Abstract: With the speedy and hot airplane turbojet exhaust gases a lot of energy is blown away and wasted nowadays. By this invention a venturi (35) and a diverging duct (14) transform this exhaust energy into a useful and strong low pressure gas stream that sucks outside air through a fan (3) and a bypass (9,10,11) outside the original turbojet engine. (here called core engine). Thus the fan (3) is propelled and drives the central shaft (2) of the core engine (4). Now the turbine (7) in the rear of the core engine (4) can deliver less energy to the central shaft (21) for maintaining the right rotation. Likewise turbine (7) can absorb less energy out of the hot and speedy gases inside the core engine. A bigger part of this energy is available for creating thrust now. That is the major profit of this new invention.