hawaii

Posted: Mon Dec 08, 2008 7:33 pm Post subject: Re: VG affect on stall

With the Landshorter VG's installed on my Firestar as recommended by Landshorter, the stall is more abrubt than without the VG's.  Without the VG's there is no classic stall with a break, but more of a mush that started at 40 mph indicated airspeed with my Firestar.  Slow flight below 40 mph was not possible, and final needed to be flown at 50-55 mph (power off) to avoid a hard landing during the flare.



After VG installation, control was rock solid and responsive right down to the stall, which takes place at about 30 mph wings level unaccelerated.  There is no pre-stall buffet, and the break is distinct, much like that of a sailplane with laminar flow wing.  With VG's, final can be flown as low as 40 mph power off with sufficient energy to flare without a hard landing.



There is nothing dangerous or radical about the stall with VG's, but it not as forgiving as without VG's.  My recommendation for a low time pilot new to Kolbs is to get some hours on your new plane without VG's, and then install them after reaching a reasonable level of proficiency.

_________________
Dave Bigelow
Kamuela, Hawaii
FS2, HKS 700E

HShack(at)aol.com
Guest

Posted: Tue Dec 09, 2008 12:47 pm Post subject: VG affect on stall

What if you didn't put on quite so many of the little rascals?

  

 Howard  Shackleford

FS II

SC  do not archive

  In a message dated 12/8/2008 10:34:11 P.M. Eastern Standard Time,  up_country(at)hotmail.com writes:

  	  Quote: 	
		  With the    Landshorter VG's installed on my Firestar as recommended by Landshorter, the    stall is more abrubt than without the VG's.   	






Make your life easier with all your friends, email, and favorite sites in one plid=emlcntaolcom00000010">Try it now.

  [quote][b]

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Dec 12, 2008 9:00 am Post subject: Re: VG affect on stall

Grant R,



I have about 140 VG's on my MK III Xtra, from the Center of the wing all the way to the wingtips, the stall is very gentle, as gentle as any Cessna I have ever flown.    My stall speed was lowered 10 MPH, and the handling of the plane improved immensely.   I have a video posted of stalls, and slow flight with VG's on my Kolb,  You can see it at:



http://www.youtube.com/watch?v=EjI7-kBptrA



To see how the VG's help keep the Kolb from dropping and landing hard at low landing speeds watch this video:



http://www.youtube.com/watch?v=L508itf3oy8



I use VG's from www.landshorter.com.   Making your own VG's will probably help, but the design of the VG's are CRITICAL.  If you don't make them the right dimensions they wont work as well as they should.   Its important to place the VG's in the EXACT place on the wing to be effective, and the PRECISE angle of the VG's in relation to the airstream is even more important if you want to get the full benefits of VG's.      



Just imagine building a wing using the " That looks about right " method, and then putting the wing on the airplane by guessing where it should be, and then wondering why your plane does not fly well ???   Some people have done this with VG's, and then reported to the list they are not very effective....   Hmmm, I wonder why ????



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Fri Dec 12, 2008 9:40 am Post subject: VG affect on stall

the stall is very gentle, as gentle as any Cessna I have ever flown.

 	  Quote: 	
		  

 Mike


	




Mike:



Most all Kolbs, without VGs, I have flown, fly much better than any Cessna I 

have flown, which is limited to a couple of old tired 152's, it took to get 

my Private Ticket in 1990.



In fact, based on my limited experience, Cessnas have a rather sharp stall 

compared to the Kolbs' mushie stall characteristics.



Cessnas also lose much more altitude than Kolbs in a spin, and much quicker.



Never spun a Kolb with VGs, and have a couple flights in one FSII equipped 

with VGs.



I am neither pro or con VG.  However, if I start wearing a flight helmet, I 

will mimic Brother Beauford's helmet, complete with appropriate VGs.  I may 

even go a step further and put them on top and bottom.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Dec 12, 2008 10:04 am Post subject: Re: VG affect on stall

 	  HShack(at)aol.com wrote: 	
		  When I designed & installed my VG's some 7 or 8 yrs. ago, I put 7 on  each wing [these were the aluminum flashing kind].  My stall dropped from  41 to 36.  The stall was still very gentle; in fact it didn't really want  to stall.  

  

 I added 13 more per wing.  Stall dropped another 4 mph, but when she  stalled it was rather violent & scary.  I hated the way it felt, so  went back to the original 7 per wing.  Happy again.

  

	




If you put VG's on only part of the wing, you only get part of the benefit.   Being that you guessed where your VG's should go, and that you guessed on the design of your VG's, its no wonder you ended up with some bad characteristics and scared yourself.   If you put anything on the wrong part of a wing, including VG's, they can go from being a benefit to being dangerous very quickly.   I would not want to be the test pilot on an airplane with poorly place VG's   



Here is a video of some guys that put VG's on their airplane the right way, using precise measurements to get them in the correct place on the wing, and getting the exact angles of the VG's to the airstream using templates.  These guys also did a lot of work so the rest of us can see the effect VG's have on the airflow on the wing.   



http://www.youtube.com/watch?v=YQO7SoULc3U&feature=related



The research has already been done over many years.  I prefer to use the design and placement that a lot of aeronautical engineers have developed over the years than try to guess on VG placement.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

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