How much have you flown with this water based polyurethane? Only oil based is hot fuel resistant. There was a big discussion at one of our club meetings about this. One of our members is a finishing expert in the furniture industry and works with enamels, lacquers, acrylics, water and oil based, you name it. He has tried most all of them on his planes (he builds mostly 1/4 scale WWI stuff) and his extensive, and my very limited, experience with water base poly is that it will only last the first couple of times it gets hit with exhaust spray, then it and whatever is under it begins to wrinkle and peel. Is does dry clear and stay that way, where the oil based will yellow, but oil based gives much better protection.