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How Hypersonic Missiles Work and Why They're Starting a Global Arms Race

Hypersonic missiles are the new most advanced war technology, but how do they work, and why are they so dangerous?

The world's superpowers are developing an array of hypersonic missiles that can travel across the world faster than Mach 5, or 3,800 miles per hour.  These weapons could provide almost immediate weapons response capabilities for the countries that have them. So much so that developing new hypersonic tech is creating a new arms race around the world.

Before we can understand how hypersonic missile tech is causing a new global arms race, we need to understand how hypersonic missiles work.

What is a hypersonic missile and how do they work?

Hypersonic weapons essentially combine the speed of ballistic missiles with the maneuvering capabilities of cruise missiles. They can travel at around 5 times the speed of sound, making them hard to track compared to traditional missiles. One of the biggest advantages of modern hypersonic missiles isn't speed though, it's the added maneuverability at these high speeds that makes them so practical as both offensive and defensive weapons.

While hypersonic missile tech is key for rapid accurate delivery, the most important part of any weapon is the payload. Hypersonic weapons can deliver conventional or nuclear payloads essentially anywhere in the world within minutes.

Hypersonic missiles can be delivered in two ways: they can be fired from the last stages of Intercontinental or Submarine-Launched Ballistic Missiles to skip along the top of the atmosphere using specialized jet engines; or they can be launched independently or released from a bomber—similar to cruise missiles—before accelerating to ultra-high speeds

Behind this impressively dangerous hypersonic technology is something called a supersonic combustion ramjet, otherwise referred to as a scramjet system. 

scramjet engine function
A diagram depicting how a scramjet engine functions to create supersonic exhaust, Source: Luke490/Wikimedia

Scramjet engines collect oxygen from the atmosphere as the travel to mix with hydrogen fuel, which creates the combustion needed for hypersonic flight. Through the design of the scramjet inlet, the air is forced in and compressed before it is mixed with hydrogen fuel, which then ignites, and is directed out of the nozzle in the back. It's actually a rather simple process compared to some other combustion techniques.

Regular ramjet engines utilize liquid oxygen and hydrogen fuel, but this, in turn, makes the vessel very heavy. The best example of this engine technology would be the now-retired Space Shuttle. Herein lies the advantage to scramjet engines, they only need to carry hydrogen, eliminating the oxygen storage, which is proportionately 70% of the fuel space used in ramjet rockets.

So then, why wouldn't you just always use a scramjet rocket? Mostly because in order for the engine to work, it needs to be flying at supersonic speeds. This is necessary to kickstart the air-fuel mixture to begin combustion.

To reach supersonic speed, the vessel is usually launched with a traditional booster engine, and once it has reached the proper speed and altitude (generally around 100,000 ft) the scramjet is activated.

RELATED: A HYPERSONIC SPACEPLANE JET PASSED A CRUCIAL TEST

New developments include dual-mode ramjet engines, which use ramjet propulsion to get the craft up to speed, where it then switches over to scramjet mode. 

Conventional ballistic missiles also have to be launched at steep trajectories so that they don't burn up on launch and reentry into the earth's atmosphere. Whereas, hypersonic missiles can glide atop the atmosphere and still use their engines to accelerate and steer.

This ability to travel at high velocities and high altitudes for extended periods of time extend the range of hypersonic missiles.

It also allows them to bypass most modern missile defense and tracking systems. Finally, as we've mentioned, hypersonic missiles can maneuver in flight, so their trajectories don't need to be set in advance. This is in sharp contrast to the highly defined and steep trajectories of traditional ballistic missiles, which are easier to track and intercept.

With a basic understanding of how hypersonic missiles work and why they are so advantageous to militaries around the world, we begin to get a clearer picture of why they might be kickstarting an arms race between superpowers. 

How fast can a hypersonic missile go?

The last thing that provides some context to this whole discussion is understanding exactly how fast hypersonic missiles travel. Roughly, these missiles travel 1 mile (1.61 km) every second. This equates to around 5 times the speed of sound and is over 3600 mph (5793 kph)

The hypersonic arms race

Currently, the U.S., China, and Russia are testing hypersonic missiles that can deliver various types of payloads. Notably, the U.S. is focusing primarily on conventional payloads, while China and Russia are developing both conventional and nuclear delivery methods. At least, that's public knowledge on the matter.

X-51A WaveRider
An X-51A WaveRider hypersonic flight test vehicle is uploaded to an Air Force Flight Test Center B-52Source: U.S. Air Force

In the spring of 2018, Russian President Vladimir Putin premiered and promoted the country's new hypersonic weapons. He claimed that the six new prototype weapons unveiled would be ready for battle in 2020.

In 2018, as well, China also announced that it had successfully tested hypersonic aircraft, something that the U.S. hasn't accomplished to that point – again, that is known to the public. 

Falcon HTV-2 flight path
A diagram of the proposed flight path of the Falcon HTV-2, a prototype hypersonic craft developed by DARPA, which failed it's testing back in 2011, Source: DARPA/Wikimedia Commons

Because China and Russia have both made such massive strides to hypersonic dominance, it has created great tension in the realm of missile arsenals. We now see a race between these three top players in the global war industry to create the best and most-advanced hypersonic missile technologies.

The U.S. Army and Navy are planning to conduct three flight tests of a hypersonic glide body in 2021, significantly accelerating the pace of development. In March of this year, the Army and Navy had a successful flight test of the Common-Hypersonic Glide Body. This glide body will serve as the base of a new U.S. offensive hypersonic missile

The biggest aspect of this race, however, isn't the missiles themselves, but rather the defenses against them. The U.S. currently has no means of protecting itself from hypersonic weapons that otherwise travel at more than a mile per second.

Should we be concerned about the arms race?

While there is no question that there is currently a global hypersonic arms race, the real question remains. How worried should we be about this escalating back and forth between superpowers focused on creating the best hypersonic weapons system? Chances are, no more worried than we already were about a global nuclear war between superpowers. 

This may seem a little counterintuitive. The development of weapons systems that other countries can’t easily counteract could put in place a power imbalance. However, in order to understand why hypersonic (nuclear) missiles aren’t as scary as they sound, we need to understand the state of weapons defense systems around the world

Essentially, every established power around the world possesses some form of missile defense, but in their totality, all of these systems are still very far in their infancy. The US currently has the largest missile defense system, but it’s largely positioned to defend against North Korea and Iran. The US is largely underprepared to stop a barrage of non-hypersonic missiles coming from a peer like Russia.

This fact underscores that while one might think the world’s superpowers have high-tech impenetrable missile defense systems, that really isn't the case. Hypersonic missiles pose the same threat as regular missiles if the underlying defense system can’t stop either, thus there seems to be little need for severe concern in this growing hypersonic arms race. 

It’s also important when discussing the hypersonic arms race that we make sure we put it in the correct light. While Russia and China appear to be far ahead of the United States in terms of hypersonic missiles, the reality is that those countries aren't necessarily shooting for the same goal, which makes it hard to characterize the hypersonic arms race as a “race”.

Races typically can only be measured when all competitors are shooting for one goal, such as the space race of the Cold War which aimed to land a man on the moon. 

The hypersonic arms race is, in reality, a bunch of superpowers chasing after their own version of what they believe will be the most strategically important weapons system. The US, for example, while still a few years off from hypersonic capabilities, has largely focused on hypersonic non-nuclear missiles, which infers that the missiles would need to be far more accurate than nuclear counterparts. This may explain why the US’s technology is taking longer to develop. 

Lastly, when looking at military might and determining how competitors measure up, the competition of “who has the bigger stick” isn’t as simple as it sounds.

In the 1950s, the US was faced with far greater Russian forces in Europe, but Eisenhower was able to counteract the forces with nuclear weapons. 

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In this instance, the lack of conventional US forces was supplemented with nuclear capability. The same could be posed for any potential difference in firepower between the US and Russia. Counteracting weapons capabilities doesn’t occur on a linear plane

So at the end of the day, while the impending doom brought about by a hypersonic weapons race makes for a good headline, it’s probably a little bit sensationalistic. 

The actual consequences of the hypersonic arms race are likely to play out slowly in baby steps over time. It’s the differences in these baby steps that we should concern ourselves with, not the race as a whole.

Baby steps in weapons development tend to be the path to the strategic divide. Rifts in global politics don’t happen overnight and tensions that rise slowly are less likely to be stopped. So, we probably shouldn’t be concerned with the hypersonic missiles themselves, but perhaps more with the competition that developing futuristic weapons systems may create between the most powerful forces in the world. 

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