kc Posted March 10, 2023 Share Posted March 10, 2023 I think the aileron is cut out by cutting the TE at final stage. My drawing of a completely different wing shows the method Phil Kent uses - LE sheeting is fitted OVER the false LE (blue) and later actual LE cap( black) is fitted and shaped after. 1 Quote Link to comment Share on other sites More sharing options...
kc Posted March 10, 2023 Share Posted March 10, 2023 Lower trailing edge seems to be 1/16th balsa, then another sanded to triangle section finally top TE sheet. All as the section at AA 1 Quote Link to comment Share on other sites More sharing options...
kc Posted March 11, 2023 Share Posted March 11, 2023 (edited) 4 hours ago, kc said: another sanded to triangle section The 3/8 by 7/16 cap ( caps the ends of the ribs to form TE middle section ) would seem to be this triangle section which goes onto the lower TE 1/16 sheet and then has another 1/16 sheet on top. This would allow the ribs to be glued to the lower 1/16 TE, also to the 3/8 by 7/16 and the top 1/16. Allows plenty of glue area. To shape this 3/8 by 7/16 balsa I would get a full width sheet of 3/8 and plane & sand the edge to shape. Cut to 7/16 width after shaping. Starting with a full width sheet means you can hold the sheet without cutting your fingers! You could also fix the balsa to a piece of softwood ( or preferably melamine coated chipboard like Contiplas ) for shaping using about 4 pieces of double sided sellotape about 1/2 inch long. Longer than 1/2 will be difficult to remove balsa from softwood base afterwards! Edited March 11, 2023 by kc 1 Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted March 12, 2023 Author Share Posted March 12, 2023 Thanks for all this, am I barking up the wrong tree or could this triangular capping be 3/8 x 1/16? Assuming this it what its referring to? I feel really thick! lol # Quote Link to comment Share on other sites More sharing options...
kc Posted March 12, 2023 Share Posted March 12, 2023 (edited) If you have the full size plan you can see if it's the right size for that or not. Actually I now suspect its the bit on the aileron front in your drawing - the part that is rounded. You need wood shaped for both those parts and they can be produced in the way I suggested if you cannot buy the size needed. Edited March 12, 2023 by kc 1 Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted March 12, 2023 Author Share Posted March 12, 2023 Thanks, I just need to stop over thinking and get on with it. Quote Link to comment Share on other sites More sharing options...
kc Posted March 12, 2023 Share Posted March 12, 2023 Thinking is good! It's much easier to shape balsa on the bench than try to cut large amounts off when already affixed to wing. Avoids loosening the joints in the wing and it's just easier. Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 15, 2023 Author Share Posted August 15, 2023 Just thought I'd update this with a picture......and ask a question! I'm finally getting around to bringing this model together and one part I'm not sure on is the jury struts. On a model this size (1/6 ish) are they necesary? The wings, although not finished, don't fill me with confidence strength wise. Without wishing to upset the purists, I'm not fussed about scale appearance and only want to add them A) if there is a simple way and B) If they add value strength wise. If it helps the main strusts are 18 swg and balsa clad with flattened tube brass ends. Opinions please? Getting there..... Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted August 15, 2023 Share Posted August 15, 2023 They'll without doubt add strength FS, but having owned numerous Cubs, I would say yes devise a quick rig system if you can, pain in the rear dealing with small screws/bolts. 1 Quote Link to comment Share on other sites More sharing options...
kc Posted August 16, 2023 Share Posted August 16, 2023 Did you build it as a one piece wing? I cannot see anything that joins the 2 wing spars across the fuselage. Is that just incomplete? Normally I would expect to see either alloy wing joiner tubes with piano wire inserts - or the spars to meet in fuselage centre and ply joiners to go right across as well. Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 16, 2023 Author Share Posted August 16, 2023 8 minutes ago, kc said: Did you build it as a one piece wing? I cannot see anything that joins the 2 wing spars across the fuselage. Is that just incomplete? Normally I would expect to see either alloy wing joiner tubes with piano wire inserts - or the spars to meet in fuselage centre and ply joiners to go right across as well. Its a two piece wing, each wing has two 16swg 'dowels' with corresponding brass tube in the centre section (short sections at present). The fixing is a 6mm nylon bolt on to threaded plywood. Pretty sure it's all to plan but I'm not too comfortable with the strength but assume this will improve greatly once the struts are fixed in place? Quote Link to comment Share on other sites More sharing options...
RottenRow Posted August 16, 2023 Share Posted August 16, 2023 7 minutes ago, Flying Squirrel said: (short sections at present) Why did you make them short sections? The plan shows these brass tubes running all of the way across the fuselage. As KC suggests these tubes will in effect be a continuation of the wing spars. Well almost anyway. The 16 SWG wire 'dowels' are shown long and would meet in the middle of each of the tubes. To answer your question, I would definitely fit the jury struts, they not only stiffen up the wing and main strut assembly but also a Cub doesn't look right without them. Small brass tubes sewn and glued to the ply plates in the wings are all that would be required to fit them, the ends of the jury struts would be bent so that they slot into these tubes. Depending on your transport and storage space, you might not even need to remove then when removing the wings from the model. Brian. Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 16, 2023 Author Share Posted August 16, 2023 The short sections are just temporary and will be replaced, I thought it would help get things lined up. I will fit the jury struts then. I understand your fixing method to the wing but how to fix them to the 18SWG main struts, I guess it needs to be 'rigid' if the top section is push fit? Sorry, still new at this building game. Quote Link to comment Share on other sites More sharing options...
