China’s new hypersonic test tunnel zooms by US

China has just built the world’s largest free-piston shock tunnel, potentially expanding its lead over the United States and its struggling hypersonic weapons program.

The South China Morning Post reported that its Sichuan-based facility can simulate extreme flight conditions up to Mach 33, or 2.5 to 11.5 kilometers per second.

The facility has a diameter of 80 centimeters, twice the size of the University of Queensland’s X3 expansion tube in Australia, which until recently was the largest such facility.

The new facility could provide ground test support for the development of hypersonic vehicles such as scramjet jet aircraft by simulating the escape velocity of the Earth’s gravitational field.

China’s new hypersonic wind tunnel is based on an Australian invention known as the Stalker tube, named after Australian scientist Raymond Stalker, who came up with the design during the Cold War.

Earlier hypersonic wind tunnels used expensive and difficult explosives to store hot hydrogen, which made building and maintaining these facilities expensive and complex.

In contrast, the Stalker design uses relatively cheap, inert, high-pressure nitrogen gas to drive a piston at several hundred miles per hour. The design can compress air and burst through multiple solid membranes to generate extremely hot and fast shock waves, like those encountered by airplanes at hypersonic speeds.

The South China Morning Post article notes that the design was so successful that it allowed Australia to develop hypersonic-related technology, such as the scramjet, despite its limited resources and manpower. .

Representative image of a hypersonic weapon wind tunnel test. Image: Twitter/Eurasian Times

It also notes that in 2020 the United States signed an agreement with Australia for the joint development of a Mach 8 hypersonic glider vehicle in response to China and Russia’s progress in developing hypersonic weapons. .

The South China Morning Post says China’s hypersonic wind tunnel marks substantial improvements over its Western-made counterparts. For one thing, it features a high-pressure nitrogen tank wrapped around the piston launch tube, which reduces vibration that can affect the accuracy of test results.

It also reduces installation size and complexity compared to standard Stalker tubes. The plant’s 840-kilogram piston also features a unique structural design and new materials, enabling full reuse and reducing operating costs.

However, the South China Morning Post mentions that Stalker tubes are limited by the short simulation time which lasts only a thousandth of a second, which is too short for some experiments. The article states that the new Chinese installation will work with other types of wind tunnels to overcome this limitation.

The South China Morning Post reported in January that China unveiled the world’s first wind tunnel capable of ground-testing a full-scale hypersonic missile through its various stages of flight. This approach identifies critical design and engineering issues, avoiding costly test failures that have plagued the US hypersonic weapons program.

Although details of the facility remain classified, it is known to enable tests that span the separation stage between a hypersonic weapon’s booster stage, which propels it to near-hypersonic speeds, and activating her scramjet engine, which drives her to hypersonic speeds. .

As for the Chinese researchers, there are no other such facilities anywhere in the world, the same article says, noting that US hypersonic test facilities can only simulate a particular stage of flight due to limitations. techniques.

Additionally, China is also building a JF-22 wind tunnel, a potentially game-changing facility it says will give it a 20-30 year lead over the United States in the hypersonic arms race, as reported by the South. China Morning Post last May. year. When completed this year, the JF-22 can simulate flights of up to 10 kilometers per second or up to Mach 30.

China claims the JF-22 is more powerful than any known hypersonic test facility in the United States, according to the same article. This includes LENS II, the most advanced hypersonic weapons test facility in the United States, which has simulated flights up to Mach 7, the simulation lasting 30 milliseconds.

In contrast, the JF-22 can simulate Mach 30 flights in up to 130 milliseconds, with a much higher top speed.

China’s JF-22 wind tunnel has been described as a “game changer” for hypersonic weapons testing. Picture: document

Despite this progress, the South China Morning Post notes that the powerful wind tunnels consume huge amounts of energy, with Sichuan’s power grid experiencing blackouts when researchers started the machines. Additionally, some wind tunnels cannot be connected to the local power grid but must rely on dedicated generator facilities.

Advances in hypersonic weapons by China and Russia have given the United States a sense of urgency to ramp up its testing program. The US Senate Armed Services Committee (SASC) Defense Policy Bill 2023 notes that the United States can only maintain strategic nuclear deterrence through the rapid modernization of its legacy nuclear capabilities and accelerated missile development. ballistic, cruising and hypersonic.

He also notes that the US Department of Defense (DOD) and the Secretary of Energy should leverage all available tools to reduce the risk of delays in nuclear modernization and hypersonic missile programs.

Although the United States has the most hypersonic weapons testing facilities, there are growing concerns that its testing capabilities lag behind its close competitors. A July 2022 report from the U.S. Congressional Research Service (CRS) notes that in 2014, the United States had 48 critical hypersonic test facilities needed to mature hypersonic defense systems for defense system development until ‘in 2030.

Additionally, SASC notes in the National Defense Authorization Act of 2023 the DOD’s overdue investment in establishing hypersonic offensive and defensive capabilities and encourages additional funding for hypersonic weapons research to overtake close competitors China and Russia.

The SASC also emphasizes that new investments in hypersonic test infrastructure are critical to rapidly bringing emerging hypersonic weapons technologies into service.

DARPA’s Operational Fires (OpFires) program aims to develop a ground-launched system that allows hypersonic boost-glide weapons to penetrate enemy air defenses. Photo: DARPA

Asia Times also reported on the US rush to ramp up its hypersonic weapons testing program, noting that America aims to enlist private sector help to increase its hypersonic weapons testing by a few tests per month. year to one test per week.

Asia Times and others have noted that the aggressive pace of hypersonic weapons testing in the United States, coupled with overly complicated and poor weapons design, test planning, and pre-flight testing shortcomings, have conspired to delay US development of hypersonic weapons systems. Nevertheless, the United States is looking to expand its hypersonic weapons testing facilities.

Last April, Defense News reported that while the Biden administration has not released detailed spending tables for the 2023 U.S. defense budget, it aims to upgrade the hypersonic testing facilities at the Arnold Engineering Development Complex in Tullahoma, Tennessee, among other hypersonic-related proposals.

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