Serge:
So, are you saying you use 1/16" sides in the back? What total fuselage thickness do you use?
Tim-
Yes, 1/16" thick balsa from the aft edge of the nose ply to the end of the fuselage. I put it on a 1/2" core for a total thickness of 1/2" + 2 x 1/16" = 5/8". My original intent had been to use a beautiful piece of 1/2" balsa for a solid fuselage. So I did not take full advantage of the technique. Next one will be from strips of 1/2" thick balsa (
Edit: probably more like 1/2" wide strips of 1/4" balsa? Whatever...). I'll post a picture of the fuselage, after I'd switched gears, making the cutout and inserting the diagonals. After a long pause, I started to finish it this week. So I'm laminating .56-oz glass, biased 45 degrees, with West systems epoxy. This thing is really stiff torsionally.
Progressive fuselage weights were recorded as follows - so far (weights +/- .03 oz scale error):
w/maple engine bearers: 3.85 oz
w/aft cut-out: 3.35 oz
w/nine balsa (10#/ft^3) diagonals epoxied in: 3.40 oz
w/left-side 1/16" ply nose doubler (epoxied) and hard point for fair lead: 4.10 oz
w/left-side 1/16" aft balsa laminate epoxied and trimmed: 4.40 oz
w/tank recess material removed: 4.30 oz
w/1/64" ply epoxied to back, front, and rear of tank recess: 4.40- oz
w/1/16" right-side ply nose doubler (epoxied): 4.90 oz
w/aft right-side balsa doubler plus recessed aluminum engine pads (.16 oz): 5.35 oz
w/l.g. tube carry-throughs and engine recess gussets: 5.40 oz
w/roughly contoured 9/16" balsa cheek tripler: 6.5 oz
After fully contouring fins, cheek, and fuselage: 5.60 oz
w/rubbed epoxy during paper-towel removal after aborted bias-glass application: 5.65 oz
w/.56-oz glass lamination followed by surface glassing of about 35%-40% of fuselage/fin surface: 5.90- oz
after wet sanding (#400 emory paper) with Prep-Sol: 5.80 oz
That's where it stands now. The left rear fuselage is satin smooth with glass weave ready to show. So that gives a projected pre-primer/color finished weight of about 6.2 - 6.4 oz. We'll see.
Incidentally, should you try the 45-degree weave bias, be prepared for a real mess, if you don't do it in sections. Norm Skuderin read my adventures in this month's club newsletter and suggested that I might have less trouble, if I thinned the epoxy 50% with alcohol (I rolled it out, following by a Speedwell roller over waxed paper, but had major troubles). The idea was to anchor the glass with a surface sheen of epoxy set to tackiness, followed by a second coat to fill the weave. The end result seems to justify that approach, IF one can actually position biased weave without creating the worst mess imaginable. I finally got the important part down with the weave biased 45 degrees, but covered the fins with thread directions vertical and horizontal. Sanding the indentations where the glass pieces meet is not fun. The fuselage picture is of the un-glassed side, but both sides look the same, with the left being very smooth.
SK