This news is that the F-47 is expected to make its maiden flight in 2028, rather than starting mass production in 2028. Do not intentionally confuse concepts. It is a naive fantasy to believe that the United States will enter service with 6G fighter jets in 2028.
The B-21 is not a 6G fighter jet either. The standards for 6G fighter jets include:
1. Variable cycle engines and hypersonic cruising (reaching speeds of up to 5 Mach). The B-21 uses F-135 engines and is only subsonic.
2. Using AI as the core of avionics, it can make autonomous decisions for combat and control swarm drones, making it a node in the air combat network. B-21 does not possess these capabilities.
3. 6G fighter jets need to achieve omnidirectional wideband stealth, while B-21 can only achieve omnidirectional stealth.
btw: The omnidirectional wideband stealth technology used in 6G fighter jets refers to achieving stealth in multiple directions, including front, rear, left, right, up, and down, within multiple radar frequency bands such as very high frequency, ultra-high frequency, L, S, C, X, and Ku. The B-21 and 5G fighter jets can only be stealth in the L, S, C, and X bands, and cannot evade the capture of anti stealth radar.
4. 6G fighter jets have a disruptive aerodynamic layout and are equipped with directional energy weapons such as lasers. The B-21 adopts the flying wing layout that emerged during World War II and does not have any new directed energy weapons.
btw: Of course, some PDF members can claim that China's development of 6G fighter standards is not the standard for US 6G fighter jets. But you need to also acknowledge that the US 6G fighter standard is much lower than China's standard, and even about equal to the 5G fighter standard. Oh, I was wrong. The B-21 can't even meet one of the 5G fighter jet standards, supersonic cruising.