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Sail Trim and Aeronautic Theories.

May 23, 2016
214
O'Day 1984 23 Island Park, NY
Yes, as I understand you create the vortex but as you pass away from the point of creation this vortex is worked on by the flow of wind and is absorbed eventually.
So u r saying that as soon as the starting vortex detaches and starts moving downstream a new one starts?
One inconsistency is that in the bath tub illustration and the airplane model there is a source of power (Your arm or jet engine) that is external to the system. In the sailing model there isn’t that source and the comparison may not hold up.
The source exists in the sailing model as well... It's the thermal energy that creates the wind... Ultimately the sun...
What shemandr is saying is that, because the wind is the source of forward movement of the sailboat on the water, there is a fundamental difference in the dynamics than when an airplane, fully immersed in the air, is acting as the driving force.

The direction of forces from wind over a sail lead to forward motion, where, with an airplane wing or a model for such, the forces are for air producing perpendicular lift. An airplane moves head on into the wind, a sailboat moves at some angle of the wind. The physics are the same, but the application is significantly different.
It's not really that different, except for the exact angles and speeds and magnitudes involved... Its just a different frame of reference, berthing is relative... If you take the same frame of reference, that of the airfoil, in either case there's air flowing... Doesn't matter what makes it happen, there's still form drag in the direction of he airflow, there's still lift in a direction perpendicular to that drag... An airplane wing still doesn't work unless it has an angle of attack to the air flow... It's just more efficient at a much smaller angle because of the higher speeds
 
May 23, 2016
214
O'Day 1984 23 Island Park, NY
Interesting idea to put the tips at he head... Maybe fixed ones on each side... Cut down he induced drag significantly...