Rocket engine with one-piece combustion chamber step structure, and its fabrication

A method of fabricating a rocket engine, comprising the steps of

• fabricating a combustion chamber comprising an annular wall with a chamber wall inner surface and a chamber wall outer surface, the annular wall including
• a first axial region having a first inner diameter of the chamber wall inner surface,
• a second axial region having a second inner diameter of the chamber wall inner surface, wherein the second inner diameter is greater than the first inner diameter, and
• an inner wall step transition between the first axial region and the second axial region, the step of fabricating including the steps of
• providing a combustion chamber wall blank that is oversize relative to the final combustion chamber wall, and
• removing material from the combustion chamber wall blank to reach the final annular wall by a removal method which does not substantially deform and cold work any material which is not removed from the wall blank;
• providing an injector;
• and
• attaching the combustion chamber and the injector, the step of attaching including the steps of
• bonding an annular metallic deposit to the first axial region of the combustion chamber,
• providing an annular adaptor ring,
• first welding the adaptor ring to the metallic deposit, and
• second welding the adaptor ring to the injector.