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Jan 24, 2020, 10:40 AM
Everything's A Composite
Knoll53's Avatar
I see that you did a mock up first to test the procedure.

It's more than modeling building.............it's an art form.
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Jan 24, 2020, 10:59 AM
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Kenneth Paine's Avatar
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Quote:
Originally Posted by Knoll53
I see that you did a mock up first to test the procedure.

It's more than modeling building.............it's an art form.
Thanks Kent but I actually did the wings first and then though "maybe I ought to explain my process just in case it is of interest to someone" (as if!), so I photographed the mockup after completing the wing . Also it is much easier to photograph a mockup than it is to mess around with the whole wing panel which is only one foot shorter than my bench.

K
Feb 08, 2020, 12:40 PM
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Kenneth Paine's Avatar
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Preparing for the Root Ribs


Next I cut 6mm (1/4") off the wing roots to make room for the plywood root rib that will transfer the loads from the joiner rod and incidence pins into the stressed skin. Because of the glass shear web and trailing edge structure, this would be a challenge.

I have a great blade from a Japanese pull saw with 0.3mm kerf to tackle the glass with but it is very flexible, so how to keep it straight and square in order to do a neat job? Follow the slide show below:
Last edited by Kenneth Paine; Feb 12, 2020 at 06:13 AM.
Feb 08, 2020, 05:47 PM
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Why not just add the rib onto the end? Or cut the core 6mm shorter in the first place?
Feb 08, 2020, 08:18 PM
Old guy who plays with toys
VintageScale's Avatar
Or, cut it as straight as you can by eye and use thickened epoxy to glue it in. But, to each his own, if you want to make a 5 minute job into a 50 minute job more power to you!
Feb 09, 2020, 07:34 PM
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rrcdoug's Avatar
I am learning lots frim this thread. I especially like the method of laminating the hinge line before the skin. I have found 3m77 to be unreliable for holding these parts when using ultra slow epoxy in the bagging process. My clumsy hands and inaccurate sense of vertical make me appreciate the use of these cutting guides. For the endcap cut, I find the end of the foam shucks are a convenient guide, provided they were cut at the cirrect angle.
Feb 10, 2020, 02:50 AM
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Kenneth Paine's Avatar
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Quote:
Originally Posted by HarryC
Why not just add the rib onto the end? Or cut the core 6mm shorter in the first place?
Harry,

On both counts it is because I don't like things hanging out of the foam beds. Some strong forces are generated during vacuum bagging that may lead to unexpected curling, specially on trailing edges.

With my Rotors I just tacked the rib to the root and trimmed the tip to compensate because their wing panels are single taper. With the Discus I can't do that because both taper breaks in each panel would be out by 6mm relative to the foam beds unless the root rib were left hanging out.

K
Last edited by Kenneth Paine; Feb 10, 2020 at 03:08 AM.
Feb 10, 2020, 02:54 AM
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Kenneth Paine's Avatar
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Quote:
Originally Posted by VintageScale
Or, cut it as straight as you can by eye and use thickened epoxy to glue it in. But, to each his own, if you want to make a 5 minute job into a 50 minute job more power to you!
Quite right, your method would have worked just fine. I like trying new methods and aiming for the best fit and finish I can achieve, so this embellished job serves more purposes for me than just tacking a ply rib to the foam core.
Feb 10, 2020, 03:02 AM
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Kenneth Paine's Avatar
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Quote:
Originally Posted by rrcdoug
I am learning lots frim this thread. I especially like the method of laminating the hinge line before the skin. I have found 3m77 to be unreliable for holding these parts when using ultra slow epoxy in the bagging process. My clumsy hands and inaccurate sense of vertical make me appreciate the use of these cutting guides.
Thanks Doug. I am glad somebody found something useful. Bear in mind this is all new to me and I am making things up as I go along, so exercise some discretion before copying me

Quote:
Originally Posted by rrcdoug
For the endcap cut, I find the end of the foam shucks are a convenient guide, provided they were cut at the cirrect angle.
I did consider this method and the more I think about it the more I believe it would be as good as the way I ended up doing things, but I just can't help myself.
Feb 10, 2020, 04:21 AM
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Quote:
Originally Posted by Kenneth Paine
Harry,

On both counts it is because I don't like things hanging out of the foam beds. Some strong forces are generated during vacuum bagging that may lead to unexpected curling, specially on trailing edges.
Ah, a very good reason!
Feb 16, 2020, 01:24 PM
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Kenneth Paine's Avatar
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Woodwork


The woodwork and brassware were glued into the cores with thickened laminating epoxy.

The sub rib and incidence pin inserts are slightly undersize and the gaps will be filled flush with the cores next.

The root rib was trimmed slightly oversize for sanding in-situ flush with the cores. Barely visible is protective tape just inboard of the root rib, full chord. The sanding was done with 10" sanding bars with one end covered in masking tape so that it slides over the foam until the other end cuts down to the protective tape. 80 grit to start and then 200 to creep up on the core until the Sharpie guide marks start to fade.
Last edited by Kenneth Paine; Feb 17, 2020 at 01:46 AM.
Feb 17, 2020, 03:39 PM
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I'm following with interest


Kenneth,
I am following with great interest. I got almost for free a hull of DG-600 ( guess really old Multiplex one, not really sure ). Wings which i got are throwaways, so i'm building new ones, the same manner as you do, along the way repairing the broken hull and reinforcing it.' Your scratch build and all the comments are really helpfull for making me even more confused of what i'll do ;-)
to give back to community, i am documenting every step , so hopefully i will post step by step what i am building so.maybe this comes handy for somebody.
Keep going
Urban
Last edited by Urbans; Feb 17, 2020 at 03:41 PM. Reason: Grammar mistake
Feb 17, 2020, 04:40 PM
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Kenneth Paine's Avatar
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Thank you Urban. I look forward to following your thread in due course.

Kind regards,

Kenneth
Feb 23, 2020, 10:17 AM
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Kenneth Paine's Avatar
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Filling Gaps


The ply inserts were made undersized so the gap was filled with thickened epoxy.

I also took the opportunity to cast the flap and aileron end caps in-situ with microballoons. I know this is not strictly necessary but it gives me the option to cut the surfaces before painting if I choose to do so. When the control surfaces are cut, there will be no blue foam exposed to paint.

I originally intended to run the ailerons all the way out to the wing tip but these are so narrow that it would be asking for trouble, so I wussed out and will leave them scale.

The cores look a mess at the moment but will all look great after bagging, as if cast in resin like my stab does.
Feb 24, 2020, 04:14 PM
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Jets:)'s Avatar
Good work Ken.

Very meticulous and well thought out


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