Fuel load is dependent on bomb load.
Look at the first post. An increase of 10,000lb of bombs had the fuel reduced by ~8000lb.
Not always. Even short hops across the English Channel had B-26s and B-24s topping off the gas tanks. Fuel was life. You could always put 500 bombers in the air to get more bombs on target. Most times bombers carried as much fuel as possible. It's only a rare few examples with some overload bomb situation that had reduced fuel, but the fuel reduction was still the max capable (it wasn't "oh, let's only put 100 gallons in the tanks today, boys")
It's historically inaccurate to have any 4-engine bomber (hell, any 2-engine bomber) from taking off with less than full fuel.
Forget fighters for a moment. The most common retort to this is "same for fighters" but this is obviously not even comparable. We're talking apples to astronomic units.
Bombers accelerate far faster, climb way better, top out at MUCH higher alts than historically possible, and get up there in a fraction of the time, compared to historical real-world performances. In this game they also run full power despite less fuel, so even in the real world they'd climb at reduced power, cruise to targets and back, and go through the combat zone much slower, lower, and heavier than anything in Aces High.
When you have something designed to fly 1000 miles and back, but it's only going 50mi and back in-game, you will never need more than 25% ever. If we had customizable fuel loads, folks would exploit this even further, by exaggerating bomber performance with 1% fuel loads, so be thankful it's not worse than it really is.
If we get a B-29 in AH I only hope it has a 30-minute "WEP" speed after which your power drops to max continuous, as even in the real plane you risked having a meltdown in the engines if you ran them that long at full power. I'd say this plane will be faster, more effect, and more dangerous than an Ar234 because its performance will be so unhistorically "boosted" by AH modeling concessions.