What made Concorde so heavy? The Concorde burnt five times more fuel per passenger mile than the 747. A huge contributor must have been the immense empty weight per seat, three times that of the B747.





B747-300
Concorde




Empty Weight
174,000 kg
78,700 kg


Passengers
400–660
92–128


EW/Passenger
263–435 kg
615–855 kg




This weight excess is distributed among the slender fuselage, thin wings, long landing gear, big engines, and (possibly) material constraints.
But how much of the weight increase comes from each of these components, and why? I am looking for a comparison with the weight breakdown of a conventional jetliner
The Concorde mainly transported fuel across the Atlantic so that enough was available to land safely. Passengers were just an extra on top. Also, being first-class only, it held fewer passengers than what low budget airlines have taken to cramming into their planes lately.
To look at the structure relative to passengers is a bit misleading. Let's look at the fuel load and the mass fraction of empty weight relative to MTOW instead:





747-100
Concorde




MTOW
333.4 tons
186.88 tons


Empty mass
162.5 tons
78.9 tons


Fuel
183,380 liters
119,800 liters


Fuel to empty mass
1.1285 L/kg
1.5146 L/kg


Mass fraction of empty to MTOW
48.74%
42.22%




If you compare passengers plus fuel to the empty mass of each airplane, the Concorde actually comes out well ahead of the 747 and looks like a prize of lightweight design. Having structurally efficient delta wings helped and should explain most of the difference.