Rib Stitching
From time to time questions come up about rib stitching.
For some people, the very idea is obnoxious, they prefer the fabric
rivets that come with the Kolb kits. Personally, I dislike rib
stitching much less than I dislike drilling hundreds of little
holes in 5/16" ribs. And in the back of my mind, I remember
the wings of a friend who cartwheeled his Twinstar MKII a number
of years ago, totaling it. (He walked away) All the wing ribs
had broken through the center of various 1/8" fabric rivet
holes. On the other hand, they probably would have broken somewhere
anyway, so you pays yer money and you takes yer choice... Anyway,
for those who have asked about rib stitching on a Kolb, here it
is.
On the left is a shot of the underside of the right
wing, looking from the trailing edge toward the front. On a 5/16"
rib, use 1/4" reinforcement tape instead of the wider tape
normally used with rivets. That way, the stitching does not pull
the deges of the tape down so much. You can see it still pulls
it down a bit, causing a slight dimple. On the right is a high
contrast shot of one of the more shoddy examples. Hate to display
my mediocre workmanship, but there is a lesson to be learned:
Sometimes it is hard to get the finishing tapes to lay down and
stick really well. You can mix about 10% of Polytack in with the
Polybrush and get it to stick better without screwing up the finish.
But if you mix in too much, it gives it a yukky gloss alongside
of the tape.
Here are the sides of the rudder, sewn over 1/4"
reinforcing tape.
Lay the connecting cord alongside the rib tubing instead
of along the high point, and tuck the knot into the hole after
you tie it. Makes a smaller bump that way.
I stood the wing up on the leading edge, used the old
rag-on-a-milkcrate ploy to rest them on. To keep them steady I
poked a bolt & nut through the rear spar attach point and
hose clamped it to the floor brace in the middle of the garage.
Crude, but...
Here was the fun part, having friends help you poke
the needle back and forth, drink coffee, and listen to the stereo.
This is fellow controller and sailplane pilot Greg Godsey &
son Hunter taking a poke at the Kolb.
Finally, here is what the bottom of the wing looks
like with all it's little stitches, plus, this also shows the
normal angle of attack relative to the horizon my MKIII flies
at. Before I modified the fuselage to allow more air to get to
the lower half of the prop, I remember the angle of attack as
being a bit more than this, wish I had taken a picture back them
to compare to now. Oh, well...
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