I can attest to the battery making a fine missile.

I made a pair of 3/8 x 1/4 x 3" notched "racks" that I glued about 1" above (below?) the fuselage deck to either side and the battery slides in between them. I then took a piece of 3/8 x 1/4 balsa cut as wide as the fuselage and formed on either end to engage the notches in the racks. The foam rubber lifts the cross-piece and keeps it pressed into the notches. With this set-up I can lock the battery in place anywhere ahead of F4 up to the rear servo rail. This way I can adjust the C/G a bit. The servos and control rods will catch the batteries in the event of a crash and the rack/bar system lets loose. And that might not matter because if I hit that hard I would probably replace the servos (along with the rest of the plane). I put the receiver under the cockpit floor in one of the Great Planes reveiver boxes. It fits there like it was made for this plane.