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issues with plans/templates

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Old 01-05-2012, 11:24 AM
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crash bandicoute
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Default issues with plans/templates

so i just got my plans for a Swick T-Craft from a buddy, and i have some issues to run across you guys concerning the templates and sizes of them. i was wondering if you guys have had issues of this nature, and what to do about it.

the first thing is the drawings of the wing panels. the wings are the same length on the drawings, but the inboard end of the aileron on one wing panel is 1/8" further out, but the other tip of the aileron is lined up with the same on the other wing panel. essentially making one aileron longer than the other. not a problem, i can trace the wing on the back side of the print and build as if mirrored on the same panel drawing.

next comes the firewall. excluding the sheeting, the firewall template is 1/2" wider than it is shown on the drawing of the fuselage. it's rounded on the sides, not flat, so...

the template for the very nose of the cowl is 1/2" wider and taller than shown on the fuselage drawing.

the cowl business will probably not matter, as i'm going to glass my own anyway, but the firewall part not lining up properly is going to throw a wrench into the mix. AND the fuselage sides are flat. they're not even contoured. so how do i have a rounded firewall and a flat-sided fuselage?

this one kills me. the drawing of the wing rootfrom a cross section detailing the build-up is 3/4" longer (chord wise) than it is shown on the side and top drawing of the fuselage. on the wing panel drawings, the build up is the same chord-wise, as the panel. if i build according to the wing panel and 'template' for the wing ribs and leading and trailing edges and such, and the fuselage according to those drawings, the wing is going to be too long chord-wise for the seat on the fuselage. there is a root rib drawn into the fuselage side view, but it also is the 3/4" shorter. i'm attaching a couple photos.

now i can understand a little expansion and contraction of the plans due to temp and humidity, but, i think this goes a little further than that.

if i build the wing panels according to those drawings, it's going to change the incidence of the wing a little. maybe just slightly, but none-the-less. is this change going to affect the way she flies?
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Old 01-05-2012, 04:21 PM
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limeybob
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Default RE: issues with plans/templates

Well, this is not an unusual situation, I see many many plans and some are very bad indeed, still the suppliers sell them anyway.
I have to scan and redraw the parts for my laser, so I can correct the errors I can find.
The fuselage/wing match/incidence is a particular problem and I check this routinely.
As to your problems If this is intended as a scale model, then checking a three view is in order for the fuselage.
This should also resolve the problem with the fuselage/wing fit and one will have to be redrawn . Lets hope its the fuselage
Bob
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Old 01-05-2012, 04:26 PM
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fledermaus
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Default RE: issues with plans/templates

Since older plans were hand-drawn, there was a good likelihood of errors creeping in. Thus, left and right wings might well not be identical if a measurement error was made in drawing one of them. It's a case of "builder beware" I guess - measure twice and cut once and all that.

Nowadays with CAD you can still get mistakes, but usually left and right wings or stabilizers will be drawn by duplicating and mirroring so at least that fault is less likely.
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