目前对飞船只进行了一些低海拔的飞行测试，平流层的测试则仅仅是由气象探测气球负载着规模缩小的模型原型机来进行的。

So far, apart from some low-altitude test flights, the only stratospheric tests have involved a scaled-down version tethered to a weather balloon.

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还有就是要求所有设计的飞行器的速度必须不低于85%音速水平；航程必须达到7000英里；在负载量上无论乘客还是货物必须达到50,000到100；000磅。

And each design has to fly up to 85 percent of the speed of sound; cover a range of approximately 7, 000 miles; and carry between 50, 000 and 100, 000 pounds of payload, either passengers or cargo.

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U8E最高飞行速度一小时150公里，续飞时间四个小时，航程150公里（从操作员）和负载40公斤（88磅）。

The U8E has a top speed of 150 kilometers an hour, endurance of four hours, range (from operator) of 150 kilometers and a payload of 40 kg (88 pounds).

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