It sounds like a fun project.
How will you attach the ribs to the spar box?
By the sound of it Your main wing section chord length will be large.
That in itself will create strength.
My pivot point or tee mainwing control is about 28'' infront of the
center of the runner plank. I I magine yours will be similar. That
short distance should help strength wise in atorsional sense.





--- In wingboats@yahoogroups.com, "wind2nice" <wind2nice@...> wrote:
>
> John:
>
> I am over-thinking this. I have the wood for the hull and wings
and
> am making the mast and steering hardware. I had a very complex
> fuselage design, and it would have been heavy and strong as a tank.
> Your pix shoved that away, and now I am thinking very simple.
>
> I am half-way through a load analysis. I am presuming several cases
> to determind the design loads for sizing the fuselage, mast spar,
and
> shrouds. The design case seems to be one with the mast is laid over
> (side shroud loose) for heavy air.
>
> I have some different views on design than you do, and am going in a
> direction that may make a light and durable rig. I am going to
build
> the main wing more like an airplane wing, and use epoxy throughout.
> First will build a spar box with rectangular wood pieces just under
> the skin, tied together with plywood sheer caps fore and aft. This
> will be centered about 1/3 chord back from the leading edge.
Planning
> on nose and tail ribs glued to the sheer webs and a thin tail spar
> like yours. The nose ribs will be tied together with a leading-edge
> stringer just behind the front skin. The front skin will either be
> thin ply or edge-glued strips, not a solid block. The trailing ribs
> will either be 3mm ply or trusses of thin wood, like traditional
> airplane ribs.
>
> The flap construction will also be much simpler, as it doesn't
support
> much span-wise load. Gougeon Brothers West magazines published a
> wing-mast article some years ago that showed that gluing the skin to
> the front spar in a V-angle, then just bending the skins together at
> the trailing edge (tapered and over a strip of fiberglass for
> durability) made a foil shape very close to the NACA 4-digit
section.
> Shaping the nose spar to the NACA section completes the
construction.
> Makes sense, as the NACA section is a mathematical spline curve,
and
> the plywood is a material spline.
>
> I am going to experiment with flap twist control to unload the top
of
> the wing at speed. The control is simple and a one-string or one-
lever
> control will either twist or untwist the flap.
>
> I am leaning toward a fully tapered wing/flap. That works out to
just
> a bit over a two-foot wing and two-foot flap at the base, and a
> one-foot wing and one-foot flap at the tip. This is a bit more
work,
> but lowers the vertical center of effort some.
>
> I will have to make a separate plank for wheels. Your rules force
me
> in that direction as I intend to use DN runners on the sides and
must
> use chocks, rather than pillow block bearings on the wheel axles, as
> you must be doing.
>
> I have the wing profile Tom Speer designed for LYDIA, and that is my
> wing section plan, with a 0012 flap (approximately). I wish I dared
> to go to foam ribs, as that would make life go very fast. I'd
> appreciate Tom's thoughts on that foil now some 17 years later.
>
> One last thought: Flying on a 757 last week, I noticed the aft-most
> fowler flaps had vortex generators tucked in the slot. Has anyone
> ever tufted the flaps to see if they are causing separation at high
> angles?
>
> Well, hopefully I will get this thing on the ice in January. That
is
> my target date.
>
> Ken
>