[EricH]

Originally Posted by lemon1324

If you theoretically create a huge fan at the end of a runway, that will shorten the ground roll of the aircraft. However, the aircraft will not have enough speed to fly if it immediately leaves this stream of moving air. Thus you can have a shorter runway but the aircraft will need to remain in the accelerated air for some time.

I dunno...on a simulator, I've been able to take off at about half the speed I'd otherwise need. I finished accelerating in the air. There are these tricks known as high-lift devices. Specifically, flaps on the wing's trailing edge. Once in the air, I'd pull them in.

Edit: Lemon1324, I know how to fly. The flaps would get retracted once I was at a decent speed, and only when I was at a flying speed. I might not even use them until I cleared the accelerated air, an then use them only until I got a better speed.