Defence Industry

Hypersonic PGMS and Conventional Missiles: Need for Manned Multi-Role Aircraft
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Issue Vol. 37.2, Apr-Jun 2022 | Date : 15 Jul , 2022

Russia launching hypersonic missiles during the Ukraine war heralds a new era of warfare introducing the cocktail of high speed and lethality. The Russian claims of launching Kh-47M2 Kinzhal “hypersonic missiles” to destroy an ammunition warehouse in western Ukraine has been confirmed by the US administration. The global weapons race is already heating up with hypersonic weapons technology demonstrations by major players such as Russia, China and the US having put their money where the bang is. India is the next player on the block and is accelerating the hypersonic technology development. Similarly, long-range conventionally armed cruise missiles and aerial missiles are being touted by some as challenge to manned multirole aircraft.

Long Range Missiles and Stand-off Weapons

A cruise missile is a guided missile used against terrestrial targets that remains in the atmosphere and flies the major portion of its flight path at approximately constant speed. Cruise missiles are designed to deliver a large warhead over long distances with high precision. Modern cruise missiles are capable of travelling at high subsonic, supersonic, or hypersonic speeds, are self-navigating, and are able to fly on a non-ballistic, extremely low-altitude trajectory. Stand-off weapons are missiles or bombs which may be launched from a distance sufficient to allow attacking personnel to evade defensive fire from the target area. Typically, they are used against land- and sea-based targets in an offensive operation. Stand-off weapons include cruise missiles, glide bombs and short-range ballistic missiles. Air-to-air missiles such as China’s PL-15, MBDA Meteor, and AIM-260 JATM reportedly have operational ranges around 200 kilometres.

Hypersonic Weapons

Weapons flying at speeds in excess of five Mach or five times the speed of sound are normally termed as ‘hypersonic weapons’. Most ballistic missiles travel at hypersonic speeds and execute terminal manoeuvres in their atmospheric re-entry phase. By this logic, all these could be termed as hypersonic weapons. Hypersonic weapons are not just about speed but also manoeuvrability and low-altitude flying. Hypersonic flight should be sustainable within the earth’s atmosphere. They would thus experience aerodynamic and thermal forces related to those speeds. Hypersonic flight conditions involve overheating, laminar flow disruption, ionisation of surrounding gases, and plasma formation. The ballistic missiles thus cannot be characterised as hypersonic weapons. The hypersonic flight at low-altitude must be sustained for a period lasting in minutes, and should have ability to execute manoeuvres.

Two Types of Hypersonic Weapons

Hypersonic weapons could be rocket-boosted Hypersonic Glide Vehicles (HGV) or Hypersonic Cruise Missiles (HCM). HGVs are aerodynamic vehicles propelled by rockets into space. They rely on the aerodynamic lift to travel unpowered (glide) over long distances in the atmosphere. Closer to target, the weapon exits the gliding trajectory, carries out terminal manoeuvres using internal boosters, and impacts the target. HGVs combine the speed of ballistic missiles and manoeuvrability and low altitude flying of cruise missiles and follow unpredictable trajectory. HCMs, on the other hand, are hypersonic versions of traditional cruise missiles. They are powered throughout their trajectory and can execute manoeuvres during the flight. HCMs powered by scramjets are faster (hypersonic) than ramjet-powered missiles (supersonic). Future hypersonic weapons may combine the attributes of HGV/HCM.

Disruptive Technology – Fast and Furiously Accurate

‘One mile per second’ is the hypersonic regime and uses kinetic energy which is a function of the square of velocity. A one-kilogramme object delivered precisely at such high speed can be more destructive than one kilogramme of TNT. By offering the precision of near-zero-miss weapons, the speed of ballistic missiles, and the manoeuvrability of cruise missiles, hypersonic weapons are a disruptive technology capable of striking in short time.

While some contend that hypersonic weapons lack defined mission requirements, hypersonic weapons provide long-range, high-speed, strike options against distant, defended, and/or time-critical targets. HGV/HCMs potentially armed with nuclear warheads bring a new dimension. Operational use of conventional hypersonic weapons against high-value targets such as aircraft carriers or strategic ground targets will require factoring.

The low-altitude path helps mask HCMs making them invisible to early warning radars. This, when combined with possible last minute manoeuvres, would reduce chances of interception. Since the hypersonic weapon could also carry a nuclear warhead, this complicates the missile warning and reaction dynamics and poses the risk of nuclear escalation. China, Russia and the US, who have begun operationalising hypersonic capabilities, are also looking for countermeasures to address emerging hypersonic threats. In fact, one of reasons the hypersonic weapons are being developed is to neutralise the advantage of better Ballistic Missile Defence (BMD) systems, and re-establish nuclear strategic stability.

