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Land Shorter VG's on Firestar II
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John Jung

Joined: 10 Jan 2006
Posts: 108
Location: Surprise, AZ, USA

Posted: Mon Mar 13, 2006 4:54 pm Post subject: Land Shorter VG's on Firestar II

Group,



This afternoon, I just took my first flight with 102 LandShorter VG's on my Firestar II. It sure is different! It used to stall with a somewhat clean break at 38 to 40 mph. I had it down to 30 mph with no actual break. It was sinking at 500 ft/min at 30 mph and it sort of rocked from side to side, but the nose never dropped. It was a thermally afternoon, so I will get better information on future flights. The one landing was a little surprising. I sort of expected it to float down the runway, but it settled gently at 38 mph.

_________________
John Jung
Firestar II N6163J
Surprise, AZ

Possum

Joined: 12 Jan 2006
Posts: 112
Location: Georgia

Posted: Tue Mar 14, 2006 4:43 pm Post subject: Land Shorter VG's on Firestar II

So where did you stick the VGs on the wings?



 	  Quote: 	
		  



Group,



This afternoon, I just took my first flight with 102 LandShorter 

VG's on my Firestar II. It sure is different! It used to stall with 

a somewhat clean break at 38 to 40 mph. I had it down to 30 mph with 

no actual break. It was sinking at 500 ft/min at 30 mph and it sort 

of rocked from side to side, but the nose never dropped. It was a 

thermally afternoon, so I will get better information on future 

flights. The one landing was a little surprising. I sort of expected 

it to float down the runway, but it settled gently at 38 mph.



--------

John Jung

Firestar II N6163J

Surprise, AZ





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=21607#21607

jbhart(at)onlyinternet.ne
Guest

Posted: Tue Mar 14, 2006 5:27 pm Post subject: Land Shorter VG's on Firestar II

At 04:54 PM 3/13/06 -0800, you wrote:

 	  Quote: 	
		  



Group,



This afternoon, I just took my first flight with 102 LandShorter VG's on my Firestar II. It sure is different! It used to stall with a somewhat clean break at 38 to 40 mph. I had it down to 30 mph with no actual break. It was sinking at 500 ft/min at 30 mph and it sort of rocked from side to side, but the nose never dropped. It was a thermally afternoon, so I will get better information on future flights. The one landing was a little surprising. I sort of expected it to float down the runway, but it settled gently at 38 mph.



--------

John Jung

Firestar II N6163J

Surprise, AZ




	


John,



I believe we have another believer in the making.  



Jack B. Hart FF004

Winchester, IN



do not archive

John Jung

Joined: 10 Jan 2006
Posts: 108
Location: Surprise, AZ, USA

Posted: Tue Mar 14, 2006 5:35 pm Post subject: Re: Land Shorter VG's on Firestar II

 	  Possum wrote: 	
		  So where did you stick the VGs on the wings? 	




I placed them 2.75 inches apart and 8 inches back from the leading edge.

_________________
John Jung
Firestar II N6163J
Surprise, AZ

wcm(at)tampabay.rr.com
Guest

Posted: Tue Mar 14, 2006 6:36 pm Post subject: Land Shorter VG's on Firestar II

John,

How did you arrive at the distance aft of the leading edge?



Chris Mallory



do not archive

---

John Jung

Joined: 10 Jan 2006
Posts: 108
Location: Surprise, AZ, USA

Posted: Tue Mar 14, 2006 8:19 pm Post subject: Re: Land Shorter VG's on Firestar II

 	  wcm(at)tampabay.rr.com wrote: 	
		  John,

How did you arrive at the distance aft of the leading edge?



Chris Mallory



do not archive

--- 	




The distance is a compromise. Not as far forward as LandShorter recommends, and not as far back as the flashing type that are common  on Kolbs. I'll get some good data after I fly in smooth air, but for now it looks promising.

_________________
John Jung
Firestar II N6163J
Surprise, AZ

Possum

Joined: 12 Jan 2006
Posts: 112
Location: Georgia

Posted: Thu Mar 16, 2006 6:00 am Post subject: Land Shorter VG's on Firestar II

At 07:54 PM 3/13/2006, you wrote:

 	  Quote: 	
		  



Group,



This afternoon, I just took my first flight with 102 LandShorter 

VG's on my Firestar II. It sure is different! It used to stall with 

a somewhat clean break at 38 to 40 mph. I had it down to 30 mph with 

no actual break.


	


Try easing the stick back at full throttle and see if it feels like 

your pointing up at almost a 40 degree angle before it stalls or 

"mushes". Then try a "high bank" circle at 30 or 32 mph. That's what 

impressed me the most about the addition of the VGs.

