General question. I finished up a Kraftkit 4 Seasons 40 and had to add some weight to the tail to balance out the cg. I generally use stick on weights and attached these to the monokote on the back of the tail area.

What does everyone else do?

As far rearward as you can get it. But never on the moveable surfaces (e.g. rudder or elevator).

I agree as far rearward as possible. I know stick on weights are ugly. Won't these some loose on monokote? Other suggestions? Maybe the next time building a compartment for weights.

Jim

As far back as possible on a NON MOVEABLE SURFACE.

Then outline the weight and CAREFULLY remove the covering about 1/16" INSIDE the outline.

Stick the weight on and then wick some THIN CA between the foamj and the wood.

The weight will not come off.

What I do when building a kit (or scratch ) is to make a hatch in the back in case I need to add weight.

before adding weight, try and move things around inside your plane first(like batts or reciever) try and only add weight as a last resort

I added the weights on the top of the horizontal stab and then covered them with monokote. Not the prettiest but i will be able to tell if they fall off. I was afraid them being on the bottom and one did fall off i would not notice it.

I just wipe the covering with alcohol and stick them straight on the covering. Never had a problem with them sticking, just trying to get them off. I do put them on the opposite side of the muffler just to keep them out of the exhaust as good as can be, and on the bottom side of the stab to keep them out of sight while on the ground (you don't see them in the air).

Hogflyer

The battery pack and the receiver is close the c.g. of the model. I could get rid of the spinner and maybe swap out the european muffler that came with the super tigre 40 with an older muffler. Change to lighter lower bounce tires.

Jim

it depends on model itself and what i'm in the mood for. i generally just cut through the covering and epoxy
the wieght to the rear former. At the flying field for a quick job. I use CA or 5 mins expoxy.
If i built a model previousely and knows it's going to be nose heavy. then I don't
mind beefing up the rear section of the fuselege. The 4* 40 is a go example. The weak piont of the fuselage is
behind the former of the wing mount. i also paint the canopy black and screw on the canopy. The cokpit becomes
the battery's mounting bay. It allows me to move the battey pack farther. Nothing fancy, tie straps to secure it.

For tail heavy model, sometime the battery pack has to go into fuel tank area.

I build in hatches to most of my models anyways. it's alot easier to remove the fuel tank at the flying fly,
if the clunk line gets sholved forward and get stuck, then to be shacking the heck out of my model.lol

The battery in the nose area under the fuel tank would have been easy if the model was tail heavy, but it's nose heavy. Not much 1.5 oz is all i needed in the tail. I would probably have to find 3-4 oz to remove in the front of the plane.

Jim

would you be able to add a battery hatch behind the cg?

This is one my dad built for a great planes super sportster


this would allow you to not have to add anything.

Steven

I'll have to work these in on the next plane.

Jim

I usually try to build a weight box, or at least a blind nut I can screw sheet lead to, inside where it doesn't show. If you have rear servos you're gold. I use electrical tape to fasten pennies or flat leat weights to the servo box (works for lateral balancing with the aileron servos, too). I have shimmed lead between a tail-wheel bracket and the fuselage . . . faired nicely it looks almost like it was intentionally designed that way. Or, with a nose wheel model, added a lead skeg at the tail. The farther back you can get it the less weight you need to add. It is always worth trying to accomplish balance with the battery pack. Adding no weight at all is the best solution.

I cast lead round balls for muzzleloaders and it is handy to be able to carve a mold as needed out of wood and pour the lead to any size and shape I need.

One of the moderators said it once before.. remove the covering as outlined above, remove the covering, then fit the weights. Drill through the weights and the wood underneat, hit the holes with some CA then use the sticky tape on the weights to hold them in place and put a servo screw in the holes to hold it in place. One on each end if using more than 3 of those dubro small sticky weights.

Thanks to all for your replies. I'll use a combination of adjusting the weight in the nose, and try to minimize the stick on weights at the tail end.

Next build I'll do some hatches to install the weights. I have an old Jemco AT-6 kit at home (not started), might just cut a hole and pour the lead in at the tail end.

I'll bring the marsmallows and skewers.

I can almost always find a way to move the batt around. If the model has openings in the bottom(through the lite ply, for example) I just seal the covering around the edges of said opening, remove the covering over the open part, put a lip around the inside edge of the opening, and make a cover out of material the same thickness as the fuse material. Actual location of hatch depends on where the batt sits on outside of fuse to get plane to balance. Can either cover hatch and screw in place or cover hatch directly to fuse. If there are no openings already, I make one.

If you have to add weight (battrey relocation doesn't work) then I suggest drilling, or cutting a 1/2" hole as close the rear of the fuse as you can on the bottom side. Hang the plane up by the prop and insert enough "Bullet" shaped lead fishing weights coated with epoxy until you get the CG you're looking for. To accurately do this, you will need to know how many weights is required before you start stuffing the weights in. Also account for a little extra weight that the epoxy will add. Keep the plane suspended by the prop until the epoxy has curred. A small covering patch over the 1/2" hole and you're almost done. Double check the CG. Now you're done!

Jim, I had to add weight to the tail end of my Solo sport (looks like an Alpha 40). What I did was move the battery back as far as I could and made a little ply box for it to sit in and then ran two screws from the under side of the fuselage into that little box. Easier to say then do....lining up the screws is a big pain but it can be done. I had to add extra support to the fuselage floor for the added weight and tension from the screws and nylon washers outside, nothing major. Then I added the rest of the needed weight to the inside of the very end of the fuselage opening. I got some of those tape on weights and stacked them and drilled a hole threw them so I could fasten them to the fuselage bottom with a screw. On this deal make sure you add extra support if you don't it'll break the balsa wood from the weight alone during a loop. It happened to me and I was lucky since the weights were just loose and rollin around in the plane...very lucky nothing went wrong! Anyway with extra support (pop can aluminum) inside and bigger nylon washer outside that fixed that.