Plane very difficult or ''not possible'' to trim? (Grand Duke)
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I'm seeing this behaviour too, on Su15 with the Piston grand duke at cruise with power set (32in @ 2500rpm leaned 50 deg F ROP), trimmed level at a constant airspeed and hands off I always notice a very small drift either up or down start. Leave it for a couple of minutes and it swiftly develops into a unstable up / down oscillation until the VSI is swinging between maximum stops. I usually wrestle control back at this point but something seems very off here.
Not a real pilot but isn't a trimmed plane supposed to converge back to it's trimmed state (eventually) when disturbed?
Such a pleasant plane to hand fly otherwise.
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Aircraft that are inherently stable should converge back to their trimmed state, assuming their CG is properly balanced. However, not all planes are inherently stable, as stability is the opposite of maneuverability. Generally, the more high performance an airplane is, the less inherently stable it is.
All of that being said, I find the Duke to be quite stable when trimmed, and hand flying it is a joy. -
Is there any reason why I shouldn't reduce the TrimEffectivess in the Duke config files from 1.0 to 0.5 if I'm finding it over-sensitive with the Honeycomb Alpha and Bravo devices?
@Captain_J It will limit the total amount of trim available to you, but if you don't find yourself using more than 50% of the trim in either direction, then it should be okay.
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Mmm, OK, thanks.
Do you have 'elevator_trim_time_constant or elevator_trim_max_speed as available variables in the config files?
@Captain_J I wish it were that easy, unfortunately. It feels like something we should have had decades ago.
