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Hypersonic glide vehicle
In the 21st century the Second Artillery’s nuclear deterrence force is facing new challenges. The United States and its allies in the region are paying increasing attention to put in place ballistic missile defence and long range precision strike capability. These developments might in the future upset the deterrence balance between the two countries. Hence China is continuously improving its nuclear deterrence capability by working on futuristic weapon technologies. Hypersonic is the emerging technology that will play a vital role in the twenty first century and China is working hard to close the capability gap with the US, as at present, US has the lead in this area. The technology also offers asymmetric advantage which fits well with the current Chinese strategy.

So far China has conducted three tests of its hypersonic glide weapon. The third test was carried out in early December 2014 which was, as usual, brought to light by western media. However, the Chinese Ministry of National Defence Information Office acknowledged the test and gave out its usual statement that it is a routine process conducted within its territory and is not directed against any country. China is proceeding at a rapid phase in developing hypersonic glide weapon system as these weapons cannot be intercepted by any of the currently deployed missile defence systems.

Hypersonic weapon

China has conducted three tests of its hypersonic glide weapon in just a year which points to the rapid phase and progress it is making in developing the vehicle. There are three countries in the business of developing hypersonic weapons: the United States, China and Russia. Among these countries United States and China are taking the lead.

The speed band of weapons are being shifted from supersonic to hypersonic as speed is one parameter which has been traditionally used to defeat defences. The game of speed has been on ever since mobile warfare began. The primary reason for the increasing focus on developing hypersonic weapons is because defences are evolving to intercept weapons that can travel at supersonic speed. Speed above Mach 5 is considered to fall in the hypersonic regime.

There are two types of hypersonic weapons; the weapons with its own propulsion system like a scram or RAM jet engine, for example the X-51A uses a hydrocarbon fuel scramjet engine. The other type uses a ballistic missile booster to attain the hypersonic velocity and thereafter glide its way to its target. China has opted for the second type of hypersonic vehicle for obvious reasons; firstly, it is technologically less complex compared to self propelled (scram or RAM jet) vehicles. Secondly, China has not yet mastered the art of developing even jet engines for its fighter aircraft while hypersonic vehicles would require the technologically advanced scramjet or RAM jet engines which would take a long time to master. Third, China has already mastered ballistic missile technology and has got some experience in making manoeuvrable ballistic missile warheads which could be adopted to develop the second variety of hypersonic vehicles and moreover this method would make it quicker and still give equal effect as the self propelled vehicles.

Manoeuvrability

One aspect regarding the Chinese hypersonic glide weapon that needs clarification is that it is not only about the speed but the manoeuvrability factor of the vehicle that helps in defeating missile defences. As against what is widely believed, the vehicle does not accelerate after re-entry rather it is decelerated.

The vehicle is said to have attained a speed of Mach 10 while cruising within the atmosphere and also it is reported that an ICBM booster was used to launch the glide vehicle. The re-entry velocity of an ICBM warhead is around Mach 20-Mach 24 which means the glide vehicle decelerated to Mach 10. The reason for decelerating the vehicle is to make it more manoeuvrable as manoeuvrability, as per the laws of aerodynamics, is inversely proportional to speed. At slower speed the G load on the vehicle is reduced and hence become easy to control which would convert to better precision.

When the Wu-14 re-enters the atmosphere, it might probably use attitude control thrusters and/or use aerodynamics to change attitude to a flat course using the varying atmospheric density along with heavy deceleration. When this is accomplished the resultant hypersonic velocity of Mach 10 and its manoeuvrability would be a lethal combine to defeat the existing ballistic missile defence systems. Ballistic missile defence systems usually predict the normal trajectory of a ballistic missile (parabolic) to intercept it. By adding manoeuvrability i.e. altering the conventional trajectory, the predictability of the BMD fire control system is neutralised which sometime might result in the defence system not even recognising the incoming warhead as a threat.

As predicted by many experts the Chinese Wu-14 can easily penetrate the US ballistic missile defence system. Already, the US Ground Based missile Defence (GMD) system is in a nascent stage having more number of test failures than successful interception, which mostly involved unitary warhead as a target.

One other advantage of a hypersonic glide vehicle is that it increases the range of the system enabling longer reach. This will also mean that the midcourse phase of the attacking missile will be much farther in distance from the target making it even more complicated to intercept. It is to be remembered that the US ICBM defence is a mid-course interception system. Hence the Wu-14 would be highly efficient in evading the US defences and delivering nuclear warheads on its continental landmass if shot with an ICBM booster.

China could employ the same technology to evade the defences and attack the regional adversaries by using a smaller booster (DF-11, DF-21 etc) depending on the required range. For regional strikes the application would most possibly involve conventional warheads. Further, it is feared that China might adopt the glide vehicle to target aircraft carriers and other large ships used for long distance power projection. The hypersonic glide vehicle is a suitable technology for anti-carrier operation as the velocity is reduced considerable which results in better manoeuvrability. This combination gives the terminal sensor more time to search and acquire the target before zeroing in on it. The enhanced aerodynamics improves accuracy which is a vital element when attacking a moving target.

So far China has remained extremely secretive regarding its nuclear weapons programme which makes it a little unusual as the test was officially confirmed. China continues with the asymmetric approach in challenging the US military supremacy and will continue to do so by applying new technology. The main role for the hypersonic glide vehicle seems to be for nuclear deterrence against the United States. However, it is highly likely that the weapon will be modified and adopted for anti-carrier role. The rapid phase at which the weapon development project is moving has given rise to speculations in the west which says that China will be able to deploy this weapon by 2020.