Wing 1: ideas
by, 12-03-2010 at 08:18 PM (564 Views)
Wing 1: ideas
I have spent the last month or two searching wing building ideas. I have been through hundreds of posts and pictures here at SC.org and also else where on the web. I think I have familiarized myself with the Piper L-21A drawings fairly well.
What I think I know:
1. A 13 rib wing is adequate for a light super cub.
2. The original design is the lightest and adequate for a light build.
3. For low speed, wing tips could be left off with a 10 knot penalty in cruise.
4. Spars normally fail first by "twisting".
5. Lifting is done by rib stitching, transfered to ribs, then spars, lift struts and finally fuselage. Wing hinge bolts may experience "downward" pressure due to cantelever action of wing tips on lift struts.
6. Wings lift because of down wash (hope that is correct term) from rear of wing, ie basically a verticle force from wing rear and equivalent to the weight of the aircraft. (this was a suprise to me as I was taught differently but it makes sense)
7. Extended leading edges add 10# and not much low speed lift.
8. To take advantage of many high lift designs requires advanced piloting and is not for me this build.
9. A wing mechanism consists of: fuselage attach points, spars, lift struts, compression members and attachments to spar web, drag/anti-drag wires, ribs, stitching, covering. The fuel tank is also a major consideration when planning a wing build but not technically "structural".