Former Member Posted July 18, 2015 Share Posted July 18, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Area 51 Posted July 18, 2015 Share Posted July 18, 2015 Looking forward to this Steve, good work so far... Anything resembling the profile of the turbulent gets my attention.. Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 19, 2015 Author Share Posted July 19, 2015 More progress today. Hurry up Brian! It's the maiden next week Bulkheads from 1/4 birch ply, F1, F2 and F3. F4 was from 1.4" Liteply. There is no F4 on the larger drawing, so scanned the smaller F4 into MSWord, incresed size to 125%, Job done. Internals were cut by the Fretsaw. Waiting for Permagrit tools to arrive totidy them up. Two fuselage sides were also completed as much as I can. Quote Link to comment Share on other sites More sharing options...
cymaz Posted July 19, 2015 Share Posted July 19, 2015 Stevo Have you seen this ?? Quote Link to comment Share on other sites More sharing options...
kc Posted July 19, 2015 Share Posted July 19, 2015 A couple of things occur to me - 1. the false leading edge idea is that the front section is not covered by sheeting ( only the 1/8 dummy LE is covered) I mention this because it affects the airfoil shape quite a lot. ( forget my intrusion if you have already allowed for this! ) 2. mentioning the windscreen framing reminds me of an idea I had but never actually tried.......old umbrellas are a mass of U section metal which looks right for windshield framing and might be bendable. plenty of scrap material to get it right eventually by trial and error. I suggested this material on the forum a while back but nobody reported back that it worked or not. 3. as the spars are set back from the thickest part of airfoil they do not present a parallel face to allow the webs to glue on flat ( or if between spars webbing needs a bevelled edge) ( again I mention this now just in case, but perhaps you have worked this all out ) Edited By kc on 19/07/2015 16:39:08 Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 19, 2015 Author Share Posted July 19, 2015 Yep Cymaz.... Seen that one. It's our Percy's fault I'm building one! Keith, yes agreed and all planned for. Last thing on is the 10mm L.E afer the capping/sheeting, keeping to the original design, but larger. Ilike the ide of the umbrella spoke. My late father fashioned one as a micro gouge. Still got it and shar as ever!! Yes the ribs are back from the thickest section - I could move them forward, I'll consult the originals in a minute. No ribs cut yet. And Percy... Yes I have one of these.... Edited By Stevo on 19/07/2015 17:07:11 Edited By Stevo on 19/07/2015 17:13:35 Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 19, 2015 Author Share Posted July 19, 2015 Just looked at the originals; and yes Keith that is exactly how they are drawn - the webs not gluing to a parallel face. I'll use some gap filling glue i.e. not thin CA! Quote Link to comment Share on other sites More sharing options...
kc Posted July 19, 2015 Share Posted July 19, 2015 If the spars are not well connected to the webbing the wing will not be as strong as one with perfect glue joints ( in my opinion) Although theory suggests putting the wide part of the spars as near to the surfaces as possible, in practice putting the spars long side vertical would make it easier to be well connected to both the webbing and the LE sheeting and would make a stronger wing ( again just in my opinion ) Also if there is an undercarriage bearer then it would be better if fitted to webbing which is strongly connected to both spars. Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 20, 2015 Author Share Posted July 20, 2015 I fully concur Keith! Theories:- Move the spars forward; This would now limit the size of the sheeting strengthening the wing Carry on regardless use a Permagrit file and gently flatten the front faces of the spar once the wing is assembled, to provide a larger surface area for gluing - this would weaken the spar by reducing the overall CSA. However the CSA of the spars is double what it is on the smaller version- 1/4 x 1/2, from 1/4 x 1/4 Belt and braces; do (3) but use a balsa-hardwood-balsa laminated sandwich for the spars. Thoughts, anyone? Quote Link to comment Share on other sites More sharing options...
