Hi all,
Looking to see if I can save any weight on the wing rebuild for my Hiperbipe. The standard wings are all wood with 3 spars, sheet ribs spaced 12" apart, and plywood skins. Strong and light. Only two problems with them on a rebuild: the skin sags between the ribs, and aircraft grade plywood is eye watering expensive. On my lower wing rebuilds, I solved the sagging problem by inserting 1 inch blue foam ribs between the existing ply ribs. I solved the cost problem by using Okume plywood. The resulting structure was covered with 1 layer of glass and painted. It still looks fantastic after two years - perfectly straight. The problem is the weight of the Okume compared to the original mahogany - it contributed most of the 7 pounds per wing increase.
For the upper wings, I'm thinking that I can save the weight of the okume by eliminating it all together. My plan is to simply replace most of the existing ply ribs with a solid section of foam. The resulting wing would be a "Rutan style" foam wing with a few imbedded wood parts. I'd then cover the whole structure with the appropriate plys of glass.
So my questions:
Will I see the weight savings I am looking for?
Will I compromise the structure?
Is this dumb?
Thanks,
Mike
Looking to see if I can save any weight on the wing rebuild for my Hiperbipe. The standard wings are all wood with 3 spars, sheet ribs spaced 12" apart, and plywood skins. Strong and light. Only two problems with them on a rebuild: the skin sags between the ribs, and aircraft grade plywood is eye watering expensive. On my lower wing rebuilds, I solved the sagging problem by inserting 1 inch blue foam ribs between the existing ply ribs. I solved the cost problem by using Okume plywood. The resulting structure was covered with 1 layer of glass and painted. It still looks fantastic after two years - perfectly straight. The problem is the weight of the Okume compared to the original mahogany - it contributed most of the 7 pounds per wing increase.
For the upper wings, I'm thinking that I can save the weight of the okume by eliminating it all together. My plan is to simply replace most of the existing ply ribs with a solid section of foam. The resulting wing would be a "Rutan style" foam wing with a few imbedded wood parts. I'd then cover the whole structure with the appropriate plys of glass.
So my questions:
Will I see the weight savings I am looking for?
Will I compromise the structure?
Is this dumb?
Thanks,
Mike
