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GetDynPressure for docked vessel on 1st clbkPreStep wrong Issue Tools
issueid=1374 08-20-2018 01:33 PM
GetDynPressure for docked vessel on 1st clbkPreStep wrong
(rev. 78) GetDynPressure() gives "wrong" value for a docked vehicle during 1st call to clbkPreStep

To reproduce this issue, just run the default scenario 'Space Shuttle Atlantis\Atlantis docked at ISS.scn'. The Shuttle has no RCS available.

The shuttle switches to "mode = 4", as in the first call of clbkPreStep GetDynPressure() returns something like 107316.233. Therefore it disables its RCS! [1]

The 2nd time clbkPreStep is called, GetDynPressure() returns something more reasonable (0.0001179). I believe this is because Orbiter (core) has now propagated the values over the complete (docked) stack.

The issue can be fixed, when the Shuttle has position values set
(ELEMENTS, RPOS, RVEL, AROT, VROT, ...) I think ELEMENTS might be enough.
A quick fix would therefore be to patch all the according scenario files

If the position-state can not be calculated at that time easily in Orbiter core, I would suggest to save-guard the transition to "mode = 4" in Atlantis.cpp somehow.

[1] Atlantis.cpp lines 1613 ff.
Issue Details
Project ORBITER: 2010-P1 and newer
Status Fixed
Priority 5 - Medium
Affected Version Revision denoted in description
Fixed Version (none)
Users able to reproduce bug 0
Users unable to reproduce bug 0
Assigned Users (none)
Tags (none)

08-20-2018 11:57 PM
Orbiter Founder
This issue has been addressed in SVN r.79:

Surface-relative parameters (including position, altitude, ground and airspeed, atmospheric parameters) for each component of a SuperVessel immediately after assembly of the SuperVessel. For docked assemblies at simulation start this means that the surface parameters are up to date at the first clbkPreStep.

Can you please check if this fixes the issue?
This petition for a change to Fixed was accepted
08-21-2018 08:02 AM
I can confirm the issue is fixed.
Individual members of a superstructure inherit surface-relative parameters from superstructure, letting e.g. GetDynPressure() deliver reasonable results.
Tested with r79 and r80.

Thanks a lot

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