John Jung

Joined: 10 Jan 2006
Posts: 108
Location: Surprise, AZ, USA

Posted: Fri Mar 17, 2006 12:18 pm Post subject: VG's on Firestar II, The Rest of the Story!

Group,



This morning, I got a chance to fly in calm air, and really test the LandShorter VG's on my Firestar II. Wow! Call me a believer. This was the most sigificant change that I have made to my Firestar by a long shot. I was one that found the VG reports by others a little hard to believe. I thought that they had to be exagerating some. No more. 



My Firestar II now has a 10 mph lower stall speed. That's 40 mph indicateed down to 30 mph indicated. But that is only for starters: The stall, before, was sharp enough to bend the aluminum gear by flairing too soon and stalling just 10 feet over the runway. Now the stall is almost none existant. The break can be felt, it's eazy to notice, but the nose hardly drops and the wing starts flying again with no input from me. I did full power stalls, cruise power stalls, and power at idle stalls. All were at 30 mph and with similar results. 



Possum said to take steep turns at 30 mph. I'm not ready to try that, but I did try steep turns at 40 mph. Amazing! My Firestar did a good imitation of a glider. It held altitude in a steep turn with only about 100 rpm more than it took to hold altitude on the level. 



And that brings up the next change: I needed about 400 rpm less to hold altitude then before. Used to be 4,900, now 4,500. I know that density altitude can change this so the results are not final. They are promising.



So, you ask "What is lost to gain these things? It can't be all good, can it?" I did a top speed run to see if it is still in the ball park. Best guess from today is a a 3 mph loss. As far as rpms to hold cruise speed, it appeared to be too close to call. I am more concerned about how much gas I will burn per hour at a given speed. If it goes up, that will be a loss that I care about, but I will need a few trips to evaluate that.



Can I really land slower? I think only a little. In order to get the speed down below 40, the tail must be lower. If I try to do that over the runway, the tail just touches and the mains come down. I do believe that it will be easier to get into a small strip, because I will be able to fly the approach 10 mph slower.



Now that I have a new 10 mph range to fly, where is the wing most efficient? What speed is the sink the least? I tried this at 4,500 rpms and idle. The results were the same. No change from 40 to 30. I could hold altitude at 4,500 rpms at any speed between 30 and 40, no climb and no sink. If I went faster than 40, I needed more rpms. At idle, I had a 500 to 600 ft/min sink anywhere between 30 and 40 mph.



Here is my recomendation: If you haven't flown a Kolb yet, put VGs on before the first flight. If you are already flying a Kolb without VG's, try them, you will like them.

_________________
John Jung
Firestar II N6163J
Surprise, AZ

agustafson(at)chartermi.n
Guest

Posted: Fri Mar 17, 2006 1:06 pm Post subject: Land Shorter VG's on Firestar II

My FSII flies that good right out of the box! It's for sale, by the way. 95, 

431 hrs.,8G w/ enc. trailer. Upper Michigan. Contact me direct and put "Kolb 

for sale" in the subject line or I won't get it.



Aaron     agustafson(at)chartermi.net   do not archive

 	  Quote: 	
		  >> That's 40 mph indicateed down to 30 mph indicated. <<<

wcm(at)tampabay.rr.com
Guest

Posted: Fri Mar 17, 2006 1:45 pm Post subject: Land Shorter VG's on Firestar II

John, 



Did you  install the VG's on your horizontal stabilizer also?



Chris Mallory



do not archive

wcm(at)tampabay.rr.com
Guest

Posted: Fri Mar 17, 2006 1:59 pm Post subject: Land Shorter VG's on Firestar II

John,



Did you  install the VG's on your horizontal stabilizer also?



Chris Mallory



do not archive



---

John Jung

Joined: 10 Jan 2006
Posts: 108
Location: Surprise, AZ, USA

Posted: Fri Mar 17, 2006 4:27 pm Post subject: Re: Land Shorter VG's on Firestar II

 	  wcm(at)tampabay.rr.com wrote: 	
		  John,



Did you  install the VG's on your horizontal stabilizer also?



Chris Mallory



do not archive



--- 	




No, just on the wings. My Firestar has a 37% CG, so I had no problem with enough up elevator.

_________________
John Jung
Firestar II N6163J
Surprise, AZ

John Hauck

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

Posted: Fri Mar 17, 2006 5:41 pm Post subject: Land Shorter VG's on Firestar II

Hi John J/All:



"But that is only for starters: The stall, before, was sharp enough to 

bend the aluminum gear by flairing too soon and stalling just 10 feet 

over the runway."



I might be reading this wrong, but you can straighten me out if I am. 

I don't know of any Kolb that won't spread the gear as the result of a 

10 ft drop.



