柏愛德教授是航空工程專家。他在《交談》網站上這篇文章報導和分析「超音速飛彈」的優勢、技術、和防禦。摘譯要點於下(超連接是我加上的)：

1.  優勢和威力

超音速飛彈和一般飛彈相比較，前者具有高速和遠射程等優勢；超音速飛彈和洲際彈道飛彈相比較，前者具有低造價、高操縱性、和方便發射等優勢。

中國在此項武器上的發展目前先進於美國。由於具有以上種種優勢，如果發生台海衝突，中國有能力摧毀美國的航母戰鬥群。導致美國在台海戰爭中馳援台灣的能力大打折扣。這不但改變了西太平洋軍力的平衡狀態，也威脅到「全球安全」(引號是我加上的)。

評論：「威脅到『全球安全』」這句話完全從「美國本位主義」立場出發。事實上，美國政府不但沒有以美國獨霸全球的地位來扮演稱職的「世界警察」角色；反而幹著掠奪全球的勾當。一旦有其它國家能夠跟美國別別苗頭，白宮發言人和財團圍事如柏愛德教授者，就氣急敗壞的嚷嚷著：「威脅到『全球安全』！」。好像「威脅『全球安全』」是美國政府的專利。

2.  技術

譯註：原文對「超音速」、「洲際彈道飛彈」、以及以上三種超音速飛彈技術有簡單說明，請自行參閱。

3.  防禦及侷限

由於超音速飛彈優勢之一是它彈道的全程可操縱性，要防禦超音速飛彈就需要針對它進行全程追蹤。

比起一般飛彈，超音速飛彈的造價昂貴；在難以量產的限制下，它通常只適用於攻擊高價值的目標。從而，它不是一個決定戰局或終止衝突的工具。


China's hypersonic missiles threaten US power in the Pacific – an aerospace engineer explains how the weapons work and the unique threats they pose

Iain Boyd, 06/10/23

China’s newest hypersonic missile, the DF-27, can fly as far as Hawaii, penetrate U.S. missile defenses and pose a particular threat to U.S. aircraft carriers, according to news reports of an assessment from the Pentagon.

Chinese researchers claimed in a May 2023 research journal report that the country’s hypersonic missiles could destroy a U.S. carrier group “with certainty.” This capability threatens to sideline U.S. aircraft carrier groups in the Pacific, potentially shifting the strategic balance of power and leaving the U.S. with limited options for assisting Taiwan in the event China invades.

This shift in the balance of power highlights how the next-generation hypersonic missiles that China, Russia and the U.S. are developing pose a significant threat to global security. I am an aerospace engineer who studies space and defense systems, including hypersonic systems. These new systems pose an important challenge due to their maneuverability all along their trajectory. Because their flight paths can change as they travel, defending against these missiles requires tracking them throughout their flight.

A second important challenge stems from the fact that they operate in a different region of the atmosphere from other existing threats. The new hypersonic weapons fly much higher than slower subsonic missiles but much lower than intercontinental ballistic missiles. The U.S. and its allies do not have good tracking coverage for this in-between region, nor do Russia or China.

Destabilizing effect

Russia has claimed that some of its hypersonic weapons can carry a nuclear warhead. This statement alone is a cause for concern whether or not it is true. If Russia ever operates this system against an enemy, that country would have to decide the probability of the weapon being conventional or nuclear.

In the case of the U.S., if the determination were made that the weapon was nuclear, then there is a very high likelihood that the U.S. would consider this a first strike attack and respond by unloading its nuclear weapons on Russia. The hypersonic speed of these weapons increases the precariousness of the situation because the time for any last-minute diplomatic resolution would be severely reduced.

It is the destabilizing influence that modern hypersonic missiles represent that is perhaps the greatest risk they pose. I believe the U.S. and its allies should rapidly field their own hypersonic weapons to bring other nations such as Russia and China to the negotiating table to develop a diplomatic approach to managing these weapons.

What is hypersonic?

Describing a vehicle as hypersonic means that it flies much faster than the speed of sound, which is 761 miles per hour (1,225 kilometers per hour) at sea level and 663 mph (1,067 kph) at 35,000 feet (10,668 meters) where passenger jets fly. Passenger jets travel at just under 600 mph (966 kph), whereas hypersonic systems operate at speeds of 3,500 mph (5,633 kph) – about 1 mile (1.6 kilometers) per second – and higher.

Hypersonic systems have been in use for decades. When John Glenn came back to Earth in 1962 from the first U.S. crewed flight around the Earth, his capsule entered the atmosphere at hypersonic speed. All of the intercontinental ballistic missiles in the world’s nuclear arsenals are hypersonic, reaching about 15,000 mph (24,140 kph), or about 4 miles (6.4 km) per second at their maximum velocity.

Intercontinental ballistic missiles are launched on large rockets and then fly on a predictable trajectory that takes them out of the atmosphere into space and then back into the atmosphere again. The new generation of hypersonic missiles fly very fast, but not as fast as ICBMs. They are launched on smaller rockets that keep them within the upper reaches of the atmosphere.

Three types of hypersonic missiles

There are three different types of non-ICBM hypersonic weapons: aero-ballistic, glide vehicles and cruise missiles. A hypersonic aero-ballistic system is dropped from an aircraft, accelerated to hypersonic speed using a rocket and then follows a ballistic, meaning unpowered, trajectory. The system Russian forces have been using to attack Ukraine, the Kinzhal, is an aero-ballistic missile. The technology has been around since about 1980.

A hypersonic glide vehicle is boosted on a rocket to high altitude and then glides to its target, maneuvering along the way. Examples of hypersonic glide vehicles include China’s Dongfeng-17, Russia’s Avangard and the U.S. Navy’s Conventional Prompt Strike system. U.S. officials have expressed concern that China’s hypersonic glide vehicle technology is further advanced than the U.S. system.

A hypersonic cruise missile is boosted by a rocket to hypersonic speed and then uses an air-breathing engine called a scramjet to sustain that speed. Because they ingest air into their engines, hypersonic cruise missiles require smaller launch rockets than hypersonic glide vehicles, which means they can cost less and be launched from more places. Hypersonic cruise missiles are under development by China and the U.S. The U.S. reportedly conducted a test flight of a scramjet hypersonic missile in March 2020.

Defensive measures

The primary reason nations are developing these next-generation hypersonic weapons is how difficult they are to defend against due to their speed, maneuverability and flight path. The U.S. is starting to develop a layered approach to defending against hypersonic weapons that includes a constellation of sensors in space and close cooperation with key allies

With all of this activity on hypersonic weapons and defending against them, it is important to assess the threat they pose to national security. Hypersonic missiles with conventional, non-nuclear warheads are primarily useful against high-value targets, such as an aircraft carrier. Being able to take out such a target could have a significant impact on the outcome of a major conflict.

However, hypersonic missiles are expensive and therefore not likely to be produced in large quantities. As seen in the recent use by Russia, hypersonic weapons are not necessarily a silver bullet that ends a conflict.

This is an updated version of an article that was originally published on April 15, 2022.

Read more:

*  A game of numbers: How air defense systems work and why Ukraine is eager for more protection
*  Would Putin use nuclear weapons? An arms control expert explains what has and hasn’t changed since the invasion of Ukraine
*  What countries have nuclear weapons, and where are they?

Iain Boyd receives funding from the U.S. Department of Defense, the U.S. Department of Energy, NASA, and Lockheed-Martin.