Hey, I have a pretty basic question about an odd configuration.
I have a conceptual aluminum-construction configuration with a ring carry-through that will meet with a basically-unswept main spar (built-up). However, for this configuration, CG position is critical. The spar sits on the CG, and I'd like to put the fuel there as well.
What I'm basically considering is to have twin spar webbings, separated by about 6" fore and aft, forming a box spar with a shared spar cap. Fuel would go within this box spar (along with ribs/baffles), and the ring carry-through would be widened to 6" just at the spar attach point (it's normally about 2" thick at the thickest) to attach both spar webs to the carry-through.
First off, is this sufficient description, or do I need a drawing?
Second off, are there any obvious problems here?
I know fuel-in-spar isn't rare (BD), but I haven't seen it done with a built-up aluminum spar. I'm paying the cost in needing to overbuild my webbing (no lightening holes, probably thicker than I need, and more of them), but I don't see any way to avoid equivalent structure to get fuel that close to CG; and double webbing / box spar should (??) allow me to have a thinner, wider spar cap as it's doubly-supported.
I have a conceptual aluminum-construction configuration with a ring carry-through that will meet with a basically-unswept main spar (built-up). However, for this configuration, CG position is critical. The spar sits on the CG, and I'd like to put the fuel there as well.
What I'm basically considering is to have twin spar webbings, separated by about 6" fore and aft, forming a box spar with a shared spar cap. Fuel would go within this box spar (along with ribs/baffles), and the ring carry-through would be widened to 6" just at the spar attach point (it's normally about 2" thick at the thickest) to attach both spar webs to the carry-through.
First off, is this sufficient description, or do I need a drawing?
Second off, are there any obvious problems here?
I know fuel-in-spar isn't rare (BD), but I haven't seen it done with a built-up aluminum spar. I'm paying the cost in needing to overbuild my webbing (no lightening holes, probably thicker than I need, and more of them), but I don't see any way to avoid equivalent structure to get fuel that close to CG; and double webbing / box spar should (??) allow me to have a thinner, wider spar cap as it's doubly-supported.
