The H-1-J engine and how it works (my imagination). In yellow-Air intake for effective fuel combustion in jet engine. In Purple-Oxygen duct to carry the air from the intake to the engine. In Orange-Separate Cryogenic fuel duct for carrying the Cryogenic fuel which consists of LOX (liquid oxygen) and LHY (liquid hydrogen) to the rocket engine. In Red-Extra air intake for cooling down the Cryogenic engine to maximise efficiency. In blue-Jet engine which combusts liquid fuel and air to create a jet of hot air shooting out the back. In Green-The cryogenic engine which mixes LOX and LHY together to create ahighly combustable mixture, the nozzle also extends while on full power to allow more combustion to happen. The mixture then mixes with the hot jet of gass from the jet engine and rapidly expands wile combusting and creating huge power with great efficiency.