Parkspeed Posted June 25, 2015 Share Posted June 25, 2015 Greetings all, I'm a new member. I am relatively new to flying large mouldy models. I went out to fly my ASW27 4m but I accidentally left my winglets at home, so I decided to fly without them. During a medium speed pass both wing tips fluttered severely, but after pulling up hard the flutter disappeared. Is this due to the winglets not being fitted? I've heard mixed comments whether winglets actually work on gliders. Can any of you shed any light? Many thanksParkspeed Link to comment Share on other sites More sharing options...
Phil.Taylor Posted June 25, 2015 Share Posted June 25, 2015 (edited) Flutter is telling you that you are flying too fast ! - with or without winglets - you've hit VNE "Velocity Never Exceed"Flutter is a combination of aerodynamic forces, mechanical stiffness & weight. Obvious question is whether you get similar flutter at a similar speed with the winglets on - but difficult to reproduce the exact same speed. The winglets will change the aerodynamics at the tip, they will also change the weight at the tip - so they may affect flutter characteristics.So - remember the winglets next time, and if you still get flutter, slow down a bit ! If you have a big need-for-speed - fly an F3F plane or DS plane instead Phil. Edited June 25, 2015 by Phil.Taylor 2 Link to comment Share on other sites More sharing options...
Parkspeed Posted June 25, 2015 Author Share Posted June 25, 2015 Phil, many thanks, perhaps the size of the model makes the speed deceptive, it didn't look relatively quick! Ive been flying my Typoon too much I'll try agin with the winglets, I'm not needing my pipe and slippers just yet, I'll try and master some scale flying Cheers Simon Link to comment Share on other sites More sharing options...
swarrans Posted June 25, 2015 Share Posted June 25, 2015 Almost on topic can I ask what ASW27 it is? I've just got a lovely old Purbeck 4m one and it is quite speedy but I wouldn't push its covered foam wings as much as a fully moulded one from Paritech! Simon Link to comment Share on other sites More sharing options...
MooSe Posted June 25, 2015 Share Posted June 25, 2015 (edited) What sort of linkages do you have fitted and how much slop? If you manually waggle an aileron is the much perceivable movement? Sloppy linkages and long servo arms will give you flutter. Edited June 25, 2015 by MooSe Link to comment Share on other sites More sharing options...
Parkspeed Posted June 25, 2015 Author Share Posted June 25, 2015 Simon, spot on, PURBECK SAILPLANES! I've just dug old paper work I got with it, I bought it second hand, I'm guessing it's 10 years old plus? Covered foam wings, the linkages are nice and tight, I think it flies lovely the only downside is the cracked canopy in various places ( Cannot find a replacement ) correct me if I'm wrong is it a high performance glider so to speak? I do throw it around a lot! Perhaps I shouldn't though considering its age.Cheers Simon Link to comment Share on other sites More sharing options...
simon_t Posted June 25, 2015 Share Posted June 25, 2015 The winglets will certainly reduce the rotating tip vortices, which can excite flutter in a model, as they will provide a bit of damping, but that may just extend the speed range slightly. Have you tried: http://www.sarik-vacform.com for a canopy. They have a lot of scale glider canopy plugs and it won't cost an arm and a leg!Simon Link to comment Share on other sites More sharing options...
swarrans Posted June 26, 2015 Share Posted June 26, 2015 (edited) Simon, spot on, PURBECK SAILPLANES! I've just dug old paper work I got with it, I bought it second hand, I'm guessing it's 10 years old plus? Covered foam wings, the linkages are nice and tight, I think it flies lovely the only downside is the cracked canopy in various places ( Cannot find a replacement ) correct me if I'm wrong is it a high performance glider so to speak? I do throw it around a lot! Perhaps I shouldn't though considering its age.Cheers Simon The Purbeck model is definitely high performance Simon and you can throw it around with abandon - I just meant that the wings designed and built in 1997 (yipes 18 years!) will have their limits but it is a superbly constructed model with good wing spars and reinforcements. I've had mine zooming around without any flutter but if you statically twist the wing at the tip you can tell that in comparison to a fully moulded modern wing there is a lot more flex.Simon's right (bit of a Simon-fest here!) I'm pretty sure Sarik do the canopies and it is such a great model it deserves to look its best. Don't sell it! (or if you do sell it please let me know as we have a waiting list for them locally!) Simon Edited June 26, 2015 by swarrans Link to comment Share on other sites More sharing options...
SimonWS Posted June 26, 2015 Share Posted June 26, 2015 Always interested in your opinion Pete!Interestingly though I maidened mine in very weak lift and it coped really well - it does respond well to a little camber flap. In comparison to some of my other monsters it seems incredibly light and I am considering ballast for higher wind speeds.As a comparison, I plan to fly my 25 Kg ASG29 today and nearly everything feels light after that! Si Link to comment Share on other sites More sharing options...
wookman Posted June 26, 2015 Share Posted June 26, 2015 If you go on the scale soaring forum you will find Terry White, ie Mr Purbeck Sailplanes. I am sure he would be only too willing to tell you how far you can push the 27. Link to comment Share on other sites More sharing options...