kc Posted July 20, 2015 Share Posted July 20, 2015 Nobody else has commented -yet! On checking the original ( smaller ) plan i notice that the spars are 1/4 by 3/8 so the increase to 1/4 by 1/2 for the larger version seems about right. ( actually the plan says 1/4 by 1/8 in one place but that seems a misprint ) Also the original used a continuous spar web of 1/8 ply - eggcrate style with notched ribs- across the centre part and also webbing on the other side of the ribs too. Does the larger one use that type of double web? I notice that the lower spar is located at an angle so that it would be flat on the board together with the ribs ( rear 2/3rds anyway ) However the wording suggests a 1/16 packing strip is used! I suggest positioning the spars with the 1/2 side vertical and both spars parallel so the web fits well. Then the 1/4 side could be located just on the 'flat' part of the airfoil to minimise angular problems. Actually I always like to use spruce instead of balsa for spars and I reckon spruce spars 1/2 side vertical and webbed nicely would be near unbreakable. I wouldn't expect the slightly smaller D box to weaken the wing at all. Edited By kc on 20/07/2015 16:53:53 Quote Link to comment Share on other sites More sharing options...
kc Posted July 20, 2015 Share Posted July 20, 2015 This is my idea of what might work ( based on a scan of the smaller plan with original spars blanked out but just visible ) This leaves the original centre section 1/8 ply web in the same place but puts the spars forward instead of aft and also shows the balsa webs in front of spars. Actually the wording says insert the centre section web ( the eggcrate bit) after ribs have been glued to spars, however to me this means any slight variation in rib spacing might prevent web fitting well so I wouldn't follow that method! Visually the airfoil section looks much blunter than Stevo's drawing due to the false LE covering the sheeting. It is this very blunt LE shape that no doubt gives the great flying qualities people reported. Edited By kc on 20/07/2015 17:17:42 Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 20, 2015 Author Share Posted July 20, 2015 KC... I think you have the idea. The wings are certainly deep enough for the 2 x1/2" spars. The larger "plan" does not detail any wing construction at all. In fact the larger plan is a set of drawings, no dimensions or constructional notes or even detail. The fuselage is represented with a side view only, and only on wing / half of the horizontal stab is shown. I like the idea of the box section, would 1/16" balsa (grain running vertically!) do for both front and rear webbing? I'll draw it out later, if the sheeting on the top is unsupported (I favour the turbulent scalloped design) for any length, I may put an extra spar perhaps 3/16" sq a little further back - but, can't tell until I've drawn it out. Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 20, 2015 Author Share Posted July 20, 2015 Like this Keith? (take it as a 'given' that the false L.E will be glued on and shaped, then the capping goes on then the L.E) This now intimates that the sheeting ends almost 1/2" shorter. Of course there's nothing to stop me puting the spars vertical as you suggest in thier original positions and then chamfering them to suit the profile.... Edited By Stevo on 20/07/2015 19:25:57 Edited By Stevo on 20/07/2015 19:28:28 Edited By Stevo on 20/07/2015 19:29:09 Quote Link to comment Share on other sites More sharing options...
kc Posted July 20, 2015 Share Posted July 20, 2015 Have you seen the smaller plan? This shows a 19.5 inch centre section full depth web from 1/8 ply one piece with dihedral and a rear 1/8 ply joiner with dihedral. These are notched into the ribs. The 19.5 one forms the rear web onto the mainspar but only extends 1/3 span. This ply part also takes the rear of the wing dowel. The front web is from 1/8 balsa vertical grain & runs full span. So the box part is only for 1/3 span, outer section has only balsa web on one side of spar My opinion is 1/8 balsa webbing would be necessary for the 72 inch version together with a 1/8 birch ply web / joiner. 1/16 balsa for webs the might buckle and fail. But it depends on the grade- as always with balsa. . The 1/8 ply web could also have the undercarriage blocks attached to it if wing mounted u/c is used. The small plan also shows 'aileron spars' which only extend along the aileron section. My view is those should also extend into the centre section and be incorporated into the wing bolt strengthening ply plate. In the latest BMFA News magazine there is a photo of a free flight model using carbon fibre formed into a lattice work on the D box section. Food for thought if you like exotic construction! Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 20, 2015 Author Share Posted July 20, 2015 Yes it would help if I rolled out the plan on the floor and actually looked at it.... Understood. 1/8 balsa webbing full span on font of spars, 1/8 birch ply dihedral brace wich forms the box section on the rear of the spar, and yes the U/C blocks will join to that. I'll may also follow your lead on the 'aileron spar', extending into centre section, I'll look at the plans later. If I followed that idea, all ribs would have to be cut to incorporate this spar and for the fully chorded part of the wing the ribs would have to be glued to the back? Edited By Stevo on 20/07/2015 19:40:44 Edited By Stevo on 20/07/2015 19:41:14 Quote Link to comment Share on other sites More sharing options...
