The US B-21 "Raider" bomber made its debut at the 42nd Air Force Factory in Palmdale, California, on December 2. Before the appearance of the bomber, the pilots emphasized to the reporters that the window shape and vision problems of the B-21 did not affect them. It was reported on the website of the US Defense News Weekly on December 10 that the test pilots who will take the lead in piloting the next generation of stealth bombers of the Air Force are currently working with officials of the Air Force and Northrop Grumman to formulate an action plan for the first flight next year. The Air Force released a B-21 art effect picture in 2021, which implied that the four windows of the bomber were strangely shaped, especially the side windows. The effect picture showed that the B-21 side windows were warped and narrow compared with its predecessor, the B-2 "Ghost" bomber. Todd Harrison, a defense budget expert and managing director of Mitya Strategic Insight, told the reporter of Defense News that the effect picture surprised many military aircraft enthusiasts, and some people therefore wondered whether the new windows might affect their vision. The physical appearance of the B-21 bomber confirmed that the shape of the cockpit window of the B-21 bomber is different from that of the B-2 bomber - the two main engine windows are spaced at a larger interval, while the side windows are slightly smaller. But test pilot Lieutenant Colonel Clifton Bell said that as far as he could see, the windshield of B-21 was not much different from that of B-2, and there should be no problem in the window design. Bell is responsible for test organization at Edwards Air Force Base in California. He has piloted B-2 bomber in his career. Bell said, "Your body is very good at adjusting. My experience when I first flew the B-2 was that you would notice (its window) in the first flight or the first hour, and then you would separate important issues from unimportant issues in your mind. I have not flown the plane that worried me because of the window." Harrison said that the choice of this window design may, to some extent, be to maximize the stealth capability of the B-21. Harrison said that since the B-21 can be designed to "choose someone to drive" or to fly remotely without a pilot, there may be cameras or other sensors to help expand the pilot's vision. In this way, the wide window design becomes less important. The B-21 bomber has made its first public appearance. In the coming months, the manufacturer Northrop Grumman will continue to conduct further ground tests on this bomber. According to the test results, sometime in 2023, the B-21 bomber will fly to Edwards Air Force Base for the first time. Once delivered to the Air Force, more formal flight tests can begin, and the bombers will be tested. Bell said that such a test flight plan is "a huge project". Chris Moss, B-21 test pilot of Northrop Grumman, said that the test pilots will conduct a comprehensive inspection of the aircraft during the test flight next year, including ensuring that the bomber flies in a predetermined manner within the necessary flight speed and altitude, ensuring that all aircraft systems work in a predetermined manner, and determining the status of the aircraft during flight. Moss said that the raiders would