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Old Dec 03, 2012, 08:12 AM
xlcrlee is offline
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Quote:
Originally Posted by Cap_n_Dave View Post
Lee:
More explanation would be nice ... I am not clear on the concept.

There is no "free lunch," the energy necessary to generate a vortex is not insignificant and contributes to overall drag. Do you have an analysis that compares the drag figures for "conventional control" vice "vortex control?"
First, I mentioned that it does need more investigation. But my education and practical experience with aircraft & aerodynamics over almost 70 years now [strange, but true], plus whatever abilites I inherited from my engineer/inventor grandfather & father [latter was an aerodynamicist, promoted to Chief of Engineering at Republic when he quit; last project the SeaBee] as well as specific knowledge [which research has shown can be passed via the gene coating], starting with talking to aerodynamic engineers when I was 9 mos. old [presumably regarding non-technical matters, although the first word I consciously remember is "Fowler flaps"] and reading my father's engineering books as soon as I could hold them .... leads me to make those posted statements.

Of course I compared the airborne behavior of these "special" wing forms with "normal" ones of similar size and wing-loadings, etc.

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To specifically respond to your statement, when something becomes more efficient, it isn't getting something for free.

These birds simply use the naturally consequential vortices & spanwise flows that HAVE to exist on a wing moving in an airflow .... in a better way systemically [net effect]. And, as a physicist, I know that "You get Nothing for Nothing" [0 = 0].

Depending on the oncoming flow, one wing's tip vortex expands and provides a better L/D, and the reverse for the other side. Disregarding entropy for the moment, the net effect is the SAME induced tip drag. But with a normal Horten/B-2 control & stabilization set-up [incl.passive!], EACH tip gets more drag with a control input .... AND requires some sort of "up-elevator or -von" setting to maintain proper AoA.

It seems that the vortex itself is used for pitch stabilization as well, at least in my toys & models [not the ones shown].

The upshot is that when I made the first pre-Acrobird prototype as a toy for my bird, I was amazed that it could slowly circle the room more than two times when thrown. And outside in a nearby park, after the looping nonsense [why it has a tail], it would slowly meander every which way when it got closer to the ground and find little bits of lift to keep it up for a surprisingly long while. It acted like it had a brain and flew like a real gliding bird would, showing me that a lot of birds' behavior is due to the physical shape of their wings and not "fly-by-wire" stabilization, etc.

Normally staid Swiss who witnessed this were astounded as well, and shouted the Swiss equivalent of "holy sheep, that's amazing; I never saw anything like that before", if you get the meaning of my drift.


Lee
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Last edited by xlcrlee; Dec 04, 2012 at 04:25 AM. Reason: typo
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