The X-4's primary importance involved proving a negative, in that a swept-wing semi-tailless design was not suitable for speeds near Mach 1.
的X - 4的主要参与的重要性，证明1负，在这后掠翼半尾巴设计时并没有接近1马赫的速度合适。
2
The more swept-back the wing Angle, the less the drag and the better for flight approaching supersonic speed.
越是掠翼角，少的阻力和为接近超音速飞行更好。
3
The aircraft is adopted with the swept forward wing is not a new configuration, but the unmanned aircraft is adopted with the swept forward wing is unprecedented.