Phil 9 Posted August 19, 2015 Share Posted August 19, 2015 most older plans show a wing construction that produces a one piece wing. It would be very useful if they could be built to split supported with a wing tube like most ARTF's. is there a rule of thumb of how far into the wing a tube needs to go and how many ribs it will need to go through Quote Link to comment Share on other sites More sharing options...
iqon Posted August 19, 2015 Share Posted August 19, 2015 I have only made the one ( but broke loads )- goes through 3 and stops before the 4th........ Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted August 19, 2015 Share Posted August 19, 2015 From my experience two is enough if the ribs concerned are thin ply or reinforced with a ply doubler where the tube goes through the ribs. This is to stop the tube crushing the balsa ribs as all the bending load is transferred from the tube to the rib. But I concur with iqon, three is better. The diameter of the tube is a factor too, bigger is generally better. Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted August 19, 2015 Author Share Posted August 19, 2015 I have some 1/2 inch aluminium tube from slec in the shed and I would say it would be strong enough for any model I would build (upto 1.20 size models) I don't see it being any less strong than a ply brace but most artf have a much larger diameter than this Quote Link to comment Share on other sites More sharing options...
Adrian Smith 1 Posted August 19, 2015 Share Posted August 19, 2015 If ever you need lightweight carbon fibre wing tubes www.easycomposites.co.uk do them. I can recommend them as I bought some CF tube to replace the metal one provided in my Weston Capiche 140 was too tight and was a pain to remove. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 19, 2015 Share Posted August 19, 2015 I've done two conversions and used a tube length of around 30% of the span. I've bent 20mm tubes on 60 powered models, so my King Altair has something like a 25mm tube and the 40cc petrol powered Thunderbird is getting a 31mm one. I've used liteply half rib doublers on those ribs that the tube passes through to tie it to the spars, with full section 1/16" ply facing ribs at the join. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted August 19, 2015 Share Posted August 19, 2015 The approaches adopted by modellers is quite interesting. It does go to show there is no one way that works, and others that do not. Perhaps looking at some contemporary glass high performance models demonstrates how short the beam actually can be. Some are not more than 3" long on semi spans that are well over 50". many of these will take a full on winch launch. If you go back in time to the 70s you will find wings with similarly short wing joiners. So what matters? It is apparent that the stresses must be distributed into the either the wing monocoupe, or in the old days into the spars. Also of great importance is the jointing tube/bar. It needs to be strong enough in itself to take the loads, particularly at the intersection of the wing to body. In the old days on highly stressed wings, extruded brass box section, with a drawn high tensile steel blade, would often be used. The major issue was the depth to width ratio was high. If not completely constrained, a twisting force could cause kinking. So in my opinion, today a nice square CF bar works very well, can be very short, as long as the forces are distributed into the wing structure well. The use of some ply wing ribs can be helpful in the effective transfer of forces. Dependant on the design, the body can also see some crushing/compression forces into the body, if some consideration is not taken to what forces the body in this region could experience. It is easy to get carried away in how difficult wing dowel design and construction can be. Yet a look at a book such as the George Stringwell "Thermal Gliding" shows how simple in reality the task is, even with a big glider. Quote Link to comment Share on other sites More sharing options...
Geoff Peacock Posted February 22, 2018 Share Posted February 22, 2018 I'm modifying an old plan for a 48" Sopwith Scooter monoplane (changing it from single wing to split wing - and adding ailerons) and although reasonably happy with the info above, I'm not sure about securing the wings to the centre section I'm re-designing? Has anyone had experience of DB Sport & Scale's Wing Retaining Clips? I'm familiar with how they work, but not actually seen them in action. The wings will be supported by working flying and landing wires (I hope). Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted February 22, 2018 Share Posted February 22, 2018 Geoff, I have done this split wing set up with a small Taylorcraft Leaving the wing centre section as built in with the canopy, and wing tube Each wing is located and held by nylon bolt accessed inside the cabin Edited By Denis Watkins on 22/02/2018 16:03:24 Quote Link to comment Share on other sites More sharing options...
