---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Thu 03/20/14: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:12 AM - Re: Drag Reduction Paradox/VGs (JC Gilpin) 2. 05:48 AM - Re: Re: Drag Reduction Paradox/VGs (John Hauck) ________________________________ Message 1 _____________________________________ Time: 03:12:19 AM PST US Subject: Kolb-List: Re: Drag Reduction Paradox/VGs From: JC Gilpin *One of the VG manufacturers and marketer shared with me the following, "The only reason I have them on my Kolb is because I sell them. Wouldn't look good if I didn't" * Well that manufacturer would probably be me. I manufacture the Stolspeed VGs, and have spent some good times yarning with JH. But I do have to correct some misremembering here. I certainly never would have said, "Wouldn't look good if I didn't...", cause that's not my attitude and I never do anything just for image..... I don't remember my exact words, but as I remember, the wording would have been more like. "Of course I had to put my VGs on my Kolb, cause I make 'em..." But that's because I'm a curious and avid experimenter, and want to test VGs on any aircraft I get my hands on. I also would have said that. " The VGs didn't give any effective landing advantage on the FireFly...", but that has to do with the FireFly design rather than the effect of the VGs. Now I must explain...... The addition of the VGs did lower the stall speed several mph (I don't have the actual figures any longer). This was the stall speed measured at altitude. Of course a lower stall speed also means a higher Angle of Attack, and with the VGs the FireFly was very stable at this higher AofA and lower airspeed. The stall was very benign and gentle, but then it was so before, characteristically due to the low aspect ratio of that short rectangular wing, which tends to give such stall characteristics. But I found that I wasn't able to use that higher AofA and slower speed for landing, due to the landing gear design on the FireFly. It sits very flat on the ground, nowhere near the AofA at stall speed. When I tried to do full stall landings with VGs at the slowest speed, the tail wheel touched down first while the mains were way off the ground, then the mains came down with an almighty thump....... I'm used to regularly doing full stall landings - hold off, hold off, hold off, with the mains a few inches from the ground, AofA increasing and speed decreasing until it stalls on as slow as possible with no energy left to bounce or swerve. But with the FireFly had to learn to 'fly it on', and at the three-pointer attitude that was considerably faster than a stall landing. It's still a fairly short landing but not near as short and slow as it could be. I can well understand why some Kolb owners have gone to taller main gear legs..... But point is that the VGs actually couldn't help any at that flat attitude, so they were fairly useless on the FireFly, as regards to slow landings. The VGs did give crisper aileron authority at slow speed, and much more stability in very slow speed turns, but then you shouldn't be doin' them anyhow, eh.... So that's the story as I remember it..... John Gilpin ________________________________ Message 2 _____________________________________ Time: 05:48:30 AM PST US From: "John Hauck" Subject: RE: Kolb-List: Re: Drag Reduction Paradox/VGs JC G/Kolbers: I apologize for the misunderstanding. Would like to blame it on old age, but have to admit I got things screwed up. Now that you have told me the story again, I remember what we were talking about, it was the tail wheel hitting first while the mains were well off the ground. Most Kolbs do that when performing full stall landings. Homer Kolb designed his airplanes, except the Sling Shot, to sit fairly level on the ground. His intention was the prevent low time pilots from pulling the aircraft off the ground too soon, too slow, at too steep an angle, and stalling. Landings must be done fairly level, requiring more speed, and reducing the possibility of stalls. Any time someone got hurt in a Kolb, Homer took it personally. He wanted his airplanes to be as safe as possible. Despite that, we still manage to break his airplanes. My MKIII doesn't have that problem because it has been modified to sit nose high. Even at the nose high attitude, it is possible to hit the tail wheel first if I get too aggressive in a full stall approach. I don't have that problem much, now days, because I am not nearly as aggressive as I was when I was younger. Again, I am sorry for the mix up. JC has a much better memory than me. His recollection of our conversation, two or three years ago, is right on. john h mkIII Titus, Alabama From: owner-kolb-list-server@matronics.com [mailto:owner-kolb-list-server@matronics.com] On Behalf Of JC Gilpin Sent: Thursday, March 20, 2014 5:12 AM Subject: Kolb-List: Re: Drag Reduction Paradox/VGs One of the VG manufacturers and marketer shared with me the following, "The only reason I have them on my Kolb is because I sell them. Wouldn't look good if I didn't" Well that manufacturer would probably be me. I manufacture the Stolspeed VGs, and have spent some good times yarning with JH. But I do have to correct some misremembering here. I certainly never would have said, "Wouldn't look good if I didn't...", cause that's not my attitude and I never do anything just for image..... I don't remember my exact words, but as I remember, the wording would have been more like. "Of course I had to put my VGs on my Kolb, cause I make 'em..." But that's because I'm a curious and avid experimenter, and want to test VGs on any aircraft I get my hands on. I also would have said that. " The VGs didn't give any effective landing advantage on the FireFly...", but that has to do with the FireFly design rather than the effect of the VGs. Now I must explain...... The addition of the VGs did lower the stall speed several mph (I don't have the actual figures any longer). This was the stall speed measured at altitude. Of course a lower stall speed also means a higher Angle of Attack, and with the VGs the FireFly was very stable at this higher AofA and lower airspeed. The stall was very benign and gentle, but then it was so before, characteristically due to the low aspect ratio of that short rectangular wing, which tends to give such stall characteristics. But I found that I wasn't able to use that higher AofA and slower speed for landing, due to the landing gear design on the FireFly. It sits very flat on the ground, nowhere near the AofA at stall speed. When I tried to do full stall landings with VGs at the slowest speed, the tail wheel touched down first while the mains were way off the ground, then the mains came down with an almighty thump....... I'm used to regularly doing full stall landings - hold off, hold off, hold off, with the mains a few inches from the ground, AofA increasing and speed decreasing until it stalls on as slow as possible with no energy left to bounce or swerve. But with the FireFly had to learn to 'fly it on', and at the three-pointer attitude that was considerably faster than a stall landing. It's still a fairly short landing but not near as short and slow as it could be. I can well understand why some Kolb owners have gone to taller main gear legs..... But point is that the VGs actually couldn't help any at that flat attitude, so they were fairly useless on the FireFly, as regards to slow landings. The VGs did give crisper aileron authority at slow speed, and much more stability in very slow speed turns, but then you shouldn't be doin' them anyhow, eh.... So that's the story as I remember it..... John Gilpin ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kolb-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kolb-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kolb-list Browse Digests http://www.matronics.com/digest/kolb-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.