eaglelope,
that's only part of the story. Water has a density of ~1 g/ml. Anything with a density less than that will also float--whether or not it displaces it's weight in water. Balsa has a density of much less than one, therefore it will float. However, airplanes aren't entirely balsa, now are they? There's the landing gear, motor, covering, etc. Problem is, if the density of the balsa can't float the ship by itself, then you have to go to the displacement theory. The only way it will float using that principle is if the bird is sank up to the wing--there is probably enough wing surface to float the airplane. by this time, however, the electronics are probably filled with water. I would do what a lot of people have suggested--wrap them in a baggie and seal them up real good. In this case, simple works. It's the KISS principle--keep it simple, stupid! (no offense).