> -----Original Message----- For the faster and more > maneuverable military jets though, I found that I really needed > guaranteed higher rates to both ensure a crisp response and avoid > instabilities. For example, I could tune an altitude-hold cascade > that would work fine at speeds up to 400kt say, but which would > become unstable above that. The reason was that the rate of > deviation increases with aircraft speed as the control surfaces > generate more force for a given deflection, so for a given > deflection of the control surfaces by the controller, it sees a > greater response result in its next sample. Eventually, it can't > help but over-correct and go into oscillation. Running the > controller at a higher rate though, would mean that it would see a > smaller deviation because the aircraft would have moved less in the > shorter time period.
Did you try scheduling your autoplilot´s height-error to pitch demand gain with 1/V (speed inverse) ? Alan ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
