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Carlo is getting close to needing the tail surfaces to get his aft fuse control runs done (avionics and interior already done on his bird... too cold to weld = not too cold to wire or set nut plates), so he asked me to block time to fab the stab/elevator and rudder jigs. The stab and elevator layout are detailed, but the same approach handles the elevator and any full scale layout jig needed for the vertical stab. Worth a couple shots to capture the approach we used... if you have a better/different method, please feel free to add to the thread or link to your post here.
Job One was figuring out a reference line, and our decision was to use the LE of the elevator for fore and aft ref and elevator forward extension for the lateral ref. We gridded off the plans page in 1/2" increment for the elevator and stab using those references, then added some 1/4" increment gridding at the elevator tip to fine-tune the shape there. Once that was done, I laid out and cut two pieces of plywood to nest together along the reference line and duplicated the grid layout using 2" squares (1" at the tip). We added the plan stab and elevator centerline, hinge centerlines, and a few other control points based on that fuselage CL (ends of the T13/14 leading edges and aft T14 stab spar).
Nested Ele and Stab Laout.jpg
With just a 4x increase in size to handle, a good pair of dividers handles the transfer of plan to jig grid intersection, and some thin box nails at about every 3rd or 4th grid line give me the ability to wrap a plastic spline (an 8' x 1/2" x 5/16" piece of cellular PVC offcut... Azek or Veranda) around those initial control points, then adjust the nails for a fair curve (plus add additional nails to keep the baton in place). For stuff like this, an eye-sweet curve is important - any up-scale always introduces some measurement error, so it is worth understanding what has to be dead-on (e.g., tubing cut-off for interface to fuselage mounts) and what just needs to be a fair curve that is reasonably close (+/- 1/4") to Bob's layout (e.g., elevator tip shape). A fine Sharpie allowed us to trace the applicable edge of the baton for the outside of the tubing, and a carefully selected washer handled the offset to lay out both sides of the T3 (3/8" offset) and the T13/14 (7/8") stab leading edge tubing.
Elevator Spline.jpg
We decided to use a 1" vertical lift for the T13 and T14 tubing to allow room for the airfoil-shaped stab ribs plus some room to allow back-side tacking. A little arithmetic give us blocking height for the T1, T3, and T5 tubing. Other than that, we added vertical reference blocks on one side of the blocking with the intent of using steel spring clamps to keep things aligned and allow easier adjustment where necessary. For the ribs and the T1 stuff, we cut a number of blocks from scrap to allow temporary squaring of ribs, etc. using clamps or hot glue gun for temporary tack of block.
Stab Blocking.jpg Elevator Blocking.jpg
Will post on actual construction if there is anything to add to the convo.
Job One was figuring out a reference line, and our decision was to use the LE of the elevator for fore and aft ref and elevator forward extension for the lateral ref. We gridded off the plans page in 1/2" increment for the elevator and stab using those references, then added some 1/4" increment gridding at the elevator tip to fine-tune the shape there. Once that was done, I laid out and cut two pieces of plywood to nest together along the reference line and duplicated the grid layout using 2" squares (1" at the tip). We added the plan stab and elevator centerline, hinge centerlines, and a few other control points based on that fuselage CL (ends of the T13/14 leading edges and aft T14 stab spar).
Nested Ele and Stab Laout.jpg
With just a 4x increase in size to handle, a good pair of dividers handles the transfer of plan to jig grid intersection, and some thin box nails at about every 3rd or 4th grid line give me the ability to wrap a plastic spline (an 8' x 1/2" x 5/16" piece of cellular PVC offcut... Azek or Veranda) around those initial control points, then adjust the nails for a fair curve (plus add additional nails to keep the baton in place). For stuff like this, an eye-sweet curve is important - any up-scale always introduces some measurement error, so it is worth understanding what has to be dead-on (e.g., tubing cut-off for interface to fuselage mounts) and what just needs to be a fair curve that is reasonably close (+/- 1/4") to Bob's layout (e.g., elevator tip shape). A fine Sharpie allowed us to trace the applicable edge of the baton for the outside of the tubing, and a carefully selected washer handled the offset to lay out both sides of the T3 (3/8" offset) and the T13/14 (7/8") stab leading edge tubing.
Elevator Spline.jpg
We decided to use a 1" vertical lift for the T13 and T14 tubing to allow room for the airfoil-shaped stab ribs plus some room to allow back-side tacking. A little arithmetic give us blocking height for the T1, T3, and T5 tubing. Other than that, we added vertical reference blocks on one side of the blocking with the intent of using steel spring clamps to keep things aligned and allow easier adjustment where necessary. For the ribs and the T1 stuff, we cut a number of blocks from scrap to allow temporary squaring of ribs, etc. using clamps or hot glue gun for temporary tack of block.
Stab Blocking.jpg Elevator Blocking.jpg
Will post on actual construction if there is anything to add to the convo.
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