Ok,
so in order to build the elevators I needed some 3/8" to 1/2" (call it 7/16 inch) sheet balsa stock (1/2" for ailerons). Since 1/2" balsa is somewhat dear and I had a sheet of 1/4" (which I'll need to replace for the fuse bottom block and belly pan), I decided to build the elevators (E) & ailerons (A) by cutting
four E and A each and laminating them in pairs. From one 36" sheet I pulled the two elevators halves and one aileron. Although more work and harder to sand, there were several nice aspects of this approach:
[ul][*] Absolute centerline [*] Rock hard[*] Dead straight[*] Unwarpable[*] Lower cost
[/ul]
I made a template of the elevators (ailerons are straight 1" plus 1/8" hardwood TE for a total width of 1-1/8 inch), marked the medium 1/4" sheet with four of them, and cut and glued the two elevators
sandwiches. I then added 1/8" hardwood strips to the elevator TE's on centerline using pins on either side to align the hardwood. Then sanded both halves to identical planform and to match the plans. Tack glued each sandwich to the stab TE's and then... the work began...
I started with 60 grit and after about half an hour (don't ask why it took me so long), switched to the coarsest grit I could find - 0 grit! Typically you might want to use a planer to rough them to shape but I didn't want to risk ripping the stab TE off by this approach. I suppose you could rough them in before hand by holding them between two slabs of wood in a vice since there's not much to hold on. Since my vice broke and I didn't feel like tooling the slabs of wood, I tack glued.
After an hour I had finished the top of one half! [sm=52_52.gif] Just getting warmed up... Flip sides, 40 minutes. Another 5 of final smooth sanding. Next one, top side, 30 minutes, bottom side, a little less - I'm getting faster! Once the two panels felt like tiny silk smooth surf boards I moved on to the tips.
Sand stab tips to plan top view removing 1/8" off the TE. Attach 1/8" hardwood strips. Align tips on stab ends on centerline and insure the hardwood strips on elevators and stab tips are in line. Check that the panels are symmetric, flush and at 0 deg incidence when resting on stab tip blocks and but joined on stab centerline. Green light, OK, attach tips with epoxy.
My arms are warm now, but this time I've got some meat between the stabs and tips holding them together. Hit the planer and rough the tips to contour. Final sand with 60, 120 and 400 grit until those tips look and feel like my daughters cheeks! The stab now truly is a surf board split in half by a rough wave...
Now another fun part, slice those elevators off despite the stubborn but strong medium CA. Crack, one off, and another. A little final sanding at the junction, ooops! We've now lost alignment at the TE's between tips and elevators
- pause - we'll be OK, DB epoxy hinges, even when countersunk will put the 1/16" back into the elevators.
Mark hinges on stabs, cut out using #11 as a guide followed by my trusty 25 year old DuBro hinge knives (the DB centerline gadget doesn't work for me - eyes are better). Countersink hinges. Elevators next. Mark and begin with #11. There's not much there to work with. Fortunately the elevators are hard as a rock. Proceed cautiously with the hinge knife. Success!
Mount, bevel, test. Smooth - nice. We're done!
1/2" deflection up/down according to plans for 60 sized model. 62% scale shows up elevator deflection to 7/16" before hitting the rudder - something to think about later.
A long, hopefully not too boring read but it took considerably less time to write than the
simple finishing of this stab!
David.