Northrop Grumman's new B-21 Raider bomber has completed its preliminary design review, a US Air Force official revealed. The bomber will now move forward to the next step before assembly of the first aircraft; the critical design review. Northrop Grumman has also delivered the first set of software for the B-21 programme. USAF plans to purchase 100 B-21s and the first deliveries are expected to begin in the mid-2020s. Northrop has been awarded the Long Range Strike Bomber (LRSB) contract in 2015 and will build the aircraft at a company facility in Palmdale, California. The USAF's fiscal 2019 budget request includes $2,3 billion for the bomber program.