Mike, a very nice and relevant image!
Adam, Re the Ventus, I wonder what information the factory might have on file???? (And will they make it available to you???) Does the factory know of anybody who has already gone down the route you are proposing? Adam, have you asked them these questions? If not, maybe you should consider an approach to the factory through Maddog .... if Mike is willing to cooperate. I suggest that this is worth at least a phone call or two. I know that the wing root to fuselage junction problem was bad for Libelles and Hornets, and now of course you can now buy retrofit fairings for the Libelle, which DO make a significant performance difference, as one would expect. >From memory, the wing to fuselage junction was something that was given great attention in the design of the Concordia - was it something like 7 or 8 different profiles over a distance of 500 mm or so? As always, it is much better to polish the pilot, rather than the glider, but of course to be able to do both is a real bonus. Dick Johnston did quite a bit of testing of gliders over the years. What he measured was sometimes quite subtle, and required some quite sophisticated (and no doubt expensive), equipment ... and always not enough high tows at dawn! How are you going to measure the effect of any change you make? Here is one thought for you that might be worth following up on: Can you get your hands on the test equipment that Dick used, if it has not already been sent to landfill? Have you done any costing for your proposed project? What is your time frame? You might find that is much more economic just to go out and buy something like an ASG29, which quite possibly will give you more bang for your buck. I look forward to an update if you decide to proceed. Maybe an article in the mag. too? Good luck. Gary From: aus-soaring-boun...@lists.internode.on.net [mailto:aus-soaring-boun...@lists.internode.on.net] On Behalf Of Mike Borgelt Sent: Tuesday, 10 March 2015 5:45 PM To: Discussion of issues relating to Soaring in Australia. Subject: Re: [Aus-soaring] Wool tuft testing Take a look at the root fairings on the P-38 http://www.gayot.com/blog/wp-content/uploads/2009/04/lockheed-p-38-lightning .jpg Note the fairing is at the leading edge. Particularly noticeable on the wing to fuselage but also on the wing to booms. No fairing or fillet at the TE. Fixed an airflow problem apparently. A more blended wing/body junction may have some merit. Mike At 01:54 PM 10/03/2015, you wrote: 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 <anthony.sm...@adelaide.on.net> 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: aus-soaring-boun...@lists.internode.on.net > [ <mailto:aus-soaring-boun...@lists.internode.on.net> mailto:aus-soaring-boun...@lists.internode.on.net] 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 > Aus-soaring@lists.internode.on.net > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > > _______________________________________________ > Aus-soaring mailing list > Aus-soaring@lists.internode.on.net > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring > _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring Borgelt Instruments - design & manufacture of quality soaring instrumentation since 1978 www.borgeltinstruments.com <http://www.borgeltinstruments.com/> tel: 07 4635 5784 overseas: int+61-7-4635 5784 mob: 042835 5784 : int+61-42835 5784 P O Box 4607, Toowoomba East, QLD 4350, Australia
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