---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Wed 03/12/14: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:43 AM - Re: Drag reduction (KIRBY, DENNIS T GS-13 USAF AFMC AFNWC/ENS) 2. 08:08 AM - Re: Re: Drag reduction (b young) 3. 08:28 AM - reduced drag and speed. (b young) 4. 09:03 AM - Re: reduced drag and speed. (John Hauck) 5. 12:00 PM - Re: Re: Drag Reduction Paradox (Jack B. Hart) 6. 12:04 PM - Re: Drag Reduction Paradox (Arizona Flyer) 7. 12:25 PM - Re: Re: Drag Reduction Paradox (Sky Biker) 8. 09:39 PM - Re: Drag Reduction Paradox (Richard Pike) ________________________________ Message 1 _____________________________________ Time: 07:43:57 AM PST US From: "KIRBY, DENNIS T GS-13 USAF AFMC AFNWC/ENS" Subject: Kolb-List: Re: Drag reduction Hauck wrote: << Loose fabric makes a lot different airfoil than tight fabric. As tight as the fabric is on my wing, I still get a concave lower wing surface in flight - The more concave that surface, the slower the airplane will fly, but probably kill a lot of top and cruise speed. >> ?! I did not know this! Will hafta check it out the underside of my wing, next time I fly. Rick Girard wrote: << Pareto Principle? To generalize, we could say that 80% of the drag of a Kolb is caused by 20% of the drag producers. >> Rick is correct - I have also seen it written (by Barnaby Wainfan, in one of his Kitplanes columns) that to reduce drag, the most benefit will come from tackling the biggies first: Streamline any struts in the airflow (like wing struts and landing gear legs), use gap seals for all the moving control surfaces, close up any open areas on the fuselage (Kolbs pods are notorious for this), and try to avoid sharp bends along the path of the airflow. On my Mark-3, this happens as air flows past the aft edges of the doors - it's a pretty sharp corner for the air to flow around. My stock Mark-3 had open sides on the upper-rear area of the pod. I covered this area with Lexan sheet, and that helped. Hauck was right about the windshield-to-wing junction being a source of stagnation - lots of drag there. I made an aluminum fairing to smooth the airflow at that area. That helped too. Boyd suggested that now, with all my clean-ups, I actually CAN get that extra knot or two added to my top airspeed if I now dial in an additional degree to my prop pitch. At the same power settings as before, I should now see a bit more airspeed. Didn't think of that - I might try it. Dennis Kirby Tackling the drag on my Kolb, one molecule at a time do not archive ________________________________ Message 2 _____________________________________ Time: 08:08:05 AM PST US From: "b young" Subject: Re: Kolb-List: Re: Drag reduction maybe a quarter to half degree.... a full degree may be a bit much.... boyd >>>>>>>>>>>>>>>>>>>>>>>>>> Boyd suggested that now, with all my clean-ups, I actually CAN get that extra knot or two added to my top airspeed if I now dial in an additional degree to my prop pitch. At the same power settings as before, I should now see a bit more airspeed. Didn't think of that - I might try it. Dennis Kirby --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ________________________________ Message 3 _____________________________________ Time: 08:28:19 AM PST US From: "b young" Subject: Kolb-List: reduced drag and speed. kolbers... maybe I should explain my thought process,,, it seems logical to me... but I am a retired plumber, not aerospace engineer. I think when Dennis has reduced drag, he said he is at the same speed, ru nning the same power settings, at the same rpm... ( at least that is what I comprehended).. but with reduced drag. the same rpm is not the same p ower setting,,, this is evident by the reduced fuel consumption. when m aking changes, it is best to change only one thing at a time. thus you can quantify the changes to the results. now that Dennis has reduced the dra g, and kept notes on the changes,,, IMHO in my humble opinion,,, in orde r to quantify the changes, he has to get the power setting back to the orig inal settings. he could do this in 2 ways,,, first, increase the rpm ti ll he reaches the same fuel burn, that should show an increase in speed,,, second, and the purest change here is increase load on the engine equal to the drag reduction, by increasing pitch, so he gets the same rpm at the same fuel burn that he had before drag reductions. with the same rpm a nd fuel burn the net difference in speed would be the benefit of reduction of drag. I am sure there are some on the list that could tell me if I have thought t his through correctly,,, or if I am full of wishful thinking. boyd young --- This email is free from viruses and malware because avast! Antivirus protec tion is active. http://www.avast.com ________________________________ Message 4 _____________________________________ Time: 09:03:34 AM PST US From: "John Hauck" Subject: RE: Kolb-List: reduced drag and speed. Hi Boyd Y/Kolbers: My qualifications to comment on this are few. I am a retired soldier. Beans and bullets is about all I know. I buy your theory. While experimenting, you can use different prop settings to accomplish your goal. If