Originally Posted by
tartare
Agree.
Building a hypersonic tunnel is the easy bit.
Using it to find materials that can withstand hypersonic flight, designing engines that can transition to and sustain prolonged Mach five plus speeds, designing a vehicle that can be controlled effectively at those speeds, guiding it effectively and to target, then doing it all repeatedly and reliably - a lot more difficult.
Despite Chinese and Russian boasts, threats and parading of so-called operational weapons, I'd wager the Yanks still have the lead in hypersonics.
Momentary hypersonic speed is fairly easy and is what the Chinese are talking about, using an explosion driven pulse.
That does not help with the materials or the actual propulsion system, as those need sustained flow to be properly evaluated. I've seen no claim that the Chinese are close to sustained hypersonics in a wind tunnel.
Imho, that is why progress has been so slow, in effect the early prototypes such as the X-51 were really acting as wind tunnel test specimens.