Construction Manual
Mount Tail Group
The first thing I like to do here is to scuff the whole boom with fine sandpaper. This should be something like 400-600 wet or dry and the boom should be sanded in a lengthwise direction.
Both the fin/rudder and the stab/elevator should have the leading edges shaped now. Take the time to make the leading edge oval or egg shaped as opposed to just rounding them off. When satisfied with the shape, seal all around both with thin CA. This will waterproof and greatly add to the stiffness of the parts.
Now prepare the stab by marking exact center at the hinge line and with a small square make a line on top of the stab. This is where the mounting holes will be located. On my own planes I like to make a small plate out of 1/32nd ply to keep from crushing the stab with the screws. Drill stab-mounting holes and attach to stab mount. (try the mount on the boom, there is a front and a back) On the stab mount, clean the inside of the rings with fine sandpaper and then split the bottom of each mounting ring with a Dremel cut off tool. Slide the stab assembly on the boom. Hold the fin/rudder assembly beside the boom. The rudder hinge line should be about ¼ to 3/8 ‘ from the end of the boom and the elevator should JUST CLEAR the fin. This is the front/back position for the stab/elevator. Put a mark by one of the rings so that you don’t lose this front to back position. Bolt the wing on the fuse. Now you can align the stab by sighting from the front or rear and aligning with the wing. When satisfied with the alignment, put a drop of thin CA on each ring. Double check alignment and put another drop of thin CA on each ring and the stab is done.
The fin fits to the boom at the widest part of the chord. I recommend slotting the front half of the fin and the rest in the boom per picture. The rudder hinge line should be perpendicular to the top of the boom and the fin should be perpendicular to the stab.
When satisfied with the alignment of the fin/rudder tack with CA to the boom. Double check alignment and then when satisfied, fillet the boom/fin joint with medium CA on all four joints. Use some lightweight fiberglass cloth to reinforce the joints starting on the fin, up over the boom and back on to the fin. Attach with thin CA. Take a minute and put a quick wrap or two of kevlar thread or heavy sewing thread around the boom at the very front of the fin. This will greatly reduce the possibility of splitting the boom on a bad landing.
We now have an airframe!