Struggling to loft a thin shell with spline curves and rails

[Anonymous]

I am trying to create an inner and outer mold that I can 3D print.  I want the mold to be 2mm wall thickness so that it is strong enough to keep its shape, but thin enough to flex like an old fashioned ice cube tray so I can pop the molded part out of the mold.  I want to create two halves of a fuselage, I've only modeled the right half so far.  The fuselage wall thickness is supposed to be nominally 6mm, but I don't want any interior sharp corners to prevent cracks, so in some areas it will be thicker than that.

I have managed to loft the outer surface of the fuselage as a body using the rails (Crown, Keel, and Max Half-Breadth) that is named $Fuselage.   From here I want to create offsets at 2mm out, 6mm in, and 8 mm in.

The $Fuselage body is too complicated to shell or offset - at least I have had no success.

I have managed to loft 4 separate bodies and use Combine+Cut to create thin walled shells, but the inner and outer walls intersect and I end up with a body that has holes in it.

I really want to create the flat surface on the side where the Wing and Wing Kfoil Good touch and then transition into the distinctive SU-34 chined nose.  I am trying to get the profile and cross sections to match as much as possible and still fit the motor.

I've tried t-splines but not had much luck in holding them to the flat sides at the wing intersection.

Any help greatly appreciated.

Here is a link to the model.  You can see from the history how much I've struggled on this...

https://a360.co/34hMtcv 

https://a360.co/34hMtcv 

[laughingcreek]

it's entirely possible that one of those errors in the timeline is preventing this from working.  you won't know till you clean all that up.  simplify and keep things clean, don't let unused features pile or errors pile up in your timeline.  No body looking at this is going to be really motivated to look at this deeply because it will be like chasing a ghost.

more than likely the root of the issue starts with the quality of your curves.  they weren't as bad as I was expecting, but there is a lot of room for improvement.  curve quality contributes to surface quality. surface quality largely determines if something can be shelled, offset, etc.

[Anonymous]

You should see the surfaces on the real airplane!  I tried to match the actual cross sections as much as I could.

Thanks for the advice - I'll start over from scratch and see if I can create a cleaner timeline.  All that really matters is the cross sections and the rails.

I don't have a lot of confidence in this workflow.  Is there a better way, or am I on the right track?

[wmhazzard]

Here is a great video on surfaces and curves. 

https://www.youtube.com/watch?v=AOZVIrd7wj4&t=21s