it was me, when it comes to prop pitch, I would continue to use the same practice as I always have: Just bump the red line, for a 912UL it is 5,500 rpm, at wide open throttle/straight and level flight. When you get that, you have gotten to best performance for climb and cruise. The engine is happy. The airplane is happy. Therefore, the pilot and experimenter is happy, I hope. ;-) john h mkIII Titus, Alabama : Kolb-List: reduced drag and speed. kolbers... maybe I should explain my thought process,,, it seems logical to me... but I am a retired plumber, not aerospace engineer. I think when Dennis has reduced drag, he said he is at the same speed, running the same power settings, at the same rpm... ( at least that is what I comprehended).. but with reduced drag. the same rpm is not the same power setting,,, this is evident by the reduced fuel consumption. when making changes, it is best to change only one thing at a time. thus you can quantify the changes to the results. now that Dennis has reduced the drag, and kept notes on the changes,,, IMHO in my humble opinion,,, in order to quantify the changes, he has to get the power setting back to the original settings. he could do this in 2 ways,,, first, increase the rpm till he reaches the same fuel burn, that should show an increase in speed,,, second, and the purest change here is increase load on the engine equal to the drag reduction, by increasing pitch, so he gets the same rpm at the same fuel burn that he had before drag reductions. with the same rpm and fuel burn the net difference in speed would be the benefit of reduction of drag. I am sure there are some on the list that could tell me if I have thought this through correctly,,, or if I am full of wishful thinking. boyd young ________________________________ Message 5 _____________________________________ Time: 12:00:04 PM PST US From: "Jack B. Hart" Subject: Re: Kolb-List: Re: Drag Reduction Paradox At 01:32 PM 3/11/2014 -0700, you wrote: > >> >> file:///C:/Users/Charlie/Downloads/Streamline_SAA.pdf >> >> Charlie > > >Um - Charlie? I don't think that's a web url - I think it's a file on your hard drive. > >-------- >Richard Pike > Could this be what you are looking for? http://www.jackbhart.com/firefly/pdrag.html Jack B. Hart FF004 Winchester, IN ________________________________ Message 6 _____________________________________ Time: 12:04:11 PM PST US Subject: Kolb-List: Re: Drag Reduction Paradox From: "Arizona Flyer" Also waxing your airplane will increase efficiency & speed. On my Rans S-7 after I put wax on I gained 3 to 5 mph at cruise & top speed. -------- "Life should be lived as a bold adventure, I refuse to tiptoe through life just to arrive safely at death" Read this topic online here: http://forums.matronics.com/viewtopic.php?p=420213#420213 ________________________________ Message 7 _____________________________________ Time: 12:25:40 PM PST US From: Sky Biker Subject: RE: Kolb-List: Re: Drag Reduction Paradox I haven't noticed any one saying any thing about vortex generators to help performance. I have a Mark 111 / 912 80hp with the enclosed rear area=2C f airing on the struts=2C steel landing gear with tundra tires. After instal ling the vortex generators I noticed a lower stall speed=2C increase in cru ising speed and climb. There was also a decrease in fuel usage both solo an d duel. My main reason for installing them was the short field and beach l anding and take off...less roll out and was surprised by the above added ad vantages. > Subject: Kolb-List: Re: Drag Reduction Paradox > From: heracesthesun@yahoo.com > Date: Wed=2C 12 Mar 2014 12:03:48 -0700 > To: kolb-list@matronics.com > > > > Also waxing your airplane will increase efficiency & speed. On my Rans S- 7 after I put wax on I gained 3 to 5 mph at cruise & top speed. > > -------- > "=3BLife should be lived as a bold adventure=2C I refuse to tiptoe th rough life just to arrive safely at death"=3B > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=420213#420213 > > > > > > > =========== =========== =========== =========== > > > ________________________________ Message 8 _____________________________________ Time: 09:39:49 PM PST US Subject: Kolb-List: Re: Drag Reduction Paradox From: "Richard Pike" smlplanet(at)msn.com wrote: > I haven't noticed any one saying any thing about vortex generators to help performance. I have a Mark 111 / 912 80hp with the enclosed rear area, fairing on the struts, steel landing gear with tundra tires. After installing the vortex generators I noticed a lower stall speed, increase in cruising speed and climb. There was also a decrease in fuel usage both solo and duel. 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. > Yep. My experience exactly. Isn't it wonderfully simple and straightforward? Enjoy. -------- Richard Pike Kolb MKIII N420P (420ldPoops) Kingsport, TN 3TN0 My soul shall be joyful in the LORD; It shall rejoice in His salvation. Psalm 35:9 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=420251#420251 ------------------------------------------------------------------------------------- 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.