Hatz Biplane Association

OK, I finally just ordered wood, and am calling it good!
Todays snow made so that the office was shut down, so it was a perfect day for working on the plane!

I started to cut the gussets, and while I am thinking I am just going to start cutting them the easiest way it is to cut.... but there are those zig zag lines on the gussets... what in the world do those mean?!?!

1) the lines run in the direction the wood grain should be....... This means that most gussets are going to be 45 degrees to the cut of the wood.

2) the zig zag's show the direction of the two 90 degree plys in the two parts.... so this would make the guests lay and need to be cut just like you would expect to.

3) The zig zag's are just there to show the gussets from the rest of the page.... so it really does not matter which direction you cut the gussets.

OK, I think I am just going to go with 2 or 3 and just start cutting! Someone out there tell me if I am wrong!

I cut my gussets so the face grain ran left to right not up and down.

Jeff Moore

Structurally the orientation doesn't matter. It's just an appearance issue before the wings are covered.
Mark

Check out this thread: Gusset Grain

I cut my pieces so the squiggly lines matched up with the lines on the drawings.

In the applications we are using gussets for the wing ribs, grain orientation really is insignificant, IMHO.

Hello

I have oriented the gussets according to a recommendation which I found in an older german book on glider building ("Werkstattpraxis" Jacobs, Lück). I'll try to translate the corresponding paragraph:

"…If the orientation of the gussets is not prescribed, the following rule applies: the grain orientation shall be parallel to the free, not supported by a truss element, edge of the plywood. Where this is not possible (when there are two connected free edges which are at an angle to each other), the grain orientation is chosen to be perpendicular to the capstrip"

The included sketch shows the resulting grain orientations for the gussets of a Hatz CB-1 rib.

The logic behind this orientation is not given in the text. My assumption is that, because the plywood is stiffer in the direction of the face grain, the stability of the unsupported free edge is increased.

Now, if you have oriented your gussets in a different direction, you don't need to start over. I have never heard about a Hatz or any other airplane for that matter, which would have had a structural failure because of wrongly oriented gussets!

Juerg, Hatz SN-622