Another includes experimental aircraft, such as the X-37, a cut-down, unmanned descendant of the space shuttle.

另一项计划则包括研制诸如X-37这样的实验飞机，它是美国航天飞机的简化及无人驾驶版本。

This was achieved by a NASA experimental hypersonic aircraft called the X-43.

这是通过名为 X-43 的 NASA 实验性高超音速飞机实现的。

The bomber has frequently served as a 'mothership' for air-launching experimental aircraft such as the X-15 and X-43 over the years.

多年来，该轰炸机经常充当 X-15 和 X-43 等空射实验飞机的“母舰”。