It's completely evolutionary! To add context here. The B-21 is an manned version of a drone called a RQ-180, which is an extremely stealthy flying wing. Coupled

It's completely evolutionary! To add context here. The B-21 is an manned version of a drone called a RQ-180, which is an extremely stealthy flying wing. Coupled to existing engines (widely believed to be F-35 engines possibly with an increased bypass ratio). The B-2 had this huge problem where the original design (called "Senior Ice") was a stealthy high altitude bomber - like the B-21. But, at the last moment, the B-2 was completely redesigned to have low altitude flying capabilities - greatly increasing the cost of development and timeline. With the B-21, Northrop reverted to the original (Senior Ice) design. Building on top of all the technologies proved out by the RQ-180. And with a development team at the Strategic Capabilities Office organized to prevent anyone from adding or changing requirements. Evolutionary design + proven subsystems + focused and stable requirements. Likely the best managed DoD acquisition program in the last one to two decades.