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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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 Posted: Fri Mar 31, 2017 9:49 am Post subject: VG's |
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<<...>>
Hi Folks:
After 25 years, Miss P'fer, my MKIII, has VG's.
I installed the VGs per John Gilpin's instructions, tips at 7%, 4.5 inches from the leading edge. Instead of installing the first 15 VGs from the outboard rib at 60mm and the rest inboard at 90mm spacing, I installed all of them at 60mm. The reason I did this is because they fit nicely in the valleys between the ribs and false ribs.
They definitely lowered my stall speed and make landings a bit softer when I'm not on my game. I got a chance to do a little testing before the wind came up this morning. I'll learn more about the VG's as I fly. Haven't put them on the horizontal stabilizers. Right now, I don't see a need for them there. Maybe later. Ailerons seem to have a little more authority at slower speeds. Seem to feel sharper near the stall.
If I can decipher my notes I'll give you all some numbers.
Stalls were performed between 1000 and 3000 feet ASL. OAT was 60F.
Aircraft loaded lightly. 10 gal fuel on board and 176 lb pilot.
Numbers on the left are w/o VGs. On the right with VGs.
Power off stall:
Clean: 39 mph/33 to 34 mph
Flaps, 20 deg: 32 mph/30 mph
40 deg: 30 mph/28 mph
Biggest improvement was clean, power off. Stall reduced 5 to 6 mph. A little bit of difference with flaps, about 2 mph.
Now when I get right to the edge of the stall I get a vibration in the prop, engine at idle, with a tiny shudder. I did not have this before VGs.
BTW: Empty weight of my MKIII is 630 lbs.
I didn't do any engine off stalls today. I'll check them out and see if there is a difference between dead stick and idling prop.
Might have lost a little top end and cruise. Can't verify that at this time. I'll have to get some more time on the VGs to determine that.
So far, I'm happy with the Stoll Speed VGs from John Gilpin, down under. I believe they will make my airplane a little safer. That never hurts. The wind kicked up before I had a chance to check out stall in ground effect on landing. I intentionally landed a little high, several times, but the VGs kept the MKIII from making that sharp break normally associated with landing a couple feet on the ground. That is a great improvement.
john h
mkIII
Titus, Alabama
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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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byoungplumbing(at)gmail.c
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| Posted: Fri Mar 31, 2017 10:21 am Post subject: VG's |
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Your numbers are very close to mine. With differences in Asi I think they are preforming good. The big difference in the vgs on the horizontal comes with 2 people on board at near grose weight.
Boyd
On Mar 31, 2017 12:11 PM, "John Hauck" <jhauck(at)elmore.rr.com (jhauck(at)elmore.rr.com)> wrote: | Quote: |
<<...>>
Hi Folks:
After 25 years, Miss P'fer, my MKIII, has VG's.
I installed the VGs per John Gilpin's instructions, tips at 7%, 4.5 inches from the leading edge. Instead of installing the first 15 VGs from the outboard rib at 60mm and the rest inboard at 90mm spacing, I installed all of them at 60mm. The reason I did this is because they fit nicely in the valleys between the ribs and false ribs.
They definitely lowered my stall speed and make landings a bit softer when I'm not on my game. I got a chance to do a little testing before the wind came up this morning. I'll learn more about the VG's as I fly. Haven't put them on the horizontal stabilizers. Right now, I don't see a need for them there. Maybe later. Ailerons seem to have a little more authority at slower speeds. Seem to feel sharper near the stall.
If I can decipher my notes I'll give you all some numbers.
Stalls were performed between 1000 and 3000 feet ASL. OAT was 60F.
Aircraft loaded lightly. 10 gal fuel on board and 176 lb pilot.
Numbers on the left are w/o VGs. On the right with VGs.
Power off stall:
Clean: 39 mph/33 to 34 mph
Flaps, 20 deg: 32 mph/30 mph
40 deg: 30 mph/28 mph
Biggest improvement was clean, power off. Stall reduced 5 to 6 mph. A little bit of difference with flaps, about 2 mph.
Now when I get right to the edge of the stall I get a vibration in the prop, engine at idle, with a tiny shudder. I did not have this before VGs.
BTW: Empty weight of my MKIII is 630 lbs.
I didn't do any engine off stalls today. I'll check them out and see if there is a difference between dead stick and idling prop.
Might have lost a little top end and cruise. Can't verify that at this time. I'll have to get some more time on the VGs to determine that.
So far, I'm happy with the Stoll Speed VGs from John Gilpin, down under. I believe they will make my airplane a little safer. That never hurts. The wind kicked up before I had a chance to check out stall in ground effect on landing. I intentionally landed a little high, several times, but the VGs kept the MKIII from making that sharp break normally associated with landing a couple feet on the ground. That is a great improvement.
john h
mkIII
Titus, Alabama
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lcottrell
Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or
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| Posted: Fri Mar 31, 2017 12:58 pm Post subject: vg's |
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I have to admit that I am quite proud of you. Whether you believe it or not, the ones on the elevator do help t keep the tail flying and will also improve the landings. As I mentioned earlier, without them the tail feathers stall before the wing.
Larry
--
The older I get, the less tolerant I am of those who are intolerant of others.
If you forward this email, or any part of it, please remove my email address before sending.
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John Hauck
Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)
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| Posted: Fri Mar 31, 2017 1:27 pm Post subject: vg's |
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Larry C/Kolbers:
Thanks for the comment.
For the moment, my tail is not stalling. 
However, I do have enough VGs to do the tail, plus I am thinking about doing the same thing to both entrance doors and maybe a few on the windshield. Just aft of the doors is dead air which can be seen when flying in the rain. Lots of dead air. Also, the area where the rear of the windshield meets the bottom of the center section. Have to figure out how to configure the VGs on the windshield to get that air to split and move around the dead space.
