1·Airships. Autogyros. Hovercraft. They all work. They even have niche applications. But they have never lived up to their promise and been widely adopted.
飞艇、旋翼飞机、气垫船，这些交通工具都能运行，甚至也有合适的应用领域，但它们的表现总是差强人意，从未得到大规模地应用。
2·Early autogyros resembled the fixed-wing aircraft of the day, with wings and a front-mounted engine and propeller in a tractor configuration to pull the aircraft through the air.
早期自转旋翼机有着与固定翼航空器类似的机翼和前置的动力装置，拖动自身向前飞行。