ENGINES

heat engines
- combustion engines
  - internal
  - external
  - air breathing engines
    - Reciprocating engine
    - Steam engine
    - Gas turbine
    - Airbreathing jet engine
    - Turbo-propeller engine
    - Pulse detonation engine
    - Pulse jet
    - Ramjet
    - Scramjet
    - Liquid air cycle engine/Reaction Engines SABRE.