I have a problem with balancing my 4*40. The plane is completely covered and built, but to balance it I have found that I need to install the battery behind the radio bay bulkhead(behind the wing). Problem is I can't figure out how to install the battery back there. Does anybody have any suggestions as to how to accomplish this. The control rods are in the middle of the fuselage. My last option if I can't get it in the fuselage was to build a cover for it and install it under the canopy. Help please.

I know you probably don't want to, but what about removing the covering from the first lightening hole (on the bottom) behind the wing? Strap the battery to a length of wood that runs from behind the the first former aft of the wing to the second one aft of the wing and glue in place between the two formers... you'll wind up with a patch in your covering, but at least it's on the bottom where it won't be seen.

What about 1/2 to 1oz of foam stick tape lead strip under the horiz stab ?

Far too much work cutting covering and moving battery back behind bulkhead.
Did you put a .75 on a .46 plane ?

I just put a 4*40 ARF together last week. I had the same problem you did. I couldn't figure out a way to mount the battery back there. I ended up just wrapping my reciever in foam and packing it under the front of the servo tray. Then I wrapped the battery in foam and placed it in front of the reciever. (between the fuel tank and the servo tray) I then took a piece of 1/4" balsa and made a brace to hold it in place. It was a litte nose heavy. With 3/4 oz. under the horizontal stab it balances just towards the front of the main spar.
Another thing I did per my instructor was ignore the aileron placement template. He had me align them with the bottom of the fuse. Took 2 clicks of elevator, and 2 clicks of aileron to get her to flight straight and level on her madien.

I cut and patched the covering over the first lightening hole. I then zip tied the battery to the pushrod tubes, with strings to keep it at the distance I wanted it.

I have also seen people cut a hatch that fits inside the lightening hole so that you can access the battery for maintenance.

I'm not sure if the 4*40 wing hold downs is the same as the 4*60,
But as I was moving my weight back to get it a little more tail heavy
I drilled a small hole between the wing bolts/screws on the fuse
spar and just wire tied it.. It's worked great so far..

Not sure putting the weight of the battery pack on the pushrod tubes is a great idea. COuld cause unwanted deflection of the surfaces during manuevers.

Add a little stick on weight under the stab.
Dennis-

Thanks all,
I guess just adding a little weight to the stab is the way to go. By the way the engine is a TT .46

Please let us know how it flies and your experience with the TT46. I am also building one and plan to use the TT46 as well. Thanks.

I think if you can move existing weight around to get the CG right on
is the way to go.. Most times it's not that hard.. But, true a little bit of
stick on weight won't hurt, But, why add to your planes total weight...