---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Thu 03/13/14: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:15 AM - Re: Kolb-List Digest: 7 Msgs - 03/11/14 (George Bearden) 2. 02:42 AM - Re: Re: Drag Reduction Paradox (Robert Gillisse) 3. 04:49 AM - Re: Re: Drag Reduction Paradox (Pat Ladd) 4. 06:58 AM - Re: Re: Drag Reduction Paradox (Mike) 5. 07:31 AM - Re: Re: Kolb-List Digest: 7 Msgs - 03/11/14 (Charlie England) 6. 07:59 AM - Re: Re: Kolb-List Digest: 7 Msgs - 03/11/14 (Jack B. Hart) 7. 08:37 AM - Re: Re: Drag Reduction Paradox (Richard Girard) 8. 11:41 AM - Re: Re: Drag Reduction Paradox (Robert Gillisse) 9. 12:49 PM - Re: Re: Drag Reduction Paradox (Rick Neilsen) 10. 03:43 PM - Re: Drag Reduction Paradox (Larlaeb) 11. 05:20 PM - Re: Re: Drag Reduction Paradox (John Hauck) ________________________________ Message 1 _____________________________________ Time: 12:15:41 AM PST US From: "George Bearden" Subject: Kolb-List: RE: Kolb-List Digest: 7 Msgs - 03/11/14 > showing the equivalent cross sections of a wire, a square rod Saw that video. Convinced me. > Note carefully the decimal point locations. Umm.. on what diagram? "Streamline That Tubing"? Do you know of a good source for the construction details other than buying another complete book? As I looked at the diagram I felt it was missing the dimension that locates the widest part of the streamline. Plus, I wasn't sure what it means with the "4X Tubing O.D." Couldn't figger out fer sure what it meant. Not the circumference is it? Seems that would be a useless bit of info. Have any one of us built these? I have some dacron, thinking about covering foam with dacron and paint maybe. ________________________________ Message 2 _____________________________________ Time: 02:42:09 AM PST US From: Robert Gillisse Subject: Re: Kolb-List: Re: Drag Reduction Paradox Ref> Vortex Generators (VG's)... just installed them on my Firestar (43 on each wing) and the first thing I noticed was increased climb rate and bette r control at low-speed touchdowns (lowered stall speed combined with better handling is a win-win). Don't know about an increase in cruise speed, just learned that drag is not a factor at higher speeds. =0A=0ARobert Gillisse =0A2004 Kolb Firestar II=0A503 DCDI=0ACollegedale, TN=0A=0A=0A=0AOn Thursda y, March 13, 2014 12:44 AM, Richard Pike wrote:=0A =0A=0A=0Asmlplanet(at)msn.com wrote:=0A> I haven't noticed any one saying a ny thing about vortex generators to help performance. I have a Mark 111 / 9 12=EF=BD 80hp with the enclosed rear area, fairing on the struts, steel landing gear with tundra tires.=EF=BD After installing the vortex genera tors I noticed a lower stall speed, increase in cruising speed and climb. T here was also a decrease in fuel usage both solo and duel.=EF=BD My main reason for installing them was the short field and beach landing and take off...less roll out and was surprised by the above added advantages. =0A> =0A=0A=0AYep. My experience exactly. Isn't it wonderfully simple and straig htforward?=0A=0AEnjoy.=0A=0A--------=0ARichard Pike=0AKolb MKIII N420P (420 ldPoops)=0AKingsport, TN 3TN0=0AMy soul shall be joyful in the LORD; It sha ll rejoice in His salvation. Psalm 35:9=0A=0A=0A=0A=0ARead this topic onlin e here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=420251#420251=0A =========================0A =================== ________________________________ Message 3 _____________________________________ Time: 04:49:19 AM PST US From: "Pat Ladd" Subject: Re: Kolb-List: Re: Drag Reduction Paradox <> Huh!, I thought drag increased by the square of the speed (or something like that) In essence the faster you go the MORE drag you create.. Pat ________________________________ Message 4 _____________________________________ Time: 06:58:41 AM PST US From: Mike Subject: RE: Kolb-List: Re: Drag Reduction Paradox Pat=2C So did I=2C Pat. I'm not trying to speak completely on behalf of Robert (who said "just le arned that drag is not a factor at higher speeds" )=2C but what I "think" h e meant was=2C (since he said something we all know is wrong)=2C "in re gards to the addition of VGs and their affect on the top end of "my" plane' s speed ranges=3B "I just learned that drag (of only the VGs) is not a fac tor at higher speeds". Yeah=2C took me reading what he said about three or four times before I f igured out what he "may" have meant. If I'm incorrect=2C and he meant precisely what he said=2C well.......... ...maybe he will explain what I missed=2C too. Mike Welchdo not archive From: pj.ladd@btinternet.com Subject: Re: Kolb-List: Re: Drag Reduction Paradox =0A =0A =0A =0A =0A =0A =0A <>=0A =0A Huh!