"Now the stall is almost none existant. The break can be felt, it's 

eazy to notice, but the nose hardly drops and the wing starts flying 

again with no input from me. I did full power stalls, cruise power 

stalls, and power at idle stalls. All were at 30 mph and with similar 

results."



How did the above change your landing technique?



Interesting to note, FSII stalled at 30 mph full power, cruise power, 

and power off.



| Possum said to take steep turns at 30 mph. I'm not ready to try 

that, but I did try steep turns at 40 mph. Amazing! My Firestar did a 

good imitation of a glider. It held altitude in a steep turn with only 

about 100 rpm more than it took to hold altitude on the level.



Correct me if I am wrong.  If you stall at 30 mph straight and level, 

your stall speed will increase quite a bit in a tight turn, or do the 

VG's take care of that little problem?



 | --------

| John Jung

JJ, glad you are happy with the VG's.  Keep us informed as you gain 

more experience with them.  Still contemplating sticking those little 

things all over my wings.  First, I have to get back in the MKIII and 

get some flying done to get my flying skills up a bit.  For the most 

part, most Kolbs I have flown without VG's perform as described by 

those of you that are now flying them, with the major exception of 

shaving 10 mph off the indicated stall speed.



Lot's to be learned about these little critters, VG's and Kolbs.



john h

MKIII

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

John Jung

Joined: 10 Jan 2006
Posts: 108
Location: Surprise, AZ, USA

Posted: Sat Mar 18, 2006 4:44 am Post subject: Re: Land Shorter VG's on Firestar II

 	  John Hauck wrote: 	
		  Hi John J/All:



For the most 

part, most Kolbs I have flown without VG's perform as described by 

those of you that are now flying them, with the major exception of 

shaving 10 mph off the indicated stall speed.



Lot's to be learned about these little critters, VG's and Kolbs.



john h

MKIII 	




John H and Group,



That is what I thought, too. It is hard to imagine that such great planes could be this much better. It is somewhat like the upgrade to the DRE 6000. It is one thing to read a description the difference and quite another to experience it.

_________________
John Jung
Firestar II N6163J
Surprise, AZ

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sat Mar 18, 2006 7:06 am Post subject: Re: Land Shorter VG's on Firestar II

John,



I made my own VGs for the early Firestar I once had but put them back about 11" from the leading edge. I think you said yours are at about 8" back. My stall speed was definitely reduced buy not quite as much as yours, which makes sense since the high AOA at stall apparently puts your VGs prettly close to the "burble" point whereas mine were a bit aft of that point and thus less effective.



Mine however had different effects to the stall characteristics. Without VGs the Firestar's stall was very gentle with mild break. With the VGs the break was quick and quite abrupt. My cruise power speeds were unaffected by the VGs, probably because at cruise AOA the VGs were aft of the highest point of the airfoil, whereas yours are at a relatively high pressure point forward of the airfoil peak.



As you noted, the landing speed is unaffected because of the three point stance has an AOA well below the stall AOA. This lack of slowing the touchdown speed (landings not shorter) and the sharper break were the determinining factors for me deciding to remove them. I knew beforehand that a slower stall speed would not reduce the landing speed in any Kolb with short main gear legs but just wanted to experiment with them and am glad I did. It was fun and proved that VGs do indeed reduce stall speed. 



MY persoanal conclusions:

1. VGs will reduce the stall speed of a Kolb.

2. VGs may of may not changed the stall characteristics, depending upon where they are installed.

3. VGs may or may not change power required for a given cruise speed, depending upon where they are installed.

4. Kolbs with long gear legs might actually get a slower touchdown speed and thus shorter landing roll with properly installed VGs.

5. Wether you make your own or buy store bought ones, makes little difference, since all they do is twirl the air to where turbulence begins at high AOA without VGs.



Question about your lower approach speed:

Normal approach speed on final is (according to most authorities) 1.3 x Vs. If you were stalling at 40 IAS was your final speed about 52 IAS before and now 39 mph (1.3x30)? If so then to land three point I guess you have to speed up 1 mph to land .



Thom in Buffalo

Possum

Joined: 12 Jan 2006
Posts: 112
Location: Georgia

Posted: Sat Mar 18, 2006 7:08 am Post subject: Land Shorter VG's on Firestar II

At 03:18 PM 3/17/2006, you wrote:

 	  Quote: 	
		  

Possum said to take steep turns at 30 mph. I'm not ready to try 

that, but I did try steep turns at 40 mph. Amazing! My Firestar did 

a good imitation of a glider.


	




I don't think anything bad will happen.

Even when I stall the plane in one of these turns - the high wing

stalls first and it just drops back to level.

I know that is not what supposed to happen.

It might have done that even before the VGs.



