Hi, all. I'm from an r/c modelling background and I want to start planning out a Horten-esque sailplane to build sometime in the future when I have the resources.
Such a plane would likely require reflex, and from what I've heard, cloth under tension has trouble following negative curves. I just realized that the foam I use to build model flying wings might actually be a suitable material to cover a wooden frame with. A 1-2 meter model is built with this stuff by folding a sheet over a single spar, and the internal pressures of the foam maintain an approximate airfoil shape. This would be out of the question on the 15+ meter scale, but MPF might be able to work without a huge amount of tension in it, so it could follow a reflexed airfoil along the top surface.
I know what you're probably thinking, but MPF is no ordinary Staples foam board, it is certainly aircraft grade. If it turns out it would work structurally, I would definitely trust this material.
Specifications:
-0.61x1.22 meter sheets (2ftx4ft), may be able to organize larger sheets for a bulk order.
-6mm (1/4")thickness
-~200g/m2 (0.66 oz/ft2)
-very flexible, can be formed to tight radii
-sandable, paintable, can be covered in a plastic coating
Pros:
-will follow a concave surface with enough ribs
-can compress/stretch a bit at model scale, so will likely handle bending of the wing at full scale
-VERY lightweight
-takes no UV damage as far as I know, but long duration exposure tests have not been performed (note to self....)
Cons:
-dents and scratches easily, plastic coating like monocote usually required (i.e. airborne debris and hangar rash pose a threat)
-pricey, $50 USD for ~12 square meters
Maybe if it is just used for the aft 2/3 of the wing, with a light ply skin in front, it would work. What do the experts think?
Such a plane would likely require reflex, and from what I've heard, cloth under tension has trouble following negative curves. I just realized that the foam I use to build model flying wings might actually be a suitable material to cover a wooden frame with. A 1-2 meter model is built with this stuff by folding a sheet over a single spar, and the internal pressures of the foam maintain an approximate airfoil shape. This would be out of the question on the 15+ meter scale, but MPF might be able to work without a huge amount of tension in it, so it could follow a reflexed airfoil along the top surface.
I know what you're probably thinking, but MPF is no ordinary Staples foam board, it is certainly aircraft grade. If it turns out it would work structurally, I would definitely trust this material.
Specifications:
-0.61x1.22 meter sheets (2ftx4ft), may be able to organize larger sheets for a bulk order.
-6mm (1/4")thickness
-~200g/m2 (0.66 oz/ft2)
-very flexible, can be formed to tight radii
-sandable, paintable, can be covered in a plastic coating
Pros:
-will follow a concave surface with enough ribs
-can compress/stretch a bit at model scale, so will likely handle bending of the wing at full scale
-VERY lightweight
-takes no UV damage as far as I know, but long duration exposure tests have not been performed (note to self....)
Cons:
-dents and scratches easily, plastic coating like monocote usually required (i.e. airborne debris and hangar rash pose a threat)
-pricey, $50 USD for ~12 square meters
Maybe if it is just used for the aft 2/3 of the wing, with a light ply skin in front, it would work. What do the experts think?
