On Tue, 2002-10-15 at 20:12, Curtis L. Olson wrote:
> FWIW, the turn coordinator ball behaves *very* differently between
> JSBSim and YASim and another FDM I am playing with. All supposedly
> return accelerations in body axis in ft/sec squared.
IMO, what we should all be aiming at providing are accels very similar
to what three body-axis aligned acclerometers mounted at the pilot
eyepoint would give. The FDMs should provide to the TC only that which
an airplane would provide, the raw forces or accels.
This means we
> can't create a single turn coordinator instrument who's ball behaves
> reasonably well for every FDM.
Well, I tried to compare the two, but got this for the yasim c172:
> YASim solution results:
Iterations: 404
Drag Coefficient: 18.9992
Lift Ratio: 87.1639
Cruise AoA: -0.124142
Tail Incidence: 0.440443
Approach Elevator: -1.00013
CG: -2.3, -0.0, 0.2
YASim SOLUTION FAILURE:
Insufficient elevator to trim for approach
[exit]
I just used fgfs --aircraft=c172-yasim, is anything else needed?
> Would it be better to force the FDM's to calculate a ball deflection
> in degrees/radians, or do we need to investigate why the body axis
> accelerations are so radically different for 3 different FDM's (who
> all are trying to model a C172.)
No and yes.
If the FDM's do the work, then they
> all have to do the failure modeling too. It would be nicer to figure
> out what's going on ... it seems to be more than a simple coordinate
> system difference, unless JSBSim/YASim swap X/Y axes or something
> strange like that.
>
> Regards,
>
> Curt.
> --
> Curtis Olson IVLab / HumanFIRST Program FlightGear Project
> Twin Cities [EMAIL PROTECTED] [EMAIL PROTECTED]
> Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org
>
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