:orphan:

.. ****************************************************************************
.. CUI//REL TO USA ONLY
..
.. 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.
.. ****************************************************************************

aircraft_signature_parameters
-----------------------------

Overview
========


.. command:: aircraft_signature_parameters ... aircraft_signature_parameters
    :block:

    .. parsed-literal::

     aircraft_signature_parameters
        // `Required Commands`_
        side_ ...
        // `Optional Commands`_
        fuselage_frontal_area_ ...
        wing_area_ ...
        tail_area_ ...
        engine_inlet_area_ ...
        engine_exit_area_ ...
        sweep_angle_ ...
        signature_reduction_factor_overall_ ...
        signature_reduction_factor_nose_ ...
        nose_signature_reduction_angle_ ...
     end_aircraft_signature_parameters

Required Commands
=================

.. command:: side [red ; blue]

   Specifies the side for which the aircraft signature parameters apply. The available options are 'red' and 'blue'.

   The `side`_ command determines the default signature parameters.
   These can be overwritten with the `Optional Commands`_. 

   For example:

   ::

      # An aircraft of side blue will have the default signature parameters, except for the sweep angle.
      aircraft_signature_parameters
         side          blue
         sweep_angle   40 degrees
      aircraft_signature_parameters

Optional Commands
=================

The commands in this section are used to determine the expected detection range of the target aircraft (:math:`R_d`). An effective cross sectional area is computed (:math:`A_{eff}`), which is used in an empirically-determined equation to obtain the detection range.
The equation used is fairly simplistic and is used in the absence of more accurate aircraft signatures. Future releases will include more sophisticated mechanisms to accurately define radar signatures.
Each command corresponds to a variable in the equations below. The following table defines the mapping between equation variable names and command names (or a description if no command exists):

.. list-table::
   :align: left
   :header-rows: 1

   * - command/description
     - variable
   * - `fuselage_frontal_area`_
     - :math:`A_f`
   * - `wing_area`_
     - :math:`A_w`
   * - `tail_area`_
     - :math:`A_t`
   * - `engine_inlet_area`_
     - :math:`A_i`
   * - `engine_exit_area`_
     - :math:`A_e`
   * - `sweep_angle`_
     - :math:`\omega`
   * - `signature_reduction_factor_overall`_
     - :math:`f_o`
   * - `signature_reduction_factor_nose`_
     - :math:`f_n`
   * - azimuth angle
     - :math:`\phi`
   * - elevation angle
     - :math:`\theta`
   * - range constant 
     - :math:`k`
   * - effective cross sectional area
     - :math:`A_{eff}`
   * - expected detection range
     - :math:`R_d`


The expected detection range is computed using Equation :eq:`detection_range`. The range constant :math:`k` is determined such that a :math:`10` :math:`m^2` target produces a detection range of :math:`200` :math:`km`. This results in a :math:`k` value of :math:`1.6e20` :math:`m^2`.

.. math::
   :label: detection_range

   R_d = (k \cdot A_{eff})^{1/4}


The effective radar cross section :math:`A_{eff}` is defined by the following equation:

.. math::
   :label: a_eff

   A_{eff} = f_o \cdot f_n \cdot [A_f + A_w \sin{\theta} + A_t \sin{\theta} \sin{\phi} + A_i \cos({\max({\theta,\phi})}) + A_e \cos({\max({\theta,\pi - \phi})}) + A_w \cos{\theta} \cos^4({\phi - \omega}) ]

Physical Attributes
~~~~~~~~~~~~~~~~~~~

.. command:: fuselage_frontal_area <area-value>

   The frontal area of the aircraft fuselage (projection on the y-z plane) to be used when determining the radar cross section. See Equation :eq:`a_eff`.

   **Default:** 3.0 m^2

.. command:: wing_area <area-value>

   The wing area of the aircraft to be used when determining the radar cross section. See Equation :eq:`a_eff`.

   **Default:** 30.0 m^2

.. command:: tail_area <area-value>

   The area of the aircraft's vertical tail to be used when determining the radar cross section. See Equation :eq:`a_eff`.

   **Default:** 4.0 m^2

.. command:: engine_inlet_area <area-value>

   The inlet area of the aircraft's engine to be used when determining the radar cross section. See Equation :eq:`a_eff`.

   **Default:** 2.0 m^2

.. command:: engine_exit_area <area-value>

   The exit area of the aircraft's engine to be used when determining the radar cross section. See Equation :eq:`a_eff`.

   **Default:** 2.0 m^2

.. command:: sweep_angle  <angle-value>

   The sweep angle of the aircraft's wing to be used when determining the radar cross section. See Equation :eq:`a_eff`.

   **Default:** 45 degrees

Signature Reduction Factors
~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. command:: signature_reduction_factor_overall <real>

   The overall reduction factor of the signature. See Equation :eq:`a_eff`.

   **Default:** 1.0

.. command:: signature_reduction_factor_nose <real>

   The reduction factor of the signature due to the aircraft's nose shape. This factor is only used if `nose_signature_reduction_angle`_ is more than the azimuth and more than the elevation.  See Equation :eq:`a_eff`.

   **Default:** 1.0

.. command:: nose_signature_reduction_angle <angle-value>

   The nose angle used to determine `signature_reduction_factor_nose`_. If `nose_signature_reduction_angle`_ is more than the azimuth and more than the elevation, then the effective radar cross section will be multiplied by `signature_reduction_factor_nose`_.

   **Default:** 45 degrees