Amy flygirl Posted January 30 Share Posted January 30 Hi peps, does anyone know what aerofil the Wots wot uses? Quote Link to comment Share on other sites More sharing options...
Don Fry Posted January 30 Share Posted January 30 I think it’s a TLAR. A Foss own design generic airfoil, nice general function section, but not fast. A lot of kit buyers take root and tip sections onto paper, I know I do, but I’ve never built a Wots Wot. Quote Link to comment Share on other sites More sharing options...
i12fly Posted February 9 Share Posted February 9 On 30/01/2024 at 19:13, Amy flygirl said: Hi peps, does anyone know what aerofil the Wots wot uses? Hi, have you managed to find the info you need? If not, if it helps I've got the artf version. The top wing separates at the middle so I could draw round it, scan it and email this to you with dimensions. The tip is more tricky as it is angled but I could measure all the relevant dimensions. If this helps pm me with an email and I'll send the info. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted February 9 Share Posted February 9 On 30/01/2024 at 19:13, Amy flygirl said: Hi peps, does anyone know what aerofil the Wots wot uses? I'm intrigued as to why you want to know this information. Are you intending to build a new wing with a different aerofoil section? Quote Link to comment Share on other sites More sharing options...
Robin Colbourne Posted February 14 Share Posted February 14 I don;t know about the Wots Wot, but at a talk Chris Foss gave to our club many years ago, when it came to questions, he was asked which aerofoil the Wot 4 used. "Size 9 left foot" was Chris's answer, i.e. he drew it around his shoe. He then went on to elaborate a bit, adding that it had a slightly of concave section between the spar and aileron to make the aileron more effective. Quote Link to comment Share on other sites More sharing options...
Weck Posted February 14 Share Posted February 14 Chris Foss's "Size 9 left foot" anecdote is hilarious and sheds light on the pragmatic, sometimes humorous, side of aircraft design. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted February 14 Share Posted February 14 8 hours ago, Robin Colbourne said: it had a slightly of concave section between the spar and aileron to make the aileron more effective. I'd love to see Chris Foss' supporting data for this claim... Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted February 14 Share Posted February 14 It's on his size 9 left foot of course! 1 Quote Link to comment Share on other sites More sharing options...
Jim Hearnden 1 Posted February 14 Share Posted February 14 I remember a David Boddington article where someone asked about his wing sections on his designs. He said its a TLAR (That Looks About Right) and then went on to say it depended on which french curve was on his drawing board at the time. This came to pass a few years ago when someone on I think RC Groups had acquired a DB Rookie. I said I built one years ago and it flew brilliantly. Quite a few piled in and said "Ah but if it had a Doppler 123 wing section it'd fly better" I replied with given how many models DB designed, I think he knew what he was doing! Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted February 14 Share Posted February 14 2 hours ago, Jim Hearnden 1 said: I remember a David Boddington article where someone asked about his wing sections on his designs. He said its a TLAR (That Looks About Right) and then went on to say it depended on which french curve was on his drawing board at the time. This came to pass a few years ago when someone on I think RC Groups had acquired a DB Rookie. I said I built one years ago and it flew brilliantly. Quite a few piled in and said "Ah but if it had a Doppler 123 wing section it'd fly better" I replied with given how many models DB designed, I think he knew what he was doing! If it looks about right it generally is 😉 Quote Link to comment Share on other sites More sharing options...
kc Posted February 14 Share Posted February 14 I don't know if Doppler did any airfoils but I guess your group suggested Eppler rather than Doppler. Boddingtons airfoils often seem the same as Vic Smeed's airfoils which were earlier. It's funny how designers are a bit cagey about their airfoils source. Quote Link to comment Share on other sites More sharing options...
Robin Colbourne Posted February 14 Share Posted February 14 In the late 1980s the Sailplanes International 'Secret Weapon' aerobatic slope soarer was very popular. The box stated that the tip aerofoil was a NACA symmetrical section, however the root was the 'LBMD001'. After searching all sorts of aerofoil databases to find info on the root aerofoil, I finally discovered that LB and MD were the initials of the two designers. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted February 14 Share Posted February 14 That's how people designed aeroplanes before the advent of the science of aerodynamics, wind tunnel testing and, now, computational fluid dynamics or CFD. Unfortunately, you need a very powerful computer to run the CFD software as well as a highly trained aerodynamicist to set up and drive the software as well as to create the airframe in a 3D web. It's amazing what this can do for aircraft design but it's far too expensive for use on model aeroplanes - unless we can persuade a friendly prof to get one of his students to take on the task of designing the perfect aircraft for.......er - rubber power, slope soaring, thermal soaring, aerobatics etc. One of these days may be! Till then SWAG and TLAR rule. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted February 14 Share Posted February 14 I know someone who does exactly this for his experimental models. He is, of course, an aerodynamicist with the correct software. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted February 14 Share Posted February 14 I believe the glider guys are way ahead there Peter, see work by Drela and previously Selig for instance. With a power aircraft we completely swamp any differences in performance with excess power. Quote Link to comment Share on other sites More sharing options...
kc Posted February 14 Share Posted February 14 The original question can be solved by putting the outlines from i12Fly's model onto a foam blank with the angles the same as the built wing. All the angles the same of course including tip angle across and down. Allow for the veneer thickness and any centre bandage etc. With the Wot4 etc the exact airfoil does not seem to matter too much - depends a lot on how each modeller sands the leading edge. Every one must turn out a little different but they all seem to fly much the same! Very early plan Wot4's had a slightly different wing section. Various Wot4 kit versions have very different tailplane and fin shapes yet they fly just as well. ( some had Acrowot tailplane & fin shape ) Individual modellers have made their own Wot4 wings with different wingtips - some chopped off square others built as per the instructions yet they still fly just the same. Why they all fly well is a good question but it seems to me that the original design had the right proportions on everything and that blunt wing sections helps a lot. Even overweight and/or overpowered they still fly well. Quote Link to comment Share on other sites More sharing options...
Robin Colbourne Posted February 14 Share Posted February 14 (edited) 11 hours ago, Nigel R said: I'd love to see Chris Foss' supporting data for this claim... NigelR, it was probably empirical data from testing a number of different aerofoils until Chris found one giving the qualities he desired. Anyway, Sukhoi used something along the same lines for the Sukhoi Su-26, and they seemed to know what they were doing. (image from RC Groups) Edited February 14 by Robin Colbourne Quote Link to comment Share on other sites More sharing options...
Nigel R Posted February 14 Share Posted February 14 Hmm. Sukhoi, whatever flavour, will fly at Reynolds far above what a Wot 4 does, apples and orange etc. One thing Chris Foss was good at was marketing and protecting his IP. Pinch of salt etc. What did this testing consist of? What results are there? What controls were in place to ensure single changes were tested and measured? I remain unconvinced that he simply didn't draw something round a handy curve and claim it was the best thing since sliced bread... 1 Quote Link to comment Share on other sites More sharing options...
kc Posted February 15 Share Posted February 15 At the time the Wot4 was first available people reckoned it was just like the Nobler from 1950's - somewhat similar wing section. Quote Link to comment Share on other sites More sharing options...
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