Here's my problem:

The tailfeathers of my Kyosho GeeBee-Z is set up so that the right and left must be installed separately. The connection for the push rod is on the left stabilizer only. In order to get the right stabilizer move up and down together with the left, a " [ " shaped piece of metal is used to connect the left with the right. It does not, however, serve as a hinge. CA hinges are used on each stabilizer. I had a few questions regarding this setup:

1. The " [ " metal piece fits INTO the balsa wood of each stabilizer half. Yes, I had to drill holes into the narrow side of the stabs for the metal piece to fit into! Over time and use, the metal piece will open up the holes and create play between the two halves of the stablizer. What can I do to prevent this? Should I glue the metal piece in there to ensure that it doesn't move? Again, it is not a hinge. It is only a connector between left and right.

2. OR....would it be better to find some kind of Y-shaped pushrod that attaches to each stabilizer, thus eliminating the need for a connection between the right and left side? When I say "better", I mean less potential for developing play between the two stab halves.

after drilling the holes use thin ca to toughen up those holes.also have a slot on the leading edge of the elev. control surface to conceal that rod. after trial fitting epoxy the rod into those holes. ca the hinges after the epoxy has set up.

Yup, that's how you do it. If it doesn't look strong enough, you can wrap come fiberglass cloth over the joint. Let the wet epoxy soak into it.

A Y shaped pushrod also works. Or you can use two pushrods and join them at the servo horn with wheel collars. You're welcome to just follow the plans, or try to make it better!

Tom

Im surprised the instructions do not say to glue them in. Three planes I've assembled/built had this setup, Sig Somethin' Extra ARF, GP Ultra Sport 60 kit and GP ElectroStreak ARF.

My Ultra Sport 60 had well over 400 flights on it before a servo went dead and it returned to kit form and it held up very well.

I drill the hole then take away some wood in between the hole and the inside of each elevator half so the rod actually sits inside. Use a fine grit sand paper to roughen up the rod so the glue can bond. Then I fill the holes with epoxy and hold the rod in place using some masking tape. Put the assembly on a flat surface and put a book on it to keep it flat while the epoxy cures.

Hope that helps.

I have a 60 size dynoflite mustang that i built in 1991 and it has over 16 gallons of fuel thrue it and it has this set-up and is still tite.I would drill hole,ca,redrill hole slightly oversize on one side to give me a little play so i can get both sides perfectly paralell to each other,test fit then glue with epoxy(ram epoxy down hole with toothpick)Just make sure before the epoxy hardens they are perfect to each other.

On the part of the wire that goes in to hole, grind off some of the metal so it is thin and flat. This part of the wire will never bend. Now you don't need to make such a big hole in the balsa. If you make the wire part thin enough (like a knife edge), you can just push it into the balsa. The idea is to not weaken the balsa with a hole.

I do the same thing where the tailwheel wire goes into the rudder.

Tom

If I understand correctly, what you're talking about is driving the metal wire into the balsa directly, kind of like a wedge. That is precisely what you don't want to do, as that will weaken the wood. The idea of drilling a hole is so that you can slide the piece in without wedging the fibers of the wood apart, which could cause it to split over time. When I drilled the hole, I drilled the smallest hole possible that would allow the wire to fit snugly.

I have a negligible amount of experience with balsa and airplanes, but this principle applies a great deal to dentistry. Sometimes, when we don't bond large fillings to teeth, we have to use pins to hold the filling in. One of the major risks of placing pins (which are less than a millimeter in diameter) is splitting of the tooth! Balsa has more give that dentin, but the physics are the same.

I knew you were a dentist! I'm sure you have the nicest set of stainless tools.

I've never done a filling, but I know balsa doesn't split that easily. Just be gentle (like you are with your patients). You may want to start with a little hole, but my idea is to not sever the wood fibers, rather just move them to the side.

Tom