Hatz Biplane Association

Hi Gang,
I just spent some time trying to put a square peg in a round hole. I know the answer, but I was wondering if anyone else ran into this. My stabilizer halves hit the fabric before they are in far enough. The elevator horns are about 1" apart (should be 3/8")and they interfere with the top longerons and the opening in the rudder. My fuse is a Weld-Tech. I was also curious as to why the root ribs have the flanges facing inboard. If they were reversed, this problem wouldn't exist. I am probably going to use a
3/4" tube as a new root rib or bend up new channel ribs. Glad I waited to cover these until after the fuse was covered!
Al

Al I'd use a bent channel, it will warp less when you iron the stab.

Steel will be at my door tomorrow. The original (Weld-Tech) seemed flexible enough to give under the tension of the fabric. I was thinking of bracing it internally, a couple of spruce diagonals meeting at the center of the span of the root rib worked nicely in a mockup. I am still going to reverse the channel so the flange points outboard, unlike the original. That is unless someone can give me a good reason not to.
Thanks,
Al

Just so I understand.....
The root rib is a pirce of steel bent into a "C" and the flat edge points to the fuselage and the open part points away from the fuselage.
If that is correct, then I can think of a couple of reasons to intsall it this way and not reversed. When you attach the fabric to the root rib, the flat edge will give you much more surface area to glue to and the sharp edges of the "C" won't rub through the fabric because you wont stitch it there.

My 2 cents worth.

Jeff Moore

Almost, The flat side is outboard, away from the fuselage. Doesn't make sense to me either. Won't be that way much longer.

Before forming the butt ribs on NX1279, I covered both side of the fin with some scrap fabric and shrunk it to shape. I was then able to form the stabilizer butt ribs to conform to the shape of the fabric in that area. You'd be suprised how much difference there is due to the offset of the fin. With the fabric in place, you can bend and shape the butt rib to achieve a very nice fit with minimal gap.
Mark

I would have done it that way but the stab halves were finished by Weld-Tech. Once the fabric was on the fuselage I found that the root rib interfered with the fabric on the fuse. At least I had the foresight to leave the stab halves uncovered suspecting just what happened. I will be making new ribs to conform to the fuselage. I may add balsa to close up the gap even more.
Al