Agreed. . not required. . but still not a bad idea.

I run 40-50 ounce tanks on all my big stuff, which would, in theory, give me 25+ minutes of flying time. I set the timer for 15 minutes, though, and follow it religiously. Why? Practicing IMAC sequences has shown me that below 1/2 tank level it is very possible to starve an engine for gas, especially in the middle of low-G meandering maneuvers such as spins where the gas may go to ne side of the tank and the clunk may not follow because there is not enough G force to make it go that far. The result is fuel starvation at low throttle (especially in nose-down attitudes where the gas goes to the front of the tank) which is a bit exciting when you come out of the dive/recovery at 50 feet wayyy out THERE on the backside of the IMAC Aerobatic box. Try it on a windy day and it gets to be even more fun. . .

I have one of the BVM Header tanks that I will be experimenting with in a 38% 260. It holds 4 ounces of gas and I'll be mounting it inside the engine box. This is to not only make sure I have a "bubbleless" fuel supply near the engine, but to add a touch of noseweight (the tank is always FULL). I'll be using a 32 ounce Main tank over the wing spar instead of my normal 50 ounce tank. My figuring is this. . I'm only using about 25-30 ounces of gas out of a 50 ounce tank anyway, so why not make SURE I have a readily available and consistent fuel supply (with the header tank), and get rid of 8-12 ounces of unnecessary weight at the same time? Since the fuel system, except for the vent to the main tank, is totally sealed, the carburetors pump will easly pull fuel from the entire system, and any air bubbles (as long as they are small) will be trapped in a corner of the header tank while the centralized pickup tube is totally immersed in gas at all times.

It's just an idea I am going to try, but if we never try things, we never progress, right? I'd rather give this a shot than constantly worry about fuel starvation at less than 1/2 tank level. Lose a $5000+ IMAC plane just ONCE to a long-distance deadstick and you'll appreciate the lengths some of us go to in order to ensure it never happens again.