Steven S Posted February 22, 2018 Share Posted February 22, 2018 Geoff - I'm not familiar with the DB Sport & Scale clips but this is how I retain the 3 pieces wings on my Flugboot. I used a shorter bolt in the completed plane Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 22, 2018 Share Posted February 22, 2018 Posted by Geoff Peacock on 22/02/2018 15:47:16: I'm modifying an old plan for a 48" Sopwith Scooter monoplane (changing it from single wing to split wing - and adding ailerons) and although reasonably happy with the info above, I'm not sure about securing the wings to the centre section I'm re-designing? Has anyone had experience of DB Sport & Scale's Wing Retaining Clips? I'm familiar with how they work, but not actually seen them in action. The wings will be supported by working flying and landing wires (I hope). These things are the working end of a mastic gun. Same principle, and they work. Proviso, the diameter of the wire the gripper grips on, is critical. I believe the previous owner d DB Sorts and Scale used to reject about 50 % of his x gauge SWG wire, as it was not quite the right size between gripping and slipping. Quote Link to comment Share on other sites More sharing options...
Flyer Posted February 22, 2018 Share Posted February 22, 2018 Posted by Geoff Peacock on 22/02/2018 15:47:16: I'm modifying an old plan for a 48" Sopwith Scooter monoplane (changing it from single wing to split wing - and adding ailerons) and although reasonably happy with the info above, I'm not sure about securing the wings to the centre section I'm re-designing? Has anyone had experience of DB Sport & Scale's Wing Retaining Clips? I'm familiar with how they work, but not actually seen them in action. The wings will be supported by working flying and landing wires (I hope). They will be fine Geoff. They work well on much larger aircraft, so for your 48inch it will be no problem. The guy who designed them is quite an engineer, and they are well over engineered for what you need. I expect the wings would fail before the retainers. Ade Quote Link to comment Share on other sites More sharing options...
Don Fry Posted February 22, 2018 Share Posted February 22, 2018 Wing tubes, replace dihedral braces. I have never seen a brace go through more than four ribs. Including the centre rib. Someone will name one with more. Quote Link to comment Share on other sites More sharing options...
John Stainforth Posted February 22, 2018 Share Posted February 22, 2018 Don, OK, I am naming one with more. For my 1/5th scale S6b I am using an 7/8" x 850 mm F3a Unlimited Gator carbon fibre tube and sleeve that passes through 9 ribs in each wing panel and 2 ribs in each wing root: And there is also a small, much shorter rear wing tube. I don't see wing tubes as dead weights that have to be minimised. The tubes are superb (strong and light) spars that add considerably to the strength of the wings. So even if my design is overkill (which it probably is) I don't think the long wing tube is in anyway detrimental (except its cost!) Quote Link to comment Share on other sites More sharing options...
Phil 9 Posted February 23, 2018 Author Share Posted February 23, 2018 If the wing has dihedral then that will limit the length of tube you can use before it will protrude from the top of the wing. With the danger being it may end up too short to be strong enough. A flat wing will allow a full width gube if you really wanted Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted February 23, 2018 Share Posted February 23, 2018 If the wing was originally designed as a one-piece, there's presumably enough strength in the main spar to stop it from folding. The length of wing joiner you need is therefore basically determined by the strength of the inner and outer tubes (so that one won't punch through the other), how tight the inner tube is in the outer one (to avoid slop), and what length you need to accomodate the retaining screw. The outer tube, of course, needs to be firmly attached to the main spar, in which case the strength of the ribs in that location is probably of little importance. Quote Link to comment Share on other sites More sharing options...
Geoff Peacock Posted February 25, 2018 Share Posted February 25, 2018 Posted by Phil 9 on 23/02/2018 05:42:32: If the wing has dihedral then that will limit the length of tube you can use before it will protrude from the top of the wing. With the danger being it may end up too short to be strong enough. A flat wing will allow a full width gube if you really wanted The Scooter's wing has no dihedral, although I will probably add a little to the design, just to make it look like it's not drooping. Thanks to all for their input - I'm now happy to go ahead, probably with the DB S&S retaining clips, but not sure about tube sizes. No doubt I'll end up with a bit of 'overkill'! Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted February 25, 2018 Share Posted February 25, 2018 Luckily Geoff, which ever tube you choose Weight wise it sits bang on the C of G, so its weight is dispersed evenly upon the model Quote Link to comment Share on other sites More sharing options...
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