RE: floats for blade cx helicopter
The block of foam I tested with weights, 2.5 x 2.5 x 15 inches has a volume of 1558 mL, which is way over what would be needed to make things float. There are commercially-made floats for planes in various sizes. You might be able to purchase a suitable pair and mount them, but the key to not going swimming is to test the float rig with weights before trusting your helicopter to them. The spray I saw described in a news clip provided remarkable protection to everyday electronics. However, keeping water out is probably a better plan. My first radio resides in the deep water just behind the dam in Chewacla State Park, AL, because I overlooked that part of staying afloat a long time ago. I do know how to make ordinary brushed motors function in fresh water - used them to power a sub - no good for saltwater, however. The servos and electronics need protection but also need cooling. That suggests that you would need a boat-like hull that still permits air flow. If you figure it out, please share pictures with the collective.