Major Hypersonic Weapons Programs

Six new Russian strategic weapons were unveiled by Russian President Vladimir Putin on March 01, 2018. The Avangard is a Russian HGV that can be carried as a MIRV payload by the UR-100UTTKh, R-36M2 and RS-28 Sarmat heavy ICBMs. It can deliver both nuclear and conventional payloads. Six Avangard-equipped UR-100NUTTH are deployed, and two Avangard HGVs are being added every year. The Kh-47M2 Kinzhal (Dagger in Russian) is a Russian nuclear-capable HCM with a claimed range of more than 2,000 km, and Mach 12 speed. It can be launched from Tu-22M3 bombers or MiG-31K interceptors. During the 2022 Ukraine conflict, Russia announced the use of Kinzhal HCM to destroy a Ukrainian underground weapons depot in Deliatyn on March 18, 2022, and a fuel depot in Konstantinovka the next day. US President Joe Biden confirmed, “It is almost impossible to stop it.” The 3M22 Zirconis, a Russian anti-ship HCM that can be launched from both underwater and surface platforms, is currently under production. There are design similarities between Zirkon and BrahMos-II. Zirkon deliveries to the Russian Navy will begin in 2022. Russia plans to arm HGVs with nuclear warheads and deploy on at least two different types of ballistic missiles (including the RS-28 Sarmat ICBM). The first test flight is planned in 2022, and it will enter service later in the year. The withdrawal of USA and Russia from t he Intermediate-Range Nuclear Forces (INF) Treaty in February 2019, spurred fresh arms developments and complications.

The DF-ZF is a Chinese HGV which has been operational since 2019. It will be mounted on the DF-17 ballistic missile which is especially designed to carry HGVs. The Chinese DF-41 ICBM could also be modified to carry HGVs. China’s hypersonic aircraft, Starry Sky-2, could be used to carry nuclear missiles at six times the speed of sound. First test flight of experimental design, which rides its own shock waves, was done in 2018. Mid 2021, China tested a Fractional Orbital Bombardment System (FOBS), which on re-entry to the atmosphere, released a manoeuvrable glide vehicle travelling at hypersonic speeds.

Hypersonic Technology Vehicle 2 (HTV-2) is an experimental HGV developed as part of the U.S. DARPA Falcon Project and designed to fly at Mach 20. It is a test bed for Prompt Global Strike technologies to allow the United States to reach any target in the world within one hour using an unmanned hypersonic bomber aircraft. The Lockheed developed AGM-183 Air-Launched Rapid Response Weapon (ARRW) is a hypersonic weapon planned for use by the US Air Force. The boost glide weapon is propelled to a maximum speed of more than Mach 20 by a missile before gliding towards its target. United States could field a hypersonic weapon in 2022. The Pentagon has requested $3.8 billion for hypersonic research in FY2022, up from $3.2 billion in the FY2021.

On September 07, 2020, India’s Defence Research and Development Organisation (DRDO) successfully flight-tested Hypersonic Technology Demonstration Vehicle (HSTDV) showcasing the hypersonic air-breathing scramjet technology. BrahMos-2 is a HCM under joint development by the DRDO and Russia’s NPO Mashinostroyenia. It is expected to have a range of 1,000 kilometres and a speed of Mach 8. The HGV-202F is an Indian HGV being designed, developed, and manufactured by an Indian defence and space company HTNP Industries. Several other countries such as Australia, France, Germany, the United Kingdom, and Japan are also developing hypersonic weapons technology.

Upsetting the Status Quo

Some contend that the high initial cost of the new hypersonic weapons may restrict them to nuclear warheads. The nuclear or conventional dilemma will be same as for cruise missiles. The non-nuclear warheads, would present a new and potentially significant security threat. Such weapons would threaten a variety of targets at very short timelines and would be difficult to defend, especially aircraft carriers. The kinetic speed will create a significant damage even with a small-sized warhead.

Defence against Hypersonic Weapons

It is often claimed that it is impossible to defend against hypersonic weapons because they are too fast. One cannot accept a defenceless stance despite the inherent difficulties of defending against their speed and manoeuverability. Ballistic missiles fly at much higher altitudes and follow relatively predictable trajectories. It is possible to predict their destination using powerful radars, such as the US Pave Paws or the Russian Voronezh radars, combined with space-based sensors, typically giving around 14 minutes tactical warning. A RAND study suggests that the detection for HGV would be only six minutes prior to impact. There will be a high degree of uncertainty about their destination. Hypersonic weapons thus add surprise to long-range strikes, and may penetrate even the most advanced air defence systems.

Some analysts believe a space sensor layer is the key to meeting the hypersonic threat. The United States is developing a new Low Earth Orbit (LEO) satellite-sensor layer, to provide continuous tracking of both ballistic missiles and hypersonic vehicles. It may require a constellation of hundreds of satellites with advanced sensors. The Russia Konteyner and Chinese J27-A new generation Over The Horizon (OTH) radars could allow detecting hypersonic missiles 3,000 km away. Delayed detection, combined with degraded decision-making environment may have consequences for threat evaluation and accidental escalation.

The ‘point defence’ systems such as the US Patriot and Terminal High-Altitude Area Defense (THAAD), and Israeli David Sling and Iron Dome, and Russian S-400 can defend finite areas against ballistic missiles. To use these SAMs as ‘area defence weapons’ against hypersonic weapons would be impossible. Russia is developing the S-500 missile interceptor system, and the United States is working on the Terminal High Altitude Area Defence-Extended Range (THAAD-ER) system. Both these systems have been conceived for larger area defence. It would be cost-prohibitive to deploy them to protect all possible targets. They could best be used to protect critical facilities like command and control nodes and land-based nuclear assets, mitigating first strike vulnerability fears.

Another way of defending against hypersonic weapons (as well as other types of missile) could be through directed-energy systems, in particular, laser weapons. However, the effectiveness of laser weapons against hypersonic missiles is difficult to assess due to the nascent stage of both technologies. The research countermeasures to hypersonic systems have begun receiving US defence funding.

Hypersonic Anti-ship Missiles (HASM) Threat

China continues to build aircraft carriers with an aim to catch up with the US. The Indian Navy has its eyes on a third aircraft carrier. All this is happening at a time when hypersonic weapons are trying to disrupt the status quo. Aircraft carriers cost a lot of money to build and large resources to maintain and defend. The threat posed by HASM is of great concern says US DoD in their missile defence review released in January 2020. It warns that the Chinese weapons could hold carrier battle groups at risk. Faster interceptor systems are required to engage HCM head-on or to catch-up from other trajectories. Unlike ballistic missiles, HCM can approach a target from changed trajectory. Their inertia alone can cause enough damage to send a carrier to sea-bed. Hypersonic weapons are neither undetectable nor un-intercept-able, but the speed of hypersonic weapons increases the distances for reaction many folds. The short warning times may eventually incentivise automated interceptor systems, to a degree not previously acceptable, including firing without human approval.

Complexity of Defending Aircraft Carrier

Aircraft carriers are viewed by many as the Indian Navy’s crown jewels, and naval aviation has grown into a primary offensive arm with global reach. Typically a carrier battle group includes ships equipped with advanced air-and-missile defence systems. But HASMs pose a unique threat with a complex intercept geometry with low success rate. HASMs are much smaller as targets, and difficult to see till much closer. Air-launched and under water-launched HASMs are adding to the complexity due short flight-time.

The debate over the efficacy of carriers in high-end conflict is nothing new, more so since funds are scarce. Sinking of Russian Cruiser Moskva in the Ukraine conflict by a normal cruise missile has also re-ignited the debate. Potency-wise, what could be more threatening, 2,000 precision HCM or one new carrier, with both costing roughly same? Could hypersonic weapons be the new equivalent of nuclear deterrence and their use considered highly escalatory. Will hypersonic missiles replace aircraft carriers in the defence budgets? China has always relied on thousands of long-range precision conventional strike assets. Prompt strike weapons could be a good investment. The US is looking at placing hypersonic weapons in the Pacific as a priority.

Die-hard naval aviators feel that finding the moving aircraft carrier, often changing its course and speed, thousands of kilometres away, in a high threat environment, is not easy. Also, like weapons against submarine threat evolved, same will happen against HASMs soon, they feel. Some even claim that naval aircraft performing combat air patrols could potentially shoot down incoming missiles before they reach the carrier strike group using AAMs designed to shoot supersonic aircraft. Directed energy weapons are the other option of the future. The US Navy has been pursuing hyper velocity projectiles that could be launched from electro-magnetic rail-guns or powder guns. They are smaller and cheaper than interceptor missiles, and a ship could carry more of them. They could contribute to point defence against enemy hypersonic weapons. Ship-based lasers, high-powered microwaves, electronic warfare, or decoys could also make things difficult for HASMs.

Meanwhile, naval aviation is pushing hard to stem the tide of criticism and contend that the lethality, agility and resilience of a full-sized nuclear-powered aircraft carrier and its air wing. A carrier strike group, by its mere presence, can shape events in the nation’s favour, they claim. Navies expect carrier battle groups to adapt to the emerging hypersonic threat, just as they did to Japanese kamikazes in World War II and Soviet bombers equipped with anti-ship missiles during the Cold War. The aircraft-carrier served well for nearly a hundred years, and like manned aircraft, at some point, the game has to be up. The threat of hypersonic weapons to high value targets like aircraft carriers is real. Of course, there are still a few years of debate ahead.

Manned Aircraft in the Age of HCM

A large number of unmanned aircraft or optionally manned aircraft are being designed. Manned-Unmanned Aircraft Teaming is also evolving. Notwithstanding Artificial Intelligence (AI) supported automation, practically the six generation aircraft of all countries are continuing to be manned. Air launched cruise missiles and HCMs have their own advantages over ground or sea launched weapons, in terms of larger range. Also with very long range air-to-air weapons, conventional air combat engagements are much less likely, and this has statistics to back. However, future aircraft are still being conceived with high manoeuvrability. Next generation aircraft will be more like weapon carrying trucks. They could be larger in size, as big as the Russian MiG 31 and the American Northrop Grumman B-21 Raider long-range, intercontinental strategic strike bomber, with heavy-payload and stealth, and the ability to deliver conventional and thermonuclear weapons. They will have high power source capacity to allow Directed Energy Weapons (DEW) and also improved electronic warfare capability. The total number of manned aircraft will reduce because of unmanned teaming. Initial high costs of HCM and even some cruise missiles would put limits on inventory sizes. For some time, most air forces will have to continue to use free-fall bombs for many targets. Medium multi-role combat aircraft are relatively cheaper. They would still be able to carry BrahMos class of Cruise and Hypersonic missiles and yet deliver significant numbers of free-fall bombs and other stand-off PGMs. Thus, multi-role aircraft would still be here for a few more decades.

A Hypersonic Treaty?

The destabilising effect of hypersonic weapons will pose a challenge for arms control. Beyond the United States, Russia and China, regional powers will seek to acquire hypersonic capabilities because they feel threatened by neighbours. There would be a need to reduce ambiguities. The weaponisation of hypersonic technologies requires sophisticated facilities that would be cost prohibitive for many nations. But this could change in the future. A complete ban on the diffusion of hypersonic technologies could be impractical but some degree of export control could work well to minimise proliferation. A major problem in this regard is that hypersonic technologies have dual use potential. Establishing ‘hot-line’ communications might reduce the risk of misinterpretation. Assurances, that early warning radars and satellites will not be targeted, may help. However, without a reliable verification mechanism for clarifying the nature of the warheads carried by hypersonic missiles, warhead ambiguity is likely to continue. In the longer term, a ‘hypersonic treaty’ could set numerical limits on the deployment of hypersonic missiles.

The Way Ahead for India

Many consider conventional hypersonic weapons or strategic non-nuclear high precision weapons to be equivalent to nuclear weapons in terms of their implications for deterrence. There is a need to worry about the potential combination of high-precision warhead delivery methods with low-yield nuclear warheads. Such weapons would be ‘tactically usable’. India was a late entrant to the game of nuclear deterrence, but now has a robust survivable nuclear triad with long-range ballistic missiles, Multiple Re-entry Launch Vehicles (MIRV), air and sea based nuclear vector, a ballistic missile defence programme, and an elaborate command and control mechanism. Rapid transformation in disruptive technologies like Artificial Intelligence, cyber weapons, hypersonic weapons and persistent surveillance is already threatening to change the status quo in place by nuclear deterrence. Nuclear delivery platforms are difficult to hide. Today it is possible to launch precision strikes on the nuclear command, communication and critical infrastructure networks, disrupting an adversary’s nuclear decision-making chains or targeting nuclear assets. As the traditional arms control weakens with the breakdown of the INF agreement, there is need to anticipate full-fledged weapon development in the coming decades.

The bottom line is that hypersonic weapons will determine who is ‘precise and ‘prompt’ enough in 21st century conflict. India has to quickly get on board and start developing the ‘disruptive technologies’ and also invest in counter-capabilities. Even in the conventional domain, these technologies will provide a significant advantage. Military disadvantage and technological incapacity invariably leads to a country’s marginalisation in international diplomacy. The time for India to act is now lest it become too late.

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The views expressed are of the author and do not necessarily represent the opinions or policies of the Indian Defence Review.

About the Author

Air Marshal Anil Chopra

Air Marshal Anil Chopra, commanded a Mirage Squadron, two operational air bases and the IAF’s Flight Test Centre ASTE

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