Parkspeed Posted June 26, 2015 Author Share Posted June 26, 2015 Gents, thanks very much for your input, there's a wealth of knowledge out there, I've contacted Sarik regarding my canopy the plan is coming together! I'm thinking of another purchase between the 27 and the Typoon, any suggestions? Also I've yet to try other slopes, Ivinghoe Beacon is my local one only 15 mins from home I've heard there are some monster lift slopes else where not far. Thanks again Simon Link to comment Share on other sites More sharing options...
wookman Posted June 26, 2015 Share Posted June 26, 2015 Get yourself an F3f machine. Get one with a high carbon content. It doesn't matter much what sort of vintage. My Pike WR Extreme (Ex Kevin Knewton from the 2000 Viking Race) is still an awesome machine, and if its blowy enough to stick a kilo of lead in it, look out! Link to comment Share on other sites More sharing options...
isoaritfirst Posted June 29, 2015 Share Posted June 29, 2015 I've had a few Purbeck 27's and currently have a very nice very early one with a chopped matt fuselage.Regarding flutter, the first one I built tried to keep scale and made the linkages to the top skin of the surfaces. I was young and inexperienced!. The result was very short horn lengths and the model would flutter if pushed hard. I eventually changed it to simple under the wing push rods to bottom mounted horns. Much better.The original build instructions suggested hooning out the polystyrene core of the trailing edge of the wing and the leading edge of the surfaces and backfilling with epoxy. The problem with doing this was tha tthe epoxy hardened the hinge material, and put a lot of extra strain on the servos and could cause the hinge to rip later.So the second one I built instead of using epoxy I closed off the surfaces with balsa. Much better. Most others that I have seen and the one I fly now, which I didn't build still have the polystyrene edges, just filmed over. It works ok but the surfaces ar prone to more twist and flutter if pushed hard.I'm sure that if you want to race around with the 27 you would be able to remake the linkages and posibly the surface edges to add significant stiffnes and stop the flutter.Pushrod lengths from the aileron servos are also quite long and would be better made of stronger material or stresses reduced by increasing servo and aileron horn lengths significantly.But then you will bend the wing joiner! Link to comment Share on other sites More sharing options...
Woodstock Posted June 29, 2015 Share Posted June 29, 2015 Get yourself an F3f machine. Get one with a high carbon content. It doesn't matter much what sort of vintage. My Pike WR Extreme (Ex Kevin Knewton from the 2000 Viking Race) is still an awesome machine, and if its blowy enough to stick a kilo of lead in it, look out!OT, but this post gelled immediately with thoughts I was having about how interesting it is to note national differences in tastes in gliders. I was viewing some photos from both a recent Italian International gliding event at Monte Cucco (http://www.radunomontecucco.it/index.php?lang=en) , as well as a French event at Menez Hom. At both F3b/f models were conspicuous in their scarcity, if not complete absence. If these had been events in the UK, I bet there would be lots of V-tailed 3 m gliders present…. Link to comment Share on other sites More sharing options...
chiloschista Posted June 29, 2015 Share Posted June 29, 2015 OT, but this post gelled immediately with thoughts I was having about how interesting it is to note national differences in tastes in gliders. I was viewing some photos from both a recent Italian International gliding event at Monte Cucco (http://www.radunomontecucco.it/index.php?lang=en) , as well as a French event at Menez Hom. At both F3b/f models were conspicuous in their scarcity, if not complete absence. If these had been events in the UK, I bet there would be lots of V-tailed 3 m gliders present…. I'm thinking that wise also. Personally I don't think I will never buy an F3F glider. About flutter, I only experienced it with a mouldy: the VectorIII, but that's a long story about turbulent lift and servos. Link to comment Share on other sites More sharing options...
isoaritfirst Posted June 29, 2015 Share Posted June 29, 2015 Having flown on a few alpine slopes with F3f machines I know why these guys don't choose to fly them.High altitudes and big vistas that often demand flying some distance away don't lend themselves to exciting compresion style F3f flying.Skinny wings and fuselages don't lend themselves to flying at any distance.The sight of a nice big glass ship infront of an ice capped mountain and grassy meadows is very appealing. Model choice is slope specific.Go to Rugen in North Germany and I would be suprised if you see any 6mtr scalies flying around.. 1 Link to comment Share on other sites More sharing options...
Andysoarer Posted February 2, 2022 Share Posted February 2, 2022 I know this post is already seven years old but I am hoping somebody will know where I can either buy winglets for the Purbeck Sailplanes ASW27 or have drawings so that I could maybe make a pair? I purchased mine last evening and there are no winglets with it. Thanks in advance Link to comment Share on other sites More sharing options...
wookman Posted February 2, 2022 Share Posted February 2, 2022 You will not buy any, Purbeck stopped trading ages ago, but you might get hold of Terry White on the Scale Soaring forum. He may be able to help. Link to comment Share on other sites More sharing options...
Stefan Bertschi Posted February 12, 2022 Share Posted February 12, 2022 On 29/06/2015 at 14:48, isoaritfirst said: Having flown on a few alpine slopes with F3f machines I know why these guys don't choose to fly them. High altitudes and big vistas that often demand flying some distance away don't lend themselves to exciting compresion style F3f flying. Skinny wings and fuselages don't lend themselves to flying at any distance. The sight of a nice big glass ship infront of an ice capped mountain and grassy meadows is very appealing. Model choice is slope specific. Go to Rugen in North Germany and I would be suprised if you see any 6mtr scalies flying around.. There is nothing more thrilling, than trying to hook a thermal 500m below you with a F3F Model (not). Link to comment Share on other sites More sharing options...
oipigface Posted February 12, 2022 Share Posted February 12, 2022 On 02/02/2022 at 20:56, wookman said: You will not buy any, Purbeck stopped trading ages ago, but you might get hold of Terry White on the Scale Soaring forum. He may be able to help. Why not try something old school and build your own? Link to comment Share on other sites More sharing options...
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