---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Sun 10/14/12: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:19 AM - Re: Re: wing strut flutter (Jack B. Hart) ________________________________ Message 1 _____________________________________ Time: 07:19:29 AM PST US From: "Jack B. Hart" Subject: Re: Kolb-List: Re: wing strut flutter At 02:27 AM 10/11/12 -0700, you wrote: > > >> is there an inexpensive fix for this > > >My curiosity gets the better of me ;-) I am just wondering if a length of chord wrapped in a helical manner around the strut might stop the vibrations. It would definitely be the most inexpensive fix I would think. >Similar effect to the strakes on chimney stacks. See the nylon chord on the pole of the weather station about half way down this page; http://www.tigranetworks.co.uk/blogs/tigranetworks/preventing-vortex-sheddin g-with-a-helical-strake/ > David, A cord spiral wound around a round strut will reduce the drag and lessen the tendency to produce von Karmann vortices that cause the strut to strum. What you are doing is tripping the boundary layer, which moves the flow separation further back behind the strut and this reduces the drag. Spiral cord wrapping with a high pitch angle is much like the smoke stack which has to withstand wind loads from all directions. But with a wing strut one has to worry about only one direction, and so the tripping can be accomplished by placing or gluing a wire to the top and bottom sides of the strut. If you would like to see some better explanation of this check out page 20 on of: http://www.bakker.org/dartmouth06/engs150/11-bl.pdf The struts on my FireFly strummed, and I streamlined my struts and the noise disappeared. How it was done can be seen at: http://jackbhart.com/firefly/firefly91.html Jack B. Hart FF004 Winchester, IN ------------------------------------------------------------------------------------- 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.