[32起落架] 猛踩刹车然后继续前进——记B747-8极限中断起飞测试

The new Boeing 747-8 is a massive machine designed to takeoff at close to 1 million pounds. Through months of flight testing the airplane has shown plenty of power on takeoff, but how would it handle all that energy if it had to suddenly stop?

全新的波音747-8的设计起飞重量可以接近1百万磅。在数个月的飞行测试中，这飞机已经展示了卓越的起飞能力，那么如果必须突然停住，它的表现如何呢？

"In the emergency event that we have to make a rejected takeoff at these heavy weights, it takes a long distance for the airplane to stop. It's just like in your car." Captain Kirk Vining in the Boeing test and evaluation team are about to put the airplane through the ultimate rejected takeoff or RTO.

“在必须以大重量中断起飞的紧急情况下，飞机需要很长的距离才能停止，这就像你的汽车。”波音测试和评估团队的机长Kirk Vining即将对这架飞机进行极限中断起飞（RTO）测试。

First the crew installs a set of 100% worn-out brakes. (747-8 Flight Test Manager Andy Hammer) "So it's down to the steps. So if you even have your own brakes, they've got them machined down and so there's this basically no material left." Technicians also fuel the airplane up to maximum takeoff weight of just over 975,000 pounds.

首先，团队给飞机安装了一组100%磨损的刹车。747-8飞行测试经理Andy Hammer说：“这是退一万步，虽然你有刹车，但是全部磨平了，基本上没剩下什么材料。”技术人员同时也给飞机加注燃油到最大起飞重量，超过975,000磅。

At the start of the runway, captain Vining begins the takeoff roll as usual, pushing all four engines to maximum thrust, but just as the airplane is going at over 200 miles or 320 km per hour, he slams on the brakes. To channel maximum energy to the carbon brakes, the pilot cannot use the thrust reversers.

在跑道起点，Vining机长像平常那样开始起飞滑跑，将四个发动机推到最大油门，但是当飞机达到超过200节（320公里/小时），他猛踩了刹车。为了将最多的能量传递给炭刹车，这位飞行员不能使用反推力装置。

(Andy Hammer)"The whole intent is to demonstrate to you in worst conditions you can safely stop the aircraft." The brakes made by Goodrich do exactly as they're supposed to do. In fact the 747-8 stops earlier than the team had hoped, beating the target by more than 700 feet or 200 meters.

Andy Hammer说：“全部的目的，就在于给你展示在最坏的情况下，你能安全地停住飞机。”Goodrich公司生产的刹车如期发挥作用。事实上，这架747-8比团队预期的停得还早，优于目标700英尺（200米）。

But stopping is just half the challenge, now the airplane must prove it can withstand the tremendous heat that built up in the wheels, estimated to be more than 1,400 degrees Celsius. (Captain Vining) "And it's a simple physics problem. We have to turn that kinetic energy into heat in the brakes."

但是停住还只是完成一半的挑战，现在飞机必须证明它能够承受住轮胎带来的、估计超过1400摄氏度的巨量热能。Vining机长说：“这是个简单的物理问题。我们必须在刹车里面把飞机的动能转换成热能。”

As expected smoke pours out from the brakes as they glow a bright orange, still the firefighters who are standing by can't do anything but watch for the next five minutes. (Andy Hammer)"That's to simulate that if you were at an airport you have an RTO, you wouldn't necessarily have the fire department right there. So as you demonstrate that worst case would be five minute response time for a fire department to get to the airplane."

正如预料的，浓烟从闪着明亮橘黄色的刹车中倾泻而出。然而在旁边待命的救火队员在接下来5分钟却什么都不能做。Andy Hammer说：“这是模拟当你在机场里实施了中断起飞，你可能不会立即就有救火队。所以演示最坏的情况，给救火队到达飞机要有五分钟的反应时间。”

By design, special fuse plugs in the tires are activated, deflating the tires before they explode. Finally at the five minute mark, firefighters move in with plenty of water, while the tires and brakes will have to be replaced. The rest of the airplane is perfectly fine.

按照设计，轮胎内部特殊的热熔塞发挥作用，在轮胎爆炸之前将它们放气。最后在五分钟节点上，消防队员接近飞机，使用了大量的水。轮胎和刹车将必须被更换，而飞机其他部分完好无损。

No sweat, even for the flight test engineers who were on board. (Boeing Flight Test Engineer Cassie Martin)"If we're amazing, it's all right. That's exactly what we expected. Great stopping, no major false."

毫无悬念，对于飞机上的飞行测试工程师亦然。工程师Cassie Martin说：”惊呆了！非常好！这就是我们想要的。稳当停住，没大问题。”

Slamming on the brakes, so the new 747-8 can continue moving towards certification and delivery.

猛踩刹车，于是崭新的747-8在认证和交付的道路上继续前进。