Seafang
Posts: 32
Joined: 9/28/2005
From: London, UNITED KINGDOM
Status: offline
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Hi Jim,
I've stuck this in the forum as you never know who this might help, hope you don't mind;
[Seafang , can you tell me the cord length on your Miles Atwood Special wing and the wing thickness,, as I said in the Miles Atwood Special post I need to build a new wing for my Miss Los Angeles and the wings on the 2 planes look much a-like, but you ribs/wing look thicker ??? ]
Cord length = 335mm ( plus 30mm leading edge & 30mm trailing edge, so a total of 395mm) (200mm last rib at tip)
Rib Thickness = 55mm (38mm last rib at tip)
These are not mean aerodynamic cord (mac) cord lengths but the length and thickness of the majority ribs, the cord and thickness change for the last 3 ribs at the wing tips. I'm assuming you just want a general idea. It's a pretty thick wing, not to scale, the prototype probably had a much thinner wing. However in the real world we want these models to fly well and without getting into the whole 'Reynolds' number thing, which I only have a shallow grasp of at the best of times, we are probably full circle and back to your original problem.
At a guess the wing I've built for this model is a Clark-Y type. I believe the Spirit of St.Louis (Ryan) had a Clark-Y airfoil.
I also understand that this model flies well but fast, despite the relative thickness of the wing but again that may have something more to do with wing loading rather than aerodynamic shape.I am going for a light wing loading I've mad the calculations in imperial measurments;
Weight 192 ounces / Wing Area 7.708 square feet. = wing loading 24.9 0z/sqft . Well, that's my goal anyway.
If you really can't be assed cutting ribs, have a play with some blue-foam, carbon spars and a few lightening holes all covered in plastic iron-on stuff. I've not done it myself but I'd have a go even though you'll still have to make some templates for the cord changes. I doubt it's easier but it's certainly different. Remember you can get a flat plank of wood to fly with the right angle of attack. Be careful not to build any twist in the wing unless you understand wash-out/in and want to accommodate that in your wing. warps and twists are a headache.
Hope that helps, J.
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