A thought. The fuel levels will show somewhat different quantities whether in the three point or level flight configuration. Also the full indication at the top of the gauge will show about 9 gallons remaining before the first air shows. I did the per gallon fill routine on my first Model IV when designing my placard and discovered these details. One of the guys we frequently flew with always flew with his wife. When fueling, she always sat in the airplane and shouted out when the fuel raised to the level she could no longer see the air. He never flew with more than 9 gallons in each tank based on my gallon by gallon test.