A mysterious, bulging turret fitted on the bow of a Chinese navy ship has provoked speculation that Beijing is testing a hypersonic “rail gun”, in what would be the first time such a weapon has been trialled at sea.

中国一艘海军舰艇的舰首出现的一座神秘、突出的炮塔引发外界猜测：中国正测试一款超音速“轨道炮”，这将是这种武器首次在海上测试。

Photos taken in a Chinese shipyard of what military experts say appears to be the new weapon come as Beijing pours money into high-tech arms aimed at changing the maritime balance of power with the US.

这些图片是在中国一造船厂拍摄的，军事专家表示，图片中的装置似乎是这种新武器。此际，中国正将资金投入高科技武器，旨在改变中美之间在海上的力量平衡。

Rail guns rely on electromagnetic pulses to fire projectiles further and faster than conventional guns, targeting enemy ships, aircraft and missiles from up to 100 nautical miles (185km) away. However, they require massive amounts of electric power to function, one of the reasons they have remained mainly on the drawing board.

轨道炮依赖电磁脉冲发射炮弹，比传统火炮射程更远，速度也更快，能够打击距离最远达100海里(185公里)的敌军舰船、飞机和导弹。然而，它们需要大量电力才能工作，这是它们目前还主要停留在构想中的原因之一。

Recent photographs published online show a hulking turret and three shipping containers fitted on the deck of the Haiyang Shan, an amphibious landing ship, berthed in Wuchang shipyard in Hubei province. Military experts said it appeared to be an experimental rail gun.

最近网上发布的照片显示，大型登陆舰“海洋山”号的甲板上安装了一座巨大的炮塔和3个航运集装箱，停靠在湖北省武昌造船厂。军事专家表示，这似乎是一门实验型轨道炮。

“Based on the pictures a rail gun is a plausible explanation, but it’s not conclusive,” said Chad Ohlandt, senior engineer at the Rand Corporation in Washington.

华盛顿兰德公司(Rand Corporation)高级工程师查德•奥兰特(Chad Ohlandt)表示：“根据照片，轨道炮是一种合理的解释，但无法完全确定。”

The US has been developing a rail gun since 2005 but a plan to test one on a US navy Spearhead catamaran in 2016 was axed due to high costs.

自2005年以来，美国一直在研制轨道炮，但由于成本高，2016年在一艘美国海军先锋级(Spearhead)双体船上测试轨道炮的计划被取消。

A two-decade military build-up by Beijing has begun to focus on high-tech weapons to challenge US dominance in the air and sea. China is developing everything from artificial intelligence and aircraft carrier-killer missiles to drone swarms.

经过20年的军事建设，中国已开始着重研究高科技武器，以挑战美国在空中和海上的主导地位。中国正研制各种产品，从人工智能导弹和航母杀手导弹到无人机蜂群。

Mr Ohlandt said the case for a rail gun in the photo was supported by the three shipping containers mounted on the deck, which may be a power source. However, he added that they did not appear big enough for such a weapon. 奥兰特表示，甲板上安装的3个航运集装箱(可能是电力来源)支持了如下判断：显示在照片中的就是轨道炮。然而，他补充称，如果是为轨道炮配的，这几个集装箱似乎又不够大。

“If those are generators and power storage systems on the deck, I’m not sure they are large enough to power a rail gun,” he said. “Rail guns typically require a large capacitor bank.”

“如果那几个箱子是甲板上的发电机和电力存储系统的话，我不确定它们的体积是否足够为轨道炮提供动力，”奥兰特表示，“轨道炮一般需要巨大的电容组。”

Mr Ohlandt said the ship could have a capacitor bank in the below-deck cargo area. “It’s also possible that the above-deck stuff is just enough to fire one shot, then wait minutes or hours until they recharge for the next test,” he said.

奥兰特表示，可能在这艘船甲板下方的货舱区域有一个电容组。他表示：“也有可能甲板上方的那几样东西仅够发射一发炮弹，然后需要等待几分钟或几小时来充电，才能进行下一次测试。”

The gun, he added, could also be a large conventional naval gun with the above-deck equipment simply powering the oversized test turret.

他补充称，这门大炮可能是一种大型海军传统大炮，甲板上方的设备只是为巨大的测试炮塔提供动力。

The most recent US test of the technology occurred in November 2016 when the navy tested a 32-megajoule rail gun built by BAE Systems at the Naval Surface Warfare Center in Dahlgren, Virginia. It fired a 16kg projectile at roughly six times the speed of sound — much faster than conventional arms. The Office of Naval Research has said the gun will eventually be able to fire 10 times a minute over 100 nautical miles.

美国最近一次测试该技术是在2016年11月，当时美国海军在弗吉尼亚州达尔格伦的海军水面作战中心(Naval Surface Warfare Center)测试了由BAE系统公司(BAE Systems)制造的32兆焦轨道炮。当时它以大约6倍声速的速度发射了一枚16公斤的炮弹，速度远远快于传统武器。美国海军研究办公室(Office of Naval Research)表示，这门大炮最终将能够每分钟发射10发炮弹，射程达100海里。