If you look closely at the picture in my gallery, you'll see one of the scale size and location Dump door hanging down, they're very large and I think the Water ball will be really cool to see

16 oz's/1lb. is a lot for your size plane I'd think instantly heavier. Mine is much larger I was hoping to be able to hold 1/2 gallon/4lbs.
But will start with less by adjusting the depth of the vent/overflow tubes

I plan to get it down and start working on it again soon,, I'll post some more pics in my gallery

It's all about Fun