RV-List Digest Archive

Mon 01/10/11


Total Messages Posted: 6



Today's Message Index:
----------------------
 
     1. 09:32 AM - Airfoil Drag Video... (Matt Dralle)
     2. 11:25 AM - Re: Airfoil Drag Video... (Ralph Finch)
     3. 11:39 AM - Re: Airfoil Drag Video... (Bill Boyd)
     4. 12:23 PM - Re: Airfoil Drag Video... (Doug Gray)
     5. 01:25 PM - Re: Airfoil Drag Video... (Bill Boyd)
     6. 04:34 PM - Re: Airfoil Drag Video... (Doug Gray)
 
 
 


Message 1


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    Time: 09:32:20 AM PST US
    From: Matt Dralle <dralle@matronics.com>
    Subject: Airfoil Drag Video...
    This is a REALLY interesting video about drag. I had no idea... http://www.youtube.com/watch?v=ftq8jTQ8ANE Matt - Matt Dralle RV-8 #82880 N998RV http://www.mattsrv8.com - Matt's RV-8 Construction Log http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel Status: 132+ Hours TTSN - The Fun Never Stops...


    Message 2


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    Time: 11:25:32 AM PST US
    From: "Ralph Finch" <ralphmariafinch@gmail.com>
    Subject: Airfoil Drag Video...
    Not repeatable therefore not real useful for comparison. The guy should rotate the airfoils to minimum drag each time, otherwise, he doesn't know if they are in comparable positions. It's also a shame he didn't replace the airfoil with an equal-flow-area rectangular shape. As a result he produces confusing and misleading results, inferring that a round shape has more drag than a rectangular shape! -----Original Message----- From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matronics.com] On Behalf Of Matt Dralle Sent: Monday, January 10, 2011 9:29 AM rv10-list@matronics.com Subject: RV-List: Airfoil Drag Video... This is a REALLY interesting video about drag. I had no idea... http://www.youtube.com/watch?v=ftq8jTQ8ANE Matt - Matt Dralle RV-8 #82880 N998RV http://www.mattsrv8.com - Matt's RV-8 Construction Log http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel Status: 132+ Hours TTSN - The Fun Never Stops...


    Message 3


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    Time: 11:39:34 AM PST US
    Subject: Re: Airfoil Drag Video...
    From: Bill Boyd <sportav8r@gmail.com>
    Would like to see this repeated with the spiral-cut profile common on automotive AM/FM whip antennas now. Seems to eliminate the resonant vibrations - probably cuts drag by vortex generation, too. -Bill B On Mon, Jan 10, 2011 at 2:11 PM, Ralph Finch <ralphmariafinch@gmail.com>wrote: > > Not repeatable therefore not real useful for comparison. The guy should > rotate the airfoils to minimum drag each time, otherwise, he doesn't know > if > they are in comparable positions. It's also a shame he didn't replace the > airfoil with an equal-flow-area rectangular shape. As a result he produces > confusing and misleading results, inferring that a round shape has more > drag > than a rectangular shape! > > -----Original Message----- > From: owner-rv-list-server@matronics.com > [mailto:owner-rv-list-server@matronics.com] On Behalf Of Matt Dralle > Sent: Monday, January 10, 2011 9:29 AM > To: rv-list@matronics.com; rv7-list@matronics.com; rv8-list@matronics.com; > rv10-list@matronics.com > Subject: RV-List: Airfoil Drag Video... > > > This is a REALLY interesting video about drag. I had no idea... > > > http://www.youtube.com/watch?v=ftq8jTQ8ANE > > Matt > > - > Matt Dralle > RV-8 #82880 N998RV > http://www.mattsrv8.com - Matt's RV-8 Construction Log > http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel > Status: 132+ Hours TTSN - The Fun Never Stops... > >


    Message 4


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    Time: 12:23:08 PM PST US
    Subject: Re: Airfoil Drag Video...
    From: Doug Gray <dgra1233@bigpond.net.au>
    For a clear easily understood mathematical discussion see page 27 and Appendix A of this document: www.dsto.defence.gov.au/publications/3442/DSTO-TR-1622.pdf After reading this I designed and manufactured my own gearleg fairings with an accurate aerodynamic profile. Angled round whip antennas will present an elliptical profile - this does reduce their drag coefficient slightly. Doug Gray RV-6 flying On Mon, 2011-01-10 at 09:29 -0800, Matt Dralle wrote: > > This is a REALLY interesting video about drag. I had no idea... > > > http://www.youtube.com/watch?v=ftq8jTQ8ANE > > Matt > > - > Matt Dralle > RV-8 #82880 N998RV > http://www.mattsrv8.com - Matt's RV-8 Construction Log > http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel > Status: 132+ Hours TTSN - The Fun Never Stops... > > > > >


