:orphan:

.. ****************************************************************************
.. CUI
..
.. The Advanced Framework for Simulation, Integration, and Modeling (AFSIM)
..
.. The use, dissemination or disclosure of data in this file is subject to
.. limitation or restriction. See accompanying README and LICENSE for details.
.. ****************************************************************************

.. _P6DOF_Atmosphere_File_Definition:

P6DOF Atmosphere File Definition
================================

A P6DOF atmosphere file defines five atmospheric properties:

* Density versus altitude
* Pressure versus altitude
* Temperature versus altitude
* Speed of sound versus altitude
* Altitude band where contrailing may occur (optional)

The density, pressure, temperature, and speed of sound properties are defined in tables with altitude/data pairings. Altitude is measured in feet and data units are slugs/cu-ft (density), lbs/sq-ft (pressure), deg-Rankine (temperature), and ft/sec (speed of sound). Format is as follows:

::

   p6dof_atmosphere

     density_altitude_table 
      # altitude_ft  density_slugs_ft3
        0            0.002377170
        1000         0.002308390
        ...          ...
        400000       0.000000000
     end_density_altitude_table
   
     pressure_altitude_table 
      # altitude_ft  pressure_lbs_ft2
        0            2116.2300
        1000         2040.8600
        ...          ...
        400000       0.0000
     end_pressure_altitude_table
   
     temperature_altitude_table
      # altitude_ft  rankine_deg
        0            518.67
        1000         515.10
        ...          ...
        400000       336.50
     end_temperature_altitude_table
   
     sonic_speed_altitude_table
      # altitude_ft  sonic_speed_ft_s
        0            1116.45
        1000         1112.61
        ...          ...
        400000       899.27
     end_sonic_speed_altitude_table
	 
     contrail_min_altitude_ ...
     contrail_max_altitude_ ...
   
   end_p6dof_atmosphere
   
For the tables, altitude must be listed in increasing values. It is recommended that the altitudes in the tables reach well beyond the maximum altitude of any P6DOF objects that will be used in the scenario. The practical limit of the atmosphere is between 300,000 to 400,000 feet, but the tables may go higher, if needed.

If contrailing conditions are present, the altitude band should be defined and must include
both min and max altitudes, as follows: 

.. command:: contrail_min_altitude <length-value>
      
   This is the lowest altitude at which contrailing will occur.
	 
.. command:: contrail_max_altitude <length-value>
      
   This is the highest altitude at which contrailing will occur.


Return to :doc:`p6dof_object_types` or :ref:`P6DOF_Environment_Support`