I'd like to borrow
@Kalec's screenshot of the Weibo post on the B-21.
I'd like to highlight several points from the 2nd and 3rd paragraph into focus:
It's been a long time since we've had a major model this exciting, so let's take a good look at the main targets and sources of air defense pressure we'll be facing in the coming decades. The B-21 will be our number one enemy for quite some time, and countermeasures to counter it will be on the main agenda, as will the lessons learned from past studies on how to counter the B-2.
Since this thing is scheduled to be procured in very large numbers, it marks the point where the U.S. military is finally somewhat ready to fight a big war with its peer opponents. This will make the future Western Pacific airspace more lively than ever, and our anti-stealth needs will be much greater than they were back in the days when the B-2 was the only one, so we will have to invest more. Also looking forward to the H-20 coming out soon, but some people told me in my dream that it will be very different from the B-21 in the way it is used, and that will likely lead to something that is still quite different in the end although it also values stealth.
There are some who are rather dimissive of the B-21, claiming that the B-21s would be a toned-down version of the B-2s, similarly to how the Virginias is like to the Seawolfs.
However, I beg to differ. There are several things to consider:
First, the
numbers - Unlike the prohibitively expensive B-2s, the B-21s are meant to be procured in the 100s (some in the USAF even want that number to go as high up as 200). This presents a systematic challenge to China's air defenses across the whole Pacific front (and even the Himalayan front, if the Indian government permits the passage of B-21 through Indian airspace to strike targets deep inside China's interior), as the PLA would not be dealing with only 20 stealth bombers, but more than 100 stealth bombers as we are going into the second half of the 2020s and 2030s.
Second, the
design - It is clear that the intakes are designed to be much slimmer and tapered to the wings and fuselage of the B-21 compared to the B-2. Seemingly the B-21's wings are also much tapered compared to the B-2. Although we would never know the true overall design of the B-21 for at least a couple more months or years, I think it is valid to assume that such design features would enhance the stealth capability of the B-21s better than the B-2. This definitely poses a greater challenge for the PLA in detecting and hunting them before they could drop their payload.
Third, the
system and technological level - Remember that the B-2s were designed using technology from the 1970s and 1980s. Compare this to the B-21s, which were designed using technologies and systems from the 2010s and 2020s. That period of technological leap should never be ignored, as the designers of the B-21 would have a much better and more powerful design and engineering tools to them compared to the designers of the B-2. Similar analogy would be like one doing graphic design using Microsoft Paint on Windows XP, and another doing graphic design using Adobe Photoshop on Windows 10.
Fourth,
experience - The US has a wealth of design, engineering and operational experience of the B-2 for the past 4 decades, of which all of those can be utilized for the design and engineering processes of the B-21. Similarly, the team of designers and engineers who have worked on the B-2 can also be called upon and referenced upon for when the team of designers and engineers are working on the B-21. This is a huge bonus for Northrop Grumman and the USAF because this is something that no other country has ever possessed.
Finally,
viability of cost - Don't forget that the USAF and Northrop Grumman have experience on the financial side of things as well. When claiming that B-21s are Viginias to how B-2s are Seawolfs, this question should follow: Do the Virginia-class SSNs suck? The answer is no. The Virginias are still respectable and formidable foe for the PLAN, despite being a step down compared to the Seawolfs. Therefore, the PLA hould expect and be prepared that even if the B-21s are just downgraded versions of the B-2s, they are still a pretty viable stealth platform for conducting bombing and strike operations in the Pacific.
