China military scientists work on laser to improve hypersonic missile and plane speeds
- Device could help aircraft and missiles go faster and fly for longer, says Beijing’s Space Engineering University
- Air resistance ‘reduced by 70 per cent or more’, meaning potential for less fuel and safer flights
Streamlining their shape can help to reduce this resistance, known as “drag”, but further improvements need a more aggressive approach.
Now a team of laser experts at Beijing’s Space Engineering University have come up with a powerful laser gun mounted on the head of a hypersonic aircraft or missile, aimed not at an enemy but at the thin air molecules just ahead. The device can reduce air resistance by 70 per cent or more, according to researchers’ calculations.
The new technology “can change the shock wave structure in front of the hypersonic vehicle and then change the speed and pressure distribution to achieve drag reduction”, said Wang Diankai and colleagues in a paper published in the Chinese journal Laser and Infrared this month.
“Shock wave resistance seriously reduces the safety and economy of the flight,” they added.
China would make use of the technology when engineering weapons although some technical issues still needed resolving, said the researchers, whose university is part of the PLA Strategic Support Force. China set up this dedicated force for space and cyber warfare in 2015.
The higher the “Mach” number – which indicates the ratio of the speed of an object to the speed of sound in the medium through which the object is moving – the greater the benefit, according to studies in China and abroad.
The performance of an aircraft with an air-blasting laser could increase exponentially with speed in comparison to those without, said Wang and the team.
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The idea of an air-blasting laser has been around for decades but seems to have mostly remained on paper, mainly because scientists have different explanations on how, or why, it works.
Despite explanations being difficult for the everyday person to understand, they are still too simple, according to Wang and colleagues. No successful application of the technology has been reported worldwide because existing theories failed to capture all essential elements in the complex reality, they said.
The development of the laser technology in China has largely remained classified but the theoretical model used by the Beijing scientists was more complex than anywhere else, according to Wang.
The team believes their laser energy device would create a plasma cloud in the shape of a teardrop which would immediately break into two.
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These smaller clouds would spin in opposite directions and generate a forward-moving wind in front of a hypersonic weapon or aircraft. This would reduce drag by punching a hole in the incoming shock wave.
The laser obviously has to be small, to fit on the plane or missile, but until now laser size has been a problem.
In Shanghai, China is building the world’s most powerful laser device that can apparently generate in a split second 10,000 times more power than all electricity grids in the world combined. The device and its supporting equipment need a lot of space, though, and would fill the equivalent of several rooms.
However, a new method to reduce the size and weight of powerful lasers has been discovered. In a paper published in the British journal Nature on July 21, the Shanghai team revealed the world’s smallest “free electron” laser.
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In the past, such a device was more than 1km (0.6 miles) long. The Shanghai version is said to be 100 times smaller but scientists hope to soon reduce its size further, to the size of an everyday table.
Unlike conventional lasers that use crystals, this one employs free flying electrons to generate extremely powerful laser pulses.
It is unclear whether such lasers would be used on hypersonic or other weapon platforms but the technology has attracted military attention worldwide because its power and frequency could be fine tuned to meet a battle’s changing needs.
Adding laser hardware to a flying weapon could affect its aerodynamics performance and make it heavier. However, many scientists believe the benefit of drag reduction would outweigh such effects and associated costs, including the need for a more complex flight control system.
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China and Russia have engaged in an intensive race with the US in hypersonic flight technology, with some weapon systems already deployed.
Although the existing applications of hypersonic flight technology are mostly limited to the military, the Chinese government has plans to build a fleet of civilian hypersonic aircraft that can transport 10 passengers to anywhere on the planet within an hour by 2035.
One of the earliest proposals of laser-assisted flight came from the US. In 1983, a Nasa-funded study conducted by a military contractor proposed using a ground-based laser station to burn the atmosphere ahead of a high-speed aircraft to make the flight easier, according to openly available information. The project is not believed to have been successful.