Right now I am packing my gear to head to Lakeland. Plan on departing Gantt International Airport Tuesday morning, 4 April. Monday, my original departure date, is forecasting thunderstorms all day, plus the wind is to be strong out of the SE. Tuesday it turns around out of the W with lots of sunshine.
Probably need to check calibration of my tachometer. Haven't done that in a while. They are easy to adjust with a tiny screw driver and an RC prop tach. I think the one I have had for years is a Busy Bee. Got it out of an RC catalog. This morning I was turning 5600 rpm WOT. 5400 would be better. Still gives me good climb and a little better cruise. However, 5600 at sea level is propped just right for flying out West. Since I plan to head West in September, I think I'll leave it along.
Going back to horizontal stabilizer VGs for a moment, configured the way I am now, the tail wheel touches down (notice I didn't say hits) long before the mains, and Miss P'fer sits at a nice nose high stance. I could make the tail wheel hit even sooner and the nose higher, but don't know that I need to be doing that. However, the VGs on the wings may help soften/reduce the impact on the mains with a high nose, tail wheel first landing. Something to play around with.
john h
mkIII
Titus, Alabama
From: owner-kolb-list-server(at)matronics.com [mailto:owner-kolb-list-server(at)matronics.com] On Behalf Of Larry Cottrell
Sent: Friday, March 31, 2017 3:56 PM
To: kolb-list(at)matronics.com
Subject: vg's
I have to admit that I am quite proud of you. Whether you believe it or not, the ones on the elevator do help t keep the tail flying and will also improve the landings. As I mentioned earlier, without them the tail feathers stall before the wing.
Larry
--
The older I get, the less tolerant I am of those who are intolerant of others.
If you forward this email, or any part of it, please remove my email address before sending.
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
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_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama |
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Fri Mar 31, 2017 8:53 pm Post subject: VG's |
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I know it's been an odd winter, surely, but I really hadn't expected that Hell would freeze over so early in the spring, too. Ah, well, stranger things have happened.Good luck John and have fun.
Rick Girard
On Fri, Mar 31, 2017 at 1:20 PM, B Young <byoungplumbing(at)gmail.com (byoungplumbing(at)gmail.com)> wrote:
| Quote: |
Your numbers are very close to mine. With differences in Asi I think they are preforming good. The big difference in the vgs on the horizontal comes with 2 people on board at near grose weight.
Boyd
On Mar 31, 2017 12:11 PM, "John Hauck" <jhauck(at)elmore.rr.com (jhauck(at)elmore.rr.com)> wrote: | Quote: |
<<...>>
Hi Folks:
After 25 years, Miss P'fer, my MKIII, has VG's.
I installed the VGs per John Gilpin's instructions, tips at 7%, 4.5 inches from the leading edge. Instead of installing the first 15 VGs from the outboard rib at 60mm and the rest inboard at 90mm spacing, I installed all of them at 60mm. The reason I did this is because they fit nicely in the valleys between the ribs and false ribs.
They definitely lowered my stall speed and make landings a bit softer when I'm not on my game. I got a chance to do a little testing before the wind came up this morning. I'll learn more about the VG's as I fly. Haven't put them on the horizontal stabilizers. Right now, I don't see a need for them there. Maybe later. Ailerons seem to have a little more authority at slower speeds. Seem to feel sharper near the stall.
If I can decipher my notes I'll give you all some numbers.
Stalls were performed between 1000 and 3000 feet ASL. OAT was 60F.
Aircraft loaded lightly. 10 gal fuel on board and 176 lb pilot.
Numbers on the left are w/o VGs. On the right with VGs.
Power off stall:
Clean: 39 mph/33 to 34 mph
Flaps, 20 deg: 32 mph/30 mph
40 deg: 30 mph/28 mph
Biggest improvement was clean, power off. Stall reduced 5 to 6 mph. A little bit of difference with flaps, about 2 mph.
Now when I get right to the edge of the stall I get a vibration in the prop, engine at idle, with a tiny shudder. I did not have this before VGs.
BTW: Empty weight of my MKIII is 630 lbs.
I didn't do any engine off stalls today. I'll check them out and see if there is a difference between dead stick and idling prop.
Might have lost a little top end and cruise. Can't verify that at this time. I'll have to get some more time on the VGs to determine that.
So far, I'm happy with the Stoll Speed VGs from John Gilpin, down under. I believe they will make my airplane a little safer. That never hurts. The wind kicked up before I had a chance to check out stall in ground effect on landing. I intentionally landed a little high, several times, but the VGs kept the MKIII from making that sharp break normally associated with landing a couple feet on the ground. That is a great improvement.
john h
mkIII
Titus, Alabama
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“Blessed are the cracked, for they shall let in the light.” Groucho Marx
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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lcottrell
Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or
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| Posted: Fri Mar 31, 2017 9:43 pm Post subject: VG's |
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I am glad that John finally gave in and put VG's on his plane. We all
tend to forget that John has never said that he didn't like VG's,
merely that he didn't need them. He is right, he really didn't need
them for his landings, although there may be other benefits to them
other than slowing stall speed.
He enjoyed my Firestar with VG's and it changed it enough that it
surprised him, but when you come down to it a Kolb with flaps really
doesn't need VG's. You can see that with the results that both he and
Boyd achieved. Very little improvement with full flaps. About 6 or
more MPH without flaps. The reason of course is that the flaps changes
the airfoil and thus the plane without tipping the wing back to the
point that it loses the airflow.
Give him hell any way. 
Larry
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