Hatz Biplane Association

The Lauzon frame is this way (at least mine is).

It's pretty common on many vintage aircraft and even some contemporary ones. In a nutshell, the tailpost runs from the bottom longeron to some point a few inches above the top longeron. The vertical stab. spar then has a sleeve welded inside the spar tube that fits into the tailpost and then a bolt holds it together. The leading edge of the vertical stab also bolts to its own mounting point.

It's been done on a couple Hatz including Mehlin Smith's and also Hans & Sam from Switzerland.

"a detachable vertical stab"
That is intriguing!
How does that work?

The Classic elevator is actuated via push tube rather than cables as in the CB-1. The push tube rises between the longerons forward of the hor. stab. spar to attach to the elevator horn.

The plans show the c/l of the longerons intersecting the c/l of the vert. stab spar same as you built yours.

I did it pretty much the same as Doug.
Built the fuselage upside down on the table, drilled a hole in the table top, and attached it there. You need to make sure your table is tall enough for the full length of your tail post and that the ceiling height is high enough to remove it.
I attached the vertical stab leading edge after the fact. I filed a slot half of the diameter deep in the end of the tail post, heated the end of the tail post and worked it so it was flat against the tube for welding.
A word of caution. On the CB-1 plans, the elevators are actuated by horns on the ends of the elevators and inside the "vee" between the top longerons. I laid out my longeron-tailpost junction so the centerline of the longeron went through the centerline of the tail post. Wrong! This made the gap in the longeron "vee" narrow and I almost didn't get the horns to fit. If you look at the old classic tube and fabric planes, they line up the longeron centerline tangent to the tail post OD. I haven't seen how the Classic plans treat this junction... something to think about.

Jeff Moore

I guess you could do it either way. I attached the tailpost while building the fuselage just like the rest of the pieces. I added mine just as it appears in the sequence in the photos. I suppose you could add it later, you just need to make sure you jig it properly and keep everything aligned.

As for me, I'll be building a detachable vertical stab similar to Mehlin's Hatz.

Hatzers,
I am looking for advice regarding the tail post.
I am ready to make the last taper in the fuselage (station 151) towards the tail post. I know I need to prepare the longerons (I like Doug's sequence, beginning at http://www.damowry.com/hatz/displayimag ... play_media).
When did you actually add the tail post? after you formed the curve on the leading edge of the vertical stabilizer? what about the top of the tail post, where some heat forming and careful narrowing of the tube needs to take place? Is it better to do that on the bench prior to attaching the tail post to the rest of the fuselage?
Thanks!