User’s Guide to Running the Trajectory Code Using …



User’s Guide for prop_code_1.m

Written by Nicole Wilcox, Stephen Bluestone, and Alan Schwing

Assistance from John Tsohas, Dana Lattibeaudiere, and John Beasley

Description:

This code uses information from the NASA Chemical Equilibrium with Applications program to set up vectors that will feed into three_stages.m for calculating optimum launch vehicle staging, propellant mass, and cost. The code was integrated into the Model Analysis codes to optimize fuel and structural selection.

Assumptions:

- Thrust is assumed constant

- Isp is assumed vacuum for all three stages with balloon launch

- Mass flow rate is constant

- Area ratio based on historical data

- Isp is assumed sea level for first stage ground launch

- No throttle

Important Notes:

The NASA Chemical Equilibrium with Applications code was used to find all rocket performance parameters. These parameters are designed for a set expansion ratio and chamber pressure.

The variables of vector form are in order of stage. For instance position 1 of vector x refers to the value correlating with stage one.

Input Section:

The call line of the function is:

function [inert_mass, prop_mass, volume_ox, volume_fuel, cost_stage,cost_total, mass_fuel, mass_ox, delta_v_per, rho_ox, rho_f, O_F, e, gam, c_star, cf, Ispv, Isp, Pc_Pe, a, M, Tc, Pc] = prop_code_1(delta_v,launch_type,num_stage,prop_stage,mass_payload,f_inert,P1,P2,mass_avionics)

Input Section:

|Variable Name |Description |

|delta_v |Total delta v needed for orbit insertion (scalar) [m/s] |

|launch_type |Launch type (ground, balloon, aircraft) (scalar) |

|num_stage |Number of stages (scalar) |

|prop_stage |Propellant to be used in each stage (vector) |

|mass_payload |Mass of the payload (scalar) [kg] |

|f_inert |Inert mass fraction (vector) |

|P1 |Percentage of delta v for first stage (scalar) |

|P2 |Percentage of delta v for second stage (scalar) |

|mass_avionics |Mass of avionics equipment in each stage (vector) [kg] |

Output Section:

|Variable Name |Description |

|inert_mass |Inert mass of each stage (vector) [kg] |

|prop_mass |Mass of propellant each stage (vector) [kg] |

|volume_ox |Volume of oxidizer in each stage (vector) [m3] |

|volume_fuel |Volume of fuel in each stage (vector) [m3] |

|cost_stage |The cost of propellant for each stage (vector) [$] |

|cost_total |Total cost of propellant (scalar) [$] |

|mass_fuel |Mass of fuel in each stage (vector) [kg] |

|mass_ox |Mass of oxidizer in each stage (vector) [kg] |

|delta_v_per |Delta v acquired per stage (vector) [m/s] |

|rho_ox |Density of oxidizer in each stage (vector) [kg/m3] |

|rho_f |Density of fuel in each stage (vector) [kg/m3] |

|O_F |Oxidizer to fuel ratio in each stage (vector) |

|e |Expansion ratio of each stage (vector) |

|gam |Specific ratio for each stage (vector) |

|c_star |Characteristic velocity for each stage (vector) [m/s] |

|cf |Coefficient of thrust for each stage (vector) |

|Ispv |Vacuum specific impulse for each stage (vector) [s] |

|Isp |Sea level specific impulse for each stage (vector) [s] |

|Pc_Pe |Chamber to exit pressure ratio for each stage (vector) |

|a |Speed of sound at exit for each stage (vector) [m/s] |

|M |Exit mach number at exit for each stage (vector) [m/s] |

|Tc |Chamber temperature for each stage (vector) [K] |

|Pc |Chamber pressure for each stage (vector) [Pa] |

Flow Chart:

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Start

INPUTS

Initialize constants/ variables

Outputs

Run three_stages.m

Return

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