=2C=0A I thought drag increased by the square of the speed =0A (or something like that) In essence the faster you go the MORE drag you =0A create..=0A =0A Pat=0A =0A =0A =0A =0A =0A ============0A ============0A ============0A ============0A =0A ________________________________ Message 5 _____________________________________ Time: 07:31:50 AM PST US From: Charlie England Subject: Re: Kolb-List: RE: Kolb-List Digest: 7 Msgs - 03/11/14 On 3/13/2014 2:15 AM, George Bearden wrote: > >> showing the equivalent cross sections of a wire, a square rod > Saw that video. Convinced me. > >> Note carefully the decimal point locations. > Umm.. on what diagram? "Streamline That Tubing"? > > Do you know of a good source for the construction details other than buying > another complete book? As I looked at the diagram I felt it was missing the > dimension that locates the widest part of the streamline. Plus, I wasn't > sure what it means with the "4X Tubing O.D." Couldn't figger out fer sure > what it meant. Not the circumference is it? Seems that would be a useless > bit of info. Have any one of us built these? I have some dacron, thinking > about covering foam with dacron and paint maybe. For the decimal point reference: in the table in that article: 0.085 for streamline vs 1.03 for round. Streamline has less than 1/10th the drag of a round tube. Also interesting to note that a round tube has *higher drag* than a square tube (which would be 1.00, the reference). I agree, the '4x tube OD' in the drawing is rather vague. I think he's saying that the length of the streamline is 3x tube OD, the max width of the streamline is 1.07x tube OD, and the length around the curve of the streamline is 4x the tube OD. I can only assume that he's trying to give some rough specs for 'rolling your own', without the required (rather convoluted, for non- mathematician) calculations. Don't some of the ultralite suppliers sell plastic streamline tubing that just snaps around round tube? Charlie ________________________________ Message 6 _____________________________________ Time: 07:59:59 AM PST US From: "Jack B. Hart" Subject: Re: Kolb-List: RE: Kolb-List Digest: 7 Msgs - 03/11/14 At 12:15 AM 3/13/2014 -0700, you wrote: > >Do you know of a good source for the construction details other than buying >another complete book? As I looked at the diagram I felt it was missing the >dimension that locates the widest part of the streamline. Plus, I wasn't >sure what it means with the "4X Tubing O.D." Couldn't figger out fer sure >what it meant. Not the circumference is it? Seems that would be a useless >bit of info. Have any one of us built these? I have some dacron, thinking >about covering foam with dacron and paint maybe. > > How I made trailing edge and strut fairings: http://www.jackbhart.com/firefly/firefly105.html http://www.jackbhart.com/firefly/firefly91.html Jack B. Hart FF004 Winchester, IN ________________________________ Message 7 _____________________________________ Time: 08:37:34 AM PST US Subject: Re: Kolb-List: Re: Drag Reduction Paradox From: Richard Girard From: http://en.wikipedia.org/wiki/Drag_equation [image: F_D\, =\, \tfrac12\, \rho\, v^2\, C_D\, A] where *FD* is the drag force , which is by definition the force component in the direction of the flow velocity,[1] *=F1* is the mass density of th e fluid, [2] *v* is the velocity of the object relative to the fluid,*A* is the reference area , and*CD* is the drag coefficient - a dimensionless coefficient related to the object's geometry and taking into account both skin friction and form drag . It's that V squared that increases the drag with velocity; i.e. go twice as fast and you produce 4 times the drag. Rick Girard On Thu, Mar 13, 2014 at 8:57 AM, Mike wrote: > Pat, > So did I, Pat. > > I'm not trying to speak completely on behalf of Robert (who said "just > learned that drag is not a factor at higher speeds" ), but what I "think" > he meant was, (since he said something we all know is wrong), > "in regards to the *addition* of VGs and their affect on the top end > of "my" plane's speed ranges; "I just learned that drag (of only the > VGs) is not a factor at higher speeds". > > Yeah, took me reading what he said about three or four times before I > figured out what he "may" have meant. > > If I'm incorrect, and he meant precisely what he said, > well.............maybe he will explain what I missed, too. > > Mike Welch > do not archive > > > ------------------------------ > From: pj.ladd@btinternet.com > To: kolb-list@matronics.com > Subject: Re: Kolb-List: Re: Drag Reduction Paradox > Date: Thu, 13 Mar 2014 04:49:05 -0700 > > > <> > > Huh!, > I thought drag increased by the square of the speed (or something like > that) In essence the faster you go the MORE drag you create.. > > Pat > > * > > ========== > arget="_blank">http://www.matronics.com/Navigator?Kolb-List > ========== > http://forums.matronics.com > ========== > ="_blank">http://www.matronics.com/contribution > ========== > > * > > * > =========== onics.com/Navigator?Kolb-List> =========== =========== om/contribution> =========== > > * > > -- Zulu Delta Mk IIIC Thanks, Homer GBYM It isn't necessary to have relatives in Kansas City in order to be unhappy. - Groucho Marx ________________________________ Message 8 _____________________________________ Time: 11:41:24 AM PST US From: Robert Gillisse Subject: Re: Kolb-List: Re: Drag Reduction Paradox You are right, Mike...in the CONTEXT of what I was writing,=0Anaturally I w as referring to the associated drag factor of the VG's... not drag=0AIN GEN ERAL. That would make me look stupid if I said that. Do you see that Pat? =0ADiscussion... How Much Drag would those 1/2 inch high, slightly angled V G's produce=0Aat a position 'about' 10" behind the leading edge with the wi ng at an=0Aangle of attack commensurate with , say, 65 MPH?? I believe ther e would be a=0Avacuum there. Hmm. Where (and when) does the air separate? =0A=0A=0A=0AOn Thursday, March 13, 2014 10:05 AM, Mike wrote:=0A =0A =0APat,=0A- So did I, Pat. -=0A=0A- I'm not tryi ng to speak completely on behalf of Robert (who said "just learned that dra g is not a factor at higher speeds" ), but what I "think" he meant was, (si nce he said something we all know is wrong),-=0A- - "in regards to th e addition-of VGs and their affect on the top end of "my" plane's speed -ranges; -"I just learned that drag (of only the VGs) is not a factor a t higher speeds".=0A=0A- Yeah, took me reading what he said about three o r four times before I figured out what he "may" have meant.=0A=0A- If I'm incorrect, and he meant precisely what he said, well.............maybe he will explain what I missed, too.=0A=0AMike Welch=0Ado not archive=0A=0A=0A =0A________________________________=0AFrom: pj.ladd@btinternet.com=0ATo: ko lb-list@matronics.com=0ASubject: Re: Kolb-List: Re: Drag Reduction Paradox =0ADate: Thu, 13 Mar 2014 04:49:05 -0700=0A=0A =0A<> =0A=0AHuh!, =0AI thought drag incre ased by the square of the speed =0A(or something like that)- In essence t he faster you go the MORE drag you =0Acreate.. =0A- =0APat =0A =0A== ==========0Aarget="_blank">http://www.matronics.com/Nav igator?Kolb-List=0A============0Ahttp://forums.matron ics.com=0A============0A="_blank">http://www.matron ========= ________________________________ Message 9 _____________________________________ Time: 12:49:45 PM PST US Subject: Re: Kolb-List: Re: Drag Reduction Paradox From: Rick Neilsen I asked the question of drag from VG at a drag reduction form at Oshkosh a few years ago. The response was that VGs when properly used clean up aerodynamic issues to the point that they don't increase drag at speed and sometimes even decrease drag. Rick Neilsen Redrive VW Powered MKIIIC On Thu, Mar 13, 2014 at 2:37 PM, Robert Gillisse < thermal_hunter2002@yahoo.com> wrote: > You are right, Mike...in the CONTEXT of what I was writing, naturally I > was referring to the associated drag factor