Multiple-use rocket engines and associated systems and methods

A method for launching vehicles, comprising:

• launching a two-stage vehicle having a first stage and a second stage carried by the first stage, by powering the first stage with a first rocket engine having first rocket engine components arranged in a first component configuration, the first rocket engine components including a first combustion chamber;
• separating the second stage from the first stage;
• and
• powering the second stage with a second rocket engine having second rocket engine components arranged in a second component configuration, the second rocket engine components including a second combustion chamber that is interchangeable with the first combustion chamber.

A method for launching vehicles, comprising:

• launching a multi-stage vehicle having a first stage and at least a second stage carried by the first stage, by powering the first stage with a first engine;
• separating the second stage from the first stage;
• powering the second stage with a second engine;
• recovering engine components from one of the first and second stages;
• and
• powering the other of the first and second stages of the same or a different multi-stage vehicle with the recovered components.

A method for launching vehicles, comprising:

• launching a two-stage vehicle having a first stage and a second stage carried by the first stage, by powering the first stage with multiple first rocket engines, each having first rocket engine components arranged in a first component configuration;
• separating the second stage from the first stage;
• powering the second stage with a single second rocket engine having second rocket engine components that are interchangeable with the first rocket engine components, arranged in a second component configuration that is interchangeable with the first component configuration;
• delivering a payload to orbit with the second stage;
• recovering the first stage;
• removing at least one of the first rocket engines from the first stage;
• installing the removed first rocket engine on the second stage of the same or a different two-stage vehicle;
• and
• launching the same or the different two-stage vehicle with the removed first rocket engine powering the second stage.