Passive control versus active control

[PierreB]

Dave Santos has been advocating passive control for a long time. How to define passive control? Some of his words and links to start:

Bryan’s original framing, which dealt with both kites and powered flight.

I was honored to have been mentored by Professor Ronald Stearman (UTexas AE), Father of Modern Aeroelasticity, a direct intellectual descendent and elaborator of Bryan. Dave Lang (NASA, Boeing, Drachen) made me aware I had been trained by a giant, and now Bryan is seen as the obscure giant before, even admired by Einstein, as a Patent Clerk, 2nd Class, and Bryan peer-reviewer. Let there be no doubt whose differential equations hold, those who “wrote the book” of aeronautical science, not those who copy and paste them in a vain churn of low-impact AWE papers.

**The Art of AWETap-Root of AWE Engineering Science //Re: Bryan 1915

Just finished reading with delight-

Stability in aviation; an introduction to dynamical stability as applied to the motions of aeroplanes : Bryan, George Hartley, 1864-1928 : Internet Archive

AWE research has been recapitulating an original division in aeronautical engineering, between advocates of Active Control v. Inherent Stability. As then, active control achieves flight as an engineering short-cut, with high cost in safety-reliability. As then, active (“short-period”) flight control partisans ignore, disdain, or even disbelieve (“long-period”) passive stability (“AWE is essentially a problem of Control”, their refrain goes).

In Bryan, we see the genesis of forms and notation standard today in AE. In Bryan, flight stability became a matter of understanding aircraft as complex dynamical multi-oscillators with structurally damped limit cycles; a radical view a century ago but well settled science today. AWE theory falls squarely within , its essential praxis, is not complex digital control, but sensitive tuning of natural aero-oscillation for maximized pumping power-cycles (USP3987987fig5), across turbulence scales, matched to on-demand loading of generator shafts. Dynamical Stability.**

Fine historical context for Bryan’s achievements in aeronautics:

Bryan, Stability in Aviation, Boyd

Discussion here would not be complete without noting Kite Networks in bulk oscillation modes as AWE’s ready GW-class scaling path. Many thanks to Faust, Lang, Culp, German, Langbein and so on…

one-hundred-years-of-g-h-bryans-stability-in-aviation.pdf

Perhaps this topic could focus on ideas for training generators, or other thoughts.

[PierreB]

Dave Santos’observation quoted below:

@PierreB

A whole further subject is drogue oscillation dynamics (treated in the paper by Strouhal Number) which can be passively tapped as free-energy for AWE, which kPower over a decade at subscale mastered in praxis, but active control AWES developers disregard. All aircraft are complex oscillators. Kite Oscillations are normally damped by design but can just as well be amplified by design, within stable limit cycles.

I performed a small experiment of an oscillating parachute which is also mentioned in the initial post just above.

Perhaps some level of chaos could simplify control. Is it necessary for a kite to use a precise trajectory? It depends: it may be enough for a kite to produce while remaining in its zone, without requiring a precise trajectory. But in this case we can assume that the power will be limited, unless we compensate by the number of kites which are not likely to be destroyed in low speed collisions.