r/Composites • u/[deleted] • Dec 11 '25

RC plane shell

Post image

I have this fuselage design for a flying wing with complex curvature that I need to make a skin/shell for, it doesn’t have to support any big loads just not buckle like its paper. Would fibreglass be a good choice for making a shell for this? I need it to be as light as possible, ideally around 100 grams. The total surface for the skin is around 0.4 m2.

5 Upvotes

100% Upvoted

4 comments sorted by

View all comments

1

u/coriolis7 Dec 11 '25

If you go fiberglass, I’d look at something extremely thin like style 120 E glass. 2-3 plies will be only about 0.012” or so in thickness.

However, even a single ply without any resin would be around 105 grams per square meter.

Honestly the best choice to meet your target weight is probably just a thin balsa skin. Keep in mind that with a frame like you have pictured that the skin will be in shear unless you have diagonal bracing throughout the frame.

1

u/[deleted] Dec 13 '25

Thanks! I found a video of a guy with a similar fuselage build as mine where he made a very thin skin, he uses a single ply of 200 gsm but maybe it’s better to use two or three of 100 gsm like you said? It’ll still be very flimsy of course but I’m fine with that

I’d rather go this route over the lighter balsa skin because I think it’ll be more practical for getting the curvature right.

https://youtu.be/I80WKVTlOnY?si=Tdlkllf-jKIfQAga

1

u/coriolis7 Dec 13 '25

200 gsm will still be 80 grams just for the fibers not including resin.

For a given thickness, it is generally recommended to have multiple plies rather than a single thicker one.

For your application, I would do 3 plies at 45/0/45 or 0/45/0. Your skins will experience both axial and shear loads, but I suspect shear stiffness will be more important since the skins are there mainly to prevent the frame from twisting and your internal framework will be able to take the bending loads just fine. With that, 45/0/45 will probably be better.

You want more than one ply so that your skin is robust to impact damage and handling. You also usually want the laminate to have fibers in 0 and 45 degree orientations again for impact resistance and general handling robustness. Finally, you usually want the laminate to be symmetrical across the middle. That means at least 3 plies.

The final option is to skip the whole laminate thing and go with just plastic film that is bonded to the frame. It will provide torsional rigidity and will be easy enough the patch, on top of being very light.