The National Interest:
If everything goes according to plan, sometime in the mid-2020s the Russian Navy will adopt an anti-ship cruise missile called the Zircon. It’s a highly maneuverable and hypersonic cruise missile — meaning a weapon capable of traveling at speeds in excess of Mach 5 due to its advanced scramjet engine.
Scramjets kick in once the missile has already accelerated to high speeds with the use of a conventional solid-fuel engine. Once zooming through the air, the scramjet sucks in and compresses air already traveling at supersonic speeds to propel the vehicle further at velocities lesser engines can’t handle.
