Regarding the pull up issue, it seems fixed (partially) now. 

My first assumption regarding atmosphere was definitely wrong (even though the 
JSBSsim atmosphere feels better now and the FG atmosphere is still wrong above 
60kft).
 I have looked into the Cmalpha values and it was only fixed to a single value, 
when the actual value varied with mach number and alpha itself according to 
Nasa flight test reports.
 I fixed the table and I could fly the whole profile from Smiths ranch to 
Edwards with a 7g pullout with 700KIAS maximum (should be within qbar limits), 
and attitude control using rockets in the upper part of the trajectory.
 My landing was only spoiled by a "Warning:: Picked up error in 
TriangleIntersect" error on the console that brought FG to its knees :)

Now I guess I still have to examine closely the rest of derivatives to make 
sure it fits. I am particularly annoyed by the aerodynamic coefficient attached 
to the pitch rate rather than the alpha rate since pitch is a geometric 
(inertial) rather than aerodynamic value.

I have also a hard time understanding why the CMmach ( I understand it is there 
to model the shift in aerodynamic center) varies with altitude ... I guess it 
is all explained in NASA's reports.

Anyway still got a lot of work to do to make the X-15 release-able, but I can 
guarantee it is fun to fly ...




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affinité avec vos goûts sur http://musiline.voila.fr 



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