This sentence is grammatically correct.
Conflict will move the story forward.
To start flying, they use their legs to propel themselves forward just like we do while diving into water.
They either have a piston engine with a propeller or a jet that thrusts them forward.
synonyms for propel is push, force, impel, launch, move, shoot, send, press,and start the meaning of propel is cause to move, forward or onward.