Re: [Jsbsim-devel] IC vcas

[David C. <dav...@co...>]

More data.  This is starting the P-80 model in flight using:

--altitude=3000 --vc=300 --prop:/controls/gear/gear-down=false


The results:

FGIC: vcas: 300 , Mach: 0.477795 , vt_fps: 527.818
      alt_ASL: 3000 , SAT: 507.972 , Sos: 1104.69
FGAux: vcas: 236.417 , MachU: 0.223568 , vt_fps: 527.818
       alt_ASL: 3000 , SAT: 507.972 , Sos: 1104.69
       VAeroUVW: 246.975, 466.467, 1.8277
       Mach: 0.477795 , mUW: 60999.9 , pt: 1963.95
  Sorry, udot doesn't appear to be trimmable
  Trim Results: 
       Angle of Attack:   -3.6  wdot:  1.36e-04 Tolerance: 1e-03  Passed
              Throttle:    0.5  udot:  1.18e+02 Tolerance: 1e-03  Failed
            Pitch Trim:  -0.19  qdot: -4.19e-11 Tolerance: 1e-04  Passed

  Trim Statistics: 
    Total Iterations: 4
    Sub-iterations:
    wdot: 16 average: 4  successful:  1  stability: 15.348
    udot: 0 average: 0  successful:  0  stability: 12.625
    qdot: 7 average: 1.75  successful:  4  stability: 9.9286
    Run Count: 694


In this case the airplane flight path is bad, the udot won't trim, the AOA trims to a bad solution.  It's been a while since I started in-air, so this may have been around a long time.  I hope I'm not the only one getting this result for in-air trim in FlightGear.

Dave