When it's a ramjet that uses rotating ... Rocket Engine (RDRE), which overcomes the limitations of a rocket or jet engine by using another novel principle – again, with no moving parts.

Image: The Economist A conventional jet engine uses lots of moving parts (see diagram). Rotating blades draw in air and compress it before igniting it with fuel in a combustion chamber ...

Low-pressure turbine blades in silicon-carbide ceramic matrix composite for F414 adaptive cycle combat engine Lighter rotating parts Advance in CMC for jet propulsion Tests validate temperature ...