Mk2 spaceplane fuel tanks seem half full

[Chris_The_Crafter]

I've noticed that the mk2 fuel tanks seem extremely under capacity. Assuming the relative sizes between parts has carried over from KSP1, which looks to be the case, then a mk2 tank has slightly more than double the internal volume of a 1.25m tank of the same length. However, the current mk2 fuselage tanks have the same fuel capacity (and dry mass) as the same length 1.25m tank. And the mk2 to 1.25m adapters have 3/4 the capacity of the same length 1.25m tank despite having much more volume, comfortably above 50% more volume than the 1.25m tank. For comparison, the 1.25m tank has 2T of fuel, the .625m to 1.25m adapter has 1.2T of fuel (which is spot-on according to my math), but the1.25 to mk2 adapter has only 1.5T of fuel, barely more than the next size down in adapters.  Then there's the mk2 to 2.5m adapter, which is a bit harder to calculate, but clipping 1.25m tanks into it suggests it may also be at half capacity. I'm not quite sure what to make of the mk2 to mk3 adapter yet, since it is even trickier to measure and that might belong in a discussion on how underfilled the mk3 tanks are, but the mk2 to mk3 adapter definitely  seems more underfilled than the rest of the mk3 tanks. This is why this looks like a bug to me, because it looks like being at half capacity afflicts the whole mk2 parts family. This has the effect of making mk2 stuff behave really draggy because they have more surface area and volume, but less fuel and mass than the same length of 1.25m tanks, and more drag, less fuel, and less mass are a perfect combo for a poorly performing plane that must be built larger than it has any right to be. This was a problem in KSP1, but players lived with it because the adapters wasn't quite as bad as in KSP2 is at the moment, mk2 stuff looks cool, 1.25m tanks could be added to make up the bulk of the functionality of the craft, and because mk2 parts had no competition in KSP1. But in KSP2, the drag and fuel capacity of the mk2 parts is a big deal, since mk2 stuff now has to compete with 2.5m planes due to the new 2.5m cargo bays. I could understand if the devs decided that the mk2 parts shouldn't be filled to their full geometric volume because they are a more complicated shape for a fuel tank, will have higher heat tolerance, and have some body lift, luckily 1.8x or 1.6x the current values for dry mass and fuel would result in nice round numbers. I'd like to see at least 1.8x, but the parts will still be semi-usable with 1.6x their current values. Side note: mk2 parts were really draggy in ksp1 yet had less than 1/3 the body lift that their horizontal area suggested when measured, seems like it had something to do with both the large but lightweight mk2 fuel tanks creating lots of drag and generating extra drag from the lifting surface they had to simulate body lift, I'm not sure if that's been changed for KSP2, but in the end, the aerodynamics will need to be fair for these parts to compete against planes made from cylindrical tanks and cargo bays. Anyway, devs, please fix the mk2 part fuel levels (and dry mass), I think it's important this be done soon, before players get too used to building with the bugged fuel tanks.