Allan Bennett Posted October 20, 2009 Share Posted October 20, 2009 I'm just getting around to attaching the 4.5mm stringers to the main frame of my Lysander and I've found that former F7 is about 8mm too short. I'm working from the plan, not with the CNC set, so I don't know if this affects those who've bought the set. Anyway, I've copied F7 off the plan and then stretched it heightwise by 10.5% to make it the right height (width is okay) so I can cut a new one. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted October 21, 2009 Author Share Posted October 21, 2009 Oops! I've just fitted my new F7, and it's too big! Seems like 5% stretch might have been enough, but at least with the too-big version I've been able to file out the slots to fit the stringers nicely, and then sand down the external profile to the correct curve. Quote Link to comment Share on other sites More sharing options...
Peter 'Ivanna Crashalot' Savage Posted October 28, 2009 Share Posted October 28, 2009 I did notice my stringers werent straight when fully seated so i just didn't push the stringer fully into the former Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted October 30, 2009 Author Share Posted October 30, 2009 Did you make yours from plan, or did you have the CNC set? On the plan, I'm convinced the F7 they've drawn is a true elevation of the former (as if it were vertical) which hasn't allowed for the extra height required because of the slope. Before I realised what the error was, I was filing away at the bottoms of the notches in F8 so that the stringers could drop fully into F7 without me having to bend them down. If you didn't push the stringers fully in, you're going to have to infill between them before you start covering, to give a smooth end to the covered section, and a smooth seating for the canopy. Quote Link to comment Share on other sites More sharing options...
Peter 'Ivanna Crashalot' Savage Posted October 30, 2009 Share Posted October 30, 2009 Oh it wasn't F7 that i didn't put the stringers fully in, they go all the way in, its the front one that only goes through the top stringers Quote Link to comment Share on other sites More sharing options...
Peter 'Ivanna Crashalot' Savage Posted October 30, 2009 Share Posted October 30, 2009 Mine was the CNC packEdited By Peter Savage on 30/10/2009 19:15:23 Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted October 30, 2009 Author Share Posted October 30, 2009 Posted by Peter Savage on 30/10/2009 14:38:48:Oh it wasn't F7 that i didn't put the stringers fully in, they go all the way in, its the front one that only goes through the top stringers The one that's leaning backwards, and forms the back of the cockpit? That's F7 on the plans Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted November 2, 2009 Share Posted November 2, 2009 Guys, On the plan and cnc part F7, both are identical so I cant see much in the way of error....From Peter's build F7 looks fine. If you overlay F7 on to F8 I hope you can see the angle of F7 has been taken into account! Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted November 3, 2009 Author Share Posted November 3, 2009 Hi Tony, thanks for the great design. I've just about finished the fuse, and it's one of the easiest plan-builds I've done so far. Anyway, about F7: If I draw a line across the bottom of it on the plan, and then measure top to bottom, I get just short of 76mm; if I then go to the fuselage side elevation on the other sheet, and measure the top-to-bottom slope height of F7 in position, I get 82mm. So, it still seems to me that F7 is 6mm too short, and this is exactly how it was in my build before I realised where the problem was ... the top stringer already sitting in its notches in F8, 9, and 10 flew over the top of F7 without touching it when F7 was sitting properly on the two side stringers #7, at the correct slope. Comparing F7 with F8 is not valid because F8 (according to my measurment off the fuselage side elevation) should be about 4mm shorter in elevation than F7 because of the slope of the top stringer. That's discounting the fact that F7 should also be taller and wider overall because the stringers are notched full-depth into it instead of by only 2mm or so. So, if F7 matches the top part of F8, then it's too short. Quote Link to comment Share on other sites More sharing options...
Tony Nijhuis Posted November 3, 2009 Share Posted November 3, 2009 Alan, the 82mm is a bit misleading as F7 dosen't extend past stringer 7....I think F7 may be a couple of mm short because I have measured 77mm from top of stringer 1 to the centre tangent of stringer 7 at the rake back angle.....the bottom line is F7 should be about 79mm (top to bottom edge) to fit perfectly Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted November 3, 2009 Author Share Posted November 3, 2009 Posted by Tony Nijhuis on 03/11/2009 13:13:31:Alan, the 82mm is a bit misleading as F7 dosen't extend past stringer 7....I think F7 may be a couple of mm short because I have measured 77mm from top of stringer 1 to the centre tangent of stringer 7 at the rake back angle.....the bottom line is F7 should be about 79mm (top to bottom edge) to fit perfectly OK, I was measuring on the front face of F7, so my 82mm results in the back edge of F7 extending down beyond stringer 7 a bit. Checking my plan again, this is exactly what is shown on the side elevation -- the front face of F7 extends 4mm below the centreline of stringer 7 (i.e. 1 or 2mm beyond the bottom edge of stringer 7), and the back face about 6mm. Contradicting that, I see that the size of the notch for stringer 7 in F7 is 4.5mm, which prevents the bottom of F7 dropping below the bottom of stringer 7 which, I think, is why I my replacement F7, made to my 82mm measurement, was too tall. Anyway, it's not a big deal, so thanks for responding in such detail. Quote Link to comment Share on other sites More sharing options...
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