On Thu, 2002-02-14 at 18:04, Tony Peden wrote:
> On Thu, 2002-02-14 at 09:09, Alex Perry wrote:
> > The current CVS hangs for me when ground started at KMYF, yet is fine at KSFO.
> > Immediate crash.  It's a long way to commute, could we fix that sometime?
> 
> It looks to me like there are at least a couple of problems.
> 1) the altitude is initially set to 382.53 feet, then later reset
>    to the correct 413 ft.
> 2) when it is reset, JSBSim still thinks its 382 and trims to that.
> 
OK, I've figured out what the problem is.
At intialization both the altitude and runway altitude are set:

Start common FDM init
...initializing position...
FGJSBsim::set_Longitude: -2.0444
FGJSBsim::set_Latitude: 0.572695
 cur alt (ft) =  0
FGJSBsim::set_Altitude: 382.535
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  lat (deg) = 32.813
...initializing ground elevation to 382.535ft...
common_init(): set ground elevation 382.535
FGJSBsim::set_Runway_altitude: 382.535
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...initializing sea-level radius...
 lat = 32.813 alt = 382.535
FGJSBsim::set_Sea_level_radius: 2.09052e+07
...initializing velocities...
FGJSBsim::set_V_calibrated_kts: 0
...initializing Euler angles...
FGJSBsim::set_Euler_Angles: 0, 0.0074002, 5.14977
End common FDM init

However, when the altitude is changed (for whatever reason)
the ground elevation is not reset:

fgFDMForceAltitude: 126.073
FGJSBsim::set_Altitude: 413.625
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  lat (deg) = 32.813
FGJSBsim::set_Sea_level_radius: 2.09256e+07
(*) Current Altitude = 116.60 < 123.07 forcing to 126.07
  Ground Trim

So as far as JSBSim is concerned, the ground is still 
at 382.53 ft and the trimming routine does exactly the
right thing with that piece of information: it lowers
the aircraft until the gear are holding it up.



> 
> 
-- 
Tony Peden
[EMAIL PROTECTED]
We all know Linux is great ... it does infinite loops in 5 seconds. 
-- attributed to Linus Torvalds

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