I am covering a Herr Piper J-3 Cub balsa/plywood plane kit with Utracote. Do I put the hinges on the wood or the Ultracote? Do I just lay them on or do I need hinge slots? What kind of glue will work? I'm using Bob Smith Industries (BSI) CA medium, in the purple bottle, I think that it's called Instaset+ Any other information would be greatly appreciated. Thank you.

You need to make slots in the wood and the covering. Generally half of the CA hinge goes in the control surface and the remainder in the stab, fin or wing. I use the Hobbico CA slot machine which is fantastic but not necessary. I install the hinges after the plane is covered. I make a slot that the CA hinge will slide in easily, drill a 3/16" diam hole in the middle of the slot, clear away the side brushing in the hole created by a rotating drill, insert the hinge, and the put a few drops of thin CA in each half of the drilled hole.

But the balsa is only 1/8" thick or so. How could I ever make a hole in that? This is a 1/2A plane, so the pieces are either small, thin, or both.

That airplane is too small to use CA style hinges on. I doubt aanyone could cut the slots without destroying the trailing edges and control surfaces.

As an alternative, I recommend making hinges from your covering material. Sand the leading edges of your control surfaces to a chisel edge, pivot at the top instead of the centerline. Place the control surface (aileron or elevator) in contact with the trailing edge of the fixed surface (wing or hor stab). Cover the bottom of both parts with a single piece of covering. Be sure to iron the material down inside the "v" where the two surfaces meet.

Now turn the joined parts over and lay a single piece of covering over both surfaces. Secure the covering to the top of the fixed surface. Derflect the control surface about twice as much as you will need and now secure the covering to the control surface.

For the rudder, it doesn't matter which side you sand the chisel point to.

Not only do you have a secure hings, your gaps are sealed.


Rob

This plane is 3 channel, it only has rudder, elevator, and throttle. This is also a 1/2A plane. The kit recommends CA hinges. I would like to have help from people that have built Herr kits before. Thank you.

Use the CA hinges.

Cut a slot to slide them into, but don't drill the hole.

And (this is VERY important) USE THIN CA!!!!!

Not medium, not thick, use ONLY thin!

Here's another trick... Stick a pin through the center of the each hinge. Then put the hinges into the stab up to the pin. Now put the elevator(s) on to the other side of the hinges. The pin will keep the hinges centered until everything is in place. Now, pull out the pins, and add the THIN CA.

I recently built a Great Planes Fundango, the te was also 1/8" it used ca hinges and they seem to work well. On the fundango the CA hinge was cut into 8 smaller pieces so each hinge was now 1/2 as long and 1/4 as wide.

Hope this helps

Killer_Matt

The plans show the hinges as thin little rectangles but the real hinges are an odd octogan shape, with the top and bottom longer than the rest of the hinge. What should I do when the wood "bulges out" when I cut the hinge slot? I'm using Du-Bro's hinge sloter kit. It is spreading th wood in some spots. Is Great Planes Hinge Slotter Machine any good?

The gp hinge slotter works great. Get the slot guide as well for use on bevelled surfaces. The gp hinges are more reliable than sig. Tested them once and the sig tend to fail between the fiber and film layers, while the gp pulls the balsa out with it. Good luck...........

I built this kit in the spring, all I did was cut a regular CA hinge into 3 then take a #11 exacto and slice the slot one direction, then turn it around and slice it the other way....the thickness of the #11 is perfect for these hinges....Oh, and after their in and glued, you really could'nt see any bulging on the surfaces...

This little cub fly's great on a Norvel .061, but I found mine needed to be hand launch 'cause of the tendency to ground loop.
Aaron

"Ground Loop"? MynameisAARON, if there is any other information on this plane, would you tell me? This could elp me. I'm just getting ready to cover. What radio are you using? And is this a good "park flyer" type plane? I'm a beginner and have no experience flying. Could I try out with this? Thank you.

Ground loop=Plane would not go strait down runway( kept spinning around in circles...Pavement or packed dirt and you won't have this problem)..Carefull with the rudder throw, set to the plans it doesn't take much...I am using a OLD futaba attack 4 channel with 2 hs-81s and a hs-55 on throttle....Oh, and a standard size nicad stuffed under the tank as far forward as possible....needed it there to balances with the .061....It is a great football field flyer,thats what I would call it...Looks are deceiving, this little plane WILL move out at full throttle...Only needed for launch then 1/3 was more than plenty with a master airscrew 6/3...loops, barrel rolls,spins, all the 3 channel stuff...

This was my second plane after relearning to fly on an electric, it was still a hand full the first time..
IMHO it would be best to get help if possible the first few flights..
hope this helps,
Aaron

what's the CG? I don't see where it says it.

The CG should be marked somewhere on the plans, It is usually on the side view and may be represented as a symbol that looks similar to this:

Yeah, but I have the Great Planes CG finder. It says that you find the # of the CG and put the balance on that number.