Adam I have done it on the wing tip of a large military aircraft.
Wing loading is only a problem if you have a particular issue that is wing loading related. In essence what are you looking for? Is it Reynolds Number related or is it Angle of Attack related? Or both? Wool lengths need to be visible to the camera or observer. For my project we had a PC-9 as a chase plane with a photographer and video camera in the back seat. So we had really big tufts. For your purpose, quite fine wool may work depending on how you plan to record the results. You do not want the tufts to overlap. Typical patterns have the end of each tuft, a small gap and then the start of the tape adhering the next tuft. Lateral spacing is the same. Wool thickness will depend on what speed you are operating at. Also will depend on how visible you want it. I used the thickest wool we could find in order to be visible to the camera. Also we were operating at much higher speeds than your average glider. You will not need to be that thick. Some simple experimenting with a range of wool sizes stuck to the wing root may give you an answer. How many tufts will depend on the length of the wool tuft. For my project, we adopted a diamond pattern. This aligned really well with some features on the wingtip that we wanted to study. The size of the diamond was dictated by the length of the tuft and the features on the wingtip. A square pattern may work better for your problem. Installation: You need to tie a knot in both ends of the wool tuft. The knot under the tape helps to hold the tuft in place. The knot in the free end stops the wool unravelling. A simple knot will do. Don't get carried away or the mass of the knot will affect the results. A dob of super glue on the free end may also work just as well. We used triangular pieces of fabric reinforced tape (instant airframe) to secure each tuft in place. We had the point of the triangle faving forwards. Wing gap tape with a good adhesive may suit you better. Some experimentation may be required. However if you start off with typical yaw string lengths you will not be far long. You can also space them out a bit initially (say at twice the tuft length) and then increase the density as you need to and where you need it. There appear to be plenty of photos if you google 'flow visualization tuft'. Anthony -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Adam Woolley Sent: Monday, 9 March 2015 6:32 PM To: Discussion of issues relating to Soaring in Australia. Subject: [Aus-soaring] Wool tuft testing G'day all, Has anyone got any experience or thoughts on wool tuft testing a wing root? Does wing loading matter? What wool lengths & thickness is best? How many? What pattern? Cheers, WPP _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
