The 5th generation Su-57 fighter used internal fuel tanks installed inside the weapon bays during its flight to the El Alamein International Airshow in Egypt. This was reported by Rostec.
The new design solution allowed not to occupy external hardpoints with fuel tanks. After an intermediate landing, the Su-57E still had a fuel reserve for approximately 1000 km.
The ability to use internal fuel tanks inside the weapon bays instead of external hardpoints fully corresponds to the concept of a 5th generation aircraft. This solution allows maintaining the aircraft's aerodynamics and providing a significant ferry range.
The state corporation clarified that the flight took place with one intermediate landing. The next day, the Su-57E performed a demonstration flight, comparable in fuel consumption to a full-fledged aerial combat.
Recall that the Su-57 has four internal compartments. Two main ones are located directly between the engines – they can accommodate, for example, R-77M missiles, as well as Kh-69 and Kh-58UShK. Also, small side bays at the wing roots have recesses for R-74M2 short-range missiles.