But........ it is certainly easier to heard geese and follow buzzards

when you don't have to run over them or do S-turns.

John Hauck

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

Posted: Sat Mar 18, 2006 7:50 am Post subject: Land Shorter VG's on Firestar II

| 4. Kolbs with long gear legs might actually get a slower touchdown 

speed and thus shorter landing roll with properly installed VGs.

 |

| Thom in Buffalo

Thom/Gang:



I have never flown with VG's on a Kolb or any other aircraft, that I 

know of.  So.....I can only speak from experience without them. 

However, many of the attributes claimed after addition of VG's were 

there, in our Kolbs, prior to VG installation.



1.  Most every Kolb will climb at full power with the stick pulled all 

the way back to the stop.  Angle of attack is extremely high.



2.  Extremely tight turns at extremely high bank angles, left and 

right.



3.  Very gentle stall characteristics.



4.  Fully controllable mush/stall.  Permits altitude lose quickly, 

while maintaining reduced airspeeds.



5.  Equipped with sufficiently tall main landing gear legs, all Kolb 

models perform excellent 3 point landings naturally, with or without 

full flaps.  Touch down speeds, at the break, in ground effect, are 

somewhat lower than Kolbs with standard gear legs.



All of the above, with the exception of paragraph 5, can be performed 

with any standard Kolb model.  The mere thought of the additional 

capability of my airplane with a good set of VG's, properly installed, 

is frightening............   



john h

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

jbhart(at)onlyinternet.ne
Guest

Posted: Sat Mar 18, 2006 2:16 pm Post subject: Land Shorter VG's on Firestar II

At 07:06 AM 3/18/06 -0800, you wrote:

 	  Quote: 	
		  



4. Kolbs with long gear legs might actually get a slower touchdown speed 

and thus shorter landing roll with properly installed VGs.
	


 	  Quote: 	
		  


	


Thom,



The same is true for standard leg Kolbs.  VG's increase wing lift for any 

speed above stall.  Because of this, any Kolb with VGs can fly a little 

slower and generate the same lift as it did at a higher speed before the 

addition of VGs.



For a FireFly, it is not necessary to increase leg length to enable slower 

touch down speeds.  All one has to do is droop the flaperons a few degrees 

and it will three point nicely. 



Jack B. Hart FF004

Winchester, IN

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sat Mar 18, 2006 2:48 pm Post subject: Re: Land Shorter VG's on Firestar II

Jack,



If the aircraft has flaps or flaperons (my old Firestar had neither) then the nose down pitch resulting from their use certainly would allow slower landing speeds at the same angle of attack as without the VGs. This assumes that the VGs do actually increase lift at this AOA, not merely increase the critical AOA. In my mental analysis of the situation, I can see this happening only if the point on the airfoil where the turbulence starts is changed (moved aft) at this AOA by the VGs presence, thus subjecting more of the upper camber to smooth, non-turbulent flow which could then produce more effective lift at the same AOA.



I would guess that the only easy/simple way to determine if this is the case for a particular installation, is to carefully document airspeeds, power (rpm) settings, and airspeeds in smooth air. A change in any of these (outside known measurement accuracy) would indicate a change in lift per the equation: Lift = 1/2 rho x V^2 x S(wing area). 



The AOA at low speeds (approaching stall) varies quite rapidly with speed changes but at cruise speeds the AOA changes very little with changes in speed. Therefore the most likely speed range to detect this change in lift due to VGs would be at very slow speeds. Perhaps you or others have done this to confirm a change in lift due to VGs holding all else fixed. I did not bother to do this sort of documentation because the only location I tried the VGs on resulted in a rather unsavory abrupt break at stall. Apparently locating them somewhat more forward would have made a difference in this regard but it would also have increased drag at cruise and that was not a result I wanted.



Thinking back now, I believe I noticed (didn't document) a slightly lower liftoff speed in three point with the VGs than without. That sounds like confirmation of increased lift right there because of necessity, the angle of attack is fixed. 



Sorry for the "thinking out loud" long winded discussion but I think I am now convinced that they do increase lift at standard Kolb 3-point AOA.

Thom in Buffalo

Earl Zimmerman

Joined: 13 Jan 2006
Posts: 35
Location: Elizabethtown, PA

Posted: Sat Mar 18, 2006 3:07 pm Post subject: Land Shorter VG's on Firestar II

John Hauck wrote:



 	  Quote: 	
		   

 I have never flown with VG's on a Kolb or any other aircraft, that I 

 know of.  So.....I can only speak from experience without them. 


	


Any volunteers out there to sneak out to Hauck's Holler some night and 

stick a set of VG's on Mr. Hauck's Kolb so that he can enhance his 

experience.    ~ Earl



P.S. He still might not believe so just put them on the left wing only!

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