Comment Re:gullwing doors (Score 1) 136
Rocket engines very typically ARE internal combustion engines.
The definition of 'internal combustion' is that the pressures from the combustion gases cause the motion. (In external combustion engines, such as steam engines, the heat from the combustion goes through a heat exchanger and the working fluid on the other side of that does the work.)
In a rocket the exhaust gases push directly on the exhaust nozzle, and the interior of the combustion chamber and causes the motion, making it an internal combustion engine.
Some rockets (such as nuclear-thermal or solar-thermal rockets) do have a heat exchanger, and are not internal combustion engines, but not the common ones.