Dynaflite Talon Notes

I've completed construction on my first from-scratch balsa kit, a Dynaflite Talon. I didn't follow the plan completely. Modifications include:

V-Tail, but not all-flying: ruddervators instead
One servo per aileron for flapperon experimentation
Fiberglassed lower section of fuse

This puts it up to four servos instead of the two as specified, so it'll be somewhat heavier than the original design. Hopefully I won't need to rename this to "Project Lawn Dart".

Here's a series of photos detailing the interesting parts of the construction process, as well as a considerable number of first-timer errors.

Since my V-tail deviates from the plans (it isn't all-flying), and at least one other builder thought it was too weak to begin with, I strengthened it up somewhat. If you look at the picture, you can see two spars (not yet cut to length) exiting the root of the stabilizers. These will get joined into the tail block in (next picture), so that the stabilizers aren't just tack-glued onto it. There's also an additional cross member (the one that starts at the root) since I don't have to account for the torque rod that was per-plan.

Here we can see the stabilizers inserted into the V-tail. You can also see the pushrod exits for the ruddervators. Mistake: I glued the V-tail assembly together at this point. While this helped with final alignment somewhat, it would have been better to have waited until they were covered. Mistake: I miscalculated where the control horns were going to be. As a result, the pushrod exits are too low and needed to be moved upwards. Since this involved enlarging the holes, I had to do some work to strengthen the fuselage back up. Not a big deal, but irritating nonetheless. Mistake: The pushrods exit just aft of the second to last former. I did this to simplify my cuts in the fuse around the former, but this makes the final bend somewhat sharper than it should be. Next time, I'd make them exit just ahead of that former instead. But this still seems to work; I used cable rods instead of the nylon that I was planning on, which trade increased weight for increased flexibility.

Here we can see the nearly completed fuselage and canopy. No plan deviations here, except for the additional pushrod coming from the tail. Glass that fuselage! Lots of fiberglass! Let me restate this in case it was not clear. FIBERGLASS THE FUSE. Even then, it'll probably still break. The fuse is very attractive, but extremely fragile, particularly just aft of the wing cutout. If you're really trying to make this an HLG, maybe you could ignore this, but if it's going to be a sloper, you'll need all the strength you can get. The two ruddervator servos are laid down, one on top of the other. They fit between a former, a brace to aft, and two rails on the bottom of the fuse, and are held down by the wing. No screws required, which is lucky since I have no idea how I'd get a screwdriver in there.

Mistake: I was hoping I could paint the completed wing, then Monokote over. That way, there'd be coloring underneath, no matter how badly I flubbed the cutting of the Monokote. Unfortunately, I couldn't get the iron temperature low enough to bond the Monokote to the paint without bubbling the paint a little. It's not too noticeable, but I'd definitely mask next time. Mistake: since I planned to insert two servos (HS-81's) into the wing instead of one, I widened the separation between the root ribs slightly to make room. Unfortunately, I didn't make enough room, and missed by about 1/16". I cut part of the rib out to make room. I doubt there's much stress here, so it shouldn't be a problem. I kept having visions of the wing separating from the fuselage during aerobatics, so I re-tapped the threads in the wing and used a helicoil insert.

The completed, covered plane. As you can probably guess from the last picture, when it's flying at eye level it tends to disappear...