Dung Tran Military12.4K subscribersThe first B-21 prototype will undergo engine testing, getting ready for its maiden flight from Air Force Plant 42 to Edwards Air Force Base in California. Mr. Costello said Northrop Grumman Corporation currently has six B-21 stealth bombers at different stages of production. “We are on track for our first flight and are staying on schedule,” Costello said, without detailing the test plan.