US Air Force B-21 "Raider" strategic bomber. Since the moon phase in December 2022, the operational capability and subsequent development of the US Air Force B-21 "Raider" strategic bomber (hereinafter referred to as B-21) has been attracting attention from all walks of life. According to the report on the website of the US National Defense magazine in the middle of January, as the project continues to advance, various challenges come one after another, how to solve the financial problem, whether 100 aircraft can be delivered on schedule, and whether they will go back to the "old way" of the F-35 fighter project... Northrop Grumman, the manufacturer of the B-21, said that before determining the final configuration, The company has tested thousands of bomber designs in a digital environment. It can be said that the machine plan is one from a thousand miles. Austin, the US Secretary of Defense, has previously revealed that this bomber can ensure that any target is in danger without being stationed in the theater and specific logistics support, implying that the B-21 has a long range and considerable payload. Austin also mentioned that the heavy bomber is a multifunctional aircraft with intelligence, surveillance, reconnaissance and combat management capabilities. According to the current public situation, the B-21 continues to use the flying wing layout scheme of the B-2 bomber and has made progress in stealth design. The machine uses the open system architecture and "global joint command and control" technology, and can share data across platforms. At present, the US military has not disclosed whether the B-21 uses two or four engines. Judging from the small air inlet of the aircraft, it will probably use two F135 engines. If the afterburner is not turned on, the two F135 can generate 25.4 tons of maximum thrust. Northrop Grumman called the B-21 the sixth generation aircraft and "the first of the sixth generation systems". In fact, there was no authoritative or widely recognized scheme for the generation of bombers. This time, the United States called the B-21 the sixth generation aircraft rather than the sixth generation bomber, which is intended to integrate it with the sixth generation fighter and other systems, but also has a lot of publicity. However, this deliberate propaganda makes people feel that the US military is not so confident about spending a lot of money to develop an aircraft with no essential difference between the shape and the B-2 bomber, so it has repeatedly stressed its significance and placed the title of the sixth generation aircraft on it. The B-21, which carries out the penetrating strike mission, is a bomber with both nuclear and conventional capabilities. When carrying out the nuclear strike mission, it can carry the new B61-12 nuclear bomb under development and the "long-range stand-off" missile with nuclear warhead. When performing the conventional strike mission, the B-21 will perform the so-called penetrating strike mission, that is, the aircraft will break through the enemy's air defense system and strike in the depth of the enemy's defense. The advantage of this attack is that relatively cheap weapons and ammunition can be used in large quantities. It is estimated that the unit price of air-launched cruise missiles is more than US $1 million, the cost of hypersonic missiles is more than US $30 million, and the unit price of economical guided weapons such as GPS guided bombs can be reduced to less than US $30000. International armed conflicts in recent years have shown that cruise missiles are often not enough to fight, but can be used in large numbers