Quote:
Originally posted by socalpunx:
Quote:
Originally posted by Mobycat:
[b]
Quote:
Originally posted by socalpunx:
[b]
I also used the Harrier reference because there are two forces at work there. First it uses downword thrust to achieve lift, and then forward propultion to achieve speed.

Try to imagine a hovering Harrier. It is hovering in mid air and then when maximum thrust is applied to forward motion it reaches speed and is no longer reliant on downword thrust to defy gravity. But by "floating" it is eliminating the need for a runway, thus no need for wheels. Yet, from a standing start, mid air, it is able to achieve flight.
Try taking that harrier and switching the vents instantaneously from vertical to horizontal.

It's going to drop like a rock. Because there is no lift on the wings.[/b]
At what moment is vertical thrust insignificant and horizontal thrust applied? Aren't we still talking about achieving maximum thrust in flight without the use of the wheels making the wheels irrelevant.

I still think it would take off in the conveyor scenario, but why is it that jet pilots appply thrust gradually as opposed to appplying full throttle and reducing runway distances? [/b]
That question I can answer: engine wear. Maximum thrust is not used by airliners for takeoff, "takeoff thrust" is computed using the final weight and balance figures and is usually not maximum thrust but a percentage thereof. This minimizes engine wear and allows a safety cushion of available power if needed.