    Message 5


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    Time: 01:25:44 PM PST US
    Subject: Re: Airfoil Drag Video...
    From: Bill Boyd <sportav8r@gmail.com>
    Does the article give actual formulae or coordinates for that streamline foil shape? So as to be able to construct one? How far off the ideal are the commercially available fairings from Van's and some of the aftermarket suppliers? Inquiring minds...!!! I always wondered how much the spiraling propeller slipstream would affect ideal alignment of the gear leg fairings for minimum drag - and how to determine this experimentally. Remotely adjustable-incidence tufted gear leg fairings and remote cameras were the stuff of my pipe-dreams while my fairings were being finished, but I never got around to it. Has anyone done the work and posted results? I know my RV is kinda slow for a 160hp FP 6A, but I always wondered how much room for improvement there still was. Stormy On Mon, Jan 10, 2011 at 3:14 PM, Doug Gray <dgra1233@bigpond.net.au> wrote: > > For a clear easily understood mathematical discussion see page 27 and > Appendix A of this document: > www.dsto.defence.gov.au/publications/3442/DSTO-TR-1622.pdf > > After reading this I designed and manufactured my own gearleg fairings > with an accurate aerodynamic profile. Angled round whip antennas will > present an elliptical profile - this does reduce their drag coefficient > slightly. > > Doug Gray > RV-6 flying > > > On Mon, 2011-01-10 at 09:29 -0800, Matt Dralle wrote: > > > > This is a REALLY interesting video about drag. I had no idea... > > > > > > http://www.youtube.com/watch?v=ftq8jTQ8ANE > > > > Matt > > > > - > > Matt Dralle > > RV-8 #82880 N998RV > > http://www.mattsrv8.com - Matt's RV-8 Construction Log > > http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel > > Status: 132+ Hours TTSN - The Fun Never Stops... > > > > > > > > > > > >


    Message 6


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    Time: 04:34:38 PM PST US
    Subject: Re: Airfoil Drag Video...
    From: Doug Gray <dgra1233@bigpond.net.au>
    I used Javafoil to generate an NACA 63 airfoil plot and data points for a section that was approximately what I needed in terms of thickness ratio. I used 22% which gave me a wider fairing than most I have seen. These were used as patterns to build the parts. Javafoil also gives drag co-efficients for the shapes. Plug these values in the equations given. My guess is that the leading edge shape is critical, I cannot comment about the accuracy of Vans or other parts. Doug On Mon, 2011-01-10 at 16:16 -0500, Bill Boyd wrote: > Does the article give actual formulae or coordinates for that > streamline foil shape? So as to be able to construct one? How far > off the ideal are the commercially available fairings from Van's and > some of the aftermarket suppliers? Inquiring minds...!!! > > > > I always wondered how much the spiraling propeller slipstream would > affect ideal alignment of the gear leg fairings for minimum drag - > and how to determine this experimentally. Remotely > adjustable-incidence tufted gear leg fairings and remote cameras were > the stuff of my pipe-dreams while my fairings were being finished, but > I never got around to it. Has anyone done the work and posted > results? > > > I know my RV is kinda slow for a 160hp FP 6A, but I always wondered > how much room for improvement there still was. > > > Stormy > > > On Mon, Jan 10, 2011 at 3:14 PM, Doug Gray <dgra1233@bigpond.net.au> > wrote: > > <dgra1233@bigpond.net.au> > > For a clear easily understood mathematical discussion see page > 27 and > Appendix A of this document: > www.dsto.defence.gov.au/publications/3442/DSTO-TR-1622.pdf > > After reading this I designed and manufactured my own gearleg > fairings > with an accurate aerodynamic profile. Angled round whip > antennas will > present an elliptical profile - this does reduce their drag > coefficient > slightly. > > Doug Gray > RV-6 flying > > > > > On Mon, 2011-01-10 at 09:29 -0800, Matt Dralle wrote: > <dralle@matronics.com> > > > > This is a REALLY interesting video about drag. I had no > idea... > > > > > > http://www.youtube.com/watch?v=ftq8jTQ8ANE > > > > Matt > > > > - > > Matt Dralle > > RV-8 #82880 N998RV > > http://www.mattsrv8.com - Matt's RV-8 Construction Log > > http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube > Channel > > Status: 132+ Hours TTSN - The Fun Never Stops... > > > > > > > > > > > > > ========== > get="_blank">http://www.matronics.com/Navigator?RV-List > ========== > http://forums.matronics.com > ========== > le, List Admin. > ="_blank">http://www.matronics.com/contribution > ========== > > > > > > > > > > >




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