Pictured is a 750 gallon tank and the concord had a fuel capacity of 31,500 gallons. Thats he equivalent of 42 of these tanks

Taking an absolute guess here..

But could it be the difference between raw capacity (as shown in the tank image) vs compressed?

My thinking here is from when F1 teams started chilling down the fuel to fit more in a tank.

Funnily enough the volume of fuel is approx half the volume of the entire plane, and it uses fuel at double the rate of a 747.

Engineering is awesome.

Pretty much distributed over the entire area of the plane:

https://www.heritageconcorde.com/fuelgeneral

Like most planes, the wings are mostly fuel tanks. https://www.heritageconcorde.com/fuelgeneral

Your picture shows the scale quite well, actually. Imagine that girl sitting in the cockpit and then imagine the size of the barrel compared to that.

Fuel is typically measured by weight in aircraft so "a full tank" might be different besed on the density of the fuel.

The wings and body.

https://upload.wikimedia.org/wikipedia/commons/8/85/Concorde_fuel_tanks_en.svg

Here's two pictures showing how the tanks were arranged:

There were actually 13 fuel tanks on board.

Just realized how many things have to work smoothly in an aircraft. So many fuel pumps and they all have to distribute the fuel correctly without failing.

Are you familiar with Admiral Cloudberg's writeups of air disasters? https://admiralcloudberg.medium.com/ It's exactly what you're talking about: a lot of things have to go right on the plane, in the cockpit and on the ground.

The gains from increased density were extremely marginal, but then again F1 is a marginal gains game. Maybe you could push a couple extra % more in some parts of the race to gain or secure track position but it wouldn't change overall performance. That's also why the FIA switched to fuel weight instead of volume.

On a plane like this it wouldn't make a difference as weight is more important than volume.

At least this picture explains that oddly shaped hole in the middle: It's the place for the main landing gear to fold in.

Fuel is a liquid. What did you learn in school about liquids?

By the way, that oddly shaped hole in the middle is where the main landing gear folds into.

Now all together in unison: liquids are incompressible!

Things aside, from an engineering perspective, liquids have a much larger resistance (bulk modulus) against compression than against shear. Thus, water is considered incompressible whereas steel isn't, despite the bulk modulus of water is about 2 GPa and the one of steel is 160 GPa.

They were talking about the F1 teams chilling the fuel to fit some extra fuel inside the tank. As the thermal expansion of coefficient of fuel is about 1·10^-3 /K, they can fit another 1 % of fuel into the tank for every 10 K of extra chilling. However, this likely has its limits at low single digit percentage values, which is sufficient for some extra miles in F1 but not useful for dimensioning fuel tanks of the aircraft around that mechanism.

The FIA also added a temperature limit to reduce this effect that I was mentioning. I just did some slight research on it, looks like when it was at its most effective in the 80's, cars had a 195 litre tank, with fuel chilled to about -30c this allowed for an extra 10-12 litres, or about 6% increase.

This change was huge in that era of racing, basically meant that drivers could stay at 100% pace for longer without nursing fuel. Coincidentally, when doing some reading on this I also found that apparently chilled fuel during the refuelling era of F1 also helped increase the flow.

Anyway, that was my thinking originally lol, looks to be actually answered in the comments now though. Thanks for the reply!

When flying this plane there must be a great moment where you've used up enough fuel that it feels insanely fast and light as a feather but not so much fuel that you're stressed about having enough to get home.

I'm fully with you here. The one or two percent thermal expansion/compression is way below the usual safety margin of a plane, anyway.

By the way, those green "trim transfer tanks" were used to adjust the airplane's center of mass by pumping fuel forwards and aftwards.

There's a phenomenon called "Mach tuck" that generates a large pitch-down torque as the plane passes through the transonic regime, Mach 0.8-1.5. The fuel had to move aft to compensate.

Ha now that you mention it yes it is wheel sized.

When I read 42