A jet propulsion and feeding method

The invention relates to the field of jet propulsion devices, and in particular to a jet propulsion device (1) in which a first supply circuit (6), that supplies a main thruster (4) with a first fuel, has, downstream of the pump (8b) of a first turbopump (8), a branch-off (13) through a first regenerative heat exchanger (10) and the turbine (8a) of a first turbopump (8), a branch-off (13) through a first regenerative heat exchanger (10) and the turbine (8a) of a first turbopump (8), and a second supply circuit (7), for supplying the main thruster (4) with a second fuel, has, downstream of the pump (9b) of a second turbopump (9), a branch-off through a second regenerative heat exchanger (11) and the turbine (9a) of the second turbopump (9). The device (1) also comprises at least one secondary thruster (15) connected downstream of the turbines (8a, 9a) of the first and second turbopumps (8, 9).