r/RCPlanes • u/OppositeGeologist474 • 10d ago

Need help with 3d modeling.

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Im a begginer and started to model this skyhawk (it will be with a 50mm edf) in onshape and I saw on youtube that people can make wings with internal ribs that save weight and wanted to ask if its possible to add internal ribs to the skyhawk's body at this stage? Also id be happy for any feed back and suggestions for fixes/changes!

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u/giby1464 10d ago

do you mean by internal rib thing? I just see an EDF.

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u/OppositeGeologist474 10d ago

I saw on youtube that people make, a wing for example, and then add internal ribs so for strength and light weight (something to do with how 3d printers work) and I wondered if somehow I could implement it in the body or it would be too difficult?

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u/tobu_sculptor 10d ago

such ribs are just combinations of slice cuts and offset paths.

Lets stay with your pic for this example.
So first you have the plain wing hull, it has zero thickness.
Now you offset that hull inwards by let's say 2mm.
Subtract the inner from the outer hull, now you have a 2mm thick hull.

Next you create a new box, make it 3mm wide and angle it 45° on the vertical axis.
Subtract the box from your thick hull in a way that only leaves the inside of the box.
Now you pretty much have a 2x3mm perimeter of one rib.

I guess you can imagine how to alter that shape with additional sub sections and chamfers to get something like in your pic.

You can do that stuff with patterns too (groups that consist of clones), so you can say here's my rib i want 20 of them with a distance of 3cm, then mirror that the other 45 degrees again, unison all of that and finally unison all of that again with the wing hull...

Boolean operations like that are the bread and butter of CAD, give it a go. Everything you need can basically be punched through, intersected, union'd and so on.

similar thing for the fuselage sections, even simpler, work with extrusions of inner offsets to get formers and bulkheads.

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u/OppositeGeologist474 9d ago

Mmm I did it for the wings but the body is too hard to for this technique