kc Posted July 20, 2015 Share Posted July 20, 2015 As regards your latest drawing, I reckon if you draw a straight line along the rib underside then the spars should sit where they just touch that line - the building board surface. I think that would bring spars a little further aft than your drawing which would be convenient. Then the spar rear edge sits flat on the board as do the ribs, makes easy building. Might need a tapered packing under the spar front edge though. Worth looking at the wing construction method that Peter Miller has used on all his recent free plan designs - he pins down all the lower TE sheet etc and builds onto that. He describes it well in the text ( all his latest designs are a bit similar in wing construction ) and it worked well when I built one. Smaller span models though. But the point is the TE sheeting can just prop up the ribs enough to allow the spar to sit on lower LE sheeting flat on the board. Needs a drawing to work it out! Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 20, 2015 Author Share Posted July 20, 2015 Ok my thoughts are going this way.... Keep the spars where they are - I'm really not bothered about if it lays flat on the board or whatever - I can make a jig to suit if necassary. I could even move them back a tad more - see 2nd drawing. The spars are vertical, attach to 1/8" webs glued on the front of the spars. The 'box' comes from the birch ply dihedral brace glued to the rear. Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 20, 2015 Share Posted July 20, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 21, 2015 Author Share Posted July 21, 2015 Decided on the method of mounting. But as they came out the packet they were banana shaped... 10 minutes, a disc sander and a square later, they trued up somewhat. I used a wedge cut at 2 degrees, and 8mm Rawlnuts to lessen the vibration... Probably the first model I've had that has plenty of room behind the engine. I'll rotate that carby by 180 to get thelinkage on the outsid eof the tank. Once I've got a feel for where the tank goes, I'll drill the necassary holes for the tubing. Edited By Stevo on 21/07/2015 17:23:39 Edited By Stevo on 21/07/2015 17:25:57 Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 21, 2015 Share Posted July 21, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 23, 2015 Author Share Posted July 23, 2015 Promised you more photos and here they are! I designed a proper tank tray for a SLEC orange. The slant at the front is for ventilation and some where to shove the exhuast... Tank in situ. I had to move the tank rearward by 10mm to get the vent opened up. View from the front with tank box completed. All formers epoxied in place, and the two halve eventually come together!! Can't have too many clamps, can we Edited By Stevo on 23/07/2015 17:51:16 Quote Link to comment Share on other sites More sharing options...
Stevo Posted July 23, 2015 Author Share Posted July 23, 2015 Next stage? Glue the two halves of the rear section together, and start to plan where the servos go (3 for the tail surfaces, one for throttle) and the snakes for the control cables. Best do that without any fancy cross bracing getting in the way. I'll add that later, as well as the stringers. Quote Link to comment Share on other sites More sharing options...
Former Member Posted July 23, 2015 Share Posted July 23, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Jim Newberry - Nuviation Ltd. Posted July 23, 2015 Share Posted July 23, 2015 I've just come across this thread and I'll be following with interest - I built one of these from the RM plan years ago and it was easily the best flying model I have ever owned. Stupidity on my part destroyed the fuselage, so I rebuilt it and flew it to bits. Mine was electric powered. I always meant to get around to building it 20% bigger but never did (yet). That's it in my profile picture. Jim. Quote Link to comment Share on other sites More sharing options...
Jim Newberry - Nuviation Ltd. Posted July 23, 2015 Share Posted July 23, 2015 Quote Link to comment Share on other sites More sharing options...
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