Hatz Biplane Association

Dear friends,

I am finally starting on Hatz #954, making one rib per day and good progress on the easy stuff. 90% done, 90% to go.

I have access to CNC water jet, laser cutting and milling equipment and am thinking it should be possible to make a one-piece rib from the same 1/4" aircraft plywood used for the nose piece. I'd model them in CAD and match the size and location of 1/4" spruce sticks and gussets, with rounded fillets at all internal junctions. Since no epoxy will be needed, this should save a huge amount of time and the weight of the gussets and T88 epoxy adhesive. Not sure about the overall weight or cost, but my greater interest is saving time and making these ribs identical without the need for any final sanding, etc.

Does anyone have experience with doing this on the Hatz ribs?

Donkey Shine!

Kent Misegades
Seven Lakes, NC

I used CNC for rib pieces but built the ribs conventionally.

http://myhatz.blogspot.com/2016/09/sept ... on-my.html

I have a couple engineers/pilots that I coffee with and we discussed plywood ribs. I think the main problem is that plywood is excellent in tension, but doesn't have a lot of compression strength. So as a leading edge it's fine but cut it into little strips and it may not hold up. You could widen the strips but that would add a lot of weight. Besides the Birch plywood (heavier) vs Spruce capstrip (lighter), plywood is inherently heavier than wood because of the glue to hold it together so there is probably no weight savings.

One way to improve production of ribs is to staple the gussets after you glue them. You can pull the rib out of the jig right away and do the same to the other side. If you want to remove the staples then use cardboard over the gusset so that you can pry out the staple without damaging the gusset. That would improve the one rib per day production.

I made a jig to trim off the gussets with a router and make all the ribs identical.

http://myhatz.blogspot.com/2016/04/april-2016.html