Do you actually understand the concepts of specific gravity and the effect of temperature on SG? Such factors may be insignificant in some little mini-jet such as an A-4, but they are highly significant in large aircraft such as the A330.
Total tank volume in the A330-MRTT is 139000 litre. Assuming you can do sums, you might like to calculate the total mass at different specific gravity values, then adjust that for temperature deviation.
Oh my goodness. Those undies really are in a wad now.
All figures that follow are for A330-200 and taken from Jane's (which coincidentally are the same as wiki's)
Here's the density of the most widely used commercial and military jet fuels:
Jet A: 6.7 lb/gal
Jet B: 6.8 lb/gal
JP-4/F-40: 6.7 lb/gal
JP-5/F-44: 6.8 lb/gal
JP-8/F-34: 6.8 lb/gal
OEW= 263,700 lb
MTOGW = 534,000 lb
Volumetric fuel capacity = 36,740 gal (US)
Let's do some math:
36,740 x 6.7 = 246,158 lb = max fuel capacity
36,740 x 6.8 = 249,832 lb = max fuel capacity
534,000 - 263,700 = 270,300 lb = total fuel plus cargo capacity
No matter which fuel one loads into an A330, the airplane will volume out before it masses out.
For the airplane to mass out with just fuel the fuel density would have to be:
270,300lb / 36,740gal = 7.36 lb/gal. Even if the above fuels were cooled to just above their freezing points, they would not approach a density of 7.36 lb/gal. So given these facts, please name the fuel (and/or temperature of fuel) the RAF loads aboard their Voyagers that has a density of 7.36 lb/gal.
Yeah, I thought so.
Again, the USAF needed cargo floor and door in the Frankentanker because the B767's normal, somewhat limited underfloor cargo space is further compromised by the center tank plugs needed to meet the AAR requirements of the KC-X competition.
Really? That's an intersting assertion. Pray tell, why is there a cargo door and floor on a KC-135? And a KC-10?
But rather than muddy the water with other aircraft, let's look at just THREE of the hundreds of requirements of the recent USAF tanker RFP.
Load a full military 463L pallet.
Load a standard medevac litter stanchion.
Mission reconfigure time under 1 hr.
MRTT could accomplish NONE of the above.
KC-46 could accomplish ALL of the above.
Perhaps you're saying those three requirements were not really "needed" and were just USAF goldplating to ensure the KC-46 won. You're welcome to believe that, even if that belief does not quite comport with reality.
Edit:
Such factors may be insignificant in some little mini-jet such as an A-4....
Interesting that you brought that up. And BTW, you're dead WRONG. It was NOT "insignificant" in the Scooter. USAF used JP-4, US Navy used JP-5. These fuels not only have different mass densities, but also different energy densities. I had to recompute CG, range, my fuel ladder, weapons load, and other factors during mission planning depending on whether my Scooter was loaded with JP-4 or JP-5. So yes, I'm very familiar with the concept of fuel density and its affect on aircraft performance and limitations.
One more BTW. I also operated the P-3C for several years. When I was on a 12 hour or longer mission over blue water
and was loitering one or more engines during the mission
and operating at both high and very low altitudes
and operating at max range cruise AND max undurance cruise during different parts of the same mission,
and expending stores during the mission, I made damned sure I was certain about my fuel computations. So your assumption about my awareness of fuel density on aircraft performance is a fail.