G'day Anthony, Thanks for your detailed reply, lots to think about & plan for. I'm going to wool tuft test the wing root of my Ventus, as I want to improve on the lamina flow & induced drag in that area, which ultimately will help with climbing & handling.
Once I discover the separation points, I plan to 'fix it'.. Guessing I'll need to view the tufts at thermalling speeds/bank, & at my usual cruise speeds. Cheers, WPP > On 9 Mar 2015, at 18:38, Anthony Smith <[email protected]> wrote: > > 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 > _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