of the VG's... not drag IN > GENERAL. That would make me look stupid if I said that. Do you see that > Pat? Discussion... How Much Drag would those 1/2 inch high, slightly angled > VG's produce at a position 'about' 10" behind the leading edge with the > wing at an angle of attack commensurate with , say, 65 MPH?? I believe > there would be a vacuum there. Hmm. Where (and when) does the air separate? > > > On Thursday, March 13, 2014 10:05 AM, Mike > wrote: > Pat, > So did I, Pat. > > I'm not trying to speak completely on behalf of Robert (who said "just > learned that drag is not a factor at higher speeds" ), but what I "think" > he meant was, (since he said something we all know is wrong), > "in regards to the *addition* of VGs and their affect on the top end > of "my" plane's speed ranges; "I just learned that drag (of only the > VGs) is not a factor at higher speeds". > > Yeah, took me reading what he said about three or four times before I > figured out what he "may" have meant. > > If I'm incorrect, and he meant precisely what he said, > well.............maybe he will explain what I missed, too. > > Mike Welch > do not archive > > > From: pj.ladd@btinternet.com > To: kolb-list@matronics.com > Subject: Re: Kolb-List: Re: Drag Reduction Paradox > Date: Thu, 13 Mar 2014 04:49:05 -0700 > > <> > > Huh!, > I thought drag increased by the square of the speed (or something like > that) In essence the faster you go the MORE drag you create.. > > Pat > > * > > ========== > arget="_blank">http://www.matronics.com/Navigator?Kolb-List > ========== > http://forums.matronics.com > ========== > ="_blank">http://www.matronics.com/contribution > ========== > > * > > *http://www.matronics.c ================= > > * > > > * > > > * > > ________________________________ Message 10 ____________________________________ Time: 03:43:04 PM PST US Subject: Kolb-List: Re: Drag Reduction Paradox From: "Larlaeb" I think most of the advantages of any streamlining you do are going to be more in the area of efficiencies at lower speed (same speed with less power, better fuel consumption etc.) than a much greater top speed. This is because drag increases with speed exponentially as has already been stated and the improvement you have made in the form drag by streamlining is pretty quickly overcome by induced drag. I think the wing form of a Kolb is roughly optimized in size and shape for somewhere in the 100 mph range and pushing that big high lift wing will begin to take an unreasonable amount of power at some point even if substantially eliminate a lot of the pod form drag. I'm not saying you won't go faster, but the speed returns will rapidly diminish. Probably stating the obvious but there's my 1.5 cents. Allan :D Read this topic online here: http://forums.matronics.com/viewtopic.php?p=420304#420304 ________________________________ Message 11 ____________________________________ Time: 05:20:32 PM PST US From: "John Hauck" Subject: RE: Kolb-List: Re: Drag Reduction Paradox Wonder how that relates to a Kolb? and what is "at speed" for a Kolb? Most of the feedback I get from Kolb owners that install VGs is a slight reduction in top speed. Don't know about cruise speed. Not much difference between cruise speed for me, when I am flying Kolbs, and top speed. Top speed in a Kolb in normally never comfortable. They were not designed for speed. I have a normal "sweet spot" cruise speed, and a "get to the next way point a little quicker" cruise speed. In my MKIII, anything over 90 mph starts to get uncomfortable and is wasting a lot of fuel. Normal cruise, 5,000 rpm, 912ULS, is 80 to 85. High cruise, 5,200 rpm 912ULS, is 85 to 90, depended on I am loaded. If your Kolb is getting a speed boost with VGs, I am happy for you. john h mkIII Titus, Alabama I asked the question of drag from VG at a drag reduction form at Oshkosh a few years ago. The response was that VGs when properly used clean up aerodynamic issues to the point that they don't increase drag at speed and sometimes even decrease drag. Rick Neilsen Redrive VW Powered MKIIIC ------------------------------------------------------------------------------------- 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.