Hatz Biplane Association

Hey everybody! Galen Johnson here. Love the look of the new website. Plan S/N 672 project is back in business. Gluing ribs in place to begin assembly of top left wing. Will be doing the continuous hinge mod. on ailerons. Thought it best to do some work on the drawing board to verify relationship and motion of bell crank/aileron horn and linkage of this arrangement vs. original before commiting to the wood and metal. I plotted the arc of motion of horn on control stick assembly and used this information to plot the range of motion of the bell crank, horn and aileron. Going by the CB-1 drawings, when I drew the aileron horn and bellcrank in location specified on the plans it doesn't look right to this old machine designer's eye. Didn't look like enough aileron motion and linkage rod alignment is offset at neutral. I'd probably have the linkage rod pointed straight fore and aft in the neutral position (to prevent a shock wave at high mach.. LOL.) I did a drawing of a slightly revised arrangement that looks better--- to me. Anybody have actual degrees of aileron deflection up and down from neutral position I can use to check my work-- or tell me what sheet it's written on? If it's there, I haven't found it.

Glad your doing this research for us. Forgive my ignorance (I have yet to even start wings) but I've noticed that to plans the slave strut is out of alignment with the interplane struts. It's never really made sense to me, and I had always planned on moving mine into alignment. Is this possible, if not, why? Sorry that its a little "off subject" but figured since you'd been studying the geometry, you'd have visited the subject.

That change gets complicated. Slave strut is connected to aileron horn assembly, which is positioned to be actuated by linkage to bellcrank, which is mounted to the compression strut at that location. To do what you suggest will probably require adding a duplicate part similar to aileron horn at location you determine, depending on aileron rib location and being mindful of adding a torque reaction to aileron spar. If using the original hinge design, I'd be curious about what happens when applying a concentrated load at a location between hinges. All that said-- If you look at old airplanes, the slave strut being out of line is pretty common.

If you are surprised by how little aileron deflection there is on the Hatz, take a look at the Taperwing Waco (and others, I'm sure). I too, wandered about adding more deflection, and I did slightly, but only because the screws that attach the piano hinges lessen the deflection a little bit. I added a bit of deflection by increasing the angle of the false spar that the ailerons attach to. And again, ever so slightly.

Mark T
#493

I plan to show up at Brodhead this year with some sort of tool to measure the range of aileron deflection on as many Hatz airplanes as owners will allow. Specification of control surface motion is important information because it predicts how the airplane will react. Granted, small changes to a Hatz won't make a big difference, but I still think there should be a spec. for aileron, elevator and rudder range of deflection to use as guidelines for construction and rigging.

The aileron movement (up and down) is on the plans. The plan shows 2" and 2 1/2". This is what I built my classic to. Note that I did not use the as plan bellcrank or linkage. I used an RV10 bellcrank. worked perfect.

Michael
N838MM

Thanks. Assuming you mean trailing edge 2" down and 2 1/2" up from neutral position? That info may be called out on Classic plans, but I'm working off CB-1 plans.

Yes Hatz classic sheet 20 - 2.5" up and 2" down on the trailing edge from a neutral position. I could not find this on the Hatz plans.

michael
N838MM

I was able to get the measurements I wanted from Jim Hammond's CB-1 at Brodhead during the Hatz get-together in July this year. Thank you, Jim. I haven't plotted out the results yet, but I'm satisfied there won't be any bad surprises down the line.