Hype about Hypersonic Missiles, By James Reed

I have been concerned about the disparity between the US and both communist China and Russia who are well advanced in hypersonic missiles. Is it correct to suppose that these missiles which travel many times faster than sound are unstoppable and incapable of defending against? If armed with nuclear bombs, that could mean certain defeat of the West. As our lives are at stake, that should be of interest.

However, an insightful article at Real Clear Wire.com, puts the case against hypersonic missiles, which was something I did not know. While the article is a bit technical, the main point is that hypersonics face difficulties due to their very speed, such as immense heat by air friction, and a lack of manoeuvrability: "First, hypersonics are described as being faster than other delivery systems. While they are faster than current cruise missiles, they are not faster than ballistic missiles. Hypersonic flight within the atmosphere generates high drag and heating, which limits the speeds of hypersonic weapons. Ballistic missiles, particularly when launched on depressed trajectories, can achieve shorter delivery times due in part to their minimal interaction with the atmosphere for the majority of their flight path. This holds true for both long-range and theater-range hypersonics. If time to target is an important metric for evaluating the necessity of a weapon system, hypersonics do not necessarily offer a strategic advantage.

Long-range hypersonic systems in particular face acute technical challenges. Sustained flight at hypersonic speeds introduces extreme thermal stress that can jeopardize the structural integrity of these weapons. Additionally, at the speeds that long-range HGVs travel in the early phase of their flight, the air around the vehicle ionizes, forming a plasma sheath that disrupts radio signals and inhibits communication. This plasma blackout effect will dissipate as the HGV slows down during its glide phase but can nonetheless prevent the passage of radio signals and make it impossible to communicate with or guide the weapon in real-time prior to this point. This renders it dependent on pre-programmed instructions and less responsive to defensive countermeasures. Theater-range hypersonic weapons, which are designed for shorter distances and lower speeds, will likely not create a plasma sheath but will still encounter heating challenges.

Furthermore, the supposed stealth capabilities of hypersonic weapons may not be as robust as frequently stated. While low-altitude flight can indeed reduce their detection range by ground-based radar systems, such radars should still be able to detect them at ranges of hundreds of kilometers. Moreover, at high enough speeds, the intense heat generated by hypersonic flight in the atmosphere produces a bright infrared signature detectable by space-based early-warning satellites. But even prior to their glide phase, HGVs must first be launched using a rocket booster like that of a ballistic missile. The exhaust plumes from these launches would be likewise easily detectable by space-based detection sensors. Once picked up by early-warning satellites, the weapon's initial direction is known, giving defenders the ability to begin judging its likely targets and determining which defenses to engage. Hypersonic weapons would not be invisible bullets.

Perhaps the holy grail of characteristics — that which separates hypersonics from traditional ballistic missiles — is their ability to maneuver during midcourse, or the middle phase of their flight. However, as with speed and stealth, the ability to maneuver has also been exaggerated. Changing trajectory during glide phase requires using aerodynamic forces acting upon the vehicle. Maneuvering produces increased drag, which in turn slows the vehicle, reduces the overall range it can travel, and compounds the surface heating issue, meaning whatever the vehicle gains in evasion, it forfeits in range and speed. Thus, the idea of a hypersonic weapon free to meander throughout the atmosphere evading any and all defenses is incorrect. In reality, all hypersonics will face a trade-off between manoeuvring capability, speed and range that will inhibit their utility."

So, things may not be so bad for the West if the strategy was to not go the hypersonics way, but instead seek to counter them.

https://realclearwire.com/articles/2025/02/04/hypersonic_overhype_1089142.html