Post by Pij on May 27, 2008 22:39:13 GMT 10
Just posting some pics of an old unfinished project for Felix.
Info copied from other thread:
i did notice the shear type webbing on your spar design.shows a very intuitive side to your thinking.much respect there mate!
i have just made a composite spar as a testbed for my own design wing and at 25mm x 6mm and 1000mm long it supported 30kgs in it's centre with no visible bend and about 150kgs with heaps of bend but no breakage! will keep you posted on this one as the design progresses (if it ever gets off the drawing board lol).
I think you'd be interested in my composite spar. I would have to measure to remember the exact dimensions, but it was about 900mm long and 12 or so thick. Yes, we were working THIN at the time. Everybody told me it was a bad idea to deliberately lock in opposing forces, I referred them to pre-stressed concrete construction, but they didn't agree. I know it would go BOING in a nasty way if the bindings let go, but I don't think they will. I'll send you a pic of it if you like. I did consider stressing it to breaking point (when I decided not to finish the wing) to find out just how strong it actually was. The reason I discontinued was that I had been putting carbon-reinforced ribs on it, quite expensive, then calculated that I didn't have enough chord to achieve a glide-able wing-loading, so I retired it. It might be ok with no ribs, an EPP leading third, and maybe EPP back 2/3 too.
I went down to my plane-room and found it in a box of balsa bits.
It's about 860mm long on the curve, 8mm thick, and weighs 18g.
Pics to follow.
Info copied from other thread:
i did notice the shear type webbing on your spar design.shows a very intuitive side to your thinking.much respect there mate!
i have just made a composite spar as a testbed for my own design wing and at 25mm x 6mm and 1000mm long it supported 30kgs in it's centre with no visible bend and about 150kgs with heaps of bend but no breakage! will keep you posted on this one as the design progresses (if it ever gets off the drawing board lol).
It's about 860mm long on the curve, 8mm thick, and weighs 18g.
Pics to follow.