kc Posted August 16, 2023 Share Posted August 16, 2023 If it's built to the plan it should be OK - I see the plan shows a bit of sheeting on the 2 inner ribs that is not yet on your model. That will help with covering the wing as well as making it more rigid. Finish the wing to the plan and see if it seems strong enough when the struts are fitted - if in doubt ask again before covering. Of course the type of covering will also affect the stiffness of wing. Probably Phil Kent used Solartex - do you have some for your model? Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 16, 2023 Author Share Posted August 16, 2023 1 hour ago, kc said: If it's built to the plan it should be OK - I see the plan shows a bit of sheeting on the 2 inner ribs that is not yet on your model. That will help with covering the wing as well as making it more rigid. Finish the wing to the plan and see if it seems strong enough when the struts are fitted - if in doubt ask again before covering. Of course the type of covering will also affect the stiffness of wing. Probably Phil Kent used Solartex - do you have some for your model? Thanks, I'll get the next few bits done and see what it's like. I'm using the ripmax covering on this one. Quote Link to comment Share on other sites More sharing options...
RottenRow Posted August 16, 2023 Share Posted August 16, 2023 I have just taken some photos of the jury struts on my (now sadly broken) Cub, see below. The jury struts are fitted to the wing through brass tubes (these are screwed to the wing but could be sewn and glued), if the ends weren't bent over they would be easily removable if required. Similar fittings are used where they attach to the main struts, though on my model these are made from hardwood (not piano wire) so you would need to adapt to suit. You will see that the jury struts are made from a single length of piano wire and are permanently (but flexibly) fixed to the main struts. If the fixings to the wing were made removable the main struts and jury struts would both fold flat against the wing undersurface for storage. Brian. 1 Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 17, 2023 Author Share Posted August 17, 2023 Thanks, that's very helpful as I was imagining a much more complex affair. Quote Link to comment Share on other sites More sharing options...
kc Posted August 17, 2023 Share Posted August 17, 2023 Brians strut fixing looks good but maybe a piece of thin piano wire could be used as a spring clip to retain instead of bolts. Looking at the plan I wonder why the wing riblets project further than the sheeting but don't connect with anything. Strange? Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 17, 2023 Author Share Posted August 17, 2023 47 minutes ago, kc said: Brians strut fixing looks good but maybe a piece of thin piano wire could be used as a spring clip to retain instead of bolts. Looking at the plan I wonder why the wing riblets project further than the sheeting but don't connect with anything. Strange? Yeah I'm not sure about the riblets, I actually broke a couple during the build but as they were beyond the sheeting I didn't worry too much. I Need to figure out a way to fix the Jury struts to the 18swg wire as it's only balsa clad, perhaps some form of brass 'tab'? Quote Link to comment Share on other sites More sharing options...
kc Posted August 17, 2023 Share Posted August 17, 2023 Yes probably some sort of tab - tinplate ( proper tinplate not modern alloy or coated stuff) or brass. If free to rotate the struts can be stored flat. Looking at your model and the plans it looks very light construction. Very little sheeting shown on the plan. That's good for weight but make sure the wing and fuselage are stiff enough. Film covering does not add as much to the structure as Solartex does. Maybe a few diagonals on the fuselage might be needed. I wonder if you might encounter problems with the wing mounting tubes? Unless everything is dead square it may be difficult to fit both sides in the same tube. If so fit separate tubes for each wing half - it's more important both wings are aligned properly for flight. The tubes from either side must be firmly fixed to each other and both fuselage sides even if they are separate. Balsa cross pieces might be needed to brace the tube halves. Make the struts and trial fit the wing before covering. If it does not seem strong and stiff enough to resist twisting when the struts and jury struts are fitted then maybe ask for ideas on stiffening the structure. A few extra bits to stiffen could easily be fitted BEFORE covering. My guess is that where the spars go thro the ribs might be a little loose and therefore a few tiny 1/8 sq balsa bits cyanoed on might improve a lot with minimal weight. Better than blobs of epoxy! Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 17, 2023 Author Share Posted August 17, 2023 I did use separate sections of tube in the centre as I thought I'd struggle lining things up but I can pass piano wire straight through easily, go figure. It does feel a little 'flimsy' but as I don't have a target weight I've been reluctant to add too much away from the plan. I think once I've progressed a little further I'll put some more detailed pictures up and seek opinions. Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted August 31, 2023 Author Share Posted August 31, 2023 OK, so main struts, jury struts and some diagonal bracing added and she feels much more robust. However, there's no target weight that I can see and she's coming in at 1500g - do you think the planned Saito 40FA will be enough? PS weight includes 4 cell nicad, empty tank, servos, engine prop but obviously not the covering or some control surfaces/cables Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted August 31, 2023 Share Posted August 31, 2023 24 minutes ago, Flying Squirrel said: do you think the planned Saito 40FA will be enough? More than enough Ideal motor for the model Power to spare, the 40 could fly a 5lb model 1 Quote Link to comment Share on other sites More sharing options...
RottenRow Posted August 31, 2023 Share Posted August 31, 2023 My similar-sized Cub weighed around 2.5kg in flying condition, and was more than amply powered by an SC 52 four-stroke. Allowing for your covering material, a few more bits and bobs and perhaps some balance weight yours should be well under that weight. Therefore a 40 four stroke would be ideal. The Cub (full-size) is not an over-powered plane. Brian. 1 Quote Link to comment Share on other sites More sharing options...
kc Posted August 31, 2023 Share Posted August 31, 2023 It's coming along very well! At 3.3 pounds with the Saito but without covering it's well on target for weight I reckon. However if the covering adds a lot of weight at the tail you might find a big chunk of lead is needed to get CG right. So care to avoid weight build up at the tail end should help. Yes the Saito 40 seems OK especially as Denis and Brian consider it fine. Fuel proofing will add some weight of course. 1 Quote Link to comment Share on other sites More sharing options...
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