In previous articles, we examined the capabilities of the entire range of existing strategic nuclear weapons, including intercontinental ballistic missiles (ICBMs) , ballistic-missile submarines and strategic bombers . We have also assessed the capabilities of existing and prospective missile-defense systems in Russia and the United States. There is another promising technology that can affect the future strategic balance: hypersonic weapons. In fact, any weapon can be considered hypersonic that can achieve a velocity higher than Mach 5 (Mach 1 is the sound propagation velocity, which is 767 miles per hour in air at low altitude and at 20 degrees Celsius). Both the United States and Russia are actively conducting developments in this area, as is China.
Russian Hypersonic Weapons: Cruise Missiles to Hypersonic Gliders
The Russian hypersonic weapons that are closest to production are Zircon antiship sea-launched missiles and X-32 air-launched cruise missiles. The information available about testing the Zircon is rather contradictory. According to one source , a successful test took place this year, during which the missile achieved Mach 8 speed; according to another , less authoritative, source, no tests have taken place. Judging by the information available in open sources, Zircon would be able to reach speeds of Mach 5 or 6, and hit targets at a distance of at least four hundred kilometers. The Russian army’s phase-in timing of the product is still unclear. Dates previously offered for deployment are 2019–20, but in reality, the development of such a new and complex product could drag on until the mid-2020s.
However, the X-32 cruise missile, which is being developed specifically for the modernized long-range Tu-22M3M bomber, is already at the final stage of testing; its phase-in is expected in the near future. This is explained by the missile’s slower Mach 4 to 4.5 flight speed. In addition, the missile flies on a special trajectory, covering most of its distance at an altitude of forty to forty-five kilometers and then diving to the target, which reduces air resistance and heating. Accordingly, this model minimizes missile overheating and electronics failure due to the formation of a plasma cloud around the missile, two main problems of hypersonic flight. On the other hand, the speed reached is not excessively high; in fact, the X-32 is a border-class missile positioned between supersonic and hypersonic.
The third project, perhaps the most complex and promising, is the creation of a hypersonic glide vehicle for the prospective heavy liquid-fueled RS-28 Sarmat ICBM. This project is most often referred to as “Object 4202” or U71. Unlike a conventional warhead, which also enters the atmosphere at hypersonic speeds, the glider leaves space much earlier, flying hundreds or even thousands of kilometers in the atmosphere, making it able to maneuver and fly along a trajectory different from that of a simple ballistic missile. This makes it almost impossible for antiballistic missile systems to intercept the glider. In addition, gliders can be homed onto targets with much higher accuracy than conventional warheads, which will allow using nonnuclear warheads at intercontinental distances.
The latest tests of the U-71 have been called successful so far, but it does not necessarily mean that the product is close to mass production; that depends on reaching specific parameters, such as the ability to achieve a certain desired speed. One way or another, work on the project seems to be going well, and given the delays in creating the Sarmat ICBM, it is quite possible that Object 4202 will arrive just in time for the start of production on the RS-28, which will most likely happen in the early-to-mid-2020s.
U.S. Hypersonic Projects: New Cruise Missiles, and Trouble with Gliders
In the United States, hypersonic projects have developed roughly along the same path as in Russia. For a long time, the work to create hypersonic gliders was performed within the framework of the Prompt Global Strike Initiative. Two tests were conducted for each of the competing Advanced Hypersonic Weapon (AHW) and Hypersonic Technology Vehicle 2 (HTV-2) projects. Only one of those—the AHW test in 2011—was successful, although there were no details provided. The last test launch was conducted in 2014 and was unsuccessful. The main problem encountered by the developers was the loss of communication with the aircraft during the flight (both tests of the HTV-2 ended in that fashion). Apparently, problems arose due to the formation of a plasma cloud around the glider, and the consequent onboard electronics failure. Solving this problem is the cornerstone of hypersonic-technology development in general. The DARPA Falcon project was closed and, accordingly, no further work on the HTV-2 is planned. As for the AHW, there is no information as to whether there will be any further testing.
Additionally, the United States is actively collaborating with Australia within the framework of the HIFiRE (Hypersonic International Flight Research Experimentation Program) research project. Within this program, several launches of hypersonic aircraft were carried out, and the last one, carried out on July 12, 2017, was successful. The hypersonic glider was able to reach Mach 7.5 (5,710 mph) speed during the penultimate tests, while no data has been published on the most recent launch. It is known that the aim of the project is to study the behavior of hypersonic gliders entering the atmosphere from a launch vehicle and conducting maneuvers.