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Aug 18, 2019, 03:54 AM
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japim's Avatar
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Originally Posted by Gnat666
BTW, the outer-walls aren't so flexible (under fingers for example) as some might think, the "panel" detail I gave it was aimed to strengthen the outer body, and it did.
I have noticed these embedded lines. These need a lot of work to model. But I know they work the same way like curved lines of car's bodywork. Can you share the tip how you made these lines?

Do they need any specific orientation of printed part? I mean if they are perpendicular to print surface they are OK. But how do they look like if you print them horizontally? Is the geometry sufficient not to cause any overhang issues?
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Aug 18, 2019, 08:27 AM
Anti-gravity = Lots of Watts
Gnat666's Avatar
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Quote:
Originally Posted by japim
... Can you share the tip how you made these lines? Do they need any specific orientation of printed part? I mean if they are perpendicular to print surface they are OK. But how do they look like if you print them horizontally? Is the geometry sufficient not to cause any overhang issues?
These detail lines seem to work well enough printed vertical or horizontal, probably because they are small detail (0.6mm x 1.2mm) and don't suffer overhand issues.

Fusion 360 method
- Generally just sketching on a flat plane to the left or right of the fuselage (or other)
- The sketch can be offset from the surfaces, doesnt have to touch the surface
- Draw a line that follows maybe real panel or seam lines. But don't do ALL the lines straight away, do these steps in sections
- Using "Offset" now do another line to the original line. I use a 0.6mm offset
- "close" the ends of these line pairs
- Finish the Sketch
- Now use "Split Face" (it projects a split perpendicular to the sketch plane)
--- Select the faces on the plane you want to split. You can do alternate (mirrored) sides of the same model, but dont recommend select the WHOLE model at once
--- Select the thin lines of your sketch
--- switch off "Extend", press OK
- Now select the newly split faces of your model
- Use "Extrude" to CUT (-) or EMBOSS (+) these lines onto your model. I used 1.2mm
- Repeat for various sections of your plane

Sometimes you'll find cross body "seams" cause errors when extruding split faces. Instead, stop you sketch line just short of a seam, then restart the line just the other side. Sure, your line isnt continuous, but you'll hardly notice if its just a 0.5mm gap.
Yesterday, 11:52 AM
Anti-gravity = Lots of Watts
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The rough prototype got thrown up today ... didnt last long
In retrospect I should have switched off RX stabilization, stupid miss, at least I could have seen what was really happening with the control ... even if it did still crash
No rudder control added to this version, but weirdly the yaw seemed extreme. Was probably just some weird physics of Torque Roll.
That was a 3S, 2200.
After chatting with others, now having second thoughts about the under-camber wing, may just go a simple Clark-Y.

Back to tweaking in Fusion360 and printing again. Still is fun.

RC 3d-printed P-39 Airacobra maiden flight attempt (2 min 2 sec)


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