Quote:
Originally posted by XPLORx4:
But your hang-up is how motion through the fluid is achieved, right?
No, not at all.

I've been discussing this hypothetical scenario. In the scenario we have NO MOTION through the fluid of air.

In the scenario we only have the thrust from the engines.

Understand? Other vital components needed for flight are absent in the scenario.

Quote:
Motion through the fluid (air) is achieved by the engines pushing against the air around the plane, not by the wheels turning on the conveyor.
Yes.. but we are not moving in the scenario. There is no motion of the plane. The plane can be at maximum thrusters, but in the scenario the conveyor matches the force created by the thrust.

We still need the plane moving forward through the air to create the lift needed for flight.

Quote:
Originally posted by Mobycat:
Another way to look at it - a plane on water.

The water is most certainly not solid. Yet the plane takes off (if it has enough power to get up to speed).
Yes... the key there is the plane on the water is moving forward through the air. It makes no difference what surface is underneath the plane, as long as the plane moves forward and can create lift and the proper angle to obtain flight.

I'm saying engine thrust against the air behind the plane is not enough for flight if the plane is not moving forward through the fluid of the air.

Am I making myself clearer now.

I think these web sites will help....

http://www.grc.nasa.gov/WWW/K-12/airplane/factors.html

http://www.grc.nasa.gov/WWW/K-12/airplane/climb.html

Remember your vectors....

http://www.grc.nasa.gov/WWW/K-12/airplane/vectors.html