For every action there is an equal and opposite reaction kind of thing...the combustion takes place in a chamber, nozzle directs the thrust and the spacecraft goes the other way.
No air needed. It can take place in an absolute vacuum.
15 posted on 02/26/2018 4:44:09 AM PST by rlmorel
(Leftists: American Liberty is the egg that requires breaking to make their Utopian omelette)