thanks!

wrote in message
oups.com...
The SkyPup ultralight uses foam spar webs and ribs with
wood for the spar caps and rib caps. There are many pictures
on this website, some will show detials of the spars/wings during
construction.

http://www.skypup.net/index2.htm

For the SKyPup, fisrt the spar is made. The foam ribs are
made in two pieces one fore and one aft of the spar, then
butt glued in to the spar web. Then the rib caps are glued on.

The spar caps carry all the compressive and tensile stress due
to bending of the spar as the wing is loaded. The web only carries
shear due to bending and that is quite small.

Clearly not the only way to do it, nor necessarily the easiest
for every builder.

If you are not familiar with beams, it can be very helpful to
study up on beams, especially I-beams and box-beams as
wing spars are essentially beams.

--

FF