That's just sort of a way I decide what size tank I'm going to install. I don't have any big floaters in my hanger so it's hard to gage how long a big Senior would fly with that size tank, I never saw what size engine you have but it looked like a 100GK?? To float around at 1/3 throttle it would fly all day. I do know a few guys that will do that but I can't focus that long myself. I do it with my little electric but get eye strain after about 20 minutes. I'm fooling with a header tank right now, it's installed but I haven't test flown the plane yet. It's a small pattern plane but the fuel tank is about a foot behind the engine. It runs and will fly well but after I use up a bit of fuel there isn't enough pressure. I added a 2 ounce header right behind the engine to see what would happen? One 16 ounce tank should fit right behind your fire wall and give you a lot of flight time and remove any fuel flow problems you have.