幾分鐘2,400哩？不要冒汗！高超聲速武器通過“容易”測試

幾分鐘2,400哩？不要冒汗！高超聲速武器通過“容易”測試
2,400 Miles in Minutes? No Sweat! Hypersonic Weapon Passes ‘Easy’ Test
By Noah Shachtman
November 17, 2011 | 2:57 pm
Updated 11/18/11 1:59 pm
Translation by Autumnson Blog

For a test of a hypersonic weapon flying at eight times the speed of sound and nailing a target thousands of miles away, this was a relatively simple demonstration. But it worked, and now the military is a small step closer to its dream of hitting a target anywhere on Earth in less than an hour.
給一件高超聲速武器以8倍音速飛行，並捕獲數千英里外的目標的測試，這是一次相對地簡單的示範。但它運作，及現在軍方又近了一小步它的夢想，即在不到一個小時擊中地球上的一個目標。
The last time the Pentagon test-fired a hypersonic missile, back in August, it live-tweeted the event — until the thing crashed into the Pacific Ocean. This time around, it kept the test relatively quiet. The results were much better.
上一次五角大樓測試發射一支高超音速導彈是早在8月，該事件活啾啾 - 直到件東西墜毀到太平洋。這一次，它將測試保持相對地安靜，結果是好得多了。
To be fair, this was also an easier test to pass. Darpa’s Falcon Hypersonic Technology Vehicle 2 — the one that splashed unsuccessfully in the Pacific — was supposed to fly 4,100 miles. The Army’s Advanced Hypersonic Weapon, lifted by a 34-foot, 36,000-pound rocket, went about 60 percent as far, 2,400 miles from Hawaii to its target by the Kwajalein Atoll in the South Pacific. Darpa’s hypersonic glider had a radical, wedge-like shape: a Mach 20 slice of deep dish pizza, basically. The Army’s vehicle relies on a decades-old, conventionally conical design. (See the illustration below.) It’s designed to fly 6,100 miles per hour, or a mere eight times the speed of sound.
公平地說，這也是一次較容易通過的測試。 DARPA的獵鷹高超音速技術飛行器2 - 那一架失敗地濺在太平洋的 - 本來只是飛約4,100哩。軍隊的先進高超聲速武器，被一支長34英尺、重36,000磅的火箭升起，去到約 60％那麼遠，從夏威夷到它在南太平洋誇賈林環礁的目標是2,400哩。 DARPA的高超聲速滑翔機有一個激進的像楔形的形狀：基本上是深盤20馬赫薄餅片。陸軍的交通工具依靠一件幾十年久、傳統的錐形設計（見下面的插圖。）它是設計來每小時飛行6,100哩的，或純是8倍音速。
But even though the test might have been relatively easy, the $200 million Advanced Hypersonic Weapon effort could wind up playing a key role in the military’s so-called “Prompt Global Strike” effort to almost instantly whack targets half a world away. A glider like it would be strapped to a missile, and sent hurtling at rogue state’s nuclear silo or a terrorist’s biological weapon cache before it’s too late.

At first, the Prompt Global Strike involved retrofitting nuclear missiles with conventional warheads; the problem was, the new weapon could’ve easily been mistaken for a doomsday one. Which meant a Prompt Global Strike could’ve invited a nuclear retaliation. No wonder Congress refused to pay for the project.

So instead, the Pentagon focused on developing superfast weapons that would mostly scream through the air, instead of drop from space like a nuclear warhead. Those hypersonic gliders may cut down on the geopolitical difficulties, but introduced all sorts of technical ones. We don’t know much about the fluid dynamics involved when something shoots through the atmosphere at hypersonic speeds. And there really aren’t any wind tunnels capable of replicating those often-strange interactions.

“You have to go fly,” says retired Gen. James “Hoss” Cartwright, who helped lead the Prompt Global Strike push as vice chairman of the Joint Chiefs of Staff and as head of U.S. Strategic Command. “You have to open up the envelope of knowledge.”

Darpa and the Air Force worked on understanding the aerodynamics of hypersonic flight — that’s one of the reasons behind the ill-fated Falcon Hypersonic Technology Vehicle tests. Meanwhile, the Army concentrated on controlling the hypersonic glider, and on thermal management. Moving through the air at Mach 8 generates a huge amount of heat. The military was keen to see if the Advanced Hypersonic Weapon’s combination of aluminum, titanium, steel, tantalum, tungsten, carbon fabric, silica, and other alloys (.pdf) could take it. The last thing the Pentagon wants is for its Prompt Global Strike weapon to burn up before hitting its target.

Judging from yesterday’s test, it looks like the composite held up. And so the plan to take out enemies from continents away just got a little easier to pull off.

Photo: Missile Defense Agency; illo: U.S. Army

http://www.wired.com/dangerroom/2011/11/2400-miles-in-minutes-hypersonic-weapon-passes-easy-test/

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