_   _                          ____  _
 | \ | | _____   ___   _ ___    / ___|(_)_ __ ___
 |  \| |/ _ \ \ / / | | / __|   \___ \| | '_ ` _ \
 | |\  | (_) \ V /| |_| \__ \    ___) | | | | | | |
 |_| \_|\___/ \_/  \__,_|___/   |____/|_|_| |_| |_|


V6.1
Simulation program for vapour pressure fed nitrous oxide hybrid rocket motors
Joe Hunt

Changelog:
 -- v6.2 H. Franks
    --- General refactor

 -- v6.1 D. Gibbons (dug20)
    --- Now stores and exports additional data that is needed for a
        more complex moment of inertia model in the 6DOF simulator.
    --- Additional properties added to motor_out.csv:
        - Vapour Density
        - Vapour Mass
        - Liquid Density
        - Liquid Mass
        - Solid Fuel Mass
        - Solid Fuel Density
        - Solid Fuel Outer Diameter
        - Solid Fuel Length


Instructions:
Modify inputs at top of motor_sim.py and run using python 3.
Program outputs file motor_out.csv (used as an input to trajectory_sim.py).


Other dependencies: numpy, scipy, matplotlib

Files:
 motor_sim.py         simulation program for motor
 motor_out.csv        motor performance output file generated by motor_sim.py
 hybrid.rasp          output .rasp file for RAS aero*
 trajectory_sim.py    simuluation program for rocket trajectory
 hybrid_functions.py  contains functions governing motor behaviour
                       and material properties

Additional input data:
 atmosphere_data.csv          1976 standard atmosphere
 drag_coefficient_data.csv    drag coefficient to mach data (RAS Aero)
 L_Nitrous_S_HDPE.propep      propep frozen and shifting outputs for
                               a range of pressures and O/F ratios


*Note that a perennial problem with RASP data is the rate of decrease of mass
is always assumed to be proportional to thrust, which is invalid as a nitrous
hybrid's ISP changes with time. Hence further use of this file introduces error
from this approximation.