are horizonal stabs symmetrical left to right ?

[fairchild1934]

wondering if I can build both the left and right sides on the same fixture on the build table ? That is-- can I build two "lefts" and then just flip one over to use as the right side stab ? or are they different somehow ?

Thanks-
Tim

[SpruceForest]

For the Patrol, that is what we did with the basic stab and elevator structure. I don't have a set of plans for the 4B or 5, but Bob seemed to have used same design (symmetrical airfoil) on the tandems and the 4B/5. Easy to verify with 4B plans, so if I am wrong, let me know. Even with an asymmetrical airfoil, the ribs are jigged to the 0 WL, so as long at you get the right ribs and left ribs separated out, plus maintain the correct orientation, the fixture will produce correctly oriented LE and TE, and the ribs are just filler pieces that want fitting and correct orientation.

Re: fixturing - we elevated the 0 WL of the stab and elevator 1-3/8" up from the fixture surface, which gave us access for better tacking and a little more room to ensure the airfoil-shaped ribs were well centered and vertical to the ref surface. I posted on fixture layout and build-up for the Patrols, and particularly doing a nested stab/elevator layout to allow for hinge gaps, etc. when laying out/scaling up the surfaces. Was milling up a bunch of synthetic trim (cellular PVC trim) to do some porch railing repairs, so got my 8' splines out of that scrap... constant density, so makes for a nice curve after a pass through the drum sander for constant cross-section.

For those with sharp eyes, we caught the missed tubing size change on the elevator tip forward of the spar... a little grinding dropped the blocks to correct height. No impact on the planform, but Bob wanted a little more beef and more forward location for balance weight that that larger size elevator tubing provides.


Nested Ele and Stab Laout.jpg Elevator Spline.jpg Stab Blocking.jpg

[fairchild1934]

Thank you SP--- as far as I can see the airfoils are the same curve on top and on bottom---

If you remember- what was the tube on the elevator counterbalance area changed to ? I have pretty new plans so I would think it has been updated- but just so I can double check......
Tim

[fairchild1934]

I have bent the LE stab tubes and I am making the rib forms now-- and will be making the little towers next.
Has anyone tried making the trim tab out of alternate materials beside the same round tubing that the elevator is made of ? I could see forming it out of sheet (like a steel rib) over a form block...... maybe a tube for a le and 3 steel ribs ? or something like that.....

[alaskabearhawk]

That's what I did. I made two stabs from one jig.

[fairchild1934]

Cool--- thanks--- that will make it go faster not having to make two separate mirror image jigs on the table....