China’s Frontier Institute for Science and Technology has developed boron fuel for a supersonic anti-ship missile that can go farther and faster than any conventional torpedo, according to specialists participating in the project, writes the South China Morning Post newspaper.
The 5 metres (16.4 feet) missile will be able to cruise at 2.5 times the speed of sound at around 10,000 metres (32,800 feet) – the same height as a commercial aircraft – for 200 kilometres (124 miles) before descending and skimming over the waves for up to 20 kilometres.
Once the missile gets within around 10 kilometres of its target, it will switch to torpedo mode and drive at up to 100 metres per second (200 knots) underwater, utilising supercavitation – the development of a big air bubble around it, which dramatically decreases drag, according to the experts.
It can also alter direction at a whim or dive to a depth of up to 100 metres without losing speed to dodge underwater defence systems.
According to team leader Li Pengfei and his colleagues, no current ship defence system is intended to withstand such a rapid “cross-media” onslaught. They said, “This may significantly enhance the missile’s penetrating capacity.”
The Fuel and the engine challenge
One of the greatest obstacles for the designers is the power system, which must generate significant thrust while breathing air or water. However, Li’s team suggested that the issue may be resolved by using boron, a light element that reacts strongly when exposed to both elements, generating enormous amounts of heat.
The team from the faculty of aerospace science and engineering at the National University of Defence Technology in Changsha, Hunan province, released a design for the missile’s power system in the September 8 edition of the Chinese Society of Astronautics’ Journal of Solid Rocket Technology.
In the 1950s, the US Air Force experimented with adding boron to jet fuel to improve the power of supersonic bombers. However, the experiment was abandoned because it was difficult to manage the fired boron particles, which generated a layer of debris that progressively lowered engine efficiency.
In recent years, the hypersonic race has reignited interest in boron. According to publicly accessible information, China has developed air-breathing scramjet engines that use solid Fuel, including boron nanoparticles, to propel missiles to five times the speed of sound or faster.
The United States military operates comparable programmes. Last year, a US Navy-funded Nasa research indicated that nanotubes manufactured from boron nitride, a mixture of boron and nitrogen, may be used to power hypersonic missiles travelling faster than 6,400 kilometres per hour (4,000 miles per hour).
However, most boron-powered engines are only suitable for use in the air. Aluminium or magnesium are the fuels of choice for supercavitating torpedoes since they react with water more readily.
The team Li claimed to have created a ramjet engine driven by boron that could operate in the air and underwater.
According to the researchers, several unique components, such as adjustable inlets and exhaust nozzles, preserve the boron’s burn efficiency in diverse settings. However, the fuel rods represent the most significant improvement.
Boron accounts for about 30% of the overall fuel weight of an air-breathing missile due to a large number of additional chemicals necessary to manage and extend the intense burning.
The team led by Li has increased the proportion of boron in the Fuel and expects that the resultant thrust will be larger than that of aluminium in water.
“The cross-media ramjet employs a fuel-rich solid propellant that burns with the external air or saltwater entering the ram to create high-temperature gas and thrust through the nozzle,” according to the report.
Its high specific impulse and easy construction make it the perfect power source for a multi-platform anti-ship missile.
The researchers said that the higher boron concentration might present issues with mass production, ignition, and combustion control. However, these issues can be resolved by modifying boron particles, enhancing manufacturing, and studying grain mass characteristics.
It is difficult to adjust the thrust of a solid fuel engine, and once the process has begun, it cannot be halted. Boron powder, for example, acts as both a solid and a liquid when introduced into the combustion chamber, which makes physical modelling or management of the burning process difficult.
In recent years, China claims to have achieved considerable advances in solid propellant technology, including applying many layers of coating on nano fuel particles to control their explosive properties.
China Aerospace Science and Technology Corporation constructed and tested a 3.5-meter-wide motor that produced 500 tonnes of thrust last year. It is the most powerful single-segment solid propellant rocket engine ever constructed.
Chinese Academy of Sciences’ new civilian solid-fuelled rocket Lijian One, which is claimed to have advanced combustion control technology, is twice as massive as the DF-41, China’s biggest road-mobile intercontinental ballistic missile.
A Beijing-based materials expert studying the volatile element told SCMP that China’s reliance on borofuels for mass-produced weapons is concerned.
About fifty per cent of China’s boron ore is imported from outside, mostly from the United States, and it is about one hundred times more costly than aluminium.
There is increasing worry that boron may become a trade war target, said the researcher.
DRDO SMART
India has a 650 km range DRDO SMART long-range Supersonic Missile Assisted Torpedo for a similar purpose but solves the problem by using a rocket to carry a torpedo to the target. The concept is not new, and the US and Russia have already used a similar concept with ASROC and Metel Anti-Ship Complex, respectively but at a shorter distance. The Chinese, too, are known